Iwamoto M., Kwon Y.-S., Lee T. (Eds.) Nanoscale Interface for Organic Electronics

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Training and Fatigue of Conducting Polymer

Fig. 4.

Relationship between stokes radius of cations

PPy/DBS films.

3. Stress-

Strain Characteristics

Tensile

stress dependence of ECMD

The strain

shows the

increasing the stress

obtained at the interception is

Young’s

modulus. As evident from Fig.

PPy/CF

film is better than that of PPy/DBS

anion is larger than that of cation

Fig. 5. Stress-strain

curves in (a) anion

Training and Fatigue of Conducting Polymer

Artificial Muscles

Relationship between stokes radius of cations

and

strain in cation driven ECMD of

Strain Characteristics

of Polymer Actuators

stress dependence of ECMD

strain of PPy

is shown

in Fig.

shows the

maximum at stress free and linearly

decreases with

increasing the stress

until it crosses

to the zero of strain. The stress

obtained at the interception is

a blocking force, which relates

modulus. As evident from Fig.

the performance of

film is better than that of PPy/DBS

, because the size of

anion is larger than that of cation

curves in (a) anion

(CF

) driven and (b) cation (Li

)

driven films.

229

strain in cation driven ECMD of

in Fig.

decreases with

to the zero of strain. The stress

to the

the performance of

, because the size of

driven films.

230

Fig. 6.

Strain dependencies of energy conversion efficiencies.

4. Energy

Conversion Efficienc

Soft actuator is an

mechanical energy.

relation of E

∫

during contraction of the film

= mg∆l

, where

lifting distance of

of strain-

stress curve in Fig.

in %) obtained from Fig.

driven ECMDs.

It has been found that the electrical input energy

scarcely depend on tensile loads, since the electrochemical reaction

mostly charging and discharging of a secondary battery

polymers

. However, the mec

weight and lifting distance.

The conversion efficiencies of PPy/CF

are 0.25% and 0.13%

unexpectedly small, however, most of electrical input energy is

considered to be

output energy f

or the anion driven actuator is

5. T

raining of PPy

of PPy/DBS film in 1 M LiCl aqueous solution

stresses

is shown in Fig.

K. Kaneto

Strain dependencies of energy conversion efficiencies.

Conversion Efficienc

Soft actuator is an

energy transducer from electrical energy to

mechanical energy.

he electrical input energy is obtained from a

∫

ivdt, where i, v and t

are current, voltage and time

during contraction of the film

, respectively.

Mechanical output energy

, where

m, g and ∆l

are mass of weight, the gravity and the

weight, respectively. The E

estimated from the area

stress curve in Fig.

Energy conversion efficiencies (

in %) obtained from Fig.

5 are shown in Fig. 6

for anion and cation

It has been found that the electrical input energy

scarcely depend on tensile loads, since the electrochemical reaction

mostly charging and discharging of a secondary battery

of conducting

. However, the mec

hanical output strictly depends on the

weight and lifting distance.

The conversion efficiencies of PPy/CF

and PPy/DBS films

are 0.25% and 0.13%

respectively. The

conversion efficiencies are

unexpectedly small, however, most of electrical input energy is

considered to be

harvested like discharge of a battery. T

he maximum

or the anion driven actuator is

estimated to be 0.14 J/g.

raining of PPy

Actuators Under High Tensile Loads

of PPy/DBS film in 1 M LiCl aqueous solution

various tensile

is shown in Fig.

7(a).

With increasing the tensile stresses,

energy transducer from electrical energy to

he electrical input energy is obtained from a

are current, voltage and time

Mechanical output energy

are mass of weight, the gravity and the

estimated from the area

Energy conversion efficiencies (

for anion and cation

It has been found that the electrical input energy

scarcely depend on tensile loads, since the electrochemical reaction

of conducting

hanical output strictly depends on the

and PPy/DBS films

conversion efficiencies are

unexpectedly small, however, most of electrical input energy is

he maximum

estimated to be 0.14 J/g.

various tensile

With increasing the tensile stresses,

Training and Fatigue of Conducting Polymer

shoulders at around 0

higher potential

as seen in Fig.

-400

mV in the reduction cycle also shifted to higher potential side. After

removal of 5 MPa tensile stresses, the CV at 0 MPa traced almost the

same to that of 5 MPa

During the electrochemical cycles the film was gradually elongated

about 20%

by creeping

elongation ∆L

was the incremental

film

periodically elongated and contracted

5 MPa

due to the ECMD

deformation of films (conformation change), slipping and brea

polymer chains under

The shifting of CV peaks under tensile stress is considered to result

from the conformation change (stretching) of pol

the creeping. Namely, the stretching of polymer chains reduces the

ionization potential to positive side. During the electrochemical cycles,

however, complicated and dynamical change of rheological properties is

taking place

in polym

Curves in Fig.

of elongation (∆l

) for each cycle in the PPy/DBS film,

Figs. 7(a) and 7

(b). The

Fig. 7.

(a) CV curves of PPy/DBS film in aqueous 1

and (b) elongation L

of the film under applied tensile stresses.

Training and Fatigue of Conducting Polymer

Artificial Muscles

shoulders at around 0

V in

the oxidation cycle increased and shifted to

as seen in Fig.

7(a)

. Similarly, the peak at around

mV in the reduction cycle also shifted to higher potential side. After

removal of 5 MPa tensile stresses, the CV at 0 MPa traced almost the

same to that of 5 MPa

During the electrochemical cycles the film was gradually elongated

by creeping

as shown by curve in Fig. 7(b),

where the

was the incremental

increased length of the film. A

lso

periodically elongated and contracted

at the

tensile stress up to

due to the ECMD

. The creeping resulted

from the anisotropic

deformation of films (conformation change), slipping and brea

king of

polymer chains under

larger tensile stresses.

The shifting of CV peaks under tensile stress is considered to result

from the conformation change (stretching) of pol

ymer backbone due to

the creeping. Namely, the stretching of polymer chains reduces the

ionization potential to positive side. During the electrochemical cycles,

however, complicated and dynamical change of rheological properties is

in polym

er matrices.

8 shows the injected electrical charge (Q

) dependence

) for each cycle in the PPy/DBS film,

derived from

(b). The

∆l

contains the creeping to some extent. In the

(a) CV curves of PPy/DBS film in aqueous 1

M LiCl at the scan rate of 3 mV/s

of the film under applied tensile stresses.

231

the oxidation cycle increased and shifted to

. Similarly, the peak at around

mV in the reduction cycle also shifted to higher potential side. After

removal of 5 MPa tensile stresses, the CV at 0 MPa traced almost the

During the electrochemical cycles the film was gradually elongated

where the

lso

the

tensile stress up to

from the anisotropic

king of

The shifting of CV peaks under tensile stress is considered to result

ymer backbone due to

the creeping. Namely, the stretching of polymer chains reduces the

ionization potential to positive side. During the electrochemical cycles,

however, complicated and dynamical change of rheological properties is

) dependence

derived from

contains the creeping to some extent. In the

M LiCl at the scan rate of 3 mV/s

232

oxidation process at lower

was proportional to the

however, the film clearly showed saturation in the contraction. For the

reduction process, at lower tensile stresses the film

elongated linear

ly with

tensile stresses,

however,

charges, then steeply elongated at larger charges.

The mechanism of the ECM

and high tensile stresses is proposed. At lower tensile stresses for

oxidation (contraction)

curves 0 and 1 MPa in Fig.

the film. At h

igher tensile stress of 3

isotropic manner for smaller charges. At larger

contraction is

accounted

shrinking to the thickness direction by squeezing out of ca

the film length constant.

equilibrium with the tensile stress

ECMD

behavior during reduction (elongation) shown in Fig.

indicates the reversed mechanisms of the o

stress the film expanded by isotropic ways. At high tensile stress the film

swollen to the thickness direction at low

the tensile direction at larger

Fig. 8.

Electronic charge (

oxidation (contraction) and (b) reduction (elongation).

K. Kaneto

oxidation process at lower

tensile stresses as shown in Fig. 8(a)

, the

was proportional to the

. At higher stresses and higher charges,

however, the film clearly showed saturation in the contraction. For the

reduction process, at lower tensile stresses the film

approximately

ly with

increasing Q as seen in Fig. 8

(b). At higher

however,

the film did not elongate linearly

at lower

charges, then steeply elongated at larger charges.

The mechanism of the ECM

D strain (∆l)

in PPy/DBS film under low

and high tensile stresses is proposed. At lower tensile stresses for

oxidation (contraction)

, the linear dependence of ∆l versus Q

shown by

curves 0 and 1 MPa in Fig.

(a) is explained by the isotropic shrink

igher tensile stress of 3

-5

MPa the film contracts in

isotropic manner for smaller charges. At larger

the saturation of

accounted

by the anisotropic shrinking

of the film, namely,

shrinking to the thickness direction by squeezing out of ca

tions keeping

the film length constant.

The

contraction force of film may be

equilibrium with the tensile stress

, due to crosslinking of the film.

behavior during reduction (elongation) shown in Fig.

indicates the reversed mechanisms of the o

xidation. At lower tensile

stress the film expanded by isotropic ways. At high tensile stress the film

swollen to the thickness direction at low

, followed by elongation along

the tensile direction at larger

Electronic charge (

Q) dependence of ECMS, ∆l

in the PPy/DBS film for (a)

oxidation (contraction) and (b) reduction (elongation).

, the

∆l

. At higher stresses and higher charges,

however, the film clearly showed saturation in the contraction. For the

approximately

(b). At higher

at lower

in PPy/DBS film under low

and high tensile stresses is proposed. At lower tensile stresses for

shown by

(a) is explained by the isotropic shrink

ing of

MPa the film contracts in

the saturation of

of the film, namely,

tions keeping

contraction force of film may be

, due to crosslinking of the film.

The

behavior during reduction (elongation) shown in Fig.

8(b)

xidation. At lower tensile

stress the film expanded by isotropic ways. At high tensile stress the film

, followed by elongation along

in the PPy/DBS film for (a)

Training and Fatigue of Conducting Polymer

Fig. 9

. Cycle dependence

-850 mV and 600

mV for each 450

Figure 9

shows the cycle dependence of the

rectangular voltages under tensile stresses up to 3 MPa. Creeping of the

film was remarkably observed at higher tensile stresses. It is noted that

after removal of the tensile stress of 3 MPa, the creeping was recovered

as seen by th

e dashed curves in Fig.

for NaCl electrolyte

larger than the elasticity of the film

it is supposed that polymer chains dynamic

aligned along the external stress. By

oxidation

, however, the anisotropic deformation (largely expanded state

of the polymer along the tensile direction) should be fixed or frozen. This

is name

d as the memory of deformation. After the release of tensile

stress, the frozen and expanded state should be re

state. Detailed mechanisms of the memory effect have been discussed in

our paper.

6. T

raining of PANi

Figure 10

shows the incremental elongation of the ECMD for a PANi

film with the original length (

under tensile loads at the scan rate of 2

Training and Fatigue of Conducting Polymer

Artificial Muscles

. Cycle dependence

∆L

in PPy/DBS film by cycling of rectangular voltages of

mV for each 450

s under tensile stresses.

shows the cycle dependence of the

∆L

by the application of

rectangular voltages under tensile stresses up to 3 MPa. Creeping of the

film was remarkably observed at higher tensile stresses. It is noted that

after removal of the tensile stress of 3 MPa, the creeping was recovered

e dashed curves in Fig.

as reported in our previous paper

for NaCl electrolyte

The creeping results from that the tensile stress is

larger than the elasticity of the film

During the electrochemical reaction,

it is supposed that polymer chains dynamic

ally fluctuate and should be

aligned along the external stress. By

the

completion of electrochemical

, however, the anisotropic deformation (largely expanded state

of the polymer along the tensile direction) should be fixed or frozen. This

d as the memory of deformation. After the release of tensile

stress, the frozen and expanded state should be re

laxed

to the original

state. Detailed mechanisms of the memory effect have been discussed in

raining of PANi

Film

shows the incremental elongation of the ECMD for a PANi

film with the original length (

) of 10

mm operated by a triangle voltage

under tensile loads at the scan rate of 2

mV/s. The electrochemical cycle

233

in PPy/DBS film by cycling of rectangular voltages of

by the application of

rectangular voltages under tensile stresses up to 3 MPa. Creeping of the

film was remarkably observed at higher tensile stresses. It is noted that

after removal of the tensile stress of 3 MPa, the creeping was recovered

as reported in our previous paper

The creeping results from that the tensile stress is

During the electrochemical reaction,

ally fluctuate and should be

completion of electrochemical

, however, the anisotropic deformation (largely expanded state

of the polymer along the tensile direction) should be fixed or frozen. This

d as the memory of deformation. After the release of tensile

to the original

state. Detailed mechanisms of the memory effect have been discussed in

shows the incremental elongation of the ECMD for a PANi

mm operated by a triangle voltage

mV/s. The electrochemical cycle

234

was repeated

three

in Fig. 10

. The film showed cyclic strokes of expansion and contraction

(∆L

) being 0.4 ~ 0.6 mm (corresponding strain of 4 ~ 6%). The

induced by insertion and ejection of bulky anions

high tensile loads

. The

is interesting to note that by release of tensile loads down to 0

creeping was recovered

also noted that the

was substantially larger than

respectively, indicating the large training effect.

Curves in Fig.

Fig. 10

. By the application of tensile loads, the oxidation peaks shifted to

lower potential (easy oxidation) and the

lower potentials as shown by an arrow. By the removal of tensile load

the CV traced the nearly same curve of

slightly br

oadening of peaks. The result

of polyme

r conformation

Curves in Fig.

of the elongation (

of each tensile stress.

Fig. 10.

ECMD of PANi film operated by a triangle sweep at

with the period of 900 s under tensile

sequence of measurement.

K. Kaneto

three

times at the same tensile load as shown by

. The film showed cyclic strokes of expansion and contraction

) being 0.4 ~ 0.6 mm (corresponding strain of 4 ~ 6%). The

induced by insertion and ejection of bulky anions

as well as cree

ping by

. The

creeping was remarkable for lager tensile loads. It

is interesting to note that by release of tensile loads down to 0

MPa, the

creeping was recovered

more clearly than the case of PPy.

It should be

also noted that the

∆L as shown by and in Fig. 10

after 3

was substantially larger than

and in Fig. 11

for 0 and 1 MPa,

respectively, indicating the large training effect.

Curves in Fig.

11 show the CV

obtained in PANi film shown in

. By the application of tensile loads, the oxidation peaks shifted to

lower potential (easy oxidation) and the

reduction peaks also shifted to

lower potentials as shown by an arrow. By the removal of tensile load

the CV traced the nearly same curve of

the

highest tensile load with a

oadening of peaks. The result

suggests

some permanent change

r conformation

Curves in Fig.

12 show the injected electrical charge (Q

) dependences

of the elongation (

∆l) in PANi film. The ∆l

was obtained at the 2nd

of each tensile stress.

The Q was calculated from the CV in Fig.

ECMD of PANi film operated by a triangle sweep at

-200 ~ 550

mV Ag/AgCl

with the period of 900 s under tensile

loads up to 3 MPa, numbers in circles

indicate the

sequence of measurement.

. The film showed cyclic strokes of expansion and contraction

) being 0.4 ~ 0.6 mm (corresponding strain of 4 ~ 6%). The

∆L is

ping by

creeping was remarkable for lager tensile loads. It

MPa, the

It should be

after 3

MPa

for 0 and 1 MPa,

obtained in PANi film shown in

. By the application of tensile loads, the oxidation peaks shifted to

reduction peaks also shifted to

lower potentials as shown by an arrow. By the removal of tensile load

highest tensile load with a

some permanent change

) dependences

was obtained at the 2nd

cycle

11. ∆l

mV Ag/AgCl

indicate the

Training and Fatigue of Conducting Polymer

versus Q

in PANi films showed approximately linear dependence, which

can be compared with the case of nonlinear behavior

Fig. 8

. In the oxid

at la

rge tensile loads was due to

process shown in Fig.

stroke. It should be noted that

of high tensile stresses and the

and in

Fig.

Fig. 11.

CV curves

Fig. 12.

Elongations of PANi film

under tensile loads.

Training and Fatigue of Conducting Polymer

Artificial Muscles

in PANi films showed approximately linear dependence, which

can be compared with the case of nonlinear behavior

of PPy

shown in

. In the oxid

ation process as shown in Fig. 12

(a), the elongation

rge tensile loads was due to

creeping to some extent. In the

reduction

process shown in Fig.

12(b), the negative elongation

was the contraction

stroke. It should be noted that

∆l

apparently increased by the experience

of high tensile stresses and the

Q at ~

was apparently larger

Fig.

(b), indicating the pronounced training effect.

CV curves

of PANi film under tensile stress shown in Fig. 10.

Elongations of PANi film

against charges

during (a) oxidation and (b) reduction

235

in PANi films showed approximately linear dependence, which

shown in

(a), the elongation

∆l

reduction

was the contraction

apparently increased by the experience

was apparently larger

than

(b), indicating the pronounced training effect.

during (a) oxidation and (b) reduction

236

Fig. 13.

Time responses of current waveform by the application of rectangular voltage of

-200 ~ 550 mV,

each 450 s for oxidation and reduction cycles

Figure 13

shows the time responses of current waveform by the

application of rectangular voltage. It is noted that the oxidation took

longer time compared with

consistent with the case of PPy

film with low conductive reduced state, while the reduction starts from

high conductive state. By the ex

response became faster, indicating

inc

reased electrochemical activit

Table 5

shows

conversion efficiency in PANi films. The contraction length (stroke,

of ECMD enhanced significantly by the experience of high tensile

stresses

(training effect).

the strokes of

and

after the experience of larger tensile loads. It is

to note that training effect in the PANi film is more pronounced

compared with the case of P

present stage, however, this may be due to the longer conjugation length

of PANi polymer chains.

PANi film also is

) and the input energy were also enhanced by the training. The

maximum conversion efficiency was 0.15% at around 3

similar to 0.1

5% in

K. Kaneto

Time responses of current waveform by the application of rectangular voltage of

each 450 s for oxidation and reduction cycles

shows the time responses of current waveform by the

application of rectangular voltage. It is noted that the oxidation took

longer time compared with

the

reduction process. The results are

consistent with the case of PPy

namely, the oxidation starts fr

om the

film with low conductive reduced state, while the reduction starts from

high conductive state. By the ex

perience of large tensile loads

the current

response became faster, indicating

larger diffusion of ions

and the

reased electrochemical activit

y of the film.

shows

the summary

of ECMD including the energy

conversion efficiency in PANi films. The contraction length (stroke,

of ECMD enhanced significantly by the experience of high tensile

(training effect).

The contraction strokes

of ECMD indicated by

and in Table 4

are much larger than those of

after the experience of larger tensile loads. It is

also

interesting

to note that training effect in the PANi film is more pronounced

compared with the case of P

Py film.

The reason is not clear at the

present stage, however, this may be due to the longer conjugation length

of PANi polymer chains.

The energy conversion efficiency E

shown in Table 5.

It is noted that the injected charge

) and the input energy were also enhanced by the training. The

maximum conversion efficiency was 0.15% at around 3

MPa, being

5% in

polyaniline actuators by Smela et al.

Time responses of current waveform by the application of rectangular voltage of

shows the time responses of current waveform by the

application of rectangular voltage. It is noted that the oxidation took

reduction process. The results are

om the

film with low conductive reduced state, while the reduction starts from

the current

and the

of ECMD including the energy

conversion efficiency in PANi films. The contraction length (stroke,

∆l)

of ECMD enhanced significantly by the experience of high tensile

of ECMD indicated by

are much larger than those of

interesting

to note that training effect in the PANi film is more pronounced

The reason is not clear at the

present stage, however, this may be due to the longer conjugation length

It is noted that the injected charge

) and the input energy were also enhanced by the training. The

MPa, being

Training and Fatigue of Conducting Polymer

Table 5

. Summary of ECMD during the contraction (reduction) in a PANi film under

tensile loads.

Tensile Stress

(MPa)

Contraction

Stroke

Fig. 14. Schematic

drowing

of crosslink

by reduction in conducting polymers.

During e

lectrochemical reaction, it is considered that polymer chains

are

dynamically fluctuate

By completion of the electrochemical oxidation, however, the anisotropic

deformation should be fixed or froz

Fig. 14

(a). The anion may interact with polycations nearby and crosslink

adjacent polymer chains. This is a memory of deformation. After the

release of tensile stress and reduction, the frozen and expanded state

should be released to the original

upon electrochemical cycles. The recovery of c

elasticity or thermal vibration of polymer chains.

7. Fatigue of

Artificial Muscles

Figure 15

shows the cycle life or aging of PPy/DBS muscle under the

tensile stress of 3

MPa

Training and Fatigue of Conducting Polymer

Artificial Muscles

. Summary of ECMD during the contraction (reduction) in a PANi film under

Contraction

Stroke

∆l

(µm)

Charge

Q (mC)

Input

Energy

(mJ)

Output

Work

(mJ)

Energy

Conversion

Efficiency

(%)

490 245 49 0.0048

0.0098

453 259 51.8 0.0271

0.0523

468 282 56.5 0.0843

0.149

630 282 56.4 0.0377

0.0668

635 284 56.7 0.0062

0.0109

drowing

of (a) creation ionic

crosslink by oxidation and (b) removal

by reduction in conducting polymers.

lectrochemical reaction, it is considered that polymer chains

dynamically fluctuate

d by flow of anions

and should be easily creped.

By completion of the electrochemical oxidation, however, the anisotropic

deformation should be fixed or froz

en by ionic

crosslink as shown in

(a). The anion may interact with polycations nearby and crosslink

adjacent polymer chains. This is a memory of deformation. After the

release of tensile stress and reduction, the frozen and expanded state

should be released to the original

conformation

(recovery of creeping)

upon electrochemical cycles. The recovery of c

reeping is

driven by

elasticity or thermal vibration of polymer chains.

Artificial Muscles

shows the cycle life or aging of PPy/DBS muscle under the

MPa

In each cycle, the elongation and contraction of

237

. Summary of ECMD during the contraction (reduction) in a PANi film under

Energy

Conversion

Efficiency

(%)

0.0098

0.0523

0.149

0.0668

0.0109

crosslink by oxidation and (b) removal

lectrochemical reaction, it is considered that polymer chains

and should be easily creped.

By completion of the electrochemical oxidation, however, the anisotropic

crosslink as shown in

(a). The anion may interact with polycations nearby and crosslink

adjacent polymer chains. This is a memory of deformation. After the

release of tensile stress and reduction, the frozen and expanded state

(recovery of creeping)

driven by

the

shows the cycle life or aging of PPy/DBS muscle under the

In each cycle, the elongation and contraction of

238

the

film was superimposed with the strokes of electrochemical cycle and

creeping as shown by the inset (a)

creeping came to saturate around 30 cycles and the muscle did not

respond to the electric stimuli

inset (b) of Fig. 1

facts, the conductivity of 41 S/cm before cycling dropped to 0.1 S/cm

after 60 cycles at 3 MPa. Another result was that the conductivity of

S/cm before training decreased to 2 S/cm by 18 cycles under the

tensile loads of 1, 2, 3 to 5 MPa for the each

without tensile stress the conductivity of 28 S/cm was unchanged by 26

cycles. During the cycling test, the films kept the

mechanically breakdown.

without stress is fairly stable, however, under large tensile stresses the

degradation of the

It is interesting to note that as shown in Fig.

creeping was about 30%, which nearly coincided with the tensile

strength (breakdown strain).

was highly cross

aligned and straighten along the d

Fig. 15. Cycle

life of PPy/DBS muscle under tensile stress of 3 MPa. The deformation

(∆L

) was the increment of elongation from the original length of 10 mm.

K. Kaneto

film was superimposed with the strokes of electrochemical cycle and

creeping as shown by the inset (a)

of Fig. 15

. The elongation due to

creeping came to saturate around 30 cycles and the muscle did not

respond to the electric stimuli

and died after 52 cyc

les as shown by the

. This mainly results from

loss of the conductivity. In

facts, the conductivity of 41 S/cm before cycling dropped to 0.1 S/cm

after 60 cycles at 3 MPa. Another result was that the conductivity of

S/cm before training decreased to 2 S/cm by 18 cycles under the

tensile loads of 1, 2, 3 to 5 MPa for the each

three

cycles. However,

without tensile stress the conductivity of 28 S/cm was unchanged by 26

cycles. During the cycling test, the films kept the

shape and

did not

mechanically breakdown.

From these results, electrochemical cycle

without stress is fairly stable, however, under large tensile stresses the

degradation of the

π-electron systems severely occurs.

It is interesting to note that as shown in Fig.

the maximum

creeping was about 30%, which nearly coincided with the tensile

strength (breakdown strain).

The result indicates that the PPy/DBS film

liked. Under high tensile stress, polymer chains were

aligned and straighten along the d

irection of tensile. The energy state of

Cycles (time)

life of PPy/DBS muscle under tensile stress of 3 MPa. The deformation

) was the increment of elongation from the original length of 10 mm.

film was superimposed with the strokes of electrochemical cycle and

. The elongation due to

creeping came to saturate around 30 cycles and the muscle did not

les as shown by the

loss of the conductivity. In

facts, the conductivity of 41 S/cm before cycling dropped to 0.1 S/cm

after 60 cycles at 3 MPa. Another result was that the conductivity of

S/cm before training decreased to 2 S/cm by 18 cycles under the

cycles. However,

without tensile stress the conductivity of 28 S/cm was unchanged by 26

did not

From these results, electrochemical cycle

without stress is fairly stable, however, under large tensile stresses the

the maximum

creeping was about 30%, which nearly coincided with the tensile

The result indicates that the PPy/DBS film

liked. Under high tensile stress, polymer chains were

irection of tensile. The energy state of

life of PPy/DBS muscle under tensile stress of 3 MPa. The deformation