U.S. patent application number 15/719338 was filed with the patent office on 2018-03-29 for additive manufacturing of architectured materials.
The applicant listed for this patent is California Institute of Technology. Invention is credited to Stephane J. Delalande, Julia R. Greer, Andrey Vyatskikh.
Application Number | 20180088462 15/719338 |
Document ID | / |
Family ID | 61687216 |
Filed Date | 2018-03-29 |
United States Patent
Application |
20180088462 |
Kind Code |
A1 |
Vyatskikh; Andrey ; et
al. |
March 29, 2018 |
ADDITIVE MANUFACTURING OF ARCHITECTURED MATERIALS
Abstract
This disclosure provides a scalable and reproducible process to
create complex 3D metal materials with sub-micron features by
applying lithographic methods to transparent metal- or
inorganic-rich polymer resins.
Inventors: |
Vyatskikh; Andrey; (Irvine,
CA) ; Delalande; Stephane J.; (Longpont sur Orge,
FR) ; Greer; Julia R.; (San Marino, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
California Institute of Technology |
Pasadena |
CA |
US |
|
|
Family ID: |
61687216 |
Appl. No.: |
15/719338 |
Filed: |
September 28, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62401039 |
Sep 28, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03F 7/40 20130101; G03F
7/2053 20130101; B33Y 10/00 20141201; G03F 7/0042 20130101; G03F
7/0037 20130101; G03F 7/0043 20130101; G03F 7/027 20130101 |
International
Class: |
G03F 7/004 20060101
G03F007/004; G03F 7/20 20060101 G03F007/20; G03F 7/40 20060101
G03F007/40; B33Y 10/00 20060101 B33Y010/00 |
Goverment Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] This invention was made with government support under Grant
No. N00014-16-1-2827 awarded by the Office of Naval Research. The
government has certain rights in the invention.
Claims
1. A composition comprising a hybrid organic-inorganic polymer
resin comprising photopolymerizable functional groups and having
the general structure: M.sup.n+(--R'OC--R).sub.n where M is a
metal, a metal ion, a metalloid, a metal alloy, a metal oxide, a
metal nitride, an inorganic, an inorganic-organic hybrid and/or
metal-inorganic composite material, wherein R is a C.sub.2-10
terminal alkene and R' is N, O, F, S or Cl and wherein n is 1, 2,
3, 4, 5 or 6.
2. The composition of claim 1, having the formula:
R--COR'-M.sup.2+-R'OC--R wherein M is a divalent metal ion, alloy,
or inorganic material, R is a C.sub.2-10 terminal alkene and R' is
N, O, F, S or Cl.
3. The composition of claim 1, wherein the metal ion is selected
from the group consisting of Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+,
Cs.sup.+, Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+,
Sc.sup.3+, Sc.sup.2+, Sc.sup.+, Y.sup.3+, Y.sup.2+, Y.sup.+,
Ti.sup.4+, Ti.sup.3+, Ti.sup.2+, Zr.sup.4+, Zr.sup.3+, Zr.sup.2+,
Hf.sup.4+, Hf.sup.3+, V.sup.5+, V.sup.4+, V.sup.3+, V.sup.2+,
Nb.sup.5+, Nb.sup.4+, Nb.sup.3+, Nb.sup.2+, Ta.sup.5+, Ta.sup.4+,
Ta.sup.3+, Ta.sup.2+, Cr.sup.6+, Cr.sup.5+, Cr.sup.4+, Cr.sup.3+,
Cr.sup.2+, Cr.sup.+, Cr, Mo.sup.6+, Mo.sup.5+, Mo.sup.4+,
Mo.sup.3+, Mo.sup.2+, Mo.sup.+, Mo, W.sup.6+, W.sup.5+, W.sup.4+,
W.sup.3+, W.sup.2+, W.sup.+, W, Mn.sup.7+, Mn.sup.6+, Mn.sup.5+,
Mn.sup.4+, Mn.sup.3+, Mn.sup.2+, Mn.sup.+, Re.sup.7+, Re.sup.6+,
Re.sup.5+, Re.sup.4+, Re.sup.3+, Re.sup.2+, Re.sup.+, Re,
Fe.sup.6+, Fe.sup.4+, Fe.sup.3+, Fe.sup.2+, Fe.sup.+, Fe,
Ru.sup.8+, Ru.sup.7+, Ru.sup.6+, Ru.sup.4+, Ru.sup.3+, Ru.sup.2+,
Os.sup.8+, Os.sup.7+, Os.sup.6+, Os.sup.5+, Os.sup.4+, Os.sup.3+,
Os.sup.2+, Os.sup.+, Os, Co.sup.5+, Co.sup.4+, Co.sup.3+,
Co.sup.2+, Co.sup.+, Rh.sup.6+, Rh.sup.5+, Rh.sup.4+, Rh.sup.3+,
Rh.sup.2+, Rh.sup.+, Ir.sup.6+, Ir.sup.5+, Ir.sup.4+, Ir.sup.3+,
Ir.sup.2+, Ir.sup.+, Ir, Ni.sup.3+, Ni.sup.2+, Ni.sup.+, Ni,
Pd.sup.6+, Pd.sup.4+, Pd.sup.2+, Pd.sup.+, Pd, Pt.sup.6+,
Pt.sup.5+, Pt.sup.4+, Pt.sup.3+, Pt.sup.2+, Pt.sup.+, Cu.sup.4+,
Cu.sup.3+, Cu.sup.2+, Cu.sup.+, Ag.sup.3+, Ag.sup.2+, Ag.sup.+,
Au.sup.5+, Au.sup.4+, Au.sup.3+, Au.sup.2+, Au.sup.+, Zn.sup.2+,
Zn.sup.+, Zn, Cd.sup.2+, Cd.sup.+, Hg.sup.4+, Hg.sup.2+, Hg.sup.+,
B.sup.3+, B.sup.2+, B.sup.+, Al.sup.3+, Al.sup.2+, Al.sup.+,
Ga.sup.3+, Ga.sup.2+, Ga.sup.+, In.sup.3+, In.sup.2+, In.sup.+,
Tl.sup.3+, Tl.sup.+, Si.sup.4+, Si.sup.+, Si.sup.2+, Si.sup.+,
Ge.sup.4+, Ge.sup.3+, Ge.sup.2+, Ge.sup.+, Ge, Sn.sup.4+,
Sn.sup.2+, Pb.sup.4+, Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.2+,
As.sup.+, Sb.sup.5+, Sb.sup.3+, Bi.sup.5+, Bi.sup.3+, Te.sup.6+,
Te.sup.5+, Te.sup.4+, Te.sup.2+, La.sup.+, La.sup.2+, Ce.sup.4+,
Ce.sup.3+, Ce.sup.2+, Pr.sup.4+, Pr.sup.3+, Pr.sup.2+, Nd.sup.3+,
Nd.sup.2+, Sm.sup.3+, Sm.sup.2+, Eu.sup.3+, Eu.sup.2+, Gd.sup.3+,
Gd.sup.2+, Gd.sup.+, Tb.sup.4+, Tb.sup.3+, Tb.sup.2+, Tb.sup.+,
Db.sup.3+, Db.sup.2+, Ho.sup.3+, Er.sup.3+, Tm.sup.4+, Tm.sup.3+,
Tm.sup.2+, Yb.sup.3+, Yb.sup.2+, Lu.sup.3+ and alloys of any of the
foregoing.
4. The composition of claim 1, wherein the inorganic is a single or
mixed oxide, carbide, nitride, silicate, boride of Ti, W, Si, Zr,
Al, Y, Cr, Fe, Pb, Co, Ce, Zn, or a rare earth element.
5. The composition of claim 4, wherein the inorganic is selected
from the group consisting of TiO.sub.2, AlO.sub.2, Al.sub.2O.sub.3,
ZrO.sub.2, SiC, SiO.sub.2, SiC, CeO.sub.2, and ZnO.
6. The composition of claim 1, wherein the composition further
comprises a photoinitiator or a photoinitiator and a monomer
capable of forming a polymer with the hybrid organic-inorganic
polymer.
7. The composition of claim 1, wherein the metal-inorganic
composite comprises Au--Ni--TiO.sub.2, Ni--Co--TiO.sub.2,
Ni--Zn--Al.sub.2O.sub.3, or Ni--B--TiO.sub.2.
8. A method for manufacturing a sub-micron architectural material,
comprising patterning a hybrid organic-inorganic polymer resin
comprising photopolymerizable functional groups and having the
general structure: M.sup.n+(--R'OC--R).sub.n where M is a metal, a
metal ion, a metalloid, a metal alloy, a metal oxide, a metal
nitride, an inorganic, an inorganic-organic hybrid and/or
metal-inorganic composite material, wherein R is a C.sub.2-10
terminal alkene and R' is N, O, F, S or Cl and wherein n is 1, 2,
3, 4, 5 or 6, in the presence of a photoinitiator using a single or
two photon lithography technique to polymerize the polymer resin
and generate the sub-micron architectural material having desired
characteristic dimension of about 5 nm to 5 micron across.
9. The method of claim 8, wherein the hybrid organic-inorganic
polymer resin has the formula R--COR'-M.sup.2+-R'OC--R, wherein M
is a divalent metal ion, alloy, or inorganic material, R is a
C.sub.2-10 terminal alkene and R' is N, O, F, S or Cl.
10. The method of claim 8, wherein the metal ion is selected from
the group consisting of Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+,
Cs.sup.+, Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+,
Sc.sup.3+, Sc.sup.2+, Sc.sup.+, Y.sup.3+, Y.sup.2+, Y.sup.+,
Ti.sup.4+, Ti.sup.3+, Ti.sup.2+, Zr.sup.4+, Zr.sup.3+, Zr.sup.2+,
Hf.sup.4+, Hf.sup.3+, V.sup.5+, V.sup.4+, V.sup.3+, V.sup.2+,
Nb.sup.5+, Nb.sup.4+, Nb.sup.+, Nb.sup.2+, Ta.sup.5+, Ta.sup.4+,
Ta.sup.3+, Ta.sup.2+, Cr.sup.6+, Cr.sup.5+, Cr.sup.4+, Cr.sup.3+,
Cr.sup.2+, Cr.sup.+, Cr, Mo.sup.6+, Mo.sup.5+, Mo.sup.4+,
Mo.sup.3+, Mo.sup.2+, Mo.sup.+, Mo, W.sup.6+, W.sup.5+, W.sup.4+,
W.sup.3+, W.sup.2+, W.sup.+, W, Mn.sup.7+, Mn.sup.6+, Mn.sup.5+,
Mn.sup.4+, Mn.sup.3+, Mn.sup.2+, Mn.sup.+, Re.sup.7+, Re.sup.6+,
Re.sup.5+, Re.sup.4+, Re.sup.3+, Re.sup.2+, Re.sup.+, Re,
Fe.sup.6+, Fe.sup.4+, Fe.sup.3+, Fe.sup.2+, Fe.sup.+, Fe, Ru.sup.+,
Ru.sup.7+, Ru.sup.6+, Ru.sup.4+, Ru.sup.3+, Ru.sup.2+, Os.sup.8+,
Os.sup.7+, Os.sup.6+, Os.sup.5+, Os.sup.4+, Os.sup.3+, Os.sup.2+,
Os.sup.+, Os, Co.sup.5+, Co.sup.4+, Co.sup.3+, Co.sup.2+, Co.sup.+,
Rh.sup.6+, Rh.sup.5+, Rh.sup.4+, Rh.sup.3+, Rh.sup.2+, Rh.sup.+,
Ir.sup.6+, Ir.sup.5+, Ir.sup.4+, Ir.sup.3+, Ir.sup.2+, Ir.sup.+,
Ir, Ni.sup.3+, Ni.sup.2+, Ni.sup.+ Ni, Pd.sup.6+, Pd.sup.4+,
Pd.sup.2+, Pd.sup.+, Pd, Pt.sup.6+, Pt.sup.5+, Pt.sup.4+,
Pt.sup.3+, Pt.sup.2+, Pt.sup.+, Cu.sup.4+, Cu.sup.3+, Cu.sup.2+,
Cu.sup.+, Ag.sup.3+, Ag.sup.2+, Ag.sup.+, Au.sup.5+, Au.sup.4+,
Au.sup.3+, Au.sup.2+, Au.sup.+, Zn.sup.2+, Zn.sup.+, Zn, Cd.sup.2+,
Cd.sup.+, Hg.sup.4+, Hg.sup.2+, Hg.sup.+, B.sup.3+, B.sup.2+,
B.sup.+, Al.sup.3+, Al.sup.2+, Al.sup.+, Ga.sup.3+, Ga.sup.2+,
Ga.sup.+, In.sup.3+, In.sup.2+, In.sup.+, Tl.sup.3+, Tl.sup.+,
Si.sup.4+, Si.sup.3+, Si.sup.2+, Si.sup.+, Ge.sup.4+, Ge.sup.+,
Ge.sup.2+, Ge.sup.+, Ge, Sn.sup.4+, Sn.sup.2+, Pb.sup.4+,
Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.2+, As.sup.+, Sb.sup.5+,
Sb.sup.3+, Bi.sup.5+, Bi.sup.3+, Te.sup.6+, Te.sup.5+, Te.sup.4+,
Te.sup.2+, La.sup.3+, La.sup.2+, Ce.sup.4+, Ce.sup.3+, Ce.sup.2+,
Pr.sup.4+, Pr.sup.3+, Pr.sup.2+, Nd.sup.3+, Nd.sup.2+, Sm.sup.3+,
Sm.sup.2+, Eu.sup.3+, Eu.sup.2+, Gd.sup.+, Gd.sup.2+, Gd.sup.+,
Tb.sup.4+, Tb.sup.3+, Tb.sup.2+, Tb.sup.+, Db.sup.3+, Db.sup.2+,
Ho.sup.3+, Er.sup.3+, Tm.sup.4+, Tm.sup.+, Tm.sup.2+, Yb.sup.3+,
Yb.sup.2+, Lu.sup.3+ and alloys of any of the foregoing.
11. The method of claim 8, wherein the inorganic is a single or
mixed oxide, carbide, nitride, silicate, boride of Ti, W, Si, Zr,
Al, Y, Cr, Fe, Pb, Co, or a rare earth element.
12. The method of claim 11, wherein the inorganic is selected from
the group consisting of TiO.sub.2, AlO.sub.2, Al.sub.2O.sub.3,
ZrO.sub.2, SiC, SiO.sub.2, SiC, CeO.sub.2, and ZnO.
13. The method of claim 8, wherein the metal-inorganic composite
comprises Au--Ni--TiO.sub.2, Ni--Co--TiO.sub.2,
Ni--Zn--Al.sub.2O.sub.3, or Ni--B--TiO.sub.2.
14. The method of claim 8, further comprising removing
non-polymerized resin.
15. The method of claim 8, further comprising pyrolizing the
sub-micron architectural material to remove organic material.
16. The method of claim 15, wherein the pyrolizing comprises a
two-step pyrolysis technique to remove organic material followed by
removing oxygen.
17. The method of claim 15, wherein the sub-micron architectural
material comprises a metal, a metalloid and/or an inorganic
structure having a dimension across an axis of a metal, a metalloid
and/or a inorganic strut, beam or joint of less than 1 micron.
18. A device comprising the sub-micron architectural material made
by the method of claim 8, wherein the device comprises a metal, a
metalloid, and/or an inorganic scaffold free of organic material
having a strut radial dimension of less than 1 micron.
19. The device of claim 18, wherein the device comprises
titania.
20. The device of claim 18, wherein the device is an electrode,
photocell, filter, circuit, water purification device or nanocage.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 62/401,039, filed Sep. 28, 2016, which is
incorporated herein in its entirety for any and all purposes.
FIELD
[0003] The invention relates to methods of manufacturing micro- and
nano-scaled materials.
BACKGROUND
[0004] Methods for additive manufacturing (AM) of metals are
limited to 20-50 .mu.m resolution, which renders them inapplicable
for generating complex 3D-printed metals with smaller features.
Efforts have been devoted to fabricating metal structures with
smaller dimensions; today no established 3D-printing of metals
exists at the micron scale.
SUMMARY
[0005] The disclosure provides a lithography-based process to
create complex 3D nano- and/or micro-architected materials
comprising metals, metal ions, metalloids, inorganic, and
inorganic-organic hybrid materials ("framework materials") with
about 5 to 100 nm resolution. The process uses a photopolymerizable
resist containing the framework material. The process uses, for
example, a two-photon lithography technique to sculpt 3D polymer
scaffolds. These scaffolds can then be heat treated (e.g.,
pyrolyzed) to volatilize any organics, thereby leaving the
framework material in a desired architectural format. Using the
method, the disclosure provides the ability to produce 3D-printed
micro- and nano-architected material including, for example, metal
frameworks and structures.
[0006] The disclosure provides a composition comprising a hybrid
organic-inorganic polymer resin comprising photopolymerizable
functional groups having the general structure:
M.sup.n+(--R'OC--R).sub.n
where M is a metal, a metal ion, a metalloid, a metal alloy, a
metal oxide, a metal nitride, an inorganic, a metal-inorganic
composite, a carbon-based material and/or an inorganic-organic
hybrid material, wherein R is an alkene or a C.sub.2-10 terminal
alkene and R' is N, O, F, S or Cl and wherein n is 1, 2, 3, 4, 5 or
6. In one embodiment, the hybrid organic-inorganic polymer resin
has the formula R--COR'-M.sup.2+-R'OC--R, wherein M is a divalent
metal ion, alloy, or inorganic material, R is an alkene or
C.sub.2-10 terminal alkene and R' is N, O, F, S or Cl. In another
embodiment, the metal ion is selected from the group consisting of
Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, Be.sup.2+,
Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Sc.sup.3+, Sc.sup.2+,
Sc.sup.+, Y.sup.3+, Y.sup.2+, Y.sup.+, Ti.sup.4+, Ti.sup.3+,
Ti.sup.2+, Zr.sup.4+, Zr.sup.3+, Zr.sup.2+, Hf.sup.4+, Hf.sup.3+,
V.sup.5+, V.sup.4+, V.sup.3+, V.sup.2+, Nb.sup.5+, Nb.sup.4+,
Nb.sup.3+, Nb.sup.2+, Ta.sup.5+, Ta.sup.4+, Ta.sup.3+, Ta.sup.2+,
Cr.sup.6+, Cr.sup.5+, Cr.sup.4+, Cr.sup.3+, Cr.sup.2+, Cr.sup.+,
Cr, Mo.sup.6+, Mo.sup.5+, Mo.sup.4+, Mo.sup.3+, Mo.sup.2+,
Mo.sup.+, Mo, W.sup.6+, W.sup.5+, W.sup.4+, W.sup.3+, W.sup.2+,
W.sup.+, W, Mn.sup.7+, Mn.sup.6+, Mn.sup.5+, Mn.sup.4+, Mn.sup.3+,
Mn.sup.2+, Mn.sup.+, Re.sup.7+, Re.sup.6+, Re.sup.5+, Re.sup.4+,
Re.sup.3+, Re.sup.2+, Re.sup.+, Re, Fe.sup.6+, Fe.sup.4+,
Fe.sup.3+, Fe.sup.2+, Fe.sup.+, Fe, Ru.sup.8+, Ru.sup.7+,
Ru.sup.6+, Ru.sup.4+, Ru.sup.3+, Ru.sup.2+, Os.sup.8+, Os.sup.7+,
Os.sup.6+, Os.sup.5+, Os.sup.4+, Os.sup.3+, Os.sup.2+, Os.sup.+,
Os, Co.sup.5+, Co.sup.4+, Co.sup.3+, Co.sup.2+, Co.sup.+,
Rh.sup.6+, Rh.sup.5+, Rh.sup.4+, Rh.sup.3+, Rh.sup.2+, Rh.sup.+,
Ir.sup.6+, Ir.sup.5+, Ir.sup.4+, Ir.sup.3+, Ir.sup.2+, Ir.sup.+,
Ir, Ni.sup.3+, Ni.sup.2+, Ni.sup.+, Ni, Pd.sup.6+, Pd.sup.4+,
Pd.sup.2+, Pd.sup.+, Pd, Pt.sup.6+, Pt.sup.5+, Pt.sup.4+,
Pt.sup.3+, Pt.sup.2+, Pt.sup.+, Cu.sup.4+, Cu.sup.3+, Cu.sup.2+,
Cu.sup.+, Ag.sup.3+, Ag.sup.2+, Ag.sup.+, Au.sup.5+, Au.sup.4+,
Au.sup.3+, Au.sup.2+, Au.sup.+, Zn.sup.2+, Zn.sup.+, Zn, Cd.sup.2+,
Cd.sup.+, Hg.sup.4+, Hg.sup.2+, Hg.sup.+, B.sup.3+, B.sup.2+,
B.sup.+, Al.sup.+, Al.sup.2+, Al.sup.+, Ga.sup.3+, Ga.sup.2+,
Ga.sup.+, In.sup.3+, In.sup.2+, In.sup.1+, Tl.sup.3+, Tl.sup.+,
Si.sup.4+, Si.sup.3+, Si.sup.2+, Si.sup.+, Ge.sup.4+, Ge.sup.3+,
Ge.sup.2+, Ge.sup.+, Ge, Sn.sup.4+, Sn.sup.2+, Pb.sup.4+,
Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.2+, As.sup.+, Sb.sup.5+,
Sb.sup.3+, Bi.sup.5+, Bi.sup.3+, Te.sup.6+, Te.sup.5+, Te.sup.4+,
Te.sup.2+, La.sup.3+, La.sup.2+, Ce.sup.4+, Ce.sup.3+, Ce.sup.2+,
Pr.sup.4+, Pr.sup.3+, Pr.sup.2+, Nd.sup.3+, Nd.sup.2+, Sm.sup.3+,
Sm.sup.2+, Eu.sup.3+, Eu.sup.2+, Gd.sup.3+, Gd.sup.2+, Gd.sup.+,
Tb.sup.4+, Tb.sup.3+, Tb.sup.2+, Tb.sup.+, Db.sup.3+, Db.sup.2+,
Ho.sup.3+, Er.sup.3+, Tm.sup.4+, Tm.sup.3+, Tm.sup.2+, Yb.sup.3+,
Yb.sup.2+, Lu.sup.3+ and alloys of any of the foregoing. In another
embodiment, the inorganic is a single or mixed oxide, carbide,
nitride, silicate, boride of Ti, W, Si, Zr, Al, Y, Cr, Fe, Pb, Co,
Ce, Zn, or a rare earth element. In another embodiment, the
inorganic material is selected from the group consisting of
TiO.sub.2, AlO.sub.2, Al.sub.2O.sub.3, ZrO.sub.2, SiC, SiO.sub.2,
SiC, CeO.sub.2, and ZnO. In another embodiment, the metal-inorganic
composite material comprises Au--Ni--TiO.sub.2, Ni--Co--TiO.sub.2,
Ni--Zn--Al.sub.2O.sub.3, or Ni--B--TiO.sub.2. In another
embodiment, of any of the foregoing, the composition further
comprises a photoinitiator or a photoinitiator and a monomer
capable of forming a polymer with the hybrid organic-inorganic
polymer.
[0007] The disclosure also provides a method for manufacturing a
sub-micron architectural material, comprising patterning a hybrid
organic-inorganic polymer resin comprising photopolymerizable
functional groups having the general structure:
M.sup.n+(--R'OC--R).sub.n
where M is a metal, a metal ion, a metalloid, a metal alloy, a
metal oxide, a metal nitride, an inorganic, an inorganic-organic
hybrid a carbon-based material and/or a metal-inorganic composite
material, wherein R is an alkene or C.sub.2-10 terminal alkene and
R' is N, O, F, S or Cl and wherein n is 1, 2, 3, 4, 5 or 6, wherein
the patterning occurs in the presence of a photoinitiator using a
single or two photon lithography technique to polymerize the
polymer resin and generate the sub-micron architectural material
having desired characteristic dimension of about 5 nm to 5 microns
across. In one embodiment, the hybrid organic-inorganic polymer
resin has the formula R--COR'-M.sup.2+-R'OC--R, wherein M is a
divalent metal ion, alloy, or inorganic material, R is an alkene or
a C.sub.2-10 terminal alkene and R' is N, O, F, S or Cl. In another
embodiment, the metal ion is selected from the group consisting of
Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+, Cs.sup.+, Be.sup.2+,
Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Sc.sup.3+, Sc.sup.2+,
Sc.sup.+, Y.sup.3+, Y.sup.2+, Y.sup.+, Ti.sup.4+, Ti.sup.3+,
Ti.sup.2+, Zr.sup.4+, Zr.sup.3+, Zr.sup.2+, Hf.sup.4+, Hf.sup.3+,
V.sup.5+, V.sup.4+, V.sup.3+, V.sup.2+, Nb.sup.5+, Nb.sup.4+,
Nb.sup.3+, Nb.sup.2+, Ta.sup.5+, Ta.sup.4+, Ta.sup.3+, Ta.sup.2+,
Cr.sup.6+, Cr.sup.5+, Cr.sup.4+, Cr.sup.3+, Cr.sup.2+, Cr.sup.+,
Cr, Mo.sup.6+, Mo.sup.5+, Mo.sup.4+, Mo.sup.3+, Mo.sup.2+,
Mo.sup.+, Mo, W.sup.6+, W.sup.5+, W.sup.4+, W.sup.3+, W.sup.2+,
W.sup.+, W, Mn.sup.7+, Mn.sup.6+, Mn.sup.5+, Mn.sup.4+, Mn.sup.3+,
Mn.sup.2+, Mn.sup.+, Re.sup.7+, Re.sup.6+, Re.sup.5+, Re.sup.4+,
Re.sup.3+, Re.sup.2+, Re.sup.+, Re, Fe.sup.6+, Fe.sup.4+,
Fe.sup.3+, Fe.sup.2+, Fe.sup.+, Fe, Ru.sup.8+, Ru.sup.7+,
Ru.sup.6+, Ru.sup.4+, Ru.sup.3+, Ru.sup.2+, Os.sup.8+, Os.sup.7+,
Os.sup.6+, Os.sup.5+, Os.sup.4+, Os.sup.3+, Os.sup.2+, Os.sup.+,
Os, Co.sup.5+, Co.sup.4+, Co.sup.3+, Co.sup.2+, Co.sup.+,
Rh.sup.6+, Rh.sup.5+, Rh.sup.4+, Rh.sup.3+, Rh.sup.2+, Rh.sup.+,
Ir.sup.6+, Ir.sup.5+, Ir.sup.4+, Ir.sup.3+, Ir.sup.2+, Ir.sup.+,
Ir, Ni.sup.3+, Ni.sup.2+, Ni.sup.+, Ni, Pd.sup.6+, Pd.sup.4+,
Pd.sup.2+, Pd.sup.+, Pd, Pt.sup.6+, Pt.sup.5+, Pt.sup.4+,
Pt.sup.3+, Pt.sup.2+, Pt.sup.+, Cu.sup.4+, Cu.sup.3+, Cu.sup.2+,
Cu.sup.+, Ag.sup.3+, Ag.sup.2+, Ag.sup.+, Au.sup.5+, Au.sup.4+,
Au.sup.3+, Au.sup.2+, Au.sup.+, Zn.sup.2+, Zn.sup.+, Zn, Cd.sup.2+,
Cd.sup.+, Hg.sup.4+, Hg.sup.2+, Hg.sup.+, B.sup.3+, B.sup.2+,
B.sup.+, Al.sup.3+, Al.sup.2+, Al.sup.+, Ga.sup.3+, Ga.sup.2+,
Ga.sup.+, In.sup.3+, In.sup.2+, In.sup.1+, Tl.sup.3+, Tl.sup.+,
Si.sup.4+, Si.sup.3+, Si.sup.2+, Si.sup.+, Ge.sup.4+, Ge.sup.3+,
Ge.sup.2+, Ge.sup.+, Ge, Sn.sup.4+, Sn.sup.2+, Pb.sup.4+,
Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.2+, As.sup.+, Sb.sup.5+,
Sb.sup.3+, Bi.sup.5+, Bi.sup.3+, Te.sup.6+, Te.sup.5+, Te.sup.4+,
Te.sup.2+, La.sup.3+, La.sup.2+, Ce.sup.4+, Ce.sup.3+, Ce.sup.2+,
Pr.sup.4+, Pr.sup.3+, Pr.sup.2+, Nd.sup.3+, Nd.sup.2+, Sm.sup.3+,
Sm.sup.2+, Eu.sup.3+, Eu.sup.2+, Gd.sup.3+, Gd.sup.2+, Gd.sup.+,
Tb.sup.4+, Tb.sup.3+, Tb.sup.2+, Tb.sup.+, Db.sup.3+, Db.sup.2+,
Ho.sup.3+, Er.sup.3+, Tm.sup.4+, Tm.sup.3+, Tm.sup.2+, Yb.sup.3+,
Yb.sup.2+, Lu.sup.3+ and alloys of any of the foregoing. In another
embodiment, the inorganic is a single or mixed oxide, carbide,
nitride, silicate, boride of Ti, W, Si, Zr, Al, Y, Cr, Fe, Pb, Co,
or a rare earth element. In another embodiment, the inorganic is
selected from the group consisting of TiO.sub.2, AlO.sub.2,
Al.sub.2O.sub.3, ZrO.sub.2, SiC, SiO.sub.2, SiC, CeO.sub.2, and
ZnO. In still another embodiment, the metal-inorganic composite
comprises Au--Ni--TiO.sub.2, Ni--Co--TiO.sub.2,
Ni--Zn--Al.sub.2O.sub.3, or Ni--B--TiO.sub.2. The method can
further comprise removing non-polymerized resin. The method can yet
further comprise, or alternatively comprise, pyrolizing the
sub-micron architectural material to remove organic material. In
one embodiment, the pyrolizing comprises a two-step pyrolysis
technique to remove organic material followed by removing oxygen.
In another embodiment, the sub-micron architectural material
comprises a metal, a metalloid and/or an inorganic structure having
a dimension across an axis of a metal, a metalloid and/or an
inorganic material strut, beam or joint of less than 1 micron.
[0008] The disclosure also provides a device comprising the
sub-micron architectural material made by a method of the
disclosure wherein the device comprises a metal, a metalloid,
and/or an inorganic scaffold that is free of organic material
having a strut, beam or joint cross axis dimension (e.g., a radial
dimension) of less than 1 micron. In one embodiment, the device
device comprises titania. In another embodiment, the device is an
electrode, photocell, filter, circuit, water purification device or
nanocage.
BRIEF DESCRIPTION OF THE FIGURES
[0009] FIG. 1A-J shows a process for nanoscale additive
manufacturing of metals and SEM characterization of the fabricated
samples. (A) Ligand exchange reaction used to synthesize metal
precursor with cross-linking functionality. (B) Metal precursor,
acrylic resin, and photoinitiator are mixed to form a transparent
metal-containing photoresist. (C) Schematic of two-photon
lithography (TPL) process used to sculpt the scaffold. (D)
Schematic of fabrication of metal-containing polymer part that is
(E) pyrolized to remove organic content and to convert the polymer
into a metal. SEM images of (F-H) a representative octet lattice
made out of a nickel-containing polymer at different magnifications
and (I), (J) a representative nickel nanolattice after pyrolysis.
Magnifications in (G) and (I) (scale bars 2 .mu.m) and also (H) and
(J) (scale bars 500 nm) are identical. Scale bar is 15 .mu.m for
(F).
[0010] FIG. 2A-H shows Energy Dispersive Spectroscopy (EDS)
characterization of fabricated metal nanostructures. (A) SEM images
of supported 20 .mu.m tetrakaidekahedron unit cell on a Si chip
before pyrolysis and (B) the same structure after pyrolysis (4
.mu.m width). (C) SEM image of the structure showing where EDS data
was collected. (D) EDS spectrum taken within the beam of the
structure suggests that the chemical composition is more than 90 wt
% nickel. (E-H), EDS maps show high uniformity of the atomic
composition throughout the structure. Scale bars are 5 .mu.m for
(A) 1 .mu.m for (C) and 2 .mu.m for (D), (E-H).
[0011] FIG. 3A-F shows TEM characterization of the resulting metal
structure. (A) SEM image of nickel beams fabricated directly on a
200 nm-thick SiN membrane TEM grid (B) Low-magnification TEM of a
100 nm nickel beam overhanging the edge of 1.25 .mu.m hole in a SiN
membrane. (C) TEM image of the metal sample region where the
diffraction pattern was taken. (D) Electron diffraction pattern
shows that the printed beam consists mostly out of polycrystalline
nickel with a small amount of nickel oxide. (E) HRTEM image of a
printed metal beam. Analysis of atomic plane distances using FFT
shows predominantly polycrystalline nickel (region 1) with some
amount of nickel carbide within the structure (region 2) and nickel
oxide at the surface of the structure (region 3). (F) Grain size
histogram for n=40 particles measured from a TEM image.
[0012] FIG. 4A-F shows in-situ uniaxial compression of 3D printed
nickel octet nanolattices. (A)-(D), SEM images of the nickel
structure during the compression test a, before full contact, (B)
in the elastic regime, (C) during layer-by-layer collapse, and (D)
during densification. (E) Stress-strain diagram showing compression
of four nickel nanolattices. Letters on the graph correspond to the
regions represented by (A)-(D). (F) Specific strength-beam size
plot showing properties of nickel nanolattices compared to other
metal lattices fabricated using Selective Laser Melting (SLM),
Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM),
and ink-based methods. Scale bars are 5 .mu.m for (A)-(D).
[0013] FIG. 5 shows a comparison of minimum feature sizes for
scalable metal additive manufacturing technologies. Using
metal-containing photoresist allows to fabricate complex 3D
geometries with the resolution that is an order of magnitude finer
than that of the state-of-the-art metal AM methods.
[0014] FIG. 6 shows an SEM image of a representative supporting
structure used to decouple the part from the substrate during
pyrolysis.
[0015] FIG. 7A-C shows a concept of a household solar water
disinfection device. (A) Architected self-supported titania is
placed inside a PET bottle filled with water in the sunlight. (B)
The photocatalyst promotes generation of ROS that deactivate
microorganisms. The architecture allows for the light to be
delivered into the bulk of the photocatalyst, supporting the
disinfection throughout the whole volume of the reactor. (C) After
disinfection is complete, the water can be consumed right away,
without the need to filter out the catalyst.
[0016] FIG. 8A-E shows a process for AM of titania and SEM
characterization of printed titania structures. (A) Shows ligand
exchange reaction to add acrylic functional groups onto titanium
clusters followed by a schematic of the SLA instrument to pattern
titanium-containing photoresist into complex 3D geometries. Optical
images of a cubic lattice made from titanium-containing polymer
before and after pyrolysis. (B) Top view of a titania octet lattice
(optical image). SEM images of (C) a representative node in the
unit cell of an octet lattice and (D, E) titania nano-crystallites
on the surface of the structure. Scale bars are 5 mm for (A), 2 mm
for (B), 100 .mu.m for (C), 5 .mu.m for (D), and 500 nm for
(E).
[0017] FIG. 9A-F shows EDS and Raman characterization of printed
titania structures. (A) SEM image of an octet lattice node where
EDS maps were taken. EDS maps show uniform distribution of (B)
titanium, (D) oxygen, and (E) carbon within the structure. (C) EDS
spectrum taken from one of the beams shows mostly titanium and
oxygen content by weight. (F) Raman spectrum of a 3D printed
structure compared to reference spectra of anatase and rutile TiO2
indicates mostly rutile phase of titania. Scale bars are 100 um for
(A), (B), (D), and (E).
[0018] FIG. 10A-F shows TEM and SEM characterization of printed
titania structures. (A) SEM image of a beam cross-section shows
that the size of titania crystals gets smaller closer to the beam
center. (B) Histogram showing distribution of titania particle
sizes measured from TEM images. (C) HRTEM image showing titania
particles. FFT analysis was used to determine the orientation and
lattice spacings for one of the crystals. (D) Low-magnification TEM
image of titania nanoparticles from the printed structure. (E) TEM
image of the area where electron diffraction pattern was taken. (F)
Electron diffraction pattern indicates mostly rutile titania.
[0019] FIG. 11A-E shows uniaxial compression test of printed
titania cubic lattices. (A-D) Optical images of the structure
during uniaxial compression showing different stages during the
compression test: elastic region (A), followed by brittle failure
of the first layer (B, C) and gradual brittle failure of individual
beams and layers (D). (E) Stress-strain data for three cubic
lattices. Scale bars for (A-D) are 5 mm.
[0020] FIG. 12A-B shows 2D patterning of NiNPs. (A) Grid pattern of
NiNPs on Si after removing the organic content from a
lithographically-defined grid structure. (B) Carbon nanotube (CNT)
synthesis using pre-patterned NiNPs on Si.
DETAILED DESCRIPTION
[0021] As used herein and in the appended claims, the singular
forms "a," "an," and "the" include plural referents unless the
context clearly dictates otherwise. Thus, for example, reference to
"a photoinitiator" includes a plurality of such photoinitiators and
reference to "the metal" includes reference to one or more metals,
and so forth.
[0022] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood to one of
ordinary skill in the art to which this disclosure belongs.
Although methods and materials similar or equivalent to those
described herein can be used in the practice of the disclosed
methods and compositions, the exemplary methods, devices and
materials are described herein.
[0023] Also, the use of "or" means "and/or" unless stated
otherwise. Similarly, "comprise," "comprises," "comprising"
"include," "includes," and "including" are interchangeable and not
intended to be limiting.
[0024] It is to be further understood that where descriptions of
various embodiments use the term "comprising," those skilled in the
art would understand that in some specific instances, an embodiment
can be alternatively described using language "consisting
essentially of" or "consisting of."
[0025] Any publications discussed above and throughout the text are
provided solely for their disclosure prior to the filing date of
the present application. Nothing herein is to be construed as an
admission that the inventors are not entitled to antedate such
disclosure by virtue of prior disclosure.
[0026] Additive manufacturing (AM) represents a set of processes
that enable layer by layer fabrication of complex 3D structures
using a wide range of materials that include inorganic, hybrid
organic-inorganic materials, polymers, and metals. The development
of metal AM has revolutionized the production of complex parts for
aerospace, automotive and medical applications. Today's resolution
of most commercially available metal AM processes is .about.20-50
.mu.m.sup.2; no established method is available for printing 3D
features below these dimensions. It has been shown that unique
phenomena arise in metals with micro- and nano-dimensions, for
example light trapping in optical meta-materials and enhanced
mechanical resilience. Accessing these phenomena requires
developing a process to fabricate 3D metallic architectures with
macroscopic overall dimensions and individual constituents in the
sub-micron regime.
[0027] Minimum feature size in metal AM is generally limited by the
material feed, which include metal powder, metal wire, sheet metal,
and metal inks. Inkjet-based methods manipulate 40-60 .mu.m
droplets of metal inks; wire- and filament-based processes, i.e.
Plasma Deposition and Electron Beam Freeform Fabrication (EBF3),
rely on locally melting a >100 .mu.m-diameter metal wire; and
powder-based processes, i.e. Selective Laser Melting (SLM) and
Laser Engineered Net Shaping (LENS), consolidate .about.0.3-10
.mu.m metal powder particles. Overcoming these resolution
limitations requires developing the capability of a material feed
to manipulate nanoscale quantities of metals in a stable and
scalable 3D printing process. Alternative material feeds to
fabricate 3D metal structures with a <10 .mu.m resolution
include nanoparticle inks, ion solutions, droplets of molten metal,
and precursor gases. Methods that use localized electroplating or
metal ion reduction are capable of producing features down to 500
nm using a very slow process that is limited by the electroplating
rate. Electrochemical fabrication (EFAB) allows for manufacturing
geometries with 10 .mu.m features and 4 .mu.m layers but is limited
to structures with a total height of 25-50 layers. Other
technologies, like micro-deposition of metal nanoparticle inks or
molten metal and focused ion beam direct writing (FIBDW), also
suffer from slow throughput and are more suited for low-volume
fabrication and repair.
[0028] As used herein "framework material" refers to a metal, a
metalloid, a metal alloy, a metal oxide, a metal nitride, an
inorganic, and inorganic/organic hybrid and/or a carbon-based
material that is present in a photoresist resin of the disclosure
and that upon polymerization remains as part of a framework or
structure. Moreover, in some instances, the framework-material
remains as part of, or the only remaining component of, the
framework or structure following heat treatment (e.g.,
pyrolization). In some embodiment, the framework-material
comprises, but is not limited to, a metal ion that bridges 2 or
more monomeric ligand units comprising photopolymerizable
groups.
[0029] This disclosure provides a scalable and reproducible process
to create complex 3D metal geometries with sub-micron (i.e., less
than 1 .mu.m, for example, 5-999 nm or any value there between) up
to 50 .mu.m (and any integer size there between) features by
applying lithographic methods to metal-, inorganic-, and hybrid
inorganic/organic-rich polymer resins.
[0030] The disclosure provides a photopolymerizable resist
comprising a metal, a metalloid, a metal alloy, a metal oxide, a
metal nitride, an inorganic, and inorganic/organic hybrid and/or a
carbon-based material (the "framework-material"). The
photopolymerizable resist comprises (i) a hybrid organic-inorganic
polymer resin comprising a metal, a metalloid, a metal alloy, a
metal oxide, a metal nitride, an inorganic, and inorganic/organic
hybrid and/or a carbon-based material ("M") that are part of a
monomeric ligand unit or that bridge at least two monomeric ligand
units "L", e.g., L-M-L, (ii) a photoinitiator, and (iii) a
reactable monomer.
[0031] The photopolymerizable organic-inorganic resin can be made
by reacting a monodentate, bidentate or weak framework-material
exchange ligand with at least one monomeric ligand unit. For
example, the weak framework-material exchange ligand has the
general structure: (L.sup.-).sub.nM.sup.n+, where L.sup.- is a
negatively charged ligand, n is 1, 2, 3, 4, 5 or 6 and M is a
metal, a metal, a metalloid, a metal alloy, a metal oxide, a metal
nitride, an inorganic, and inorganic/organic hybrid and/or a
carbon-based material cation.
[0032] The monomeric ligand unit generally comprises the
structure:
##STR00001##
wherein R is an alkene or a C.sub.2-10 terminal alkene and R' is N,
O, F, S or Cl. In one embodiment, the monomeric ligand unit is an
acryloyl. In another embodiment, the monomeric ligand unit
comprises a carboxylic acid and an alkene, e.g., C.dbd.R--COOH,
wherein R is 1-10 carbons. A general scheme for producing a hybrid
organic-inorganic polymer resin is provided in Scheme I:
##STR00002##
wherein "M" is a metal, a metal ion, a metalloid, a metal alloy, a
metal oxide, a metal nitride, an inorganic, an inorganic/organic
hybrid and/or a carbon-based material. In one embodiment, the metal
or metal ion includes, but is not limited to, Li.sup.+, Na.sup.+,
K.sup.+, Rb.sup.+, Cs.sup.+, Be.sup.2+, Mg.sup.2+, Ca.sup.2+,
Sr.sup.2+, Ba.sup.2+, Sc.sup.3+, Sc.sup.2+, Sc.sup.+, Y.sup.3+,
Y.sup.2+, Y.sup.+, Ti.sup.4+, Ti.sup.3+, Ti.sup.2+, Zr.sup.4+,
Zr.sup.3+, Zr.sup.2+, Hf.sup.4+, Hf.sup.3+, V.sup.5+, V.sup.4+,
V.sup.3+, V.sup.2+, Nb.sup.5+, Nb.sup.4+, Nb.sup.3+, Nb.sup.2+,
Ta.sup.5+, Ta.sup.4+, Ta.sup.3+, Ta.sup.2+, Cr.sup.6+, Cr.sup.5+,
Cr.sup.4+, Cr.sup.3+, Cr.sup.2+, Cr.sup.+, Cr, Mo.sup.6+,
Mo.sup.5+, Mo.sup.4+, Mo.sup.3+, Mo.sup.2+, Mo.sup.+, Mo, W.sup.6+,
W.sup.5+, W.sup.4+, W.sup.3+, W.sup.2+, W.sup.+, W, Mn.sup.7+,
Mn.sup.6+, Mn.sup.5+, Mn.sup.4+, Mn.sup.3+, Mn.sup.2+, Mn.sup.+,
Re.sup.7+, Re.sup.6+, Re.sup.5+, Re.sup.4+, Re.sup.3+, Re.sup.2+,
Re.sup.+, Re, Fe.sup.6+, Fe.sup.4+, Fe.sup.3+, Fe.sup.2+, Fe.sup.+,
Fe, Ru.sup.8+, Ru.sup.7+, Ru.sup.6+, Ru.sup.4+, Ru.sup.3+,
Ru.sup.2+, Os.sup.8+, Os.sup.7+, Os.sup.6+, Os.sup.5+, Os.sup.4+,
Os.sup.3+, Os.sup.2+, Os.sup.+, Os, Co.sup.5+, Co.sup.4+,
Co.sup.3+, Co.sup.2+, Co.sup.+, Rh.sup.6+, Rh.sup.5+, Rh.sup.4+,
Rh.sup.3+, Rh.sup.2+, Rh.sup.+, Ir.sup.6+, Ir.sup.5+, Ir.sup.4+,
Ir.sup.3+, Ir.sup.2+, Ir.sup.+, Ir, Ni.sup.3+, Ni.sup.2+, Ni.sup.+,
Ni, Pd.sup.6+, Pd.sup.4+, Pd.sup.2+, Pd.sup.+, Pd, Pt.sup.6+,
Pt.sup.5+, Pt.sup.4+, Pt.sup.3+, Pt.sup.2+, Pt.sup.+, Cu.sup.4+,
Cu.sup.3+, Cu.sup.2+, Cu.sup.+, Ag.sup.3+, Ag.sup.2+, Ag.sup.+,
Au.sup.5+, Au.sup.4+, Au.sup.3+, Au.sup.2+, Au.sup.+, Zn.sup.2+,
Zn.sup.+, Zn, Cd.sup.2+, Cd.sup.+, Hg.sup.4+, Hg.sup.2+, Hg.sup.+,
B.sup.3+, B.sup.2+, B.sup.+, Al.sup.3+, Al.sup.2+, Al.sup.+,
Ga.sup.3+, Ga.sup.2+, Ga.sup.+, In.sup.3+, In.sup.2+, In.sup.+,
Tl.sup.3+, Tl.sup.+, Si.sup.4+, Si.sup.3+, Si.sup.2+, Si.sup.+,
Ge.sup.4+, Ge.sup.3+, Ge.sup.2+, Ge.sup.+, Ge, Sn.sup.4+,
Sn.sup.2+, Pb.sup.4+, Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.2+,
As.sup.+, Sb.sup.5+, Sb.sup.3+, Bi.sup.5+, Bi.sup.3+, Te.sup.6+,
Te.sup.5+, Te.sup.4+, Te.sup.2+, La.sup.3+, La.sup.2+, Ce.sup.4+,
Ce.sup.3+, Ce.sup.2+, Pr.sup.4+, Pr.sup.3+, Pr.sup.2+, Nd.sup.+,
Nd.sup.2+, Sm.sup.3+, Sm.sup.2+, Eu.sup.3+, Eu.sup.2+, Gd.sup.3+,
Gd.sup.2+, Gd.sup.+, Tb.sup.4+, Tb.sup.3+, Tb.sup.2+, Tb.sup.+,
Db.sup.3+, Db.sup.2+, Ho.sup.3+, Er.sup.3+, Tm.sup.4+, Tm.sup.3+,
Tm.sup.2+, Yb.sup.3+, Yb.sup.2+, Lu.sup.3+ and alloys of any of the
foregoing. In another embodiment, M is one or more metals or metal
ions selected from the group comprising Li.sup.+, Mg.sup.2+,
Ca.sup.2+, Ba.sup.2+, Zr.sup.4+, Zr.sup.3+, Zr.sup.2+, Mn.sup.3+,
Mn.sup.2+, Mn.sup.+, Fe.sup.3+, Fe.sup.2+, Fe.sup.+, Ni.sup.3+,
Ni.sup.2+, Ni.sup.+, Ni, Cu.sup.4+, Cu.sup.3+, Cu.sup.2+, Cu.sup.+,
V.sup.5+, V.sup.4+, V.sup.3+, V.sup.2+, Co.sup.3+, Co.sup.2+,
Co.sup.+, Zn.sup.2+, Zn.sup.+, Ce.sup.4+, Ce.sup.3+, and Ce.sup.2+
or alloys of any of the foregoing. In yet another embodiment, M is
one or more metal ions selected from the group comprising Li.sup.+,
Mg.sup.2+, Ca.sup.2+, Ba.sup.2+, Zr.sup.2+, Mn.sup.2, Fe.sup.2+,
Ni.sup.2+, Cu.sup.2+, V.sup.2+, Co.sup.2+, Zn.sup.2+, and
Ce.sup.2+. In a further embodiment, M is Ni.sup.2+ or Co.sup.2+
metal ions. The inorganic can be a single or mixed oxide, carbide,
nitride, silicate, boride of Ti, W, Si, Zr, Al, Y, Cr, Fe, Pb, Co,
or a rare earth element. For example, the inorganic can include,
but is not limited to, TiO.sub.2, AlO.sub.2, Al.sub.2O.sub.3,
ZrO.sub.2, SiC, SiO.sub.2, SiC, CeO.sub.2, or ZnO. A suitable
metal-inorganic composite includes, but is not limited to,
metal-inorganic composite coating comprises Au--Ni--TiO.sub.2,
Ni--Co--TiO.sub.2, Ni--Zn-Al.sub.2O.sub.3, or Ni--B--TiO.sub.2.
[0033] Suitable monodentate, bidentate or weak exchange ligands
("L.sup.-") include, e.g., various alkoxides. Examples of weak
framework-material exchange ligand (e.g., (L.sup.-).sub.nM) are
selected from the group consisting of aluminum triethoxide,
aluminum isopropoxide, aluminum sec-butoxide, aluminum
tri-t-butoxide, magnesium trifluoroacetylacetonate, magnesium
methoxide, magnesium ethoxide, titanium methoxide, titanium
ethoxide, titanium isopropoxide, titanium propoxide, titanium
butoxide, titanium ethylhexoxide, titanium
(triethanolaminato)isopropoxide, titanium bis(ethyl
acetoacetato)diisopropoxide, titanium
bis(2,4-pentanedionate)diisopropoxide, zirconium ethoxide,
zirconium isopropoxide, zirconium propoxide, zirconium
sec-butoxide, zirconium t-butoxide, aluminum, di-s-butoxide
ethylacetonate, calcium methoxyethoxide, calcium methoxide,
magnesium methoxyethoxide, copper ethoxide, copper
methoxyethoxyethoxide, antimony butoxide, bismuth pentoxide,
chromium isopropoxide, tin ethoxide, zinc methoxyethoxide, titanium
n-nonyloxide, vanadium tri-n-propoxide oxide, vanadium
triisobutoxide oxide, iron ethoxide, tungsten ethoxide, samarium
isopropoxide, lanthanium methoxyethoxide,
cerium(IV)2-methoxethoxide, lanthanium (III) 2-methoxethoxide,
Yttrium 2-methoxethoxide, and calcium 2-methoxethoxide.
[0034] In one embodiment, the reaction of scheme I provides a
hybrid organic-inorganic polymer resin that comprises a metal
diacrylate, metal triacrylate or 2 or more acrylate monomers
bridged or coordinated by a metal, a metalloid, a metal alloy, a
metal oxide, a metal nitride, an inorganic, and inorganic/organic
hybrid and/or a carbon-based material. For example, the hybrid
organic-inorganic polymer resin can have the general structure
(C=R.sub.mH.sub.2m+1COR').sub.nM.sup.n+ wherein m is any integer
between, and including, 1 and 10, n is an integer between 1 and 6,
wherein R is a C.sub.1-10 alkane and R' is N, O, F, S or Cl. In one
embodiment, the a hybrid organic-inorganic polymer resin has the
formula C.dbd.R--COR'-M.sup.2+--R'OC--R.dbd.C, wherein M is a
divalent metal ion. In one embodiment, the divalent ion is a
divalent metal ion selected from the group consisting of Be.sup.2+,
Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+, Sc.sup.2+, Y.sup.2+,
Ti.sup.2+, Zr.sup.2+, V.sup.2+, Nb.sup.2+, Ta.sup.2+, Cr.sup.2+,
Mo.sup.2+, W.sup.2+, Mn.sup.2+, Re.sup.2+, Fe.sup.2+, Ru.sup.2+,
Os.sup.2+, Co.sup.2+, Rh.sup.2+, Ir.sup.2+, Ni.sup.2+, Pd.sup.2+,
Pt.sup.2+, Cu.sup.2+, Ag.sup.2+, Au.sup.2+, Zn.sup.2+, Cd.sup.2+,
B.sup.2+, Al.sup.2+, Ga.sup.2+, Sn.sup.2+, Pb.sup.2+, Hg.sup.2+,
As.sup.2+, Te.sup.2+, La.sup.2+, Ce.sup.2+, Pr.sup.2+, Sm.sup.2+,
Gd.sup.2+, Nd.sup.2+, Db.sup.2+, Tb.sup.2+, Tm.sup.2+ and
Yb.sup.2+.
[0035] FIG. 1A depicts an exemplary reaction between (i) a weak
framework-material ligand (e.g., methoxyethoxide) bound to nickel
and (ii) acrylic acid as the monomeric ligand unit to yield the
hybrid organic-inorganic polymer resin, nickel acrylate.
[0036] The disclosure further provides a method of making a
photopolymerizable framework-material photoresist. The method
comprises mixing (i) a hybrid organic-inorganic polymer resin
(e.g., "metal precursor" nickel acrylate; see FIG. 1A) with (ii) a
monomer comprising a photochemical polymerizable group that allows
for propagating carbon or nitrogen chains and (iii) a
photoinitiator.
[0037] The photoinitiator used in the photopolymerizable resist
mixture causes a radical reaction or ion reaction in response to
contact by light. There are a number of photoinitiators known in
the art. For example, suitable photoinitiators include, but are not
limited to, 7-diethylamino-2-coumarin, acetophenone,
p-tert-butyltrichloro acetophenone, chloro acetophenone,
2-2-diethoxy acetophenone, hydroxy acetophenone,
2,2-dimethoxy-2'-phenyl acetophenone, 2-amino acetophenone,
dialkylamino acetophenone, benzyl, benzoin, benzoin methyl ether,
benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl
ether, 1-hydroxycyclohexyl phenyl ketone,
2-hydroxy-2-methyl-1-phenyl-2-methylpropane-1-one,
1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, benzyl
dimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoyl
benzoate, methyl-o-benzoyl benzoate, 4-phenyl benzophenone, hydroxy
benzophenone, hydroxypropyl benzophenone, acrylic benzophenone,
4-4'-bis(dimethylamino)benzophenone, perfluoro benzophenone,
thioxanthone, 2-chloro thioxanthone, 2-methyl thioxanthone, diethyl
thioxanthone, dimethyl thioxanthone, 2-methyl anthraquinone,
2-ethyl anthraquinone, 2-tert-butyl anthraquinone, 1-chloro
anthraquinone, 2-amyl anthraquinone, acetophenone dimethyl ketal,
benzyl dimethyl ketal, .alpha.-acyl oxime ester,
benzyl-(o-ethoxycarbonyl)-.alpha.-monoxime, acyl phosphine oxide,
glyoxy ester, 3-keto coumarin, 2-ethyl anthraquinone, camphor
quinone, tetramethylthiuram sulfide, azo bis isobutyl nitrile,
benzoyl peroxide, dialkyl peroxide, tert-butyl peroxy pivalate,
perfluoro tert-butyl peroxide, perfluoro benzoyl peroxide, etc.
Further, it is possible to use these photoinitiator alone or in
combination of two or more. Other photoinitiators will be known in
the art.
[0038] The monomer of the monomeric ligand unit can be any
momomeric compound having an activatable photopolymerizable group
that can propagate carbon or nitrogen bond formation. In one
embodiment, the monomer is polymerized to form a polyacrylate such
as polymethylmethacrylate, an unsaturated polyester, a saturated
polyester, a polyolefin (polyethylenes, polypropylenes,
polybutylenes, and the like), an alkyd resin, an epoxy polymer, a
polyamide, a polyimide, a polyetherimide, a polyamideimide, a
polyesterimide, a polyesteramideimide, polyurethanes,
polycarbonates, polystyrenes, polyphenols, polyvinylesters,
polysilicones, polyacetals, cellulose acetates, polyvinylchlorides,
polyvinylacetates, polyvinyl alcohols polysulfones,
polyphenylsulfones, polyethersulfones, polyketones,
polyetherketones, poyletheretherketones, polybenzimidazoles,
polybemzoxazoles, polybenzthiazoles, polyfluorocarbones,
polyphenylene ethers, polyarylates, cyanate ester polymers,
copolymers of two or more thereof, and the like.
[0039] Examples of acrylic monomers include monoacrylics,
diacrylics, triacrylics, tetraacrylics, pentacrylics, etc. Examples
of polyacrylates include polyisobornylacrylate,
polyisobornylmethacrylate, polyethoxyethoxyethyl acrylate,
poly-2-carboxyethylacrylate, polyethylhexylacrylate,
poly-2-hydroxyethylacrylate, poly-2-phenoxylethylacrylate,
poly-2-phenoxyethylmethacrylate, poly-2-ethylbutylmethacrylate,
poly-9-anthracenylmethylmethacrylate, poly-4-chlorophenylacrylate,
polycyclohexylacrylate, polydicyclopentenyloxyethyl acrylate,
poly-2-(N,N-diethylamino)ethyl methacrylate,
poly-dimethylaminoeopentyl acrylate, poly-caprolactone
2-(methacryloxy)ethylester, and polyfurfurylmethacrylate,
poly(ethylene glycol)methacrylate, polyacrylic acid and
poly(propylene glycol)methacrylate.
[0040] Examples of suitable diacrylates which can be used to form
polyacrylates include 2,2-bis(4-methacryloxyphenyl)propane,
1,2-butanediol diacrylate, 1,4-butanediol diacrylate,
1,4-butanediol dimethacrylate, 1,4-cyclohexanediol dimethacrylate,
1,10-decanediol dimethacrylate, diethylene glycol diacrylate,
dipropylene glycol diacrylate, dimethylpropanediol dimethacrylate,
triethylene glycol dimethacrylate, tetraethylene glycol
dimethacrylate, 1,6-hexanediol diacrylate, neopentyl glycol
diacrylate, polyethylene glycol dimethacrylate, tripropylene glycol
diacrylate, 2,2-bis[4-(2-acryloxyethoxy)phenyl]propane,
2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane,
bis(2-methacryloxyethyl)N,N-1,9-nonylene biscarbamate,
1,4-cycloheanedimethanol dimethacrylate, and diacrylic urethane
oligomers (reaction products of isocyanate terminate polyol and
2-hydroethylacrylate). Examples of triacrylates which can be used
to form polyacrylates include tris(2-hydroxyethyl)isocyanurate
trimethacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate,
trimethylolpropane trimethacrylate, trimethylolpropane triacrylate
and pentaerythritol triacrylate. Examples of tetracrylates include
pentaerythritol tetraacrylate, di-trimethylopropane tetraacrylate,
and ethoxylated pentaerythritol tetraacrylate. Examples of
pentaacrylates include dipentaerythritol pentaacrylate and
pentaacrylate ester.
[0041] As mentioned above the hybrid organic-inorganic polymer
resin is not limited. The hybrid organic-inorganic polymer resin
used in the photopolymerizable resist is not limited so long as the
hybrid organic-inorganic polymer resin comprises a polymerizable
monomer. Such polymerizable groups on the hybrid organic-inorganic
polymer resin typically have acryloyl group or a methacryloyl
group, monomers having a vinyl group, and monomers having an allyl
group. Further, the hybrid organic-inorganic polymer resin will
typically be polyfunctional monomers comprising a plurality of
polymerizable groups, and the number of polymerizable groups
comprises an integer of from 1 to 4. Examples an acryloyl group or
a methacryloyl group useful in a hybrid organic-inorganic polymer
resin are (meth)acrylic acids; aromatic (meth)acrylates such as
phenoxyethyl acrylate, benzyl acrylate, etc.; hydrocarbon
(meth)acrylates such as stearyl acrylate, lauryl acrylate,
2-ethylhexyl acrylate, allyl acrylate, 1,3-butanediol diacrylate,
1,4-butanediol diacrylate, 1,6-hexanediol diacrylate,
trimethylolpropane triacrylate, pentaerythritol triacrylate,
dipentaerythritol hexaacrylate, etc.; ethereal oxygen
atom-containing hydrocarbon (meth)acrylates such as ethoxyethyl
acrylate, methoxyethyl acrylate, glycidyl acrylate,
tetrahydrofurfuryl acrylate, diethylene glycol diacrylate,
neopentylglycol diacrylate, polyoxyethylene glycol diacrylate,
tripropylene glycol diacrylate, etc.
[0042] After the photopolymerizable framework-material photoresist
has been prepared, it can be stored under appropriate conditions
(depending upon the components, e.g., under inert gas and typically
in the dark). The photopolymerizable framework-material photoresist
can be applied to a substrate by spin, drop cast, dip coating or
any other commonly used methods. In some embodiments, the method
can utilize a technique to carefully control the amount, thickness
or layering of the photopolymerizable framework-material
photoresist. The photopolymerizable framework-material photoresist
can be drop cast or deposited on a substrate at any appropriate
thickness evenly or unevenly. The substrate is not limiting and can
be any of a glass, a polymer, a ceramic, an inorganic, an alumina,
a stainless steel, a titanium and a semiconductive substrate.
[0043] The photopolymerizable framework-material photoresist is
then exposed to one or more beams of photons/light to initiate free
radical production by the photoinitiator and to polymerize the
monomers to produce a polymeric material containing a
framework-material. In one embodiment, the method uses a two photon
lithography (TPL) technique. Two photon lithography allows for the
penetration of the photopolymerizable framework-material
photoresist by the individual photon beams which are individually
insufficient to cause polymerization until both contact a
photopolymerizable location. Under TPL, each of the photon beams
provides one-half the energy required to cause photoinitiation and
thus polymerization. Thus, a 3D structures can be fabricated using
a polymerizable system that requires two photons to simultaneously
impinge on a photopolymerizable material. The two photons can be
dimensionally targeted (e.g., by mirrors) or may be temporally
targeted (e.g., pulsed lasers). Local activation of the
photopolymerizable framework-material photoresist occurs by
simultaneous absorption of the two photons. Typically, the
wavelengths are in the near-infrared region.
[0044] After polymerization of a desires structure comprising a
framework-material, non-polymerized monomers and reagents are
washed away. The remaining structure can then be dried or pyrolized
to remove any remaining organic material. The resulting structure
comprises an almost entirely metal-, inorganic-, carbon-, oxide-,
nitride and/or carbon-based structure.
[0045] In any of the foregoing paragraphs, the term
"framework-material" can be replaced with the term "metal" and/or
"metal ion". For example, the term "framework-material" can be
replaced with any of Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+,
Cs.sup.+, Be.sup.2+, Mg.sup.2+, Ca.sup.2+, Sr.sup.2+, Ba.sup.2+,
Sc.sup.3+, Sc.sup.2+, Sc.sup.+, Y.sup.3+, Y.sup.2+, Y.sup.+,
Ti.sup.4+, Ti.sup.3+, Ti.sup.2+, Zr.sup.4+, Zr.sup.3+, Zr.sup.2+,
Hf.sup.4+, Hf.sup.3+, V.sup.5+, V.sup.4+, V.sup.3+, V.sup.2+,
Nb.sup.5+, Nb.sup.4+, Nb.sup.3+, Nb.sup.2+, Ta.sup.5+, Ta.sup.4+,
Ta.sup.3+, Ta.sup.2+, Cr.sup.6+, Cr.sup.5+, Cr.sup.4+, Cr.sup.3+,
Cr.sup.2+, Cr.sup.+, Cr, Mo.sup.6+, Mo.sup.5+, Mo.sup.4+,
Mo.sup.3+, Mo.sup.2+, Mo.sup.+, Mo, W.sup.6+, W.sup.5+, W.sup.4+,
W.sup.3+, W.sup.2+, W.sup.+, W, Mn.sup.7+, Mn.sup.6+, Mn.sup.5+,
Mn.sup.4+, Mn.sup.3+, Mn.sup.2+, Mn.sup.+, Re.sup.7+, Re.sup.6+,
Re.sup.5+, Re.sup.4+, Re.sup.3+, Re.sup.2+, Re.sup.+, Re,
Fe.sup.6+, Fe.sup.4+, Fe.sup.3+, Fe.sup.2+, Fe.sup.+, Fe,
Ru.sup.8+, Ru.sup.7+, Ru.sup.6+, Ru.sup.4+, Ru.sup.3+, Ru.sup.2+,
Os.sup.8+, Os.sup.7+, Os.sup.6+, Os.sup.5+, Os.sup.4+, Os.sup.3+,
Os.sup.2+, Os.sup.+, Os, Co.sup.5+, Co.sup.4+, Co.sup.3+,
Co.sup.2+, Co.sup.+, Rh.sup.6+, Rh.sup.5+, Rh.sup.4+, Rh.sup.3+,
Rh.sup.2+, Rh.sup.+, Ir.sup.6+, Ir.sup.5+, Ir.sup.4+, Ir.sup.3+,
Ir.sup.2+, Ir.sup.+, Ir, Ni.sup.3+, Ni.sup.2+, Ni.sup.+, Ni,
Pd.sup.6+, Pd.sup.4+, Pd.sup.2+, Pd.sup.+, Pd, Pt.sup.6+,
Pt.sup.5+, Pt.sup.4+, Pt.sup.3+, Pt.sup.2+, Pt.sup.+, Cu.sup.4+,
Cu.sup.3+, Cu.sup.2+, Cu.sup.+, Ag.sup.3+, Ag.sup.2+, Ag.sup.+,
Au.sup.5+, Au.sup.4+, Au.sup.3+, Au.sup.2+, Au.sup.+, Zn.sup.2+,
Zn.sup.+, Zn, Cd.sup.2+, Cd.sup.+, Hg.sup.4+, Hg.sup.2+, Hg.sup.+,
B.sup.3+, B.sup.2+, B.sup.+, Al.sup.3+, Al.sup.2+, Al.sup.+,
Ga.sup.3+, Ga.sup.2+, Ga.sup.+, In.sup.3+, In.sup.2+, In.sup.1+,
Tl.sup.3+, Tl.sup.+, Si.sup.4+, Si.sup.3+, Si.sup.2+, Si.sup.+,
Ge.sup.4+, Ge.sup.3+, Ge.sup.2+, Ge.sup.+, Ge, Sn.sup.4+,
Sn.sup.2+, Pb.sup.4+, Pb.sup.2+, As.sup.5+, As.sup.3+, As.sup.2+,
As.sup.+, Sb.sup.5+, Sb.sup.3+, Bi.sup.5+, Bi.sup.3+, Te.sup.6+,
Te.sup.5+, Te.sup.4+, Te.sup.2+, La.sup.3+, La.sup.2+, Ce.sup.4+,
Ce.sup.3+, Ce.sup.2+, Pr.sup.4+, Pr.sup.3+, Pr.sup.2+, Nd.sup.3+,
Nd.sup.2+, Sm.sup.3+, Sm.sup.2+, Eu.sup.3+, Eu.sup.2+, Gd.sup.3+,
Gd.sup.2+, Gd.sup.+, Tb.sup.4+, Tb.sup.3+, Tb.sup.2+, Tb.sup.+,
Db.sup.3+, Db.sup.2+, Ho.sup.3+, Er.sup.3+, Tm.sup.4+, Tm.sup.3+,
Tm.sup.2+, Yb.sup.3+, Yb.sup.2+ and Lu.sup.3+. In one embodiment,
the framework material is a divalent metal ion.
[0046] Although any number of materials can be used in the methods
and compositions (as described above), the disclosure exemplifies
the methods of the disclosure using, in one embodiment, nickel
acrylate made by a ligand exchange reaction between nickel alkoxide
and acrylic acid (FIG. 1A) and then combining it with another
acrylic monomer, pentaerythritol triacrylate, and a photoinitiator
(PI), 7-diethylamino-3-thenoylcoumarin, (FIG. 1B). The photoresist
is then applied (e.g., by drop casting) to a substrate (e.g., a
silicon substrate) and two-photon lithography (TPL) is used to
sculpt a desired 3D architecture (FIG. 1C). The non-polymerized
resist was then washed away, and the free-standing cross-linked
polymer nano- and/or micro-architectures were then heat processed.
The heat processing can be used to further catalyze the conversion
of a framework-material (e.g., carbon to graphene) or to remove
volatile material. For example, the nano- and/or
micro-architectured structure is pyrolyzed to volatilize the
organic content. This process yielded a .about.80% smaller replica
of the original 3D structure made entirely out of metal (FIG.
1D).
[0047] Pyrolysis can be performed in a one- or multi-step process.
For example, in one embodiment, a two-step process is used that
includes performing pyrolysis in a furnace at about
600-1000.degree. C. to remove organic content and to consolidate
metal and/or inorganic features followed by a lower temperature
heat processing of about 200-600.degree. C. to reduce the oxygen
content.
[0048] The disclosure provides a feasible and efficient method of
fabricating a metal, a metalloid, a metal alloy, a metal oxide, a
metal nitride, an inorganic, a hybrid inorganic-organic and/or a
carbon-based material nano- and/or micro-structures. For example,
the methods of the disclosure produced nanolattices with 10 .mu.m
octet unit cells comprised of 2 .mu.m-diameter circular beams out
of the synthesized photopolymerizable framework-material
photoresist using layer-by-layer TPL with 150 nm layer thickness.
SEM images in FIG. 1F-H reveal that these nanolattices had fully
dense beams and uniformly sized, high-fidelity features. These
nanolattices had four unit cells on each side, 40 .mu.m, and a
height of three unit cells, 30 .mu.m, and were supported by
vertical springs at each corner and by a vertical pillar the
center. These supports served as pedestals that would allow the
sample to release from substrate after undergoing an isotropic
.about.80% shrinkage during pyrolysis (see FIG. 6).
[0049] The disclosure thus, provides an additive manufacturing (AM)
process to create 3D nano- and micro-architected metal, metalloid,
metal alloy, metal oxide, metal nitride, inorganic,
inorganic-organic hybrid and/or carbon-based materials using a
scalable lithography-based approach. As exemplified below, the
process produced Ni octet-lattices with 2 .mu.m unit cells, 300-400
nm beams and 30 nm layers. The resolution of the method of the
disclosure allows printing metal features with 25-100 nm
dimensions, which is an order of magnitude smaller than feature
sizes produced using all other 3D-capable metal AM methods. Lateral
feature sizes of complex 3D architectures fabricated using this
process can be further refined to 24 nm. This nanoscale metal AM
method is not limited to nickel as exemplified below, but can be
applied to other organometallics as described elsewhere herein and
can be used to derive UV-curable metal-based photoresists using
similar chemical synthesis. Successful fabrication of nickel 3D
nano-structures demonstrates that this approach can be applied to
print sophisticated metallic architectures that are challenging to
3D print using established metal AM processes, e.g. molybdenum and
tungsten. Nanoscale additive manufacturing of metals has direct
implications and open opportunities for scalable production of
complex sub-millimeter devices, including 3D MEMS, 3D microbattery
electrodes, and microrobots and tools for minimally invasive
medical procedures.
[0050] For example, the methods of the disclosure allow for the
generation of metal, metalloid, metal alloy, metal oxide, metal
nitride, inorganic, inorganic-organic hybrid and/or carbon-based
nanostructures that provide high surface areas. This is important
in various applications that utilize various metal and/or inorganic
properties.
[0051] Solar disinfection of drinking water (SODIS) is an approach
for water purification widely used in households with limited
access to fresh water. SODIS relies on microorganism inactivation
triggered by sunlight energy in the UV spectrum and requires
processing times of up to 48 hr. Water treatment rate is
drastically increased by using photocatalytic materials, such as
TiO.sub.2, which can harvest sunlight to promote generation of
reactive oxygen species (ROS) that inactivate bacteria within few
hours. One main challenge that impedes the insertion of
photocatalysts in most water treatment approaches is the need to
populate the catalyst particles on a three-dimensional (3D)
structure with a high-surface area that is stable under water
flow.
[0052] The disclosure demonstrates that the method of the
disclosure can be utilized to fabricate an architectured TiO.sub.2
device that does not require expensive filtering of the catalyst.
The TiO.sub.2 device was fabricated using the additive
manufacturing (AM) method of the disclosure and using titania as
the framework-material. As described above, a weak ligand was used
to create a titanium monomers via a ligand exchange reaction
between titanium alkoxide and acrylic acid and utilize the titanium
monomers to prepare a photopolymerizable titania photoresist. This
photoresist was then used in a commercial stereolithography
apparatus to define complex 3D architectures, which was then
pyrolyzed to remove organic content. The resulting structure has
.about.40% reduced dimensions compared with its as-fabricated
counterpart and has a chemical composition of 46 wt % Ti, 31 wt %
O, and 23 wt % C, as measured at the surface by Energy-Dispersive
Spectroscopy (EDS). Using this methodology, 3D structures were
fabricated with periodic cubic and octet geometries whose unit
cells range from 0.65 to 1.14 mm, beam lengths of 115-170 .mu.m,
and relative densities of 11-31%. Transmission Electron Microscopy
(TEM) analysis reveals the microstructure of these lattices is
nanocrystalline titania (rutile) with a mean grain size of
.about.60 nm. Mechanical experiments reveal that these cubic
titania microlattices, whose density is 350-365 kg/m.sup.3, achieve
compressive strengths of up to 4.3 MPa, which is several times
stronger than what is reported for titania foams with comparable
density.
[0053] As an exemplary embodiment, the disclosure provides a water
disinfection device made by the methods of the disclosure. A
rendition of an architected titania device for household solar
water disinfection is shown in FIG. 7. A three-dimensional titania
scaffold (30) (as described above) is placed inside of an optically
transparent (e.g., PET) filled water bottle (20) and placed in the
sunlight (10) (FIG. 7A). The light interacts with the titania
photocatalyst in the titania scaffold (30), which promotes the
reaction with water and dissolved oxygen to produce hydroxyl (.OH)
and superoxide radicals (.O2-) that deactivate bacteria (FIG. 7B).
The designed open-cell architecture of the scaffold allows the
light to propagate throughout the photocatalyst volume, which
promotes the generation of ROS throughout the entire liquid volume
and efficiently disinfects the water. High strength of the
architected structure ensures that the catalytic material is not
released to the treated water, so that it can be readily consumed
after the disinfection (FIG. 7C).
[0054] The foregoing embodiment further demonstrates that various
metals, metalloids and/or inorganics can be used in the methods and
compositions of the disclosure. Moreover, that the titania AM
process can be used to create safe, efficient and cost-effective
photocatalytic reactors for household water disinfection, as well
as for applications in photocatalytic hydrogen production, CO.sub.2
conversion, and tissue engineering.
[0055] Outstanding electrical and optical properties of graphene,
sp2-hybridized planar allotrope of carbon, have made it highly
attractive for transparent conductive films (TCFs) and energy
storage/conversion device applications. Transferring the desired
properties of graphene onto non-planar devices requires methods for
defining the net shape of graphene architectures, such as 3D
printing. The existing methods for AM of graphene-containing
materials imply either low graphene/graphene oxide (G/GO) loading
of resins for stereolithography or using low-resolution
extrusion-based techniques for material deposition. These
considerations limit graphene AM either to structures with low
graphene content or to at most 100 .mu.m resolution.
[0056] Using the methods described herein an AM process for
graphene foams is provided. For example, an AM of graphene foams
with critical dimensions in the nano-scale regime. This embodiment,
includes (i) defining a 3D structure using a hybrid
organic-inorganic chemical that contains inorganic nickel clusters
branched with functional groups that allow for photopolymerization
and (ii) pyrolyzing the structure to achieve catalytic conversion
of carbon to graphene. As described herein above and in Example 1,
below, nickel-containing acrylic resin can be mixed with a
photoinitiator to form a catalyst-containing photoresist. 3D
structure made of catalyst-containing polymer can then be defined
using lithographic methods. The structure can be further pyrolyzed
leading to nickel-catalyzed conversion solid-source carbon to
sp2-hybridized form, effectively defining a G/GO 3D structure.
[0057] The method includes (i) preparing a nickel photoresist (as
described herein), (ii) defining a 3D structure with micron- or
submicron-sized features made of the Ni photoresist using
two-photon lithography, and (iii) pyrolyzing the resulting
structure in forming gas to yield a 3D printed nickel/G/GO
structure with 400 nm features.
[0058] AM of G/GO aerogel structures is accomplished using
alternative 3D-printing methods, e.g. micro-SL, SL, etc.
Furthermore, carbon nanotube (CNT) structures may be fabricated via
catalytic conversion of solid source carbon in the 3D polymer
structure using incorporated iron or nickel NPs. Additionally,
graphene foams may be architected to decouple electrical and
optical properties for TCEs. Graphene structures can be fabricated
to have a smaller footprint, yielding a more transparent film. At
the same time, more interconnects can be added to the architected
graphene film structure, which may decrease the sheet resistance of
the film.
[0059] In another aspect, a metal alkoxide-derived acrylic resin
can be used for patterning of catalytic particles to enable
nano-scale spatial control of chemical processes. In this
embodiment, a 2D pattern of metal catalyst-containing resin can be
defined on a substrate using lithography. Then the organic content
of the structure can be removed (e.g., using thermal processing),
which leaves a pattern of metal nanoparticles (NPs). Metal NP size
distribution can be controlled via metal content of the resin and
geometrical parameters of the pattern (e.g. line width and line
thickness). These NPs can be further used to locally catalyze a
chemical process, such as catalytic synthesis of nanomaterials.
EXAMPLES
Example 1
[0060] UV-Curable Metal-Based Photoresist.
[0061] Acrylic acid (anhydrous, 99%), propylene glycol monomethyl
ether acetate (PGMEA) (>99.5%), dichloromethane (anhydrous,
299.8%), 2-methoxyethanol (anhydrous, 99.8%), and isopropyl alcohol
(IPA) (99.7%) were purchased from Sigma Aldrich. Nickel
2-methoxyethoxide, 5% w/v in 2-methoxyethanol was purchased from
Alfa Aesar, and 7-diethylamino-3-thenoylcoumarin was purchased from
Exciton. Acrylic acid (100 mg) was slowly added to nickel
2-methoxyethoxide solution (1290 mg) in a glove box and manually
agitated. Nearly immediately a change of the solution color from
brown to green was observed, which is indicative of a ligand
exchange reaction. The mixture was held at low pressure in the
antechamber of the glove box for 45 min to remove .about.60% of
2-methoxyethanol. The resulting precursor was then taken out of the
glove box, mixed with 300 mg of pentaerythritol triacrylate, and
agitated using a vortex mixer for 1 min.
7-diethylamino-3-thenoylcoumarin (23 mg) was dissolved in 100 mg of
dichloromethane, added to the mixture, which was then agitated
using a vortex mixer for 1 min.
[0062] Two-Photon Lithography.
[0063] Metal-containing polymer structures were fabricated on a
silicon chip (1.times.1 cm) using a commercially available
two-photon lithography system (Photonic Professional GT, Nanoscribe
GmbH). Metal-containing photoresist was drop cast on a glass slide
(0.17 mm thick, 30 mm in diameter) and confined between the glass
slide and a silicon chip using 100 .mu.m thick, 2.times.10 mm
ribbons of Kapton tape as spacers. Laser power and scan speeds were
set at 17.5-22.5 mW and 4-6 mm s.sup.-1, respectively. After the
printing process, the samples were developed in 2-methoxyethanol
for 1 hour, followed by immersion in PGMEA for 10 min and filtered
IPA for 5 min. The samples were then processed in a critical point
dryer (Autosamdri-931).
[0064] Pyrolysis.
[0065] Pyrolysis of the cross-linked metal-containing structures
was conducted in two steps in a quartz tube furnace using 4''
quartz tube. As the first step, a heating profile of 2.degree.
C./min to 1000.degree. C., hold at 1000.degree. C. for 1 hour was
applied under 1 L/min argon flow, and the part was let to cool down
in the furnace to room temperature. During the second step the part
was heated at 2.degree. C./min to 600.degree. C. under 1 L/min
forming gas flow (5% H.sub.2, 95% N.sub.2), held at 600.degree. C.
for 1 hour, and let to cool down to room temperature. No additional
processing was performed after pyrolysis.
[0066] Material Characterization.
[0067] Scanning Electron Microscopy (SEM) images were obtained
using an FEI Versa 3D DualBeam. SEM Energy-Dispersive X-Ray
Spectroscopy (EDS) characterization was performed using a Zeiss
1550VP FESEM equipped with an Oxford X-Max SDD system using 10 kV
electron beam.
[0068] Transmission Electron Microscopy (TEM) and TEM EDS were
performed using FEI Tecnai F30ST (300 kV) transmission electron
microscope equipped with Oxford ultra-thin window EDS detector. TEM
sample was prepared by fabricating metal structures directly on
PELCO Holey Silicon Nitride Support Film for TEM with 1250 nm holes
(Ted Pella) following the process described above.
[0069] Phases and Miller indices for the phases in HRTEM image
(FIG. 3E) were assigned based on the two lattice distances
d.sub.hkl and the angle measured from FFT patterns. First, lattice
distances d.sub.hkl for nickel, nickel (II) oxide, and nickel
carbide were calculated based on the lattice parameters obtained
from. The measured distances were then compared to the calculated
values and matched within 5% error. The phase assignment was
verified by comparing the angle measured from the FFT pattern with
the theoretical value for the obtained orientation, and further
corroborated using the electron diffraction pattern in FIG. 3D.
[0070] Particle Size.
[0071] Particle sizes (see Table 1) were measured from a
bright-field TEM image using ImageJ (FIG. 7). Confidence interval
on the mean particle size was calculated assuming normal
distribution of the particle sizes and unknown variance using
t-distribution (n=40, .alpha.=0.05). Confidence interval on the
variance of the particle size was calculated using .chi..sup.2
distribution (n=40, .alpha.=0.05)
TABLE-US-00001 TABLE 1 Particle sizes collected from the
bright-field TEM image (see FIG. 7) N Size, nm 1 37.24 2 19.47 3
33.79 4 25.29 5 30.55 6 17.24 7 31.06 8 19.04 9 33.05 10 19.86 11
16.73 12 19.59 13 19.03 14 20.41 15 22.85 16 26.94 17 17.43 18
18.98 19 23.25 20 22.16 21 15.15 22 19.26 23 16.61 24 12.52 25
12.14 26 16.59 27 25.43 28 16.6 29 16.61 30 17.98 31 14.29 32 27.28
33 12.82 34 29.34 35 21.67 36 14.88 37 18.95 38 19.95 39 21.81 40
30.72
[0072] Mechanical Characterization.
[0073] Uniaxial compression experiments were conducted using in
situ nanomechanical instrument, SEMentor (InSEM; Nanomechanics and
FEI Quanta 200). Samples were compressed using a diamond flat punch
tip with a diameter of 170 .mu.m at a constant strain rate of
10.sup.-3 s.sup.-1. Relative density of each of the structures was
calculated using a CAD model created in Abaqus with average unit
cell sizes and beam diameters measured from the SEM images assuming
fully-dense beams. Real-time deformation video and the mechanical
data were simultaneously captured during the experiment (not
provided).
[0074] Specific strength values shown in Table 2 were calculated as
the lattice strength divided by the lattice density.
TABLE-US-00002 TABLE 2 Specific strength of metal lattices
fabricated using metal AM processes. Beam Material Lattice Specific
Lattice diameter, Strength, Relative density, density, strength,
Material Type Process .mu.m MPa density g/cm.sup.3 g/cm.sup.3
MPa/(g/cm.sup.3) Ti--6Al--4V Cubic Electron 810 23.70 0.063 4.43
0.26 84.92 Beam 970 34.70 0.078 0.32 100.42 Melting 1480 89.10
0.159 0.65 126.50 (EBM) 1780 180.20 0.216 0.88 188.32 Ti--6Al--4V
Topology- Selective 406 30.00 n/a 0.50 60.00 optimized Laser
Melting (SLM) AlSi10Mg Diamond Direct 405 1.42 0.050 2.67 0.12
10.63 Metal 502 4.72 0.075 0.17 23.54 Laser 659 8.54 0.100 0.23
31.98 Sintering 765 12.61 0.125 0.29 37.76 (DMLS) 862 17.40 0.150
0.35 43.45 Stainless BCC Selective 162 0.20 0.023 n/a 0.19 1.05
steel 316L Laser 181 0.33 0.029 0.23 1.43 Melting 181 0.33 0.029
0.23 1.43 (SLM) 197 0.45 0.034 0.28 1.61 197 0.45 0.035 0.28 1.61
212 0.58 0.040 0.32 1.81 212 0.60 0.041 0.33 1.82 186 0.38 0.031
0.25 1.52 210 0.55 0.039 0.31 1.77 230 0.79 0.047 0.38 2.08 249
1.00 0.055 0.44 2.27 165 0.32 0.030 0.24 1.33 166 0.33 0.032 0.26
1.27 186 0.47 0.036 0.29 1.62 188 0.46 0.034 0.28 1.64 222 0.83
0.047 0.38 2.18 211 0.73 0.043 0.34 2.15 Silver Octahedral
Pointwise 35 0.60 0.065 n/a 0.50 1.20 Spatial 38 1.27 0.270 1.74
0.73 Printing NiTi Octahedral Selective 248 21.00 0.252 6.45 1.63
12.92 Cellular laser 298 29.00 0.252 1.63 17.84 gyroid melting 210
44.00 0.266 1.72 25.65 Sheet (SLM) gyroid Nickel Octet This 0.30
18.17 8.91 2.52 7.20 work 0.30 17.08 2.55 6.71 0.28 8.91 2.60 3.42
0.27 8.18 2.75 2.98
[0075] Pyrolysis was performed in a tube furnace following a
two-step procedure: (1) at 1000.degree. C. to remove most of the
organic content from the samples and to consolidate the Ni metal
clusters into denser features, which is accompanied by
.about.5.times. linear shrinkage in feature size and (2) at
600.degree. C., to reduce the oxygen content in the mostly-Ni
samples and to facilitate grain growth. SEM images in FIG. 1I-J
show a representative 3D Ni architecture and convey that the 10
.mu.m unit cells and 2 .mu.m-diameter beams in the original
polymer-metal structure shrank to .about.2 .mu.m unit cells and
300-400 nm diameter beams in the nickel nanolattice. This also
implies that 150 nm layer thickness in the polymer structure
corresponds to 30 nm layer thickness in the metal structure. The
zoomed-in image in FIG. 1J shows that the metal beams are
.about.10%-30% porous caused by pyrolysis.
[0076] Chemical composition of the as-fabricated Ni architectures
was characterized using Energy-Dispersive X-Ray Spectroscopy (EDS),
for which individual unit cells were fabricated with
tetrakaidecahedron geometries using the same methodology. FIG. 2A
shows that these structures shrunk from 20 .mu.m-wide unit cells
and 2 .mu.m-diameter beams on 6 .mu.m pillar supports to 4 .mu.m
unit cells and 0.4 .mu.m-diameter beams after pyrolysis (FIG. 2B).
EDS spectrum (FIG. 2D) taken from a beam section shown in FIG. 2C
reveals the chemical composition to be 91.8 wt % Ni, 5.0 wt % O,
and 3.2 wt % C. A Si peak from the substrate is also present. EDS
maps in FIG. 2E-H convey a relatively homogeneous distribution of
each element within the printed structure, which consists mostly of
nickel metal and is not segregated into individual nickel-,
carbon-, or oxygen-rich phases.
[0077] A few-micron long, 25-100 nm-diameter metal beams that
spanned the 1.25 .mu.m-wide opening in a silicon nitride membrane
were fabricated directly on the Transmission Electron Microscopy
(TEM) grids (FIG. 3A) to analyze the atomic-level microstructure of
pyrolyzed materials. FIG. 3B displays a bright-field TEM image
taken along a portion of that beam that reveals multiple coalesced
grains with mean size of 21.4.+-.2.0 nm.
[0078] The electron diffraction pattern (FIG. 3D) taken from the
region shown in FIG. 3C conveys a strong Ni signal and a much
weaker contribution from NiO. A representative high-resolution TEM
(HRTEM image (FIG. 3E) of the beam edge contains multiple lattice
fringes, which allowed the calculation of interplanar atomic
spacings using Fast Fourier transform (FFT). Three distinct
spacings were identified: Ni crystals (region 1, spacings of 2.01
.ANG. and 2.04 .ANG.), Ni3C particles (region 2, spacings of 1.98
.ANG. and 2.14 .ANG.), and NiO crystals (region 3, spacing of 2.06
.ANG.). Bright-field TEM revealed that Ni crystals occupy >90%
of the examined volume, NiO<10%, and Ni.sub.3C<1%, consistent
with EDS results. TEM analysis further revealed the presence of
nickel (II) oxide nanoparticles with diameters of <5 nm at the
surface that were likely formed through surface oxidation in air
after sample preparation. The pyrolysis is equivalent to
carbothermal reduction at 1000.degree. C. followed by hydrogen and
carbothermal reduction at 600.degree. C., with no oxygen present in
the flowing gas. Literature on this type of thermal treatment
reported the composition to be mainly metallic nickel with a minor
amount of nickel carbide and/or carbon.
[0079] Uniaxial compression experiments were performed on four Ni
octet nanolattices with relative densities of .about.28-31% and
beam sizes of 300-400 nm. The experiments were conducted in-situ,
in a SEM-based nanomechanical instrument, comprised of a
nanoindenter-like module (Nanomechanics, Inc.) inside of SEM
chamber (Quanta 200 FEG, FEI), which enabled observing the
deformation while simultaneously collecting load vs. displacement
data. The collected data was converted into engineering stresses
and strains by dividing the load by the sample footprint area and
dividing the displacement by the sample height, respectively. FIG.
4A-D shows SEM snapshots obtained during a compression experiment
of a representative sample together with the stress vs. strain data
(FIG. 4E). The stress vs. strain data was typical for cellular
solids compressions, with the characteristic elastic loading,
plateau, and densification sections. The arrows on the plot in FIG.
4E are correlated with the images in FIG. 4A-D and demarcate
specific stages during compression: initial contact (region A),
elastic deformation (region B), layer-by-layer collapse (region C),
and densification (region D). A toe region in the initial portion
of each experiment (not shown) is representative of deformation
before establishing full contact between the sample and flat punch
indenter tip. The point of full contact was determined using
harmonic contact stiffness and SEM video. The slope of the elastic
loading segment, up to 10-15% strain (region B), was used to
estimate structural stiffness of the nanolattices, which ranged
from .about.53 to 174 MPa. The strength of Ni nanolattices was
defined as the maximum stress prior to the first buckling event,
marked by open circles in the data in FIG. 4E, and ranged from 8.2
MPa to 18.2 MPa. The elastic region was followed by layer-by-layer
collapse up to 65% strain (region C); two of the four samples were
unloaded at 30 and 60% strain. The two remaining samples were
compressed to 70-85% strains, reached densification (region D) and
then unloaded. None of the nanolattices recovered after
deformation.
[0080] FIG. 4F shows the specific strength of Ni nanolattices
fabricated in this work and those of the metallic lattices
fabricated using other metal AM processes as a function of beam
diameter on a log-log plot (see Table 2). Nanocrystalline Ni
nanolattices of the disclosure have the specific strength of
3.0-7.2 MPa/(g/cm.sup.3), which is an order of magnitude higher
than that of octahedral silver lattices with .about.40
.mu.m-diameter beams and .about.3-7.times. higher than the
stainless steel lattices with .about.200 .mu.m-diameter beams
described in the literature. It appears to be on the same order as
NiTi octahedral lattices with .about.250 .mu.m-diameter beams and
AlSi10Mg diamond lattices with .about.400 .mu.m beams. This
suggests that the AM process described here is capable of producing
architectures with feature sizes that are an order of magnitude
smaller than those fabricated using existing AM processes while
retaining high strength. This is in contrast to all other existing
metallic lattices whose strength rapidly deteriorates with
slenderer beams. This trend was used to extrapolate the specific
strength of lattices with beams smaller than 40 .mu.m and found
that nickel nanolattices are more than four orders of magnitude
stronger than what is expected for architectures with 0.3 .mu.m
features (FIG. 4F). This strength of Ni nanolattices represents a
lower bound because the 10-30% residual porosity lowers the
compressive strength and leads to high sample-to-sample
variation.
[0081] FIG. 5 shows minimal reported printed feature sizes enabled
by this method and some other metal AM processes available today.
The plotted ranges include both layer thickness and minimum lateral
feature size. The minimum z-feature is determined by the resolution
of a single layer of material. The minimum lateral feature is
defined by multiple factors, which include the energy beam spot
size and control over the melt pool. The data in FIG. 5
demonstrates that the AM process developed in this work is capable
of producing features that are an order of magnitude smaller
compared to those produced by other 3D-capable AM processes.
Another key aspect of any metal AM process is the throughput. Using
hybrid organic-inorganic photoresist developed in this work allows
for writing speeds of 4-6 mm s.sup.-1, which is .about.100 times
faster than that for TPL of metal salts. For a typical 300-600 nm
feature size printed by TPL35, this corresponds to defining
6700-20000 voxels s.sup.-1, a printing speed that is out of reach
for state-of-the-art micro-scale metal AM techniques, i.e.
electrohydrodynamic printing (0.05-300 voxels s.sup.-1), local
electroplating (0.04-1.0 voxels s.sup.-1), focused beam methods
(0.01-0.8 voxels s.sup.-1), and direct ink writing (0.7-3000 voxels
s.sup.-1). High scanning speeds and intrinsic advantage of
parallelizing light delivery using lithographic methods suggest
that the presented AM process lends itself to efficient scalable
manufacturing of metal nano-architectures.
Example 2
[0082] Acrylic acid (anhydrous, 99%), titanium(IV) ethoxide
(>97%), propylene glycol monomethyl ether acetate (PGMEA)
(>99.5%), and isopropyl alcohol (IPA) (99.7%) were purchased
from Sigma Aldrich. Acrylic acid (17.3 g) was slowly added to
titanium(IV) ethoxide (13.7 g) in a glovebox (FIG. 8A), and the
solution was manually agitated. The color of the solution changed
from yellow to orange, which is indicative of a ligand exchange
reaction. This mix was then placed in a vacuum antechamber of the
glovebox for 15 min to remove excess ethanol. The resulting
solution was taken out of the glovebox and mixed with 87.7 g of an
open-source Autodesk PR48 formulation (39.776 wt % Allnex Ebecryl
8210, 39.776 wt % Sartomer SR 494, 0.4 wt %
2,4,6-Trimethylbenzoyl-diphenylphosphineoxide, 19.888 wt % Rahn
Genomer 1122, 0.160 wt %
2,2'-(2,5-thiophenediyl)bis(5-tertbutylbenzoxazole); Colorado
Photopolymer Solutions) and stirred at room temperature for 1
hr.
[0083] A stereolithography-based 3D printer (Autodesk Ember) was
used to pattern the synthesized titanium-rich photoresist using a
layer-by-layer approach with 25 .mu.m layer thickness (FIG. 8A).
Structures with different geometries were printed, with the UV
exposure of the first layer for 14.0 s, four consequent layers for
9.0 s, and all remaining layers for 3.5 s. Printed structures were
developed in PGMEA for 15 min, followed by IPA wash for 10 min.
FIG. 8A shows a representative titanium-containing polymer scaffold
after development.
[0084] The final step in this AM process involved placing the
printed titanium-containing polymer structures on a fused quartz
boat and pyrolyzed in a tube furnace using 4'' quartz tube under 1
L/min argon flow. The temperature was ramped up to 1000.degree. C.
at 2.degree. C./min, kept at 1000.degree. C. for 1 hour, and cooled
down to room temperature at a natural rate. FIG. 8A (bottom) show
representative titania structures after pyrolysis.
[0085] Samples were fabricated in two geometries: (1)
10.times.10.times.10-unit cell cubic lattices with unit cell
dimensions of 1.16.+-.0.10 mm and beam diameters of 393.+-.17 .mu.m
(FIG. 8A) and (2) 5.times.5.times.5-unit cell octet lattices with
1.71.+-.0.17 mm unit cell dimensions and 179.+-.5 .mu.m beam
diameters. These samples had relative densities that range from 11%
to 31%. All samples were pyrolyzed in Ar atmosphere at 1000.degree.
C., which led to linear shrinkage of 39.0.+-.5.9% and a mass loss
of 74.2.+-.2.5%. The final products were cubic titania lattices
with unit cell sizes of 0.66.+-.0.01 mm and beam diameters of
170.+-.5 .mu.m (FIG. 8A) and octet lattices with unit cell sizes of
1.14.+-.0.01 mm and beam diameters of 115.+-.4 .mu.m (FIG. 8B).
These 3-dimensional titania architectures appeared white, blue,
black and other colors, which likely stems from (i) a change in the
visible light absorption of titania as a function of doping with
carbon, sulfur and nitrogen, all of which are present in the
initial photoresist, and (ii) a contribution to the light
absorption by the residual carbon.
[0086] FIG. 8C-E show Scanning Electron Microscopy (SEM) (FEI Versa
3D DualBeam) images of the resulting morphology of the pyrolized
titania octet lattices at different magnifications. These images
reveal uniformly sized unit cells and beams with visible
layer-to-layer transition patterns, which are inherent for the
utilized SL printer (FIG. 8C). The surface of the structure is
covered by porous nanocrystalline formations with clearly visible
facets and crystals ranging from 20 to 150 nm in size (FIG.
8D-E).
[0087] SEM Energy-Dispersive X-Ray Spectroscopy (EDS)
characterization was conducted with Zeiss 1550VP FESEM equipped
with Oxford X-Max SDD using a 10 kV electron beam. FIGS. 9A-B and D
shows EDS maps of the of the pyrolyzed titania lattices, which
convey a uniform distribution of Ti, 0 and C throughout the
structure. This EDS spectrum suggests a chemical composition of 46
wt % of Ti, 31 wt % of O, and 23 wt % of C (FIG. 9C). Raman
spectroscopy (Renishaw M1000 MicroRaman Spectrometer, 514.5 nm
laser) conducted on the surface of the pyrolyzed samples showed
predominantly rutile signature (FIG. 9F).
[0088] FIG. 10 shows the results of microstructural analysis
performed on a compressed titania lattice in a Transmission
Electron Microscope (FEI Tecnai F30ST, 300 kV). The sampled titania
particles, most likely, belong to the beam surface, since the
crystal size considerably diminishes further away from the surface
of the structure, as seen on an SEM image of a beam cross-section
(FIG. 10A). TEM images reveal the presence of TiO.sub.2 crystals
(FIG. 10D) with a mean crystal size of 59.2.+-.8.0 nm (see FIG. 10B
for particle size histogram). Electron diffraction pattern from a
mostly crystalline region of the sample (FIG. 10E) corroborates
rutile titania as the predominant phase (see FIG. 10F).
High-resolution TEM image in FIG. 10C demonstrates the presence of
crystalline and amorphous regions within the sample. FFT analysis
of a crystalline region confirms the material to be rutile
TiO.sub.2, with 3.20 .ANG. lattice spacing that corresponds to
(110) and (110) orientations (FIG. 10C, top right). Amorphous
regions closer to the beam center correspond to TiO.sub.1-xC.sub.x,
with oxygen content varying as a function of depth, as observed on
an EDS line spectrum of a beam cross-section.
[0089] Uniaxial compression tests on pyrolyzed cubic lattices were
performed using Instron 5569 electromechanical testing machine
equipped with an Instron 2525-802 load cell (R.C. 50 kN) at a
displacement rate of 0.15-0.5 mm/min. The collected load vs.
displacement data was converted into engineering stresses and
strains using the height and the footprint of the structure
measured from optical images before compression. FIG. 11 shows
optical images of the structure during compression (FIG. 11A-D) and
representative stress-strain data (FIG. 11E). This data
demonstrates that each compression began with a toe region
corresponding to the sample settling into full contact followed by
linear elastic regime up to 1-2% strain. Further compression
resulted in gradual brittle failure of individual beams and unit
cells (see FIG. 11E).
[0090] The loading slope was used to calculate the structural
elastic modulus to be 0.21-0.37 GPa. The strength was measured as
the maximum stress achieved during initial elastic loading and
ranged from 2.1 to 4.3 MPa. These strengths and moduli are
comparable to strongest reported titania foams with 2.times. higher
densities, up to 2.5 MPa at 700 kg/m.sup.3, and 2.1 to 5.6 times
stronger than titania foams with comparable densities (0.8-1.0 MPa
at 350 kg/m.sup.3). The mechanical properties of the architected
titania lattices in this work may be further improved by using a
high-temperature annealing step (21500.degree. C.) that would
induce better sintering of titania particles.
Example 3
[0091] Spatial control of catalytic synthesis of carbon nanotubes
(CNTs) was accomplished using a pattern of nickel NPs. A
preparation of a nickel-containing resin (see above) was used. Grid
patterns were defined with 5 um unit cell and 150 nm line thickness
on a silicon chip using two-photon lithography. The photoresist
pattern was pyrolyzed in argon atmosphere at 900.degree. C.,
yielding a pattern of 20-150 nm nickel nanoparticles (NiNPs)
encapsulated in carbon (FIG. 12A). The NiNP pattern was further
process in a forming gas at 900.degree. C. to grow CNTs using the
residual solid carbon source (FIG. 12B).
[0092] Other embodiments, combinations and modifications of this
invention will occur readily to those of ordinary skill in the art
in view of these teachings. Therefore, this invention is to be
limited only by the following claims, which include all such
embodiments and modifications when viewed in conjunction with the
above specification and accompanying drawings.
* * * * *