U.S. patent application number 12/393811 was filed with the patent office on 2009-08-20 for materials for data storage.
This patent application is currently assigned to K.U.Leuven R&D. Invention is credited to Gert De Cremer, Dirk De Vos, Johan Hofkens, Lesley Pandey, Maarten Roeffaers, Bert Sels, Tom Vosch.
Application Number | 20090206162 12/393811 |
Document ID | / |
Family ID | 39929721 |
Filed Date | 2009-08-20 |
United States Patent
Application |
20090206162 |
Kind Code |
A1 |
De Cremer; Gert ; et
al. |
August 20, 2009 |
MATERIALS FOR DATA STORAGE
Abstract
The present invention concerns a data storage material that
comprises an assembly of oligo atomic metal clusters confined in
molecular sieve for converting invisible radiation emitted by a
radiation source at or above room temperature to visible light. By
irradiation of specific patterns within this material with UV or
visible light, the emission from these patterns is irreversibly
enhanced.
Inventors: |
De Cremer; Gert; (Langdorp,
BE) ; De Vos; Dirk; (Holsbeek, BE) ; Hofkens;
Johan; (Brecht, BE) ; Roeffaers; Maarten;
(Hasselt, BE) ; Sels; Bert; (Balen, BE) ;
Vosch; Tom; (Heverlee, BE) ; Pandey; Lesley;
(Vilvoorde, BE) |
Correspondence
Address: |
CLARK & ELBING LLP
101 FEDERAL STREET
BOSTON
MA
02110
US
|
Assignee: |
K.U.Leuven R&D
Leuven
BE
|
Family ID: |
39929721 |
Appl. No.: |
12/393811 |
Filed: |
February 26, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/BE2008/000052 |
Jul 7, 2008 |
|
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|
12393811 |
|
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Current U.S.
Class: |
235/491 ;
106/623; 524/440 |
Current CPC
Class: |
Y02E 10/52 20130101;
C09K 11/02 20130101; H01J 61/44 20130101; C09K 11/58 20130101; G06K
19/06046 20130101 |
Class at
Publication: |
235/491 ;
106/623; 524/440 |
International
Class: |
G06K 19/02 20060101
G06K019/02; C09D 1/02 20060101 C09D001/02; C08K 3/08 20060101
C08K003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 9, 2007 |
GB |
0713250.9 |
Dec 14, 2007 |
GB |
0724442.9 |
Feb 7, 2008 |
GB |
0802265.9 |
Feb 11, 2008 |
GB |
0802400.2 |
Feb 21, 2008 |
GB |
0803185.8 |
Claims
1. A method of storing data in oligo-atomic metal clusters confined
in molecular sieves comprising the step of data-wise exposing of
said oligo-atomic metal clusters confined in molecular sieves to UV
or visible light excitation, thereby providing stored data capable
of being read as visible light emission upon exposure to UV-light
or an electrical field at or above room temperature.
2. The method according to claim 1, wherein said data-wise exposure
of said oligo-atomic metal clusters confined in molecular sieves is
sufficiently intense or long to realize an enhanced excitation
effect upon a next read at lower irradiation or illumination by UV
or visible light radiation.
3. The method according to claim 1, wherein said data-wise exposure
of said oligo-atomic metal clusters confined in molecular sieves is
sufficiently intense or long read illumination by radiation from a
laser beam, a medium wavelength UV (UVC) radiation source, a Far UV
(FUV), a vacuum UV (VUV) ray radiation source, an Extreme UV (EUV)
or a deep UV (XUV) ray radiation source to provide an enhanced
excitation effect upon a following illumination by an UV or visible
light.
4. The method according to claim 1, wherein said data-wise exposure
to UV or visible light excitation is performed with a laser or a
light-emitting diode.
5. The method according to claim 1, wherein said data-wise exposure
to UV or visible light excitation is 2-photon photoactivation.
6. The method according to claim 1, wherein the molecular sieve is
selected from among molecular sieves MCM-41, MCM-48, HSM, SBA-15,
and combinations thereof.
7. The method according to claim 1, wherein the molecular sieve is
a microporous material selected from the group consisting of
zeolites, porous oxides, silicoalumino-phosphates and
aluminosilicates.
8. The method according to claim 1, wherein the molecular sieve is
a zeolite selected the group consisting of zeolite 3A, Zeolite 13X,
Zeolite 4A and Zeolite 5A, and ZKF or combinations thereof.
9. The method according to claim 1, wherein the molecular sieves
are selected from the group consisting of Mordenite, ZSM-5, MCM-22,
Ferrierite, Faujasites X and Y.
10. The method according to claim 1, wherein said oligo-atomic
metal clusters are confined in a single molecular sieve
crystal.
11. The method according to claim 10, wherein said molecular sieve
crystal is a microporous crystal.
12. The method according to claim 10, wherein said molecular sieve
crystal is a zeolite crystal.
13. The method according to claim 1, wherein said oligo-atomic
metal clusters confined in a molecular sieve are embedded in a
rigid or flexible material.
14. The method according to claim 1 further comprising the step of
attaching said data-wise exposed oligo-atomic metal clusters
confined in a molecular sieve to a support as an identifying
tag.
15. The method according to claim 1 further comprising the step of
adding said data-wise exposed oligo-atomic metal clusters confined
in a molecular sieve to a liquid medium as an identifying tag.
16. The method according to claim 1 further comprising the step of
adding said data-wise exposed oligo-atomic metal clusters confined
in a molecular sieve to a plurality of particles as an identifying
tag.
17. The method according to claim 1, wherein said oligo-atomic
metal clusters confined in a single molecular sieve crystal are
attached to a molecule.
18. The method according to claim 1, wherein said oligo-atomic
metal clusters are confined in a molecular sieve whose pores are
coated or are closed by stopper molecules.
19. The method according to claim 1, wherein said oligo-atomic
metal clusters in a molecular sieve are covered by a film.
20. The method according to claim 1 further comprising the step of
embedding said data-wise exposed oligo-atomic metal clusters in a
molecular sieve in a rigid or flexible material.
21. The method according to claim 20, wherein said oligo-atomic
metal clusters in a molecular sieve form a mono-particulate layer
of molecular sieve particles in said rigid or flexible
material.
22. The method according to claim 20, wherein said oligo-atomic
metal clusters in a molecular sieve are structured in multi
particulate layers of molecular sieve particles in said rigid or
flexible material.
23. The method according to claim 1, wherein said oligo-atomic
metal clusters in a molecular sieve are spread as a plurality of
molecular sieve particles over a matrix.
24. The method according to claim 22, wherein said oligo-atomic
metal clusters in a molecular sieve are three dimensionally spread
over said matrix.
25. The method according to claim 1, wherein said oligo-atomic
metal clusters in a molecular sieve are incorporated as at least
one particle in a fiber.
26. The method according to claim 23 or 25, wherein the matrix or
the fiber is coated by a protective film.
27. The method according to claim 23 or 25, wherein said
oligo-atomic metal clusters in a molecular sieve are incorporated
in a polymer, copolymer or graft copolymer binder.
28. The method according to claim 1, wherein said oligo-atomic
metal clusters in a molecular sieve are silver and/or gold
clusters.
29. The method according to claim 1, wherein said oligo-atomic
metal clusters in a molecular sieve are clusters of 1-100
atoms.
30. A paint, gelling liquid or elastomer comprising molecular
sieves with oligo atomic silver clusters confined therein for
forming optical data storage membranes or optical data storage
films or for coating surfaces with a data-storage capable layer.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This application is a continuation-in-part of International
Application No. PCT/BE2008/000052 filed Jul. 7, 2008, which claims
the benefit of G.B. Application No. 0713250.9 filed Jul. 9, 2007,
G.B. Application No. 0724442.9 filed Dec. 14, 2007, G.B.
Application No. 0802265.9 filed Feb. 7, 2008, G.B. Application No.
0802400.2 filed Feb. 11, 2008 and G.B. Application No. 0803185.8
filed Feb. 21, 2008, which documents are all incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention concerns materials with data-storage
capabilities comprising emissive material of confined metal
oligo-atomic clusters in molecular sieves, such as zeolites.
BACKGROUND OF THE INVENTION
[0003] In recent years, expertise has been gained in the synthesis
of zeolites with desired properties by the choice of the structure
directing agent (SDA), control of the synthesis conditions, and
post-synthesis treatments [see van Bekkum, H. et al. (editors)
Introduction to Zeolite Science and Practice, 2nd edition; Studies
in Surface Science and Catalysis, 2001, 137; Corma, A., Chem. Rev.,
1997, volume 97, 2373-2419; Davis, M. E., Nature, 2002, volume 417,
813-821; Davis, M. E., et al., Chem. Mater., 1992, volume 4,
756-768; de Moor P-P. E. A. et al., Chem. Eur. J., 1999, volume
5(7), 2083-2088; Galo, J. de A. A., et al., Chew. Rev., 2002,
volume 102, 4093-4138]. At the same time, the family of ordered
mesoporous materials has been greatly expanded by the use of
different surfactants and synthesis conditions [see Corma, A.,
Chem. Rev., 1997, volume 97, 2373-2419; Davis, M. E., Nature, 2002,
volume 417, 813-821; Galo, J. de A. A., et al., Chem. Rev., 2002,
volume 102, 4093-4138; Ying, J. Y., et al., Angew. Chem. Int. Ed.,
1999, volume 35, 56-77]. The use of the appropriate template
enables the control of the pore size, distribution and connectivity
during the zeolite synthesis. For example, use of surfactants such
as cetyltri-methylammonium bromide or dodecyltrimethylammonium
bromide generally results in formation of mesoporous materials.
[0004] G. A. Ozin et al. in 1990 in "Inclusion Phenomena and
Molecular Recognition", edited by J. Atwood, Plenum Press, New
York, pages 379-393, discloses the synthesis of a range of novel
silver sodalites. These solid-state microstructures are viewed as
"packaged" silver salts comprised of nanoassemblies of silver
cations tetrahedrally organized with various charge balancing
anions. Intercavity communication between entrapped silver
microaggregates and expanded-metal superlattice ideas are
considered briefly. The utilization of the silver sodalites in high
resolution imaging/printing and high density write/read/erase data
storage applications are also considered.
[0005] A Stein et al. in 1990 in J. Photogr. Sci. Technol. Japan,
volume 53, pages 322-328, proposes the use of silver-containing
sodalites as novel materials for reversible optical data storage.
Sodalites can be synthesized with a variety of cation, anion and
framework compositions using simple hydrothermal and ion exchange
methods. Silver sodalites exhibit unique optical absorption and
luminescence properties which can be controlled by tuning the
material composition and unit cells sizes. The optical
characteristics of these materials can be selectively modified
using photons, heat, X-rays, pressure or moisture. A system
containing oxalate as internal reducing agent can be reversibly
marked with a laser beam for many cycles. The composition,
structure, silver distribution and optical features of this
material are discussed in detail. A possible mechanism for the
reversible changes of silver oxalate-sodalite involves electron
transfer between two types of silver clusters occluded in the
sodalite framework.
[0006] A. Stein et al. in 1993 in Proceedings of the 9th
International Zeolite Conference, Montreal 1992, Eds. R. von
Ballmoos et al., Butterworth-Heinemann, pages 93-125, discloses
that sodalite is an ancient material with great potential for
advanced applications. Recent research is reported concerning the
assembly of novel nanostructures by encapsulating clusters
consisting of the components of insulators, semiconductors and
metals inside the framework aluminosilicate sodalite. This
nanoporous host acts as a stabilizing dielectric matrix, capable of
organizing single size and shape clusters in perfectly periodic
arrays. An interesting variety of potential applications for such
materials, and the related zeolite analogues, are reported such as
nanoporous molecular electronic materials, molecular wires,
chemical sensors, zeolite electrodes, nonlinear optical materials
and high density data materials.
[0007] G. Schulz-Ekloff in 1991 discloses in "Zeolite Chemistry and
Catalysis", editors P. A. Jacobs et al., Elsevier Science
Publishers, Amsterdam, pages 65-78, describes the preparation and
characterization of zeolite-hosted materials, like metals,
semiconductors or dyes. Potential applications are summarized e.g.
in optical switching, microwave absorption, optical data storage,
microsensor devices or dispersion electrolysis.
[0008] JP 61-061894A discloses an optical recording material
constituted of a clathrate compound of silver halide and zeolite.
The silver halide is basically not limited and may, for example, be
at least one of AgCl, AgBr and AgI. Zeolite may, for example, be of
the Na mordenite type, the NaX type of the BaY type. The amount of
the silver halide used for forming the clathrate compound with
zeolite is preferably not more than 30 wt %, since an amount of
more than 30 wt % causes the clathrate compound to be formed with
difficulty. A photosensitive recording material which is capable of
being rewritten can be produced by using the clathrate
compound.
[0009] EP 1873202A discloses a transparent zeolite-polymer hybrid
material, comprising zeolite crystals dispersed in a polymer,
wherein: i) the zeolite crystals have parallel channels and/or
cavities inside the crystal and a crystal length pf 20 to 7000 nm;
ii) the channels and/or cavities of the zeolite crystals contain
guest molecules, clusters or ions; iii) the zeolite crystals are
surface-coated with a polymerizable silane; iv) polymer A is a
transparent organic polymer. EP 1873202A further discloses the use
of such transparent zeolite-polymer hybrid materials for developing
optical devices such as lenses, eye glasses, special mirrors,
filters, polarizer, grids, optical storage, monitors, window panes,
float glass, or for coating of organic and inorganic surfaces for
anti-reflection properties or light wavelength transformation.
[0010] In contrast to bulk metals, which are devoid of a band gap,
and hence are good electric conductors, small Au or Ag clusters
display interesting emissive properties from discrete energy
levels. This phenomenon has been demonstrated, e.g., for silver
smaller than 100 atoms in rare gas matrices, in aqueous solutions
and on silver oxide films.
[0011] The major problem in the study and creation of small Au or
Ag clusters is aggregation to large nanoparticles and eventually to
bulk metal, with loss of emission. Here, it is demonstrated that
the use of porous structures with limited pore, cavity and tunnel
sizes, overcomes the aggregation problem enabling emissive
entities, which are stable in time.
[0012] For oxidized silver, such as silver oxide nanoparticles, it
has been shown that reduction to metallic silver is possible by the
irradiation with UV to visible light (Peyser, L. A., Vinson, A. E.,
Bartko, A. P., Dickson, R. M. (2001) Science 291, 103-106). This
reduction causes a change in the optical properties of the
material, however for such material the final outcome of the
reduction reaction is hard to control and finally big non-emissive
silver aggregates will have formed.
[0013] N. E. Bogdanchikova et al. in 1999 in Applied Surface
Science 150, 58-64 showed that silver clusters in molecular sieves
exhibit remarkable stability and that the stability of the silver
clusters depends on the acid strength, which may be related to the
composition, e.g., the SiO.sub.2/Al.sub.2O.sub.3 molar ratio, of
the molecular sieves. Silver clusters in mordenites having weak
acidic sites are stable for at least 50 months, a sufficiently long
period with respect to the application in mind for use in a visible
light source. Disappearance of the clusters was linked to
oxidation.
[0014] The current state of the art has never suggested or
demonstrated the room temperature conversion of invisible light,
e.g., with energy in the UV region, to a lower energy, e.g.,
visible light, by oligo atomic metal clusters embedded in molecular
sieves. Also the influence of light-irradiation on the optical
properties of such materials have never been studied before.
[0015] Some technologies of the art concern the photophysical
properties of zeolites loaded with silver. For instance, Chen et
al. loaded Y zeolites with AgI, instead of silver clusters, and
pumped or charged with 254 nm light, however, without observation
or description of visible emission [W. Chen et al. Physical Review
B 65, 245404 Artn 245404 (2002), U.S. Pat. No. 7,067,072 and U.S.
Pat. No. 7,126,136]. Calzaferri et al. in 2003 in Chemical Society
Reviews, volume 32, pages 29-37, demonstrated absorption of 254 nm
light by silver metal containing zeolites without reporting any
emission. Kanan et al. in 2003 in Research on Chemical
Intermediates, volume 29, pages 691-704, showed some emission
intensity for silver(I)-exchanged zeolite Y, however only when
excited at temperatures below 200 K.
[0016] Encoded microcarriers are a key element in multiplex
(bio)assays in which multiple independent reactions are
investigated in the same solution, and in high throughput
split-and-mix synthesis methods for creating large libraries of
compounds from a set of common building blocks. In a typical
multiplex assay, each target is attached to a host particle with a
specific `barcode`. Generally this code is determined by the
incorporation of different fluorescent tags in specific
concentration ratios (optical encoding), and thus only a limited
amount of unique codes is available. While these strategies rely on
encoding of microcarriers in advance of the experiment (fixed
encoding), a more flexible approach where the encoding occurs
during the assay (active encoding) was recently worked out, based
on spatial selective photobleaching.
SUMMARY OF THE INVENTION
[0017] The present invention solves problems of the related art by
providing a material in which patterns such as bar codes can be
written optically with very high lateral and spatial resolution
using 2-photon excitation. Absorption of 2 photons only becomes
probable in zones with extremely high illumination power and hence
a high power near-infra red laser (we use a 780 nm laser) is
required focused on the sample for a given time (in our case a few
10 ms to 1 second) to write fluorescent patterns. Mostly a pulsed
laser is used in order to bundle all the intensity into short
pulses. With 2-photon excitation a 1 .mu.m resolution was
surprisingly obtained in the Z-direction and a resolution of 450 nm
in the xy-plane. Thus three layers of data can be written in a
depth of 6 .mu.m and these patterns are stable over extended
periods of time.
[0018] The present invention relates generally to the enhancement
of white light and colored light emission by photoactivation by UV
to blue irradiation using confined oligo-atomic clusters,
preferably silicon, silver, copper and gold, and more particularly
to the use of molecular sieves comprising oligo atomic silver
clusters as materials with data-storage and data imaging
capabilities, for instance, for encoding labels such as bio-labels
or tags or labels, for instance, for security items. Moreover,
individual molecular sieve crystals comprising oligo-atomic
clusters, e.g., silver clusters, can be used for active encoding of
compounds based on photo-induced formation of fluorescent
oligo-atomic clusters in a molecular sieve crystal host, which are
compatible with an aqueous environment and exhibit extraordinary
photostability.
[0019] The present invention demonstrates that oligo-atomic metal
clusters confined in molecular sieves not only exhibit remarkable
stability but also can be used for storing optical data. It has,
for instance, been demonstrated that a first time radiation of such
molecular sieve unit with UV or visible light will irreversibly
enhance the light emission by that unit upon a second UV or visible
light excitation or by subjecting it to a current or electrical
field. A matrix or carrier containing several such excitable
molecular sieve units can be used in a write radiation and read
radiation system that allows the storage of optical information and
which can be used for bit data storage or as an optical information
imager that can be used to visualize stored optical information in
an image. Irreversibly enhanced for the present application means
that a first time excitation of oligo-atomic metal clusters
confined in a molecular sieve by a radiation source (such UV or
visible light radiation) will enhance the emission by that
molecular sieve unit after a second radiation by UV or visible
light in a stable or even irreversible manner such that an
observable difference between an unwritten and written zone can be
visualized. The written zone will upon activation emit more
intensively.
[0020] Moreover, the materials of present invention, for instance,
zeolites containing oligo silver atom clusters, are cheap and
non-toxic. Zeolites, currently used in large quantities in washing
powder and silver despite its antimicrobial properties, have no
known toxic effect on human tissue. Colloidal silver has, for
instance, widely been marketed as a dietary supplement for
protective activity against oxidative stress and reactive oxygen
species formation.
[0021] A particular advantage of the present invention is not only
that the printed or coated images can comprise optical information
as such which is invisible under ambient conditions but that
additional optical information can be added to or written in the
image, for instance, by defined UV radiation.
[0022] A further particular advantage of the present invention is
the extraordinary photostability of the oligo-atomic metal clusters
in molecular sieve crystals for multiplex (bio)assay applications
over the organic dye-loaded latex spheres used in the
photobleaching-based method.
[0023] An additional particular advantage of the present invention
is the high resolution obtained with 2-photon activation of the
oligo-atomic metal clusters in molecular sieve crystals for
multiplex (bio)assay applications allowing for the creation of
several layers of advanced matrix codes such as the 2D MaxiCodes
and QR-codes inside an individual molecular sieve crystal.
[0024] An additional particular advantage over the photobleaching
approach in respect of multiplex (bio)assay applications is that,
since a dark pattern is written in a big fluorescent volume, the
activated patterns have a positive contrast and are thus easily
recognizable.
[0025] In accordance with the purpose of the invention, as embodied
and broadly described herein, the invention is broadly drawn to
data-storage material comprising an assembly of oligo-atomic
clusters of metals confined in molecular sieves, preferably
zeolites, for converting invisible radiation emitted by a radiation
source at or above room temperature to visible light and for
enhancing the emission intensity upon irradiation with UV or
visible light.
[0026] Aspects of the present invention are realized by a method of
storing data in oligo-atomic metal clusters confined in molecular
sieves comprising the step of data-wise exposing said oligo-atomic
metal clusters confined in molecular sieves to UV or visible light
excitation, thereby providing stored data capable of being read as
visible light emission upon exposure to UV-light or an electrical
field at or above room temperature.
[0027] Aspects of the present invention are also realized by a
paint, gelling liquid or elastomer comprising molecular sieves with
oligo atomic silver clusters confined therein for forming optical
data storage membranes or optical data storage films or for coating
surfaces with a data-storage capable layer.
[0028] Aspects of the present invention are also realized by the
use of molecular sieves with oligo atomic silver clusters confined
therein as 3D encodable microcarriers in multiplex (bio)
assays.
[0029] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description. It is to be understood that both the
foregoing general description and the following detailed
description are exemplary and explanatory only and are not
restrictive of the invention, as claimed.
DETAILED DESCRIPTION
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1: Graph of the emission intensity originating from an
individual silver-exchanged zeolite crystal versus time upon
excitation with 375 nm picoseconds pulsed light with average power
of 48 W/cm.sup.2 in confocal mode.
[0031] FIG. 2: Scheme of the photoactivation of specific patterns
in an individual silver-exchanged zeolite crystal in order to
generate bar codes.
[0032] FIG. 3 displays a Data Storage Medium (DSM) with the
data-storage capable porous structures (DSCPS) which are an
assembly of oligo atomic metal clusters confined in ordered porous
oxides embedded in a matrix.
[0033] FIG. 4 demonstrates [0034] a) False color emission image of
a single silver-exchanged zeolite A crystal before photo-activation
(1) and after consecutive activation of three individual spots (2,
3 and 4) in one crystal by irradiation with a ps 375 nm laser at 10
W/Cm.sup.2 for 20 minutes for each spot through a confocal
microscope. [0035] b) Total activation of a single crystal. (1)
shows the crystal before activation. After 5 min of irradiation by
a 16.7 kW/cm.sup.2 pulsed 375 nm beam the intensity increased by a
factor 10 (2). Another 20 minutes of activation at the same power
yielded a total intensity increase of a factor 20. Note the
increased scaling range from (1) to (3). The images in a) and b)
were taken by a confocal microscope under irradiation by a 375 nm
pulsed excitation source of respectively 10 and 20 W/cm.sup.2, with
2 ms integration time per pixel. [0036] c) True color image taken
with a digital camera (Canon PowerShot A710 IS with a 400 nm
longpass filter in front of the lens to filter out the excitation
light) through the eye piece of the microscope showing the green
emission from the same zeolite after complete activation at 16.7
kW/cm.sup.2 excitation power.
[0037] FIG. 5: Emission spectrum of the electroluminescence of
thermally treated silver-exchanged 3A zeolite dispersed in PVK with
Ytterbium and ITO electrodes.
[0038] FIG. 6: 2-photon activation of silver-exchanged zeolite A.
[0039] a) Fluorescence microscope image of a silver zeolite in
which the pattern of a lion was activated by 2-photon excitation.
[0040] b) Template image for writing the lion pattern in the silver
zeolites. [0041] c) black curve: Fluorescence intensity profile
along the white dashed line of the written image in panel a. grey
curve: Fluorescence intensity profile along the grey dashed line of
the template image in panel b. [0042] d) Fluorescence microscope
image of a silver zeolite in which three thin bar patterns of
varying sizes are activated by 2-photon excitation. [0043] e)
Fluorescence intensity profile along the x-axis of the area
indicated by the dashed rectangle in panel d. The profile is
averaged over the height of the dashed rectangle in panel d. The
solid line represents a Gaussian multipeak fit to the data. All of
the scaling bars represent a distance of 5 .mu.m.
[0044] FIG. 7: Writing 3D structures in silver zeolites. [0045] a)
Confocal optical sections throughout an individual silver zeolite
crystal in which the letters "K", "U" and "L" are photoactivated on
top of each other as indicated in the upper left scheme by 2-photon
excitation. [0046] b) Confocal optical section through the same
crystal as in panel a, after flipping the crystal on its side. The
orientation of this section is indicated in the upper left scheme
in panel a by the dotted rectangle. [0047] c) Fluorescence
intensity line profile along the area between the dashed lines in
panel b. The solid line represents a Gaussian fit to the data to
estimate the FWHM. All of the scaling bars represent a distance of
5 .mu.m.
[0048] FIG. 8: 3D holographic structure. After photoactivation of a
3D spiral-shaped structure in an individual silver zeolite A
crystal, confocal optical sections were imaged every 250 nm along
the axial dimension using 488 nm excitation. The image shows a
three-dimensional reconstruction of the activated volume.
[0049] FIG. 9: Fluorescence intensity-time transient for an
activated silver zeolite crystal after photoactivation on the Fluo
View 500 system using 1-photon excitation at 375 nm.
[0050] FIG. 10: Fluorescence intensity image of an [0051] activated
silver zeolite crystal imaged at 499 nm. Left side panel shows
fluorescence intensity image with the contours of the crystal
indicated by the dashed white lines. Right side panel shows the
transmission image overlaid.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0052] The present invention will be described with respect to
particular embodiments and with reference to certain drawings but
the invention is not limited thereto but only by the claims. The
drawings described are only schematic and are non-limiting. In the
drawings, the size of some of the elements may be exaggerated and
not drawn to scale for illustrative purposes. The dimensions and
the relative dimensions do not correspond to actual reductions to
practice of the invention.
[0053] Furthermore, the terms first, second, third and the like in
the description and in the claims, are used for distinguishing
between similar elements and not necessarily for describing a
sequential or chronological order. It is to be understood that the
terms so used are interchangeable under appropriate circumstances
and that the embodiments of the invention described herein are
capable of operation in other sequences than described or
illustrated herein.
[0054] Moreover, the terms top, bottom, over, under and the like in
the description and the claims are used for descriptive purposes
and not necessarily for describing relative positions. It is to be
understood that the terms so used are interchangeable under
appropriate circumstances and that the embodiments of the invention
described herein are capable of operation in other orientations
than described or illustrated herein.
[0055] It is to be noticed that the term "comprising", used in the
claims, should not be interpreted as being restricted to the means
listed thereafter; it doe not exclude other elements or steps. It
is thus to be interpreted as specifying the presence of the stated
features, integers, steps or components as referred to, but does
not preclude the presence or addition of one or more other
features, integers, steps or components, or groups thereof. Thus,
the scope of the expression "a device comprising means A and B"
should not be limited to the devices consisting only of components
A and B. It means that with respect to the present invention, the
only relevant components of the device are A and B.
[0056] The articles "a" and "an" are used herein to refer to one or
more than one (i.e., at least one) of the grammatical object of the
article. By way of example, "an element" means one element or more
than one element.
[0057] The term "including" is used to mean "including but not
limited to". "Including" and "including but not limited to" are
used interchangeably.
[0058] The term "in particular" is used to mean "in particular but
not limited thereto" and the term "particularly" is used to mean
"particularly but not limited thereto".
[0059] Reference throughout this specification to "one embodiment"
or "an embodiment" means that a particular feature, structure or
characteristic described in connection with the embodiment is
included in at least one embodiment of the present invention. Thus,
appearances of the phrases "in one embodiment" or "in an
embodiment" in various places throughout this specification are not
necessarily all referring to the same embodiment, but may.
Furthermore, the particular features, structures or characteristics
may be combined in any suitable manner, as would be apparent to one
of ordinary skill in the art from this disclosure, in one or more
embodiments.
[0060] Similarly it should be appreciated that in the description
of exemplary embodiments of the invention, various features of the
invention are sometimes grouped together in a single embodiment,
figure, or description thereof for the purpose of streamlining the
disclosure and aiding the understanding of one or more of the
various inventive aspects. This method of disclosure, however, is
not to be interpreted as reflecting an intention that the claimed
invention requires more features than are expressly recited in each
claim. Rather, as the following claims reflect, inventive aspects
lie in less than all features of a single foregoing disclosed
embodiment. Thus, the claims following the detailed description are
hereby expressly incorporated into this detailed description, with
each claim standing on its own as a separate embodiment of this
invention.
[0061] Furthermore, while some embodiments described herein include
some but not other features included in other embodiments,
combinations of features of different embodiments are meant to be
within the scope of the invention, and form different embodiments,
as would be understood by those in the art. For example, in the
following claims, any of the claimed embodiments can be used in any
combination.
[0062] In the description provided herein, numerous specific
details are set forth. However, it is understood that embodiments
of the invention may be practiced without these specific details.
In other instances, well-known methods, structures and techniques
have not been shown in detail in order not to obscure an
understanding of this description.
[0063] Several documents are cited throughout the text of this
specification. Each of the documents herein (including any
manufacturer's specifications, instructions etc.) is hereby
incorporated by reference; however, there is no admission that any
document cited is indeed prior art of the present invention.
[0064] The following terms are provided solely to aid in the
understanding of the invention.
DEFINITIONS
[0065] The term "data storage", as used in disclosing the present
invention, means the possibility of creating certain patterns
inside or on a material by locally changing the optical properties
of this material with the possibility of reading the patterns using
an electromagnetic probe beam or other reading means.
[0066] The term "molecular sieve", as used in disclosing the
present invention, means a solid with pores of the size of
molecules.
[0067] The term "zeolite", as used in disclosing the present
invention, means any member of a group, of structured
aluminosilicate minerals comprising cations such as sodium and
calcium or, less commonly, barium, beryllium, lithium, potassium,
magnesium and strontium; characterized by the ratio
(Al+Si):O=approximately 1:2, an open tetrahedral framework
structure capable of ion exchange, and loosely held water
molecules, that allow reversible dehydration. The term "zeolite"
also includes "zeolite-related materials" or "zeotypes" which are
prepared by replacing Si.sup.4+ or Al.sup.3+ with other elements as
in the case of aluminophosphates (e.g., MeAPO, SAPO, ElAPO, MeAPSO,
and ElAPSO), gallophosphates, zincophophates, titanosilicates, etc.
The zeolite can be a crystalline porous material with a frame work
as described in Pure Appl. Chem., volume 73, No. 2, pp. 381-394,
(2001) or provided in the Zeolite Framework Types database of the
IZA structure commission where under the following structure types,
as defined by the International Zeolite Association such as ABW
type, ACO type, AEI type, AEL type, AEN type, AET type, AFG AFI
type, AFN type, AFO type, AFR type, AFS type, AFT type, AFX type,
AFY type, AHT type, ANA type, APC type, APD type, AST type, ASV
type, ATN type, ATO type, ATS type, ATT type, ATV type, AWO type,
AWW type, BCT type, BEA type, BEC type, BIK type, BOG type, BPH
type, BRE type, CAN type, CAS type, CDO type, CFI type, CGF type,
CGS type, CHA type, CHI type, CLO type, CON type, CZP type, DAC
type, DDR type, DFO type, DFT type, DOH type, DON type, EAB type,
EDI type, EMT type, EON type, EPI type, ERI type, ESV type, ETR
type, EUO type, EZT type, FAR type, FAU type, FER type, FRA type,
GIS type, GIU type, GME type, GON type, GOO type, HEU type, IFR
type, IHW type, IMF type, ISV type, ITE type, ITH type, ITW type,
IWR type, IWV type, IWW type, JBW type, KFI type, LAU type, LEV
type, LIO type, LIT type, LOS type, LOV type, LTA type, LTL type,
LTN type, MAR type, MAZ type, MEI type, MEL type, MEP type, MER
type, MFI type, MFS type, MON type, MOR type, MOZ type, MSE type,
MSO type, MTF type, MTN type, MTT type, MTW type, MWW type, NAB
type, NAT type, NES type, NON type, NPO type, NSI type, OBW type,
OFF type, OSI type, OSO type, OWE type, PAR type, PAU type, PHI
type, PON type, RHO type, RON type, RRO type, RSN type, RTE type,
RTH type, RUT type, RWR type, RWY type, SAO type, SAS type, SAT
type, SAV type, SBE type, SBN type, SBS type, SBT type, SFE type,
SFF type, SFG type, SFH type, SFN type, SFO type, SGT type, SIV
type, SOD type, SOS type, SSF type, SSY type, STF type, STI type,
STO type, STT type, SZR type, TER type, THO type, TOL type, TON
type, TSC type, TUN type, UEI type, UFI type, UOZ type, USI type,
UTL type, VET type, VFI type, VNI type, VSV type, WEI type, WEN
type, YUG type and ZON type. The term "zeolite" also includes
"zeolite-related materials" or "zeotypes" which are prepared by
replacing Si.sup.4+ or Al.sup.3+ with other elements as in the case
of aluminophosphates (e.g., MeAPO, AlPO, SAPO, ElAPO, MeAPSO, and
ElAPSO), gallophosphates, zincophophates, titanosilicates, etc.
[0068] The term "macroporous material", as used in disclosing the
present invention, means a material having pore diameters of
greater than 50 nm as laid down by IUPAC [see J. Rouquerol et al.,
Pure & Appl. Chem., volume 66 (1994) 1739-1758].
[0069] The term "mesoporous material", as used in disclosing the
present invention, means a material having pore diameters between 2
nm (20 .ANG.) and 50 nm (500 .ANG.) as laid down by IUPAC [see J.
Rouquerol et al., Pure & Appl. Chem., volume 66 (1994)
1739-1758].
[0070] The term "microporous material", as used in disclosing the
present invention, means a material having pore diameters less than
2 nm [20 Angstrom (.ANG.)] as laid down by IUPAC [see J. Rouquerol
et al., Pure & Appl. Chem., volume 66 (1994) 1739-1758]. The
term "microporous materials" includes amorphous microporous solids.
Alternative amorphous microporous solids, which can be used in the
present invention include amorphous microporous mixed oxides
having, in dried form, a narrow pore size distribution (half width
<.+-.10% of the pore diameter) of micropores with diameters in
the range of <2 nm and the preparation of said amorphous
microporous mixed oxides have been well described in U.S. Pat. No.
6,121,187 and others have been well documented in WO 2001-44308A,
U.S. Pat. No. 6,753,287, U.S. Pat. No. 6,855,304, U.S. Pat. No.
6,977,237, WO 2005-097679A, U.S. Pat. No. 7,055,756 and U.S. Pat.
No. 7,132,093.
[0071] The term "microporous carrier" as used herein refers to a
solid with pores the size of molecules. It includes but is not
limited to microporous materials, ALPOs and (synthetic) zeolites,
pillared or non-pillared clays, carbon molecular sieves,
microporous titanosilicates such as ETS-10, and microporous oxides.
Microporous carriers can have multimodal pore size distribution,
also referred to as ordered ultramicropores (typically less than
0.7 nm) and supermicropores (typically in the range of about 0.7-2
nm). Particular types of microporous carriers envisaged within the
present invention are the molecular sieve zeolites. Zeolites are
the aluminosilicate members of the family of microporous carriers.
The microporous carrier can be of an ordered crystalline structure
or an amorphous material.
[0072] The term "room temperature" as used in this application
means a temperature in the range of 12 to 30.degree. C., preferably
in the range of 16 to 28.degree. C., more preferably in the range
of 17 to 25.degree. C. and most preferably is roughly 20 to
23.degree. C.
[0073] The term "luminescence" or "emissive", as used in disclosing
the present invention, includes the following types:
chemoluminescence, crystalloluminescence, electroluminescence,
photoluminescence, phosphorescence, fluorescence, and
thermo-luminescence.
[0074] The term "oligo-atomic metal cluster", as used in disclosing
the present invention, includes clusters ranging from 1 to 100
atoms of the following metals (sub-nanometer size), Si, Cu, Ag, Au,
Ni, Pd, Pt, Rh, Co and Ir or alloys thereof such as Ag/Cu, Au/Ni
etc. The clusters can be neutral, positive or negatively charged.
If the clusters are positively charged, the negatively charged
zeolite framework provides for charge compensation and hence no
charge-compensating anions are required. The oligo atomic metal
clusters can be small oligo atomic silver- (and/or gold) clusters
containing 1 to 100 atoms.
[0075] 2-photon excitation means that light of half the energy (or
double the wavelength) is used to excite the sample.
[0076] The term "matrix", as used in disclosing the present
invention, means a solid medium upon which or in which the
oligo-atomic metal clusters in a molecular sieve are situated,
which is preferably transparent or semitransparent, and embraces
any organic, inorganic or hybrid binding medium, with molecular
sieves, polysiloxanes, polymers including polymer fibres,
copolymers or elastomers being preferred.
[0077] A comprehensive list of the abbreviations utilized by
organic chemists of ordinary skill in the art appears in the first
issue of each volume of the Journal of Organic Chemistry; this list
is typically presented in a table entitled Standard List of
Abbreviations.
[0078] For purposes of this invention, the chemical elements are
identified in accordance with the Periodic Table of the Elements,
CAS version, Handbook of Chemistry and Physics, 67th Ed., 1986-87,
inside cover. Contemplated equivalents of the zeolitic structures,
subunits and other compositions described above include such
materials which otherwise correspond thereto, and which have the
same general properties thereof (e.g., biocompatible), wherein one
or more simple variations of substituents are made which do not
adversely affect the efficacy of such molecule to achieve its
intended purpose. In general, the compounds of the present
invention may be prepared by the methods illustrated in the general
reaction schemes as, for example, described below, or by
modifications thereof, using readily available starting materials,
reagents and conventional synthesis procedures. In these reactions,
it is also possible to make use of variants, which are in
themselves known, but are not mentioned here:
a) "the molecular sieve in which the oligo-atomic clusters are
confined is selected from among microporous materials, selected
from among zeolites, porous oxides, silicoaluminophosphates and
aluminosilicates". b) "zeolite selected from among the family of
small pore sized zeolites such as zeolite A and ZKF, and
combinations thereof". c) "large pore zeolites such as ZSM-5,
MCM-22, ferrierite, faujastites X and Y and microporous molecular
sieves". d) "The matrix can also be a molecular sieve selected from
among molecular sieves MCM-41, MCM-48, HSM, SBA-15, and
combinations thereof". e) "Methods are available in the art for
preparation of microporous zeolites." f) "As used herein,
microporous zeolites preferably have a pore size of about 3
angstroms to about 14 angstroms".
Method of Storing Data in Oligo-Atomic Metal Clusters Confined in
Molecular Sieves
[0079] Aspects of the present invention are realized by a method of
storing data in oligo-atomic metal clusters confined in molecular
sieves comprising the step of data-wise exposing said oligo-atomic
metal clusters confined in molecular sieves to UV or visible light
excitation, thereby providing stored data capable of being read as
visible light emission upon exposure to UV-light or an electrical
field at or above room temperature.
[0080] Aspects of the present invention are also realized by a
method of writing optical data in a pattern on the data storage
medium of any of the previous claims comprising exposing
locoregional portions of the material, with at least one assembly
of small Au and/or Ag clusters confined in a molecular sieve
particle, to radiation at a radiation power sufficient to cause
such assembly which absorbs the radiation to emit light photons and
of visualizing such stored optical data by reradiating them or by a
larger portion of the materials with lower radiation power
sufficient to only read the assemblies of small Au and/or Ag
clusters confined in a molecular sieve which store the optical
data.
[0081] According to a preferred embodiment of the method of storing
data in oligo-atomic metal clusters confined in molecular sieves,
according to the present invention, the data-wise exposure of said
oligo-atomic metal clusters confined in molecular sieves is
sufficiently intense or long to realize an enhanced excitation
effect upon a next read at lower irradiation or illumination by UV
or visible light radiation.
[0082] According to another preferred embodiment of the method of
storing data in oligo-atomic metal clusters confined in molecular
sieves, according to the present invention, the data-wise exposure
of said oligo-atomic metal clusters confined in molecular sieves is
sufficiently intense or long read illumination by radiation from a
laser beam, a medium wavelength UV (UVC) radiation source, a Far UV
(FUV), a vacuum UV (VUV) ray radiation source, an Extreme UV (EUV)
or a deep UV (XUV) ray radiation source to provide an enhanced
excitation effect upon a following illumination by an UV or visible
light.
[0083] According to another preferred embodiment of the method of
storing data in oligo-atomic metal clusters confined in molecular
sieves, according to the present invention, the data-wise exposure
to UV or visible light excitation is performed with a laser or a
light-emitting diode.
[0084] According to a preferred embodiment of the method of storing
data in oligo-atomic metal clusters confined in molecular sieves,
according to the present invention, the data-wise exposure to UV or
visible light excitation is 2-photon photoactivation.
[0085] According to another preferred embodiment of the method of
storing data in oligo-atomic metal clusters confined in molecular
sieves, according to the present invention, the oligo-atomic metal
clusters are confined in a single molecular sieve crystal,
preferably a microporous crystal and particularly preferably a
zeolite crystal.
Data-Storage Capable Porous Structures
[0086] The oligo-atomic metal clusters in the illumination system
of present invention are preferably of noble metals from the group
consisting of gold, silver, platinum, palladium, silicon and
rhodium and particularly preferably of gold and/or silver. The size
of the oligo-atomic metal cluster is preferably 1-100 atoms, the
maximum cluster size providing luminescence being dependent upon
the metal, e.g., 20-30 atoms in the case of gold and 20 atoms in
the case of silver. In the case of gold clusters, clusters of 1 to
30 atoms are preferred and in the case of silver clusters, clusters
of 1 to 20 atoms are preferred.
[0087] The molecular sieves in this invention are preferably
microporous or mesoporous materials; particularly preferably
zeolites, porous oxides, silicoalumino-phosphates, gallophosphates,
zinco-phosphates, titanosilicates and aluminosilicates, or mixtures
thereof; and especially preferably one or more selected from the
group consisting of mordenite, ZSM-5, MCM-22, A-zeolite, L-zeolite,
faujasites X and Y, ferrierite, chabazite type of zeolites, and
mixtures of the foregoing zeolites. Preferred zeolites are selected
from the group consisting of K-A (3A), Na-A (4A), Ca-A (5A),
13.times. and ZKF zeolites.
[0088] The pore size of molecular sieves can further be influenced
by the nature of the templating molecules in the synthesis. The
addition of swelling agents to the synthesis mixture can further
affect the pore size of the resulting molecular sieve. Zeolites
with different pore size have been well characterized and described
by Martin David Foster in "Computational Studies of the Topologies
and Properties of Zeolites", The Royal Institution of Great
Britain, Department of Chemistry, University College London, a
thesis submitted for the degree of Doctor of Philosophy, London,
January 2003.
[0089] In a particular embodiment of the present invention the
data-storage material for storing optical data comprising
oligo-atomic metal clusters confined in molecular sieves, the
emission upon UV or visible light excitation is irreversibly
enhanced by illumination with UV or visible light.
[0090] In one embodiment in the present invention, Au or Ag
clusters are protected from oxidation due to encapsulation in the
molecular sieves. Additionally, if required, an external coating of
the material crystals or capping of the pore entrances can be used
to further protect the occluded metal clusters.
[0091] In a particular embodiment of present invention the pores of
the molecular sieves containing the small clusters of, e.g., Au
and/or Ag are coated with a matrix, or are closed by stopper
molecules.
[0092] To transfer the UV or visible radiation into more
red-shifted light, the light system of present invention does not
require the presence of charge compensating anions, such as
oxalate, hydroxide, azide, carbonate, bicarbonate, sulfate,
sulfite, chlorate, perchlorate, acetate and formate to be in charge
association with the noble metals, such as the small metal
clusters.
[0093] FIG. 1 shows a graph of the emission intensity originating
from an individual silver-exchanged zeolite crystal versus time
upon excitation with 375 nm picoseconds pulsed light with average
power of 48 W/cm.sup.2 in confocal mode. This same excitation
sources causes the photoactivation of the emission.
Optical Data Information Carrier and Optical Data Display
[0094] An optical data information carrier and optical data display
can be made of a system that comprises oligo-atomic metal clusters,
e.g., of small Au, Ag and/or alloys thereof, confined in molecular
sieves, which are comprised, e.g., embedded or integrated, in a
matrix, e.g., a membrane or film. Such matrices may further
comprise a particle binder.
[0095] Moreover such an optical data information carrier or optical
data display system can comprise a laminate structure wherein there
is a layer of oligo-atomic metal clusters confined in molecular
sieves incorporated in a matrix, preferably a polymer matrix. Such
a polymer matrix can form a protective structure that incorporates
the oligo-atomic metal clusters confined in molecular sieves and
protects them from deterioration by external factors and improves
stability.
[0096] The above described film can be used to directly incorporate
the metal clusters confined in molecular sieves in said film or can
be used to shield or cover another layer of film which incorporates
the metal clusters confined in molecular sieves to protect such
second film from environmental factors.
[0097] Aspects of the present invention are realized by a
data-storage medium for storing optical data, characterized in that
the optical data-storage medium comprises as data storage material
oligo-atomic metal clusters confined in molecular sieves which are
embedded in a solid or flexible support, whereby the metal clusters
if subjected at room temperature or above to invisible radiation or
an electrical field in response emit visible light.
[0098] According to another preferred embodiment of the method of
storing data in oligo-atomic metal clusters confined in molecular
sieves, according to the present invention, the oligo-atomic metal
clusters confined in a molecular sieve is embedded in a rigid or
flexible material, said oligo-atomic metal clusters in a molecular
sieve preferably forming a mono-particulate layer of molecular
sieve particles in said rigid or flexible material; or the
oligo-atomic metal clusters in a molecular sieve preferably being
structured in multi-particulate layers of molecular sieve particles
in said rigid or flexible material.
[0099] According to another preferred embodiment of the method of
storing data in oligo-atomic metal clusters confined in molecular
sieves, according to the present invention, the method further
comprises the step of embedding the data-wise exposed oligo-atomic
metal clusters in a molecular sieve in a rigid or flexible
material.
[0100] FIG. 3 displays a Data Storage Medium (DSM) with the
data-storage capable porous structures or DSCPS which are an
assembly of oligo atomic metal clusters confined in ordered porous
oxides, preferably microporous silica oxides embedded in a matrix,
preferably a polymer, copolymer or elastomer matrix, which
preferably is transparent or semitransparent.
Elastomeric Polymers Suitable for Use in the Optical Data
Information Carrier and Optical Data Display
[0101] Typical but not exclusive examples of such elastomeric
polymers are polydimethylsiloxane (silicone rubber), polyisobutene
(butyl rubber), polybutadiene, polychloroprene, polyisoprene,
styrene-butadiene rubber, acrylonitrile-butadiene rubber (NBR),
ethene-propene-diene-rubber (EPDM) and
acrylonitrile-butadiene-styrene (ABS) (Murder, 1991). Such films or
membranes of the molecular sieves comprising oligo atomic silver
clusters; ordered mesoporous and/or microporous oxides comprising
oligo atomic silver clusters or porous materials with nanometer
dimension (0.3-10 nm) windows, channels and cavity architectures
comprising oligo atomic silver clusters can be coated on a
substrate.
[0102] The most important elastomers are polyisoprene [natural or
synthetic rubber (IR)], polychloroprene [chloroprene rubber (CR)],
butyl rubber (BR), styrene-butadiene rubber (SBR),
acrylonitrile-butadiene rubber (NBR), ethene-propene-diene-rubber
(EPDM), acrylonitrile-butadiene-styrene (ABS), chlorosulfonated
polyethylene (CSM), I polyacrylate (polyacrylic rubber),
polyurethane elastomers, polydimethylsiloxane (PDMS, sometimes more
generally referred to as silicone rubber), fluorosilicones and
polysulfides.
[0103] Following the ASTM (American Society for Testing and
Materials) standards, `elastomers` are defined as "macromolecular
materials that return to approximately the initial dimensions and
shape after substantial deformation by a weak stress and release of
the stress". Elastomers are sometimes also referred to as `rubbery
materials`. A `rubber` is defined as "a material that is capable of
recovering from large deformations quickly and forcibly, and can
be, or already is, modified to a state in which it is essentially
insoluble (but can swell) in boiling solvent, such as benzene,
toluene, methyl ethyl ketone, and ethanol/toluene azeotrope".
Polymers Suitable for Use in the Optical Data Information Carrier
and Optical Data Display
[0104] The data storage or data imaging of present invention may
need particular characteristics according to its environment or use
a variety of alternatives polymers that provide design freedom
which preparation protocols are available in the art to design
complex shapes, to consolidate parts into fewer components,
simplify production, to produce transparent and precolored
components, to reduce part weight, to reduce noise when the data
storage or data imaging means or element is moving, to have a
reliable performance at elevated temperature, to have chemical
resistance in harsh climates, to have the desired stiffness,
strength and toughness, to have hydrolytic stability over time, to
have electrical properties to have a desired physical
appearance.
[0105] Such polymer layers comprise a polymerization product of an
acryl-based vinyl monomer, an aromatic vinyl monomer,
acrylonitrile-based vinyl monomer, chloride-based vinyl monomer,
vinylstearate or vinylpropionate. Examples of the acryl-based vinyl
monomer include one or more mixtures selected from the group
consisting of triethylopropane triacrylate, tri(propylene
glycol)diacrylate, penthaerithritol triacrylate,
trimethylol-propane ethoxylate triacrylate, methyl methacrylate,
tri(prop-ylene glycol)glycerolate diacrylate and vinylacrylate.
Examples of the aromatic vinyl monomer include styrene and divinyl
benzene. Examples of the chloride-based vinyl monomer include
vinylidene chloride and vinylbenzyl chloride. The oligomer is one
or more mixtures selected from the group consisting of urethane
acrylate oligomer, acrylate oligomer, ether acrylate oligomer and
epoxy acrylate oligomer. The polymerization of such a film can be
initiated by a polymerization initiator Examples of the
polymerization initiator include photo initiators selected from the
group consisting of 1-hydroxy-cyclohexyl-phenyl-ketone
(Irgacur.RTM. 907),
2-methyl-1[4-(methyl-thio)phenyl]-2-morpholino-propane-1-one
(Irgacur.RTM. 184C), 1-hydroxy-2-methyl-1-phenyl-propane-1-one
(Darocu.RTM. 1173), a mixed initiator (Irgacur.RTM. 500) of
Irgacur.RTM. 184C and benzophenone, a mixed initiator (Irgacure
1000) of Irgacure 184C and Irgacur.RTM. 1173,
2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propan-one
(Irgacure.RTM. 2959), methylbenzoylformate (Darocure MBF),
.alpha.,.alpha.-dimethoxy-.alpha.-phenyl-acetophenone (Irgacur.RTM.
651),
2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone
(Irgacur.RTM. 369), a mixed initiator (Irgacur.RTM. 1300) of
Irgacur.RTM. 369 and Irgacur.RTM. 651,
diphenyl-(2,4,6-trimethylbenzoyl)-phosphine oxide (Darocur TPO), a
mixed initiator (Darocur.RTM. 4265) of Darocur.RTM. TPO and
Darocur.RTM. 1173, phosphine oxide, phenyl bis(2,4,6-trimethyl
benzoyl) (Irgacure.RTM. 819), a mixed initiator (Irgacure 2005) of
Irgacure 819 and Darocur.RTM. 1173, a mixed initiator
(Irgacure.RTM. 2010) of Irgacure.RTM. 819 and Darocur.RTM. 1173,
and a mixed initiator (Irgacure.RTM. 2020) of Irgacure.RTM. 819 and
Darocur.RTM. 1173,
bis(s-5-2,4-cyclopentadien-1-yl)bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl-
] titanium (Irgacure.RTM. 784), and a mixed initiator (HSP 188)
containing benzophenene. Also, examples of the polymerization
initiator include thermal initiators selected from the group
consisting of benzoyl peroxide (BP), acetyl peroxide (AP), diauryl
peroxide (DP), di-tert-butyl peroxide (t-BTP), cumyl hydroperoxide
(CHP), hydrogen peroxide (HP), potassium peroxide (PP),
2,2'-azobis-isobutyronitrile (AIBN), azocompound, and silver
alkyls. Further, the polymerization initiator may be initiators
utilizing an oxidation-reduction reaction selected from the group
consisting of persulfate (K.sub.2S.sub.2O.sub.8) and a redox
initiator. Coating of the polymers on another layer or on a
substrate is performed by spin coating, bar coating, printing,
spreading or dipping. Such coating or printing can be done with the
polymers that are mixed with the oligo-atomic metal clusters
confined in molecular sieves. In the step of forming the
encapsulation film, in order to cause a polymerization reaction of
the organic solution, light may be irradiated or heat may be
applied thereto. When forming film, a fluid comprising the
oligo-atomic metal clusters confined in molecular sieves, a vinyl
monomer, a polymerization initiator and an oligomer, can be
polymerized, thereby enhancing adhesion and hardness of the
encapsulation film and denseness of an encapsulation film
surface.
[0106] Polymers that are suitable for incorporation of the
data-storage capable porous structures of present invention are for
instance Spire.TM. family of ultra polymers such as 1)
KetaSpire.RTM. polyetheretherketone (PEEK) which is easy-to-mold
ultra polymer offering outstanding chemical resistance and
mechanical performance up to 300.degree. C. (570.degree. F.) or
AvaSpire.RTM. modified PEEK, a PEEK-based formulations or 2)
PrimoSpire.RTM. self-reinforced polyphenylene (SRP) known to be
designable in a very stiff, strong unreinforced polymer with a
remarkable combination of surface hardness, chemical resistance and
inherent flame-retardant properties or 3) EpiSpire.TM., an
high-temperature sulfone (HTS) known to be a transparent amorphous
polymer with excellent creep resistance at temperatures up to
265.degree. C. (510.degree. F.) or 4) Torlon.RTM. polyamide-imide
(PAI) with higher strength and stiffness that most thermoplastic up
to 275.degree. C. (525.degree. F.) combined with superior
resistance to chemicals, creep and wear. Other polymers that are
suitable for incorporation of the data-storage capable porous
structures of present invention are the family of amorphous sulfone
polymers such as 1) Udel.RTM. PSU known to be designable into
tough, transparent plastic with exceptional chemical resistance,
good hydrolytic stability and an HDT of 345.degree. F. (174.degree.
C.) or the 2) Mindel.RTM. modified polysulfone with superior
electrical propertiesor 3) the Radel.RTM. R (PPSU) known to deliver
a super-tough transparent plastic with an HDT of 405.degree. F.
(207.degree. C.), excellent chemical resistance and the unique
ability to be steam sterilized without significant loss of
properties or 4) the Radel.RTM. A (PES) know to deliver a
transparent plastic with a high HDT of 400.degree. F. (204.degree.
C.) and good chemical resistance or the Acudel.RTM. modified PPSU.
Other polymers that are suitable for incorporation of the
data-storage capable porous structures of present invention are for
instance the semi-crystalline aromatic polyamides such as for
instance the Amodel.RTM. polyphthalamide (PPA) known to deliver a
high-temperature nylon with exceptional mechanical properties, an
HDT of 535.degree. F. (280.degree. C.), excellent chemical
resistance and low moisture uptake or the Ixef.RTM. polyarylamide
(PA MXD6) known to deliver aesthetic, structural specialty nylon
that combines outstanding stiffness with exceptional surface
appearance, plus low and slow water uptake, and great flow
properties. Other polymers that are suitable for incorporation of
the data-storage capable porous structures of present invention are
for instance semi-crystalline polymers such as the Primef.RTM.
polyphenylene sulfide (PPS) which delivers a high-flow, structural
plastic with good temperature and chemical resistance as well as
inherent flame retardant properties or the Xydar.RTM. liquid
crystal polymer (LCP) known to deliver high-flow, high-temperature
plastic with an HDT of 570.degree. F. (300.degree. C.), and
extremely high chemical resistance. These are available with design
and processing guides form Solvay Advanced Polymers.
[0107] Polystyrene is a thermoplastic polymer that is particularly
resistant to irradiation.
Inorganic/Organic Polysiloxane Hybrid Polymers for Use in the
Optical Data Information Carrier and Optical Data Display
[0108] Inorganic/organic polysiloxane hybrid polymers are known in
the art and described in High Performance Ceramic Films and
Coatings (Elsevier Science Publishers B.V., 1991), which is herein
incorporated by reference. One family of these hybrid polymers
which has particular utility is commercially available from
Fraunhofer-Gesellschaft (Munich, Germany) and designated by German
trademark ORMOCERS.RTM.. Inorganic-organic polysiloxane hybrid
polymers are also disclosed in DE 43 03 570, which is herein
incorporated by reference. Also hybrid polysiloxane polymer which
acts as a matrix or binder for zeolite additives to form a
zeolite-polymer composite can be used (U.S. Pat. No. 6,248,682).
Virtually any molecular sieve materials such as zeolite material or
mixtures of zeolites may be utilized for the composite
materials.
Process for Manufacturing Data-Storage Capable Porous
Structures
[0109] Aspects of the present invention are realized by a
manufacturing method of an optical data storage or optical data
display device with ensured reliability and processing stability by
forming a structure in a simple manner that incorporates the
oligo-atomic metal clusters confined in molecular sieves in a
polymer matrix.
[0110] Aspects of the present invention are also realized by a
paint, gelling liquid or elastomer comprising molecular sieves with
oligo atomic silver clusters confined therein for forming optical
data storage membranes or optical data storage films or for coating
surfaces with a data-storage capable layer.
[0111] Aspects of the present invention are also realized by a
printing liquid or ink comprising molecular sieves with oligo
atomic silver clusters confined therein for depositing, spraying or
printing or painting an optical data storage layer or coating on a
substrate.
[0112] Paints or fluids comprising the data-storage capable porous
structures of the present invention can be used for coating
surfaces with the data-storage capable porous structures.
[0113] Media (e.g., paints, gelling liquids, elastomers) are
available and methods of manufacturing to achieve such membranes or
films, for instance, a filled elastomeric polymer, which comprises
the oligo-atomic metal clusters confined in molecular sieves or in
ordered porous oxides (microporous or mesoporous or mixed
mesoporous/microporous) or porous materials with nanometer
dimension (0.3-10 nm) windows, channels and cavity architectures,
are known.
[0114] Particularly suitable are the resin(s), water-insoluble
fatty acid esters of polyvalent alcohols, or ethinols as
solvent.
[0115] The data storage molecular sieves of present invention can
be incorporated and dispersed over a polymer matrix by state of the
art technology. ZSM-5 crystals have for instance been incorporated
into conventional polymer films and selective separations have been
achieved [see Duval, J.-M., Kemperman, A. J. B., Folkers, B.,
Mulder, M. H. V., and Desgraddchamps, G., J. Appl. Polym. Sci.,
volume 54 (1994) 409-418]. U.S. Pat. No. 4,973,606 teaches
insertion of zeolites into polymers, such as thermoplastic
elastomers or duromers, for producing membranes with controllable
selectivity for material separation. U.S. Pat. No. 5,069,794
teaches application of zeolite coatings to different substrates to
act as thin membranes.
[0116] Incorporating molecular sieve zeolites into silica films has
also been previously reported by Bein, et al. [see Bein, T., Brown,
K., Enzel, P., and Brinker, C. J., Mat. Res. Soc. Symp. Proc.,
volume 121 (1988) 761-766]. Such an approach utilizes
tetraethylorthosilicate (TEOS) as the sole source of silica
delivering nitrogen impermeable films.
[0117] The data carrying porous structures, in particular the
confined metal clusters in microporous materials that are in
molecular sieves, may be incorporated in paints or printing inks
(e.g., printable matrix printing ink or printable paints, varnishes
(e.g., overprinting varnishes) and paints for depositing, spraying,
printing or painting such as a layer or coating on a substrate such
as foil, paper and board and aluminium-vaporised paper. Printing
inks or paints of the art which are suitable for comprising the
emitting materials or data carrying porous structures of present
invention are, for instance, hard resins, colophony-modified phenol
resins, maleate resins, hydrogenated mineral oil cuts, synthetic
aromatic oils, alkyd resins in particular hydrocarbon resins and/or
a colophony resin ester and dialkyl ether such as di-n-dodecyl
ether, di-n-undecyl ether, allyl-n-octyl ether, n-hexyl-n-undecyl
ether as a vehicle.
[0118] Suitable printing inks in the art are described in U.S. Pat.
No. 4,028,291, U.S. Pat. No. 4,169,821, U.S. Pat. No. 4,196,033,
U.S. Pat. No. 4,253,397, U.S. Pat. No. 4,262,936, U.S. Pat. No.
4,357,164, U.S. Pat. No. 5,075,699, U.S. Pat. No. 5,286,287, U.S.
Pat. No. 5,431,721, U.S. Pat. No. 5,886,066, U.S. Pat. No.
5,891,943, U.S. Pat. No. 6,613,813 and U.S. Pat. No. 5,965,633. The
data storage media of present invention may be painted, printed or
coated on a substrate in an optical information carrying tag,
marker or image.
Solvent-Free Processes for Manufacturing Membranes or Films
Incorporating Data-Storage Capable Porous Structures
[0119] A matrix comprising oligo-atomic metal clusters confined in
molecular sieves of present invention can be coated by depositing a
second film on such optical information storage layers. This can be
done by plasma deposition. Plasma polymerization is a technique
used for depositing polymer-like organic materials, usually in the
form of thin films, onto surfaces in contact with or near a plasma
discharge. Unlike conventional polymers, plasma polymers do not
consist of long chains of monomeric repeat units with sparse
"cross-links" connecting the chains. Instead, they are highly
branched, three-dimensional interlinked monomer-derived networks
which result from fragmentation and dissociation in the plasma in
which the film-forming reactant species are generated. Plasma
polymerized films are formed from organic monomers and are in
general, pinhole-free, dense and amorphous. When compared with
conventional polymer films made from the same monomer(s), plasma
polymers exhibit better adhesion, and improved chemical and
mechanical resistance. Furthermore, the properties of the deposited
films can be changed by varying the deposition parameters. Plasma
polymerized films are generally formed in an apparatus that
typically consists of three parts: (1) a vacuum system, (2) an
electrical excitation system for generating a plasma, and (3) a
monomer gas delivery system. As monomer molecules flow through the
vacuum chamber, the plasma discharge energizes and disassociates
the monomer molecules into neutral particles and reactant fragments
in the form of electrons, ions and free radicals. As these reactant
fragments recombine on a substrate, a highly branched and
cross-linked three-dimensional network is formed.
[0120] Other aspects of the present invention concern the
incorporation of oligo-atomic metal clusters confined in molecular
sieves into a matrix of polymeric fibers or other synthetic or
artificial fibers which can be ordered for instance by weaving,
knitting, crocheting, knotting, or pressing fibers together in a
flexible material comprised of a network of such fibers. Such
flexible material can be further processed into a fabric. Examples
of synthetic fibers are the fibers of the group Nylon, Modacrylic,
Olefin, Acrylic, Polyester, PLA, Vinyon, Saran, Spandex, Vinalon,
Aramids (known as Nomex, Kevlar and Twaron], Modal, PBI
(Polybenzimidazole fibre), Sulfar, Lyocell, Dyneema/Spectra, M-5
(PIPD fibre), Orlon, Zylon (PBO fibre), Vectra LCP polymer,
Acrylonitrile.
Sol-Gel Processes for Manufacturing Membranes or Films
Incorporating Data-Storage Capable Porous Structures
[0121] Another approach of incorporating the data storage molecular
sieves of the present invention is to tailor the properties of
sol-gel derived materials, which involves organic compound
additions to gels for modifying the characteristics of inorganic
sol-gel materials. In this approach, the inorganic part of the
matrix-forming material provides rigidity and thermal stability,
while the organic components in general contribute elasticity and
flexibility, although at the expense of some thermal stability.
Recent studies by Mackenzie et al, and others have documented such
approaches [see Hu, Y. and Mackenzie, J. D., J. Mater. Sci., volume
27 (1992) 4415-4420; Mackenzie, J. D., Chung, Y. J., and Hu, Y., J.
Non-Cryst. Sol., volumes 147&148 (1992) 271-279; Hu, Y., Chung,
Y. J., and Mackenzie, J. D., J. Mater. Sci., volume 28 (1993)
6549-6554; Iwamoto, T. and Mackenzie, J. D., J. Mater. Sci., volume
30 (1995) 2566-2570; Nazeri, A., Bescher, E., and Mackenzie, J. D.,
Ceram. Eng. Sci. Proc., volume 14 (1993) 1-19; Rose, K., Wolter,
H., and Glaubitt, W., Mat. Res. Soc. Symp. Proc., volume 271 (1992)
731-736; Schottner, G., Rose, K., and Schubert, U., Intell. Mater.
& Sys. (1995) 251-262; Rose, K., Organosilicon Chem. II, Auner,
N. and Weis, J., eds. (1996) 649-653]. With these methods,
co-polymers are typically formed from alkoxysilanes, usually with
TEOS or tetramethylorthosilane (TMOS) as the primary silica source.
In these methods, hydrolysis reactions, usually in acid media,
precipitate silica moieties, which are then crosslinked by
condensation reactions between other silane molecules or silica
moieties, which have external-OH groups at their surfaces.
Process for Manufacturing Membranes or Films Incorporating
Data-Storage Capable Porous Structures from Solvent
[0122] In the preparation of data storage membranes, the
data-storage capable porous structures may first be dispersed in an
appropriate solvent. An appropriate solvent is a solvent of low
ionic strength, for instance an ionic strength of a value in the
range of 1 mmol/L to 0.05 mol/L, and should be able to dissolve the
elastomer as well, or at least, should be partially miscible with
the solvent in which the membrane-forming polymer is dissolved. To
improve the dispersion, ultrasonic wave treatment, high speed
mixing, modification reactions, can be applied.
[0123] The content of data-storage capable porous structures and
polymer, in the dispersion, may range from 1 wt % to 80 wt %,
preferably 20 wt % to 60 wt %. The dispersion is stirred for a
certain time to allow (polymer/filler) interactions to establish,
to improve dispersion and possibly to let a chemical reaction take
place. When appropriate, the dispersion can be heated or
sonicated.
[0124] A particular method of coating is solution-depositing of the
molecular sieves comprising oligo atomic silver clusters comprises
spray-coating, dip-casting, drop-casting, evaporating,
blade-casting, or spin-coating the molecular sieves comprising
oligo atomic silver clusters; ordered mesoporous and/or microporous
oxides comprising oligo atomic silver clusters or porous materials
with nanometer dimension (0.3-10 nm) windows, channels and cavity
architectures with an assembly of oligo atomic metal clusters
confined in such structures (hereinafter the data-storage capable
porous structures or DSCPS) onto a substrate (FIG. 3)
[0125] The (polymer/data-storage capable porous structures or
paint/data-storage capable porous structures) dispersion can be
cast on a non-porous support from which it is released afterwards
to form a self-supporting film. One way to realize this is by
soaking it previously with a solvent, which has a low affinity for
the dispersion. Also, the support can be treated with adhesion
promoters.
[0126] The (polymer/data-storage capable porous structures or
paint/data-storage capable porous structures) dispersion can be
cast or printed on a fibrous structure such as a textile, paper or
board.
[0127] After casting, printing or coating, the solvent is
evaporated and, if necessary, a heat treatment can be applied to
finish the cross-linking reactions. The heat treatment can possibly
occur under vacuum conditions to remove the remaining solvent. The
resulting supported membranes may be a filled elastomer with the
thickness of this selective layer in a range from 0.01 .mu.m to 500
.mu.m, preferably from 0.1 to 250 .mu.m and yet more preferably
from 10 to 150 .mu.m.
[0128] A particular example of manufacturing a data storage carrier
based on the data-storage capable porous structures of present
invention and a polymer is for instance the use of
polydimethylsiloxane (PDMS), RTV-615 A and B (density 1.02 g/ml)
and the adhesion promoter (SS 4155) which are obtainable from
General Electric Corp. (USA). Component A is a pre-polymer with
vinyl groups. Component B has hydride groups and acts as
cross-linker and EPDM (Keltan.RTM. 578 from DSM) and data-storage
capable porous structures of present invention, which are well
dried before use.
[0129] Such can be produced by preparing dispersing a powder of the
data-storage capable porous structures of present invention (for
instance a zeolite comprising oligo atomic silver clusters) in
hexane; adding the cross-linker (RTV 615 B) to the dispersion of
data-storage capable porous structures of present invention and
stirring this mixture at 40.degree. C. for two hours to allow
sufficient time to establish strong interactions between both
phases. Adding the pre-polymer (RTV 615 A) and stirring the mixture
for another hour at 60.degree. C. to induce pre-polymerization.
Pouring the (PDMS/ZSM-5 CBV 3002) in a petri-dish and allowing the
solvent to evaporate for several hours and the resulting film was
cured at 100.degree. C. The content of the solid components (i.e.,
PDMS and filler) in the casting solution was 18.5 wt %. The RTV 615
A/B ratio for optimal polymer curing was 7 to compensate for the
loss of hydride groups due to their reaction with the surface
silanol groups on the zeolite (normally it is in a 10/1 ratio, as
proposed by the manufacturer to be the ratio for optimal
curing).
Means of Data-Storage Detection
[0130] Aspects of the present invention are also realized by a
method of writing optical data in a pattern on the data storage
medium of any of the previous claims comprising exposing
locoregional portions of the material, with at least one assembly
of small Au and/or Ag clusters confined a molecular sieve particle,
to radiation at a radiation power sufficient to cause such assembly
which absorbs the radiation to emit light photons and of
visualizing such stored optical data by reradiating them or by a
larger portion of the materials with lower radiation power
sufficient to only read the assemblies of small Au and/or Ag
clusters confined a molecular sieve which store the optical
data.
[0131] FIG. 2 shows a Scheme of the photoactivation of specific
patterns in an individual silver-exchanged zeolite crystal in order
to generate bar codes.
[0132] FIG. 4 demonstrates a) False color emission image of a
single silver-exchanged zeolite A crystal before photoactivation
(1) and after consecutive activation of three individual spots (2,
3 and 4) in one crystal by irradiation with a ps 375 nm laser at 10
W/cm.sup.2 during 20 minutes for each spot through a confocal
microscope. b) Total activation of a single crystal. (1) shows the
crystal before activation. After 5 min of irradiation by a 16.7
kW/cm.sup.2 pulsed 375 nm beam the intensity increased by a factor
10 (2). Another 20 minutes of activation at the same power yielded
a total intensity increase of a factor 20. Note the increased
scaling range from (1) to (3). The images in a) and b) were taken
by a confocal microscope under irradiation by a 375 nm pulsed
excitation source of respectively 10 and 20 W/cm.sup.2, with 2 ms
integration time per pixel. c) True color image taken with a
digital camera (Canon PowerShot A710 IS with a 400 nm longpass
filter in front of the lens to filter out the excitation light)
through the eye piece of the microscope showing the green emission
from the same zeolite after complete activation at 16.7 kW/cm.sup.2
excitation power.
[0133] Security images generally comprise an image which is
invisible or otherwise undetectable under ambient conditions or
which comprise optical information which is invisible or otherwise
undetectable under ambient conditions, and which can be rendered
visible or detectable by application of a suitable stimulus; or
alternatively, the image may change from one color under ambient
conditions to another color upon application of a stimulus. A
stimulus suitable for the materials of present invention is for
instance voltage, electromagnetic radiation, UV radiation or
radiation with light at a wavelength below 400 nm to induce a
wavelength switch to the lower wavelengths.
[0134] Articles, which include security images, are useful in many
areas of industry, for example in packaging, identification cards,
biolabels and labels. Such articles may comprise a further printed
image, in addition to the security image. It is useful to provide
packaging which includes a security image invisible to a user under
ambient conditions, but which can be rendered visible upon
application of a stimulus; for example, if a customs and excise
official wishes to check whether imported goods are genuine or
counterfeit or simply want a radiation means or radiation element
to automatically trace a particular items with the data storage
image among other items that are not for seen of the optical
information image. If the packaging includes the security image,
rendered visible or otherwise detectable by a suitable stimulus,
the customs and excise official can determine that the packaging,
and hence the goods, are not counterfeit. Likewise, it is
advantageous to provide an identification card in which a security
image is invisible or a defined color under ambient conditions, but
which can be rendered visible or detectable, or change color upon
application of a stimulus in order to prove the identity of a user
of the identity card, in order to determine that the identity card
is genuine. For instance in the manufacture of bank notes, it is
desirable to include as many security features as possible, which
may include multiple security images using a variety of compounds
capable of changing color upon application of a stimulus or stimuli
(including movement of the bank note to change viewing angle), or
turning colored from colorless, or vice versa. The advantage of
present invention is that the microporous materials can be
integrated in fibres which can be integrated in the fibre mixing
process during production of such security documents or
banknotes.
Uses of Molecular Sieves with Oligo Atomic Silver Clusters Confined
Therein as 3D Encodable Microcarriers
[0135] The extraordinary photostability of the formed clusters and
the enhanced 3D-resolution due to 2-photon excitation allows the
creation of several layers of advanced matrix codes such as the 2D
MaxiCodes and QR-codes inside an individual molecular sieve
crystal, such as a zeolite crystal. Moreover, they are compatible
with water. This makes them suitable for use in applications such
as multiplex (bio)assays, high-throughput screening methods, in
safety and quality labels to prevent counterfeiting. Furthermore,
encoded silver zeolites can, for example be mixed in drug powders
to serve as a built-in certificate of authenticity.
[0136] According to a preferred embodiment of the method, according
to the present invention, the method according further comprises
the step of attaching said data-wise exposed oligo-atomic metal
clusters confined in a molecular sieve to a support as an
identifying tag.
[0137] According to another preferred embodiment of the method,
according to the present invention, the method further comprises
the step of adding said data-wise exposed oligo-atomic metal
clusters confined in a molecular sieve to a liquid medium as an
identifying tag.
[0138] According to another preferred embodiment of the method,
according to the present invention, the method further comprises
the step of adding said data-wise exposed oligo-atomic metal
clusters confined in a molecular sieve to a plurality of particles
as an identifying tag.
[0139] According to another preferred embodiment of the method,
according to the present invention, the oligo-atomic metal clusters
confined in a single molecular sieve crystal is attached to a
molecule.
INDUSTRIAL APPLICATION
[0140] The present invention concerns the field of data storage
materials for use as, e.g., bio-labels, and for related
applications, comprising, e.g., white light and colored luminescent
materials with emission of visible white or colored light at or
above room temperature in which the luminescent intensity can be
increased by the irradiation of light. The optical data storage
compositions with the data carrying porous structures of present
invention can be attached or integrated on articles to provide such
articles with for instance a security image or a bio-label.
EXAMPLES
Example 1
Preparation and Methods
[0141] Various methods for the production of metal ion exchanged
molecular sieves are available in the art. A method similar to that
described by Jacobs et al. (Jacobs, P. A. & Uytterhoeven, J.
B., 1979, Journal of the Chemical Society-Faraday Transactions 175,
56-64) was used for incorporating silver ions in molecular sieves
and creating silver clusters. However many parameters like loading
percentage of the zeolites, exchange time, length of temperature
treatment, initial, gradient and final temperature of the
temperature treatment, presence of gasses during the temperature
treatment (e.g. in vacuum, in presence of oxygen, in presence of
oxygen and nitrogen, in presence of hydrogen, in presence of CO
and/or CO.sub.2 gas) and the presence of moisture in the air
influences the finally formed types of clusters, oxidation state of
the clusters and distribution and polydispersity of the types of
clusters formed.
[0142] A typical procedure goes as follows: Zeolite 3A (Union
Carbide; 500 mg) was suspended in 100 mL MQ-water containing
13.+-.1 weight percent of silver nitrate (8.+-.1% Ag). After
stirring in the dark for 2 hours the ion exchange (.+-.17% of the
zeolite's cation exchange capacity) was stopped. The material was
poured on a Buchner filter and extensively washed with MQ-water.
This washing stepped proved a quantitative silver exchange since no
precipitation with chlorides was observed in the washing water. The
recovered white powder on top of the filter was heated gently until
450.degree. C. for 1 day with 5 minute stops at 50.degree. C.,
70.degree. C., 90.degree. C. and 110.degree. C. to avoid damaging
of the zeolite structure. After this heat treatment a white to
sometimes slightly yellowish powder was obtained. The powder was
stored in the dark under dry atmosphere.
Example 2
Emission
[0143] It was demonstrated that metal ion clusters especially
silver in confined molecular sieves have a distinct and tunable
emission throughout the VIS and NIR part of the electromagnetic
spectrum while they are all excitable in the UV region. Thanks to
the host matrix the confined metal clusters are prevented from
aggregation with each other to form bigger non-emissive
nanoparticles. Also they can be shielded from the outside
environment (e.g., oxygen) if required by adding a silicon coating
around the molecular sieves.
Example 3
Photoactivation of Individual Spots within an Individual
Silver-Exchanged Zeolite Crystal
Writing Patterns Inside the Zeolite Crystals
[0144] By irradiation with picoseconds pulsed 375 nm laser light of
selected spots inside a silver-exchanged zeolite crystal,
synthesized as described in example 1, using a confocal microscope
setup, highly emissive silver clusters are formed inside a
diffraction limited area, induced by the applied excitation source,
giving rise to a strongly enhanced fluorescence (up to 200 times)
from these selected spots. Typical irradiation powers for
activation are 10 to 10,000 W/cm.sup.2 for photoactivation, whereas
irradiation times vary from a 10 seconds for 10,000 W/cm.sup.2 to
1200 seconds for irradiation at 10 W/cm.sup.2.
[0145] By scanning the sample using a lower power (0.1 to 10
W/cm.sup.2), the photoactivated areas are easily recognized by
their bright emission without further photoactivation during the
scanning process.
Example 4
Tunable Color of Excitation and Emission of the Visible Emission
Source
[0146] The molecular sieves containing the oligo atomic clusters
can be excited by UV light resulting in emission in the visible
range as described in Example 3. However by changing or tuning the
excitation wavelength or by using multiple excitation wavelengths
coming from one or multiple sources and by tuning the different
ratios of excitation power between the different wavelengths, it is
possible to tune the color of the visible emission. In this way one
could have one emissive device which output color can be tuned by
the end user. This effect can be achieved by using different oligo
atomic clusters in the molecular sieves that have a different
emissive response on different UV wavelengths. An example of this
was synthesized where irradiation of the materials with 360 nm
light resulted in blue emission while exciting at 254 nm resulted
in yellow emission. If one excites with the two wavelengths, 254 nm
and 360 nm at same time and by changing the ratios of excitation
power, one creates a whole range of emission colors between blue
and yellow and all the possible sum colors.
Example 5
Bright Emissive Markers
[0147] Since the oligo atomic clusters containing molecular sieves
are a bright emissive material, consisting of generally micrometer
or submicrometer sized crystals, one can use these small crystals
as bright emissive markers. Especially when they are smaller than
100 nm they can be used as alternatives for fluorescent beads or
quantum dots.
Example 6
Read/Write
1. How to Write in the Material:
[0148] A high-intensity 375 nm ps pulsed laser beam is focused
through a confocal microscope on the material (the setup is
explained in more detail below). Lower laser intensity can be
compensated by a much longer irradiation time. For instance at 0.01
kW/cm.sup.2, an irradiation time of 1200 seconds is necessary,
whereas 10 seconds is sufficient when using 10 kW/cm.sup.2.
2. How to Read Data from the Material:
[0149] The same microscope with the same laser source is used to
map the emission of the crystal. However, much lower excitation
power is applied. Typically, the sample is scanned using an
excitation power of 0.1 till 10 W/cm.sup.2. Read out times of only
0.1-10 ms are necessary.
Example 7
Excitation by an Electrical Field and Emission of the Visible
Emission Source
[0150] A 3A zeolite was exchanged with silver (10% weight) and then
thermally treated (24 hours at 450.degree. C.) resulting in a
partial reduction and formation of small silver clusters in the
host matrix. 0.4 mg of these silver loaded zeolites were added to 1
ml of a 20 mg/ml PVK (poly-N-vinylcarbazole) in chlorobenzene
solution. From this solution a film was spincoated on an ITO
covered glass substrate. Ytterbium was then evaporated through a
patterning mask on the spincoated film as a second electrode. After
applying an electric field over this device, in which ITO
functioned as anode and ytterbium as cathode, red
electroluminescence was observed. The emission spectrum of this
electroluminescence is shown in FIG. 5. The synthesis of the oligo
metal clusters with the desired emissive properties can be tuned by
changing the synthesis parameters.
Example 8
Preparation of a Heated-Treated Ag.sub.x, K-A Zeolite
[0151] Large LTA-type crystals were obtained by employing the
following reactants: sodium hydroxide pellets (99.9%, Riedel de
Haen), Al powder (Fluka), triethanolamine (Aldrich), fumed silica
(Degussa) and distilled water. In a typical preparation A sodium
aluminate solution was prepared by dissolution of aluminum powder
(Fluka) in sodium hydroxide solution. A mixture of triethanolamine
and water was mixed with sodium aluminate solution and stirred for
5 minutes at room temperature. The silica source (fumed silica,
Degussa) was then added to the mixture stirred at room temperature
for 1 h. The synthesis was performed at 95.degree. C. for 10 days.
The solid was recovered by suction filtration and dried at
80.degree. C. overnight. The zeolite crystals obtained were first
exchanged with K.sup.+ ions by stirring an aqueous suspension of
the zeolites in the presence of an excess of KNO.sub.3 for 1 day.
After filtration and washing, the zeolites were suspended in 100 mL
MQ-water containing 13.+-.1 weight percent of silver nitrate
(8.+-.1% wt.sub.Ag/wt.sub.zeolite). After stirring in the dark for
2 hours the ion exchange (.+-.17% of the zeolite's cation exchange
capacity) was stopped. The material was poured on a Buchner filter
and extensively washed with MQ-water. This washing step provided
proof of a quantitative silver exchange since no precipitation with
chlorides was observed in the washing water. The recovered white
powder was dried at 110.degree. C. for 1 day giving a white powder.
The white powder was stored in the dark in a dry atmosphere.
Example 9
2-Photon Photoactivation Process in the Silver Zeolite Prepared in
Example 8
[0152] Emissive patterns were written in individual silver zeolite
crystals by excitation with a femtosecond pulsed (80 MHz) 780 nm
laser (Mai Tai, SpectraPhysics). The excitation light, circularly
polarized by use of a Berek polarization compensator (New Focus),
was directed using a dichroic beam splitter into the oil-immersion
objective (Olympus, 1.3 N.A., 100.times.) of an inverted
fluorescence microscope (Olympus IX70) equipped with a
piezo-controlled scanning stage (Physics Instruments). The
excitation power was adjusted with a neutral density wheel at the
entrance port of the microscope. Typical excitation powers for
writing the patterns were of the order of 400 kW/cm.sup.2. Typical
irradiation times of 250 ms per pixel were sufficient for writing
patterns with a good contrast ratio. A home built-software was used
to direct the piezo stage scanner for writing the patterns.
[0153] The image in FIG. 6a was imaged using the same setup as
described above. The fluorescence was collected by the same
objective, guided through a pinhole of 100 .mu.m diameter, filtered
and focused onto an avalanche photo-diode (SPCMAQ-15, EG & G
Electro Optics). The scanning images were obtained using a reduced
excitation power of about 50 kW/cm.sup.2 to avoid further
photoactivation during the scanning process and for each pixel the
intensity was integrated over 2 ms.
[0154] FIGS. 6d, 7 and 8 were obtained by transferring the sample
to a FluoView 500 confocal fluorescence microscope (Olympus). The
fluorescence signal generated by a 488 nm Ar.sup.+ continuous wave
laser (Spectra Physics) was detected using a photo-multiplier tube
(PMT) after passing a dichroic mirror (488 nm) and a 505 nm long
pass filter. The pinhole was set to 100 .mu.m to ensure a good
axial resolution.
[0155] FIG. 6a shows the image of the flag of the Flemish community
written into an individual silver-exchanged zeolite A particle with
dimensions of approximately 20.times.20.times.20 .mu.m.sup.3 using
a femtosecond pulsed 780 nm laser focused on the sample through a
confocal fluorescence microscope. The image is written on a plane
buried 2.5 .mu.m inside the zeolite.
[0156] FIG. 6b shows the template image of 80 by 80 pixels, which
was fed into the home-built software used to steer the sample over
the focussed laser. The intensity of every pixel was translated by
the software to the laser exposure time (0 ms for a black pixel to
255 ms laser exposure for a completely white pixel). After
photoactivation, the written pattern was imaged using the same
setup, but with reduced excitation power (less than 100
kW/cm.sup.2) to avoid further activation. Even the fine details of
the image, such as the tongue of the lion, are well resolved,
yielding a realistic replication of the original template on a
scale of .+-.17.times.17 .mu.m.sup.2.
[0157] By controlling the photoactivation time, different intensity
levels can be obtained within one image, allowing grey scale images
to be stored inside the zeolite particles. This is illustrated in
FIG. 1c, where an intensity profile along the white dashed line of
FIG. 1a is shown (black curve), together with the corresponding
profile of the template image (grey curve). The tongue of the lion,
which is grey in the template image, indeed has about half the
fluorescence intensity of the other activated regions. The
possibility of distinguishing different intensity levels provides
an additional parameter that greatly increases the amount of unique
accessible codes within one individual crystal.
[0158] The written pattern in FIG. 1a almost spans the entire
xy-plane of the crystal and yet all the white parts of the image
are activated to a similar extent. This implies on the one hand
that the silver is well dispersed throughout the whole crystal and
on the other hand that the 2-photon excitation approach is not very
sensitive towards small particles adsorbed on the outer surface and
heterogeneities and crystal imperfections which are mostly present
in large zeolite crystals. With 1-photon activation, writing such a
large pattern would be considerably hampered by the many scattering
sites on the outer surface, resulting in zones with high background
activation.
[0159] To estimate the writing resolution, three thin bar patterns
with varying inter-bar spacings were written in the zeolites (FIG.
6d). As the bars of the template image have an infinitely small
width, the width of the resulting activated area directly reflects
the spatial resolution. FIG. 6e shows the integrated intensity
profile along the x-dimension of the area between the dashed lines
in FIG. 6d. The profile reveals that bars separated by as little as
500 nm are still resolvable and that the full width at half maximum
(FWHM.sub.image,xy) of one bar is below 500 nm. The Gaussian
profile obtained is, however, in fact the convolution of the
written area and the Gaussian-shaped point-spread-function (psf)
for imaging. Upon deconvolution a writing resolution of 444 nm was
obtained.
[0160] The 2-photon excitation approach particularly confines the
region of cluster formation in the axial dimension, allowing for
the writing of three-dimensional images. FIG. 2a shows the
fluorescence images at different focal planes inside a single
zeolite crystal in which the letters "K", "U" and "L", the
abbreviation of our university, are written on top of each other
over a distance of scarcely 6 .mu.m using 2-photon excitation (780
nm).
[0161] Determining the axial resolution from this stack of images
along the z-axis is difficult since confocal microscopy has a
limited resolution for imaging along this dimension. One can thus
not know whether the obtained resolution is determined by the
writing or the reading resolution. To circumvent this problem the
crystal was mechanically flipped over on its side such that the xz
plane of writing now lies horizontal such that it can be imaged
with the higher radial resolution. FIG. 7b shows a slice of the
flipped crystal through the legs of the photoactivated letters "K",
"U" and "L", where it can be seen that the activated regions are
well resolved along the z-direction. Fitting the line profile as
indicated by the dashed lines yields a FWHM of 1 .mu.m (FIG. 7c).
This is well above the reading resolution of 213 nm and thus it
reflects the true writing resolution. To the best of our knowledge
such an axial resolution for encoding microcarriers is
unprecedented by optical light based techniques. Over a distance of
merely 6 .mu.m at least three resolved layers of information can
now be stored.
[0162] When photoactivation is performed using single-photon
excitation at 375 nm, the resolution is limited to about 636 nm in
the xy-plane and 4.3 .mu.m along the axial dimension in the case of
a smooth crystal without too many scattering sites. However, for
practical applications the surface of the zeolites will often be
functionalized to bind targets such as biological cells that can
cause some scattering of the activation light. In the case of
1-photon activation this would lead to strong scattering and as a
result worse resolution. As scattering is less of an issue in
2-photon photoactivation, this technique provides a major
improvement of the axial resolution by at least a factor 4, while
the radial resolution is enhanced by more than 30%. Moreover
2-photon photoactivation allows a more reproducible and homogeneous
photoactivation in the different zones of the crystal.
[0163] With the strongly improved three-dimensional resolution for
encoding data in microparticles, the creation of 3D
micro-structures comes within reach. A first attempt in this
direction is illustrated in FIG. 8, where a 3D-spiral structure is
activated over a depth of 7.5 .mu.m inside a single zeolite
crystal.
Example 10
2-Photon Photoactivation Process in Silver Zeolites in an Aqueous
Environment
[0164] For applying the encodable silver zeolites in multiplex
bio-assays, the photoactivation process must be compatible with
aqueous environments. Therefore a photoactivation experiment was
performed on a crystal after adding a few drops of water onto the
glass coverslip. Photoactivation was carried out on the FluoView
500 system using 1-photon excitation at 375 nm. The fluorescence
intensity time transient is shown in FIG. 9. Significant activation
clearly took place in the presence of bulk amount of water, the
water appearing not to influence the photoactivation process. The
activated area was imaged at 488 nm excitation. The left side of
FIG. 10 shows the fluorescence intensity image with the contours of
the crystals indicated by the dashed white lines, and the right
side of FIG. 10 shows the transmission image overlaid.
[0165] The processes of in situ encoding and decoding in the silver
zeolites are therefore compatible with an aqueous environment, and
the encoded patterns are stable over extended periods of time,
thanks to the steric confinement of the generated silver clusters
inside the zeolite cages and to the extraordinary photostability of
silver clusters in general.
[0166] This makes this material a potential alternative for use in
multiplex bio-assays. It was previously shown that after coating
encodable microparticles with a polyelectrolyte layer, cells can be
grown on the surface of those particles. For different cell types a
specific code can be written into the attached particle in order to
be able to identify the cell afterwards in the multiplex
experiment. A similar scheme is also feasible with zeolite
microcarriers. Moreover there is plenty of knowledge on introducing
functional groups at the outer surface of zeolites by simple
silanization chemistry or vapor deposition methods. Interactions
between functionalized zeolites and living systems have previously
been demonstrated by Z. Popovic in 2007 in Angew. Chem. Int. Ed.,
volume 46, pages 6188-6191.
[0167] All of this makes silver zeolites a versatile tool in many
kinds of (biological) high-throughput screening assays, multiplex
assays or as safety labels against counterfeiting. Moreover our
proposed method even has the potential for sub-diffraction limited
pattern writing. Indeed the combination of the non-linearity
between irradiation intensity and rate of cluster formation on the
one hand and the two-photon excitation approach on the other hand
strongly confines the actual region of cluster formation. If
scattering effects and effects from refractive index mismatches
between the different interfaces (glass-air-crystal) can be
eliminated, the writing of sub-diffraction limited patterns without
the need of complicated experimental setups, such as 4PI
microscopes, comes within reach.
* * * * *