U.S. patent application number 12/362946 was filed with the patent office on 2009-12-17 for electrically conductive polymer actuator and method for manufacturing the same.
This patent application is currently assigned to PANASONIC CORPORATION. Invention is credited to Yuji KUDOH.
Application Number | 20090308737 12/362946 |
Document ID | / |
Family ID | 40666647 |
Filed Date | 2009-12-17 |
United States Patent
Application |
20090308737 |
Kind Code |
A1 |
KUDOH; Yuji |
December 17, 2009 |
ELECTRICALLY CONDUCTIVE POLYMER ACTUATOR AND METHOD FOR
MANUFACTURING THE SAME
Abstract
To improve adhesive properties between an electrically
conductive polymer membrane and a solid electrolyte membrane to
each other, and thus to ensure the operation of an electrically
conductive polymer actuator which effects a bending motion is
aimed. The bendable electrically conductive polymer actuator of the
present invention is an electrically conductive polymer actuator
having a laminating structure of: a first organic polymer including
at least one or more of a vinylidene fluoride/hexafluoropropylene
copolymer, polyvinylidene fluoride, a perfluorosulfonic
acid/polytetrafluoroethylene copolymer, polymethyl methacrylate,
polyethylene oxide, and polyacrylonitrile; a solid electrolyte
membrane including a mixture with an ionic liquid; and an
electrically conductive polymer membrane including a mixture of
polyethylenedioxythiophene and polystyrene sulfonic acid on at
least one face of the solid electrolyte membrane, in which a second
organic polymer including polyvinylphenol is embedded in the
electrically conductive polymer membrane surface in the state being
dispersed.
Inventors: |
KUDOH; Yuji; (Kyoto,
JP) |
Correspondence
Address: |
McDERMOTT WILL & EMERY LLP
600 13th Street, N.W.
Washington
DC
20005-3096
US
|
Assignee: |
PANASONIC CORPORATION
Osaka
JP
|
Family ID: |
40666647 |
Appl. No.: |
12/362946 |
Filed: |
January 30, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2008/001485 |
Jun 11, 2008 |
|
|
|
12362946 |
|
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Current U.S.
Class: |
204/242 ;
156/60 |
Current CPC
Class: |
Y10S 310/80 20130101;
Y10T 156/10 20150115; F03G 7/005 20130101; B81B 3/0021
20130101 |
Class at
Publication: |
204/242 ;
156/60 |
International
Class: |
C25B 9/00 20060101
C25B009/00; B32B 37/00 20060101 B32B037/00 |
Claims
1. A bendable electrically conductive polymer actuator comprising:
a pair of electrodes, and a laminating structure sandwiched between
the pair of electrodes, wherein the laminating structure comprises:
a solid electrolyte membrane constituted with a mixture including
an ionic liquid, and a first organic polymer that contains at least
one or more of a vinylidene fluoride/hexafluoropropylene copolymer
[P(VDF/HFP)], polyvinylidene fluoride (PVDF), a perfluorosulfonic
acid/PTFE copolymer, polymethyl methacrylate (PMMA), polyethylene
oxide (PEO) and polyacrylonitrile (PAN); and an electrically
conductive polymer membrane which is formed on the solid
electrolyte membrane, and which is constituted with a mixture of
polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid
(PSS), and wherein a second organic polymer constituted with
polyvinylphenol (PVP) is embedded in the state being dispersed, in
the electrically conductive polymer membrane surface, and the solid
electrolyte membrane is in contact with the face of the
electrically conductive polymer membrane surface in which the
second organic polymer is embedded in the state being
dispersed.
2. The bendable electrically conductive polymer actuator according
to claim 1 wherein the electrically conductive polymer membrane is
formed on both faces of the solid electrolyte membrane.
3. A method of driving a bendable electrically conductive polymer
actuator, the method comprising the steps of: providing the
bendable electrically conductive polymer actuator comprising: a
pair of electrodes, and a laminating structure sandwiched between
the pair of electrodes, wherein the laminating structure comprises:
a solid electrolyte membrane constituted with a mixture including
an ionic liquid, and a first organic polymer that contains at least
one or more of a vinylidene fluoride/hexafluoropropylene copolymer
[P(VDF/HFP)], polyvinylidene fluoride (PVDF), a perfluorosulfonic
acid/PTFE copolymer, polymethyl methacrylate (PMMA), polyethylene
oxide (PEO) and polyacrylonitrile (PAN); and an electrically
conductive polymer membrane which is formed on the solid
electrolyte membrane, and which is constituted with a mixture of
polyethylenedioxythiophene (PEDOT)and polystyrene sulfonic acid
(PSS), and wherein a second organic polymer constituted with
polyvinylphenol (PVP) is embedded in the state being dispersed, in
the electrically conductive polymer membrane surface, and the solid
electrolyte membrane is in contact with the face of the
electrically conductive polymer membrane surface in which the
second organic polymer is embedded in the state being dispersed,
and applying a voltage to the pair of electrodes.
4. The method of driving a bendable electrically conductive polymer
actuator according to claim 3 wherein the electrically conductive
polymer membrane is formed on both faces of the solid electrolyte
membrane.
5. A method for manufacturing a bendable electrically conductive
polymer actuator comprising: a pair of electrodes, and a laminating
structure sandwiched between the pair of electrodes, wherein the
laminating structure comprises: a solid electrolyte membrane
constituted with a mixture including an ionic liquid, and a first
organic polymer that contains at least one or more of a vinylidene
fluoride/hexafluoropropylene copolymer [P(VDF/HFP)], polyvinylidene
fluoride (PVDF), a perfluorosulfonic acid/PTFE copolymer,
polymethyl methacrylate (PMMA), polyethylene oxide (PEO) and
polyacrylonitrile (PAN); and an electrically conductive polymer
membrane which is formed on the solid electrolyte membrane, and
which is constituted with a mixture of polyethylenedioxythiophene
(PEDOT) and polystyrene sulfonic acid (PSS), the method comprising
the steps of: coating a dispersion liquid or solution of an
electrically conductive polymer on a substrate, and before the
dispersion liquid or solution is dried to form a solid film,
embedding a second organic polymer constituted with polyvinylphenol
(PVP) in the state being dispersed, by means of spraying or
coating; and laminating on at least one face of the solid
electrolyte membrane so as to be opposed to the face of the
electrically conductive polymer membrane surface in which the
second organic polymer is embedded in the state being
dispersed.
6. A method for manufacturing a bendable electrically conductive
polymer actuator comprising: a pair of electrodes, and a laminating
structure sandwiched between the pair of electrodes, wherein the
laminating structure comprises: a solid electrolyte membrane
constituted with a mixture including an ionic liquid, and a first
organic polymer that contains at least one or more of a vinylidene
fluoride/hexafluoropropylene copolymer [P(VDF/HFP)], polyvinylidene
fluoride (PVDF), a perfluorosulfonic acid/PTFE copolymer,
polymethyl methacrylate (PMMA), polyethylene oxide (PEO) and
polyacrylonitrile (PAN); and an electrically conductive polymer
membrane which is formed on the solid electrolyte membrane, and
which is constituted with a mixture of polyethylenedioxythiophene
(PEDOT) and polystyrene sulfonic acid (PSS), the method comprising
the steps of: embedding a second organic polymer in the state being
dispersed, in an electrically conductive polymer membrane surface
by dispersing the second organic polymer, which is constituted with
polyvinylphenol (PVP), and which has a specific gravity smaller
than that of the electrically conductive polymer dispersion liquid
or solution, in the electrically conductive polymer dispersion
liquid or solution beforehand; and laminating on at least one face
of the solid electrolyte membrane so as to be opposed to the face
of the electrically conductive polymer membrane surface in which
the second organic polymer is embedded in the state being
dispersed.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an electrically conductive
polymer actuator which can be applied to robots for household use
and the like, and a method for manufacturing the same. In
particular, the present invention relates to an actuator in which
an electrochemical reaction is utilized, and a method for
manufacturing the same.
[0003] 2. Related Art
[0004] In recent years, necessity for actuators which are compact,
light weight, and highly flexible has been increasing in the field
of robots for household use and medical care, because properties
similar to human muscle (for example, safety which can avoid
causing injury upon contact, softness not causing pain even upon
bumping) are demanded on actuators for operating robots expected to
participate actively in close proximity to human bodies in
supporting domestic duties and jobs at home, offices, hospitals
etc., as well as in supporting for nursing of elderly persons and
handicapped persons, and the like.
[0005] As compact and light weight actuators, those of
electrostatic attraction type, piezoelectric type, ultrasonic type,
and, shape memory alloy type and the like have been already put
into practical applications. These actuators cannot be highly
flexible actuators since an inorganic material is used, and due to
their motion principles. Thus, attempts to provide a light weight
and highly flexible actuator by using an organic material such as a
polymer have been made in various fields extensively in recent
years.
[0006] For example, one in which a gel is allowed to bend by an
electric voltage (Japanese Unexamined Patent Application, First
Publication No. Hei 11-206162/Patent Document 1), one in which a
high electric voltage is applied between dielectric elastomer thin
films to permit deformation (R. Pelrine, R. Kornbluh, Q. Pei and J.
Joseph: Science, 287, 836-839 (2000)/Nonpatent Document 1), one in
which expansion and contraction of an electrically conductive
polymer is allowed by an oxidative-reductive reaction (Japanese
Unexamined Patent Application, First Publication No.
2006-050780/Patent Document 2), and the like may be
exemplified.
[0007] Since the actuator of such a type in which a gel is allowed
to bend by an electric voltage cannot maintain the bendability
unless application of the electric voltage is kept due to small
initiation stress, a problem of increase in the electric power
consumption may be raised. In addition, when a dielectric elastomer
thin film must be used, high voltage of several hundred to several
kilo volts is required for the deformation. Thus, when such
actuators are used in robots for household use, a problem of the
risk such as electric shock may be raised because of excessively
high voltage. To the contrary, the electrically conductive polymer
actuator in which expansion and contraction of an electrically
conductive polymer accompanied with an oxidative reaction is
utilized has a comparatively simple structure, is easy in
miniaturization and weight saving, and highly flexible.
Furthermore, such an actuator can be driven at a voltage as low as
several volts, and is also characterized by sufficiently high
initiation stress.
[0008] A bendable actuator in which expansion and contraction of an
electrically conductive polymer is utilized has a structure
including an electrically conductive polymer membrane laminated on
at least one face of a solid electrolyte membrane, as shown in FIG.
2. In FIG. 2, 301 designates an actuator element, 302a and 302b
designate an electrically conductive polymer membrane, 303
designates a solid electrolyte membrane, and 304a and 304b
designate an electrode. When the electrically conductive polymer
membrane is laminated on only one face of the solid electrolyte
membrane, a metal electrode thin film (counter electrode) is formed
on another face of the solid electrolyte membrane for applying a
voltage. In some cases, a metal electrode thin film may be formed
on the electrically conductive polymer membrane for applying a
voltage. Further, by applying a predetermined voltage between the
electrically conductive polymer membrane and the counter electrode,
or between the electrically conductive polymer membranes, bending
of the laminated film is caused. The motion principle of the
bending has been believed as in the following. That is, the applied
voltage allows the electrically conductive polymer to be
oxidatively reacted, and concomitantly, ions are incorporated into
the electrically conductive polymer membrane, or taken out
therefrom. The volume of the electrically conductive polymer
membrane is altered in response to such in-and-out migration of the
ion, and thus the actuator is bent since the solid electrolyte
membrane accompanied by no change in the volume is laminated. For
example, in the construction shown in FIG. 2, the actuator is bent
in a downward direction when the ion is incorporated into the
upside electrically conductive polymer membrane, or when the ion is
taken out from the downside electrically conductive polymer
membrane. To the contrary, the actuator is bent in an upward
direction when the ion is taken out from the upside electrically
conductive polymer membrane, or when the ion is incorporated into
the downside electrically conductive polymer membrane.
[0009] Examples of the electrically conductive polymer used in an
actuator include polyaniline, polypyrrole, polythiophene, and
derivatives thereof (Patent Document 2).
[0010] The electrically conductive polymer actuator utilizes the
in-and-out migration of the ion to and from the electrically
conductive polymer membrane, which is caused concomitant with an
electrical oxidation and reduction of the electrically conductive
polymer, according to the motion principle. Therefore, an
electrolyte is required as an ion supply source for executing
motion, and a solid electrolyte having a sufficient ionic
conductivity at a temperature around the room temperature is
required for permitting operation in the air. In this regard, a
material termed "ion gel" has been produced recently. It is a
material prepared by gelatinizing at least either one of a polymer
or a monomer dispersed in an ionic liquid, and allowing the ionic
liquid to be retained in the three-dimensional network structure of
the gel. Thus, it has flexibility, and achieves a value of
10.sup.-2 S/cm at room temperature, which is 100 times or higher
than that of conventional polyether type polymer solid electrolytes
(Ionic Liquid--Forefront of Development and Future--2003, Hiroyuki
Ohno, edit., CMC Publishing CO., LTD./Nonpatent Document 2).
[0011] In addition, as documents which can be relevant to the
present invention, Japanese Unexamined Patent Application, First
Publication No. 2006-129541 (Patent Document 3) and Japanese
Unexamined Patent Application, First Publication No. 2005-145987
(Patent Document 4) may be referred to.
[0012] Patent Document 3 discloses a polymer actuator device. In
FIG. 9 and its description discloses a polymer actuator device
which includes regulation electrode A (reference number: 203),
electrolytic displacement part A formed with an electrically
conductive polymer (reference number: 201), electrolyte part
(reference number: 202), electrolytic displacement part B formed
with an electrically conductive polymer (reference number: 201'),
and regulation electrode B (reference number: 203').
[0013] Moreover, it is described that polythiophene is preferred as
the electrically conductive polymer in paragraph number 0077 of
Patent Document 3. The paragraph number 0078 of Patent Document 3
discloses that a fluorine based polymer such as polyvinylidene
fluoride, and the copolymer thereof may be used as the polymer
solid electrolyte. Furthermore, it is disclosed that sulfonic acid
may be introduced into its basic skeleton.
[0014] Patent Document 4 discloses an electrically conductive
polymer gel and a method for producing the same, an actuator, a
patch label for introducing an ion, and a bioelectrode. In
addition, Patent Document 4, paragraph number 0069 (Example 7)
discloses addition of an alcohol to a
poly(3,4-ethylenedioxythiophene)-poly(ethylenesulfonate) colloid
dispersion liquid (abbreviated as PEDOT/PSS).
SUMMARY OF THE INVENTION
[0015] In conventional electrically conductive polymer actuators,
polyaniline, polypyrrole, polythiophene and derivatives thereof
have been used as electrically conductive polymers, however, just
low adhesive properties are provided to each other between such an
electrically conductive polymer membrane and a solid electrolyte
membrane formed with an ion gel. Therefore, when an electrically
conductive polymer membrane and a solid electrolyte membrane formed
with an ion gel are laminated to form a bendable actuator, a
problem of detachment of the electrically conductive polymer
membrane from the solid electrolyte membrane formed with the ion
gel has been raised in operation of the actuator.
[0016] An object of the present invention is to provide a bendable
electrically conductive polymer actuator which is not accompanied
by deterioration even though it is repeatedly operated, through
improving adhesive properties between an electrically conductive
polymer membrane and a solid electrolyte membrane formed with an
ion gel to each other. Another object of the invention is to
provide a method of manufacture for achieving this actuator.
[0017] The bendable electrically conductive polymer actuator
according to the present invention which can solve the foregoing
problems includes
[0018] a pair of electrodes, and
[0019] a laminating structure sandwiched between the pair of
electrodes, wherein
[0020] the laminating structure includes:
[0021] a solid electrolyte membrane constituted with a mixture
including an ionic liquid, and a first organic polymer that
contains at least one or more of a vinylidene
fluoride/hexafluoropropylene copolymer [P(VDF/HFP)], polyvinylidene
fluoride (PVDF), a perfluorosulfonic acid/polytetrafluoroethylene
(PTFE) copolymer, polymethyl methacrylate (PMMA), polyethylene
oxide (PEO) and polyacrylonitrile (PAN); and
[0022] an electrically conductive polymer membrane which is formed
on the solid electrolyte membrane, and which is constituted with a
mixture of polystyrene sulfonic acid (PSS) and
polyethylenedioxythiophene (PEDOT) formed on at least one face of
the solid electrolyte membrane,
and wherein
[0023] a second organic polymer constituted with polyvinylphenol
(PVP) is embedded in the state being dispersed, in the electrically
conductive polymer membrane surface, and
[0024] the solid electrolyte membrane is in contact with the face
of the electrically conductive polymer membrane surface in which
the second organic polymer is embedded in the state being
dispersed.
[0025] The method of driving the bendable electrically conductive
polymer actuator according to the present invention as described
above includes the steps of:
[0026] providing the bendable electrically conductive polymer
actuator, and
[0027] applying a voltage to the pair of electrodes.
[0028] It is preferred that the electrically conductive polymer
membrane be formed on both faces of the solid electrolyte
membrane.
[0029] The first method for manufacturing the bendable electrically
conductive polymer actuator according to the present invention as
described above includes the steps of:
[0030] coating a dispersion liquid or solution of an electrically
conductive polymer on a substrate, and before the dispersion liquid
or solution is dried to form a solid film, embedding a second
organic polymer constituted with polyvinylphenol (PVP) in the state
being dispersed, by means of spraying or coating; and
[0031] laminating on at least one face of the solid electrolyte
membrane so as to be opposed to the face of the electrically
conductive polymer membrane surface in which the second organic
polymer is embedded in the state being dispersed.
[0032] The second method for manufacturing the bendable
electrically conductive polymer actuator according to the present
invention as described above includes the steps of:
[0033] embedding a second organic polymer in the state being
dispersed, in an electrically conductive polymer membrane surface
by dispersing the second organic polymer, which is constituted with
polyvinylphenol (PVP), and which has a specific gravity smaller
than that of the electrically conductive polymer dispersion liquid
or solution, in the electrically conductive polymer dispersion
liquid or solution beforehand; and
[0034] laminating on at least one face of the solid electrolyte
membrane so as to be opposed to the face of the electrically
conductive polymer membrane surface in which the second organic
polymer is embedded in the state being dispersed.
[0035] The foregoing objects, other objects, features and
advantages of the present invention will be clarified from the
following detailed description of preferred embodiments with
reference to accompanying drawings.
[0036] According to the present invention, an electrically
conductive polymer actuator which effects a bending motion and is
not accompanied by deterioration of the characteristics even though
it is repeatedly operated, and in which adhesive properties between
an electrically conductive polymer membrane and a solid electrolyte
membrane formed with an ion gel can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 shows a schematic view illustrating an actuator of
one embodiment according to the present invention.
[0038] FIG. 2 shows a schematic view illustrating a conventional
bendable actuator.
DESCRIPTION OF REFERENCE NUMERALS AND SIGNS
DETAILED DESCRIPTION OF THE INVENTION
[0039] Hereinafter, the mode for carrying out the present invention
is explained with reference to the drawings.
[0040] FIG. 1 shows a schematic cross-sectional view illustrating
an actuator of one embodiment according to the present invention.
Actuator 101 is constituted with a laminate of electrically
conductive polymer membranes 102a and 102b, and solid electrolyte
membrane 103, in which electrodes 105a and 105b are provided so as
to sandwich one ends of the electrically conductive polymer
membranes 102a and 102b, respectively. By applying a voltage of
several volts between the electrode 105a and the electrode 105b,
the actuator 101 effects a bending motion with the part sandwiched
by the electrodes 105a and 105b which serves as a fixed part.
Similar bending motion is effected even with a structure in which
an electrically conductive polymer membrane is laminated on one
face of a solid electrolyte membrane, and a metal electrode thin
film (counter electrode) is formed on another face of the solid
electrolyte membrane for applying a voltage. However, by laminating
an electrically conductive polymer membrane on both faces of a
solid electrolyte membrane, a greater bending displacement can be
achieved.
[0041] The electrically conductive polymer which may be used in the
present invention has a conjugate double bond, whereby the p
electrons are spread through the entire polymer to contribute to
electronic conductivity. The electric conduction by an electrically
conductive polymer has been believed to be caused via polaron and
bipolaron, which are generated upon interaction of an oxidizing
agent doped in the polymer and p electrons in the polymer, and
serve as charging carriers. Although polyaniline, polypyrrole,
polythiophene and derivatives thereof can be used as the
electrically conductive polymer in the present invention,
particularly, polyethylenedioxythiophene (PEDOT) is preferably
included, and a mixture of polyethylenedioxythiophene (PEDOT) and
polystyrene sulfonic acid (PSS) is more preferably used. In the
case in which polyethylenedioxythiophene (PEDOT) is used, its
monomer can be chemically polymerized beforehand, and thus an
electrically conductive polymer membrane can be formed by merely
coating a dispersion of this polymer on a substrate. Therefore, a
polymer membrane having a uniform thickness can be readily obtained
on a substrate having a great area by employing a spin coating,
slit coating, bar coating, dipping or casting method. In addition,
it is suited for mass production owing to simple process for
production.
[0042] The polyethylenedioxythiophene (PEDOT) and polystyrene
sulfonic acid (PSS) in the mixture that constitutes the
electrically conductive polymer are represented by (chemical
formula 1) and (chemical formula 2), respectively.
Polyethylenedioxythiophene is characteristic in that it is less
likely to be subjected to oxidative deterioration since the
B-position of its chemically active five-membered ring is
previously inactivated by modification with oxygen. Additionally,
polystyrene sulfonic acid is strongly bound to
polyethylenedioxythiophene via ionic bonds in the mixture.
##STR00001##
[0043] According to the electrically conductive polymer membrane in
which the second organic polymer constituted with polyvinylphenol
(PVP) is embedded in the state being dispersed, in the surface,
particles of the second organic polymer are embedded in the
electrically conductive polymer membrane, and a part of them are
exposed to the surface of the electrically conductive polymer
membrane. The method for manufacturing this electrically conductive
polymer membrane can be executed by a procedure in which an
electrically conductive polymer dispersion liquid or solution is
coated on a substrate, and before the dispersion liquid or solution
is dried to form a solid film, the second organic polymer is
embedded in the state being dispersed, by means of spraying or
coating. Furthermore, since the second organic polymer constituted
with polyvinylphenol (PVP) has a lower specific gravity than that
of the electrically conductive polymer dispersion liquid or
solution, the second organic polymer can be also embedded in the
state being dispersed, in the electrically conductive polymer
membrane surface, by dispersing the second organic polymer in the
electrically conductive polymer dispersion liquid or solution
beforehand. In order to embed the second organic polymer in the
state being dispersed, in the surface as described above, it is
necessary that the second organic polymer is insoluble in the
solvent of the electrically conductive polymer dispersion liquid or
solution. When the second organic polymer is dispersed in the
electrically conductive polymer membrane surface after the
electrically conductive polymer membrane formed a solid film, the
second organic polymer cannot be embedded in the electrically
conductive polymer membrane. Therefore, the effect of improving the
adhesive properties between the electrically conductive polymer
membrane and the solid electrolyte cannot be achieved.
[0044] Formation of the second organic polymer constituted with
polyvinylphenol (PVP) as a continuous membrane on the electrically
conductive polymer membrane surface is not preferred since the
in-and-out migration of the ion to and from the electrolyte, which
is a motion principle of the electrically conductive polymer
actuator, is inhibited.
[0045] The amount of dispersion of the second organic polymer
constituted with polyvinylphenol (PVP) is preferably from 0.05% by
weight to 1% by weight in terms of mixing percentage of the second
organic polymer with respect to the electrically conductive polymer
dispersion liquid or solution (content of the electrically
conductive polymer solid: 1% by weight). When the amount is below
this range, the adhesive properties between the electrically
conductive polymer and the ion gel cannot be achieved, whereby the
bending motion of the actuator produced therewith may be difficult.
To the contrary, when the amount is above this range, to obtain the
membrane form of the electrically conductive polymer may be
difficult.
[0046] Although details of the mechanism which determine the
adhesive force between the electrically conductive polymer membrane
and the solid electrolyte membrane formed with an ion gel have not
been well elucidated, it is speculated from a number of experiments
conducted by the present inventors that the electrically conductive
polymer membrane is adhered to the solid electrolyte membrane
formed with an ion gel by an anchoring effect exhibited by the
second organic polymer particles.
[0047] The solid electrolyte membrane 103 used in the present
invention is a material termed "ion gel", which is prepared by
gelatinizing at least either one of a polymer or a monomer
dispersed in an ionic liquid, and allowing the ionic liquid to be
retained in the three-dimensional network structure of the gel.
Thus, it has flexibility, and achieves a value of 10.sup.-2 S/cm at
room temperature, which is 100 times or higher than that of
conventional polyether type polymer solid electrolytes. As the
solid electrolyte membrane, the ion gel can be used alone, but the
ion gel can be also used after impregnating in a porous membrane
such as paper, membrane filter or the like.
[0048] The ionic liquid is also referred to as "ordinary
temperature molten salt" or merely as "molten salt", which is a
salt that exhibits a molten state in a wide temperature range
including ordinary temperatures (room temperatures).
[0049] In the present invention, conventionally known various types
of ionic liquids can be used, but those which exhibits a liquid
state at ordinary temperatures (room temperatures) or at
temperatures approximate to ordinary temperatures (room
temperatures), and which are stable are preferred.
[0050] As the ionic liquid preferably used in the present
invention, illustrative examples include those containing a cation
represented by the following (chemical formula 3) to (chemical
formula 6), and an anion (X.sup.-).
##STR00002## [NR.sub.xH.sub.4-x]+ [chemical formula 5]
[PR.sub.xH.sub.4-x]+ [chemical formula 6]
[0051] In the above (chemical formula 3) to (chemical formula 6), R
represents an alkyl group having 1 to 12 carbon atoms, or an alkyl
group having an ether linkage and having 3 to 12 carbon and oxygen
atoms in total number. In the (chemical formula 3), R.sub.1
represents an alkyl group having 1 to 4 carbon atoms or a hydrogen
atom. In the (chemical formula 3), R is preferably different from
R.sub.1. In the (chemical formula 5) and (chemical formula 6), x
each represents an integer of from 1 to 4. In the present
invention, an imidazolium ion represented by the (chemical formula
3) is more preferred.
[0052] As the anion (X.sup.-), at least one selected from
tetrafluoroboric acid anion, hexafluorophosphoric acid anion,
bis(trifluoromethanesulfonyl)imidic acid anion, perchloric acid
anion, tris(trifluoromethanesulfonyl)carbon acid anion,
trifluoromethanesulfonic acid anion, dicyanamide anion,
trifluoroacetic acid anion, organic carboxylic acid anion and
halogen ion is preferred.
[0053] Examples of the organic polymer which can be used in
obtaining a gelatinous composition to be employed as the ion gel
include vinylidene fluoride/hexafluoropropylene copolymers
[P(VDF/HFP)], polyvinylidene fluoride (PVDF), perfluorosulfonic
acid/PTFE copolymers, polymethyl methacrylate (PMMA), polyethylene
oxide (PEO), and polyacrylonitrile (PAN).
[0054] Alternatively, a gelatinous composition to be employed as
the ion gel can be obtained also by dissolving a monomer (for
example, methyl methacrylate, MMA), a crosslinking agent (for
example, ethylene glycol dimethacrylate, EGDMA), and a
polymerization initiator (for example, azobisisobutyronitrile,
AIBN) in an ionic liquid, and permitting the polymerization
reaction in the ionic liquid to form an organic polymer.
[0055] The solid electrolyte can be obtained by preparing an ion
gel precursor by mixing the ionic liquid and at least one of the
polymer or monomer described above, and heating the mixture
followed by cooling. In light of the strength and ionic
conductivity, the weight ratio in the case of the mixture including
the ionic liquid and the organic polymer is preferably 9:1 to 6:4,
and more preferably 8:2 to 7:3. Also, the molar ratio in the case
of the mixture including the ionic liquid and the monomer is
preferably 3:7 to 7:3, and more preferably 4:6 to 6:4.
[0056] The electrode is acceptable as long as it has electronic
conductivity, and can readily accept and donate the electron from
and to the electrically conductive polymer without causing a
chemical reaction with the electrically conductive polymer.
Examples of the electrode which can be used include metals such as
gold, silver, platinum, copper and chromium, and carbon-containing
plates.
[0057] Hereinafter, the actuator according to the present invention
is explained in more detail by way of Examples, however, the
present invention is not limited thereto.
EXAMPLE 1
[0058] Production of Electrically Conductive Polymer Membrane in
which Second Organic Polymer is Embedded in the State Being
Dispersed
[0059] On a slide glass subjected to a treatment with oxygen plasma
after washing with acetone was added dropwise a predetermined
amount of an aqueous dispersion liquid (manufactured by H. C.
Starck GmbH, trade name: Baytron(R) PH500) of a mixture of PSS and
PEDOT with which 5% by weight of dimethyl sulfoxide (DMSO) and 0.5%
by weight of polyvinylphenol (PVP) were mixed. Since the specific
gravity of PVP is smaller than that of aqueous dispersion liquid of
the mixture of PSS and PEDOT, PVP was raised to the upper part of
the mixed liquid. Thereafter, the solvent was volatilized by air
drying at a room temperature, whereby an electrically conductive
polymer membrane was formed on the slide glass, in which PVP was
embedded in the state being dispersed. Finally, the electrically
conductive polymer membrane was detached from the slide glass using
a razor. Thus obtained electrically conductive polymer membrane had
a mean thickness of 19 .mu.m, and had an electric conductivity of
205 S/cm as determined with a four-probe method.
[0060] Preparation of Material of Ion Gel
[0061] In the ionic liquid for producing the ion gel, ethylmethyl
imidazolium (EMI) was used as a cation, while
bis(trifluoromethanesulfonyl)imide
[(CF.sub.3SO.sub.2).sub.2N.sup.-] (TFSI) was used as an anion. As
the polymer to be mixed, a polyvinylidene
fluoride-hexafluoropropylene copolymer [P(VDF/HFP)] was used. The
mixing ratio of EMITFSI to P(VDF/HFP) was 8:2 by weight ratio, and
after mixing, the liquid was sufficiently stirred using a magnetic
stirrer. Hereinafter, this mixed liquid is designated as ion gel
precursor.
[0062] Production of Electrolyte Ion Gel
[0063] A polyethylene terephthalate (PET) sheet having a thickness
of 0.1 mm was cut into a size of 76 mm.times.26 mm, and this piece
was brought into close contact with a slide glass having a size of
76 mm.times.26 mm. Two sets of such a combination were produced.
Thereafter, the produced slide glasses were brought into close
contact such that two PET sheets were opposed spacing with a
predetermined interval, with a capacitor separator paper having a
thickness of 40 .mu.m interposed therebetween. In this process, the
ion gel precursor was impregnated into the capacitor separator
paper. Then, an ion gel-impregnated paper having a thickness of 40
.mu.m was obtained by heating in a thermoregulated bath at
100.degree. C. for 30 min, and thereafter cooling to a room
temperature. Since the adhesive property between the PET sheet and
the ion gel-impregnated paper to each other is very poor, they
could be readily detached. Hereinafter, the ion gel hereby obtained
is referred to as "electrolyte ion gel".
[0064] Adhesion of Electrolyte Ion Gel-Electrically Conductive
Polymer Membrane
[0065] A three-layer structure of "electrically conductive polymer
membrane/electrolyte ion gel/electrically conductive polymer
membrane" was formed by overlaying the electrically conductive
polymer membrane on both faces of the electrolyte ion gel so as to
allow the faces in which PVP had been embedded in the state being
dispersed were opposed, heating in a thermoregulated bath at
100.degree. C. for 30 min, and thereafter cooling to a room
temperature. This three-layer structure was cut to provide a width
of 2.5 mm and a length of 15 mm. A platinum electrode having a
width of 2 mm and a length of 10 mm was mounted on thus obtained
structure at a region 5 mm away in the longitudinal direction from
one end. Thus, a bendable electrically conductive polymer actuator
having a length of the movable portion being 10 mm was
produced.
[0066] The bending displacement magnitude was evaluated by
triangulation measurement using a laser displacement meter. The
measurement point of the triangulation measurement was positioned 5
mm away in the lengthwise direction from the point where the
electrode was mounted.
[0067] When a voltage of .+-.1.0 V was applied to this actuator,
the bending motion was effected in response to the applied voltage
without causing detachment at the electrolyte ion gel-electrically
conductive polymer membrane boundary surface. The displacement
magnitude observed upon driving with a rectangular pulse of 1 Hz is
shown in Table 1.
TABLE-US-00001 TABLE 1 Number of driving times (time) 1 60 120 600
1800 5400 Example 1 Displacement 0.47 0.45 0.45 0.45 0.41 0.40
magnitude (mm)
[0068] From Table 1, it is suggested that the bendable electrically
conductive polymer actuator having this constitution is superior in
adhesive properties of the electrically conductive polymer membrane
and the solid electrolyte membrane, and can be operated for a long
period of time.
EXAMPLE 2
[0069] Production of Electrically Conductive Polymer Membrane in
which Second Organic Polymer is Embedded in the State Being
Dispersed
[0070] On a silicon substrate subjected to a treatment with oxygen
plasma after washing with acetone was added dropwise a
predetermined amount of an aqueous dispersion liquid (manufactured
by H. C. Starck GmbH, trade name: Baytron(R) PH500) of a mixture of
PSS and PEDOT with which 5% by weight of N-methylpyrrolidone (NMP)
was mixed. Before this membrane was dried, polyvinylphenol (PVP)
was sprayed on the surface in an amount of 0.1% by weight of the
aqueous dispersion liquid of the mixture of PSS and PEDOT.
Thereafter, the solvent was volatilized by air drying at a room
temperature, whereby an electrically conductive polymer membrane
was formed on the silicon substrate, in which PVP was embedded in
the state being dispersed.
[0071] Finally, the silicon substrate was immersed in 50% by volume
of an aqueous potassium hydroxide solution to detach the
electrically conductive polymer membrane from the substrate. Thus
obtained electrically conductive polymer membrane had a mean
thickness of 8 .mu.m, and had an electric conductivity of 251 S/cm
as determined with a four-probe method.
[0072] Preparation of Material of Ion Gel
[0073] In the ionic liquid for producing the ion gel, butylmethyl
imidazolium (BMI) was used as a cation, while hexafluorophosphoric
acid anion (PF.sub.6.sup.-) was used as an anion. As the polymer to
be mixed, a vinylidene fluoride/hexafluoropropylene copolymer
[P(VDF/HFP)] was used. The mixing ratio of EMITFSI to P(VDF/HFP)
was 8:2 by weight ratio, and after mixing, the liquid was
sufficiently stirred using a magnetic stirrer. Hereinafter, this
mixed liquid is designated as ion gel precursor.
[0074] Production of Electrolyte Ion Gel
[0075] A polyethylene terephthalate (PET) sheet having a thickness
of 0.1 mm was cut into a size of 76 mm.times.26 mm, and this piece
was brought into close contact with a slide glass having a size of
76 mm.times.26 mm. Two sets of such a combination were produced.
Thereafter, the produced slide glasses were brought into close
contact such that two PET sheets were opposed spacing with a
predetermined interval, with a capacitor separator paper having a
thickness of 40 .mu.m interposed therebetween. In this process, the
ion gel precursor was impregnated into the capacitor separator
paper. Then, an ion gel-impregnated paper having a thickness of 40
.mu.m was obtained by heating in a thermoregulated bath at
100.degree. C. for 30 min, and thereafter cooling to a room
temperature. Since the adhesive property between the PET sheet and
the ion gel-impregnated paper to each other is very poor, they
could be readily detached. Hereinafter, the ion gel-impregnated
paper hereby obtained is referred to as "electrolyte ion gel".
[0076] Lamination of Electrolyte Ion Gel-Electrically Conductive
Polymer Membrane
[0077] A three-layer structure of "electrically conductive polymer
membrane/electrolyte ion gel/electrically conductive polymer
membrane" was formed by overlaying the electrically conductive
polymer membrane on both faces of the electrolyte ion gel so as to
allow them to be opposed, heating in a thermoregulated bath at
100.degree. C. for 30 min, and thereafter cooling to a room
temperature. This three-layer structure was cut to provide a width
of 2.5 mm and a length of 15 mm. A platinum electrode having a
width of 2 mm and a length of 10 mm was mounted on thus obtained
structure at a region 5 mm away in the longitudinal direction from
one end. Thus, a bendable electrically conductive polymer actuator
having a length of the movable portion being 10 mm was
produced.
[0078] When a voltage of .+-.1.0 V was applied to this actuator,
the bending motion was effected in response to the applied voltage
without causing detachment at the electrolyte ion gel-electrically
conductive polymer membrane boundary surface. The displacement
magnitude observed upon driving with a rectangular pulse of 1 Hz is
shown in Table 2.
TABLE-US-00002 TABLE 2 Number of driving times (time) 1 60 120 600
1800 5400 Example 2 Displacement 0.51 0.47 0.46 0.45 0.41 0.38
magnitude (mm)
[0079] From Table 2, it is suggested that the bendable electrically
conductive polymer actuator having this constitution is superior in
adhesive properties of the electrically conductive polymer membrane
and the solid electrolyte membrane, and can be operated for a long
period of time.
EXAMPLE 3
[0080] A bendable electrically conductive polymer actuator was
produced in a similar manner to Example 1 except that
polyvinylphenol (PVP) was mixed in an amount of 0.05, 0.1, 1, or 5%
by weight. When avoltage of .+-.1.0 V was applied to these
actuators, the bending motion was effected in response to the
applied voltage without causing detachment at the electrolyte ion
gel-electrically conductive polymer membrane boundary surface, and
in regard to the displacement magnitude with a rectangular pulse of
1 Hz, the mean displacement magnitude of initial ten times
measurements was revealed to be no less than 0.40 mm. Thus, these
actuators can provide stable bending motion even though they were
continuously driven for a long period of time, similarly to
Examples 1 and 2. To the contrary, when the dispersion liquid in
which polyvinylphenol (PVP) had been dissolved in an amount of 5%
by weight was used, the membrane was so fragile that a bendable
electrically conductive polymer actuator could not be produced when
a similar manner to that in Example 1 was employed. (Table 3)
TABLE-US-00003 TABLE 3 Amount of mixed polybiphenyl (percent by
weight) 0 0.05 0.1 0.5 1 5 Electrically conductive Bending no less
than no less than no less than no less than Actuator polymer
actuator motion 0.40 mm 0.40 mm 0.40 mm 0.40 mm not Production and
Bending failed Bending Bending Bending Bending produced motion
motion motion motion motion effected effected effected effected
COMPARATIVE EXAMPLE 1
[0081] On a slide glass subjected to a treatment with oxygen plasma
after washing with acetone was added dropwise a predetermined
amount of an aqueous dispersion liquid (manufactured by H. C.
Starck GmbH, trade name: Baytron(R) PH500) of a mixture of PSS and
PEDOT in which 5% by weight of dimethyl sulfoxide (DMSO) was
dissolved.
[0082] Thereafter, the solvent was volatilized by air drying at a
room temperature, whereby an electrically conductive polymer
membrane was formed on the slide glass. Finally, the electrically
conductive polymer membrane was detached from the slide glass using
a razor.
[0083] A three-layer structure of was formed by overlaying the
electrically conductive polymer membrane on both faces of the
electrolyte ion gel produced in a similar manner to Example 1,
heating in a thermoregulated bath at 100.degree. C. for 30 min, and
thereafter cooling to a room temperature, thereby adhering the
electrolyte ion gel and the electrically conductive polymer
membrane. This three-layer structure was cut to provide a width of
2.5 mm and a length of 15 mm. A platinum electrode having a width
of 2 mm and a length of 10 mm was mounted on thus obtained
structure at a region 5 mm away in the longitudinal direction from
one end. Thus, a bendable electrically conductive polymer actuator
having a length of the movable portion being 10 mm was
produced.
[0084] This actuator exhibited very poor adhesive properties
between the electrolyte ion gel and the electrically conductive
polymer membrane. Further, when a voltage of .+-.1.0 V was applied,
detachment was caused at the electrolyte ion gel-electrically
conductive polymer membrane boundary surface without effecting any
bending motion in response to the applied voltage, and in regard to
the displacement magnitude with a rectangular pulse of 1 Hz, the
mean displacement magnitude of initial ten times measurements was
revealed to be no less than 0.05 mm. (Table 3)
COMPARATIVE EXAMPLE 2
[0085] On a silicon substrate subjected to a treatment with oxygen
plasma after washing with acetone was added dropwise a
predetermined amount of an aqueous dispersion liquid (manufactured
by H. C. Starck GmbH, trade name: Baytron(R) PH500) of a mixture of
PSS and PEDOT in which 5% by weight of N-methylpyrrolidone (NMP)
was dissolved. Thereafter, the solvent was volatilized by air
drying at a room temperature, whereby an electrically conductive
polymer membrane was formed on the silicon substrate. Finally, the
silicon substrate was immersed in 50% by volume of an aqueous
potassium hydroxide solution to detach the electrically conductive
polymer membrane from the substrate.
[0086] A three-layer structure of was formed by overlaying the
electrically conductive polymer membrane on both faces of the
electrolyte ion gel produced in a similar manner to Example 2,
heating in a thermoregulated bath at 100.degree. C. for 30 min, and
thereafter cooling to a room temperature, thereby adhering the
electrically conductive polymer membrane and the electrolyte ion
gel and. This three-layer structure was cut to provide a width of
2.5 mm and a length of 15 mm. A platinum electrode having a width
of 2 mm and a length of 10 mm was mounted on thus obtained
structure at a region 5 mm away in the longitudinal direction from
one end. Thus, a bendable electrically conductive polymer actuator
having a length of the movable portion being 10 mm was
produced.
[0087] This actuator exhibited very poor adhesive properties
between the electrolyte ion gel and the electrically conductive
polymer membrane. Further, when a voltage of .+-.1.0 V was applied,
detachment was caused at the electrolyte ion gel-electrically
conductive polymer membrane boundary surface without effecting any
bending motion in response to the applied voltage, and in regard to
the displacement magnitude with a rectangular pulse of 1 Hz, the
mean displacement magnitude of initial ten times measurements was
revealed to be no less than 0.05 mm.
COMPARATIVE EXAMPLE 3
[0088] On a slide glass subjected to a treatment with oxygen plasma
after washing with acetone was added dropwise a predetermined
amount of an aqueous dispersion liquid (manufactured by H. C.
Starck GmbH, trade name: Baytron(R) PH500) of a mixture of PSS and
PEDOT in which 5% by weight of dimethyl sulfoxide (DMSO) was
dissolved. Thereafter, the solvent was volatilized by air drying at
a room temperature, whereby an electrically conductive polymer
membrane was formed on the slide glass. After the electrically
conductive polymer membrane was formed, polyvinylphenol (PVP) was
sprayed on the surface. Finally, the electrically conductive
polymer membrane was detached from the slide glass using a
razor.
[0089] A three-layer structure of was formed by overlaying the
electrically conductive polymer membrane on both faces of the
electrolyte ion gel produced in a similar manner to Example 1,
heating in a thermoregulated bath at 100.degree. C. for 30 min, and
thereafter cooling to a room temperature, thereby adhering the
electrolyte ion gel and the electrically conductive polymer
membrane. This three-layer structure was cut to provide a width of
2.5 mm and a length of 15 mm. A platinum electrode having a width
of 2 mm and a length of 10 mm was mounted on thus obtained
structure at a region 5 mm away in the longitudinal direction from
one end. Thus, a bendable electrically conductive polymer actuator
having a length of the movable portion being 10 mm was
produced.
[0090] This actuator exhibited very poor adhesive properties
between the electrolyte ion gel and the electrically conductive
polymer membrane. Further, when a voltage of .+-.1.0 V was applied,
detachment was caused at the electrolyte ion gel-electrically
conductive polymer membrane boundary surface without effecting any
bending motion in response to the applied voltage, and in regard to
the displacement magnitude with a rectangular pulse of 1 Hz, the
mean displacement magnitude of initial ten times measurements was
revealed to be no less than 0.05 mm.
[0091] From the foregoing description, many modifications and other
embodiments of the present invention are apparent to persons
skilled in the art. Accordingly, the foregoing description should
be construed merely as an illustrative example, which was provided
for the purpose of teaching best modes for carrying out the present
invention to persons skilled in the art. Details of the
construction and/or function of the present invention can be
substantially altered without departing from the spirit
thereof.
INDUSTRIAL APPLICABILITY
[0092] According to the present invention, manufacture of compact
and light weight, and highly flexible actuators in a simple manner
is enabled, and they can be suitably used in the field of robots
for medical care, industry, and household use, as well as
micromachines, and the like.
* * * * *