Supplementary Information
Elastic, Conductive, Polymeric Hydrogels and Sponges
Yun Lu†1, Weina He†2, Tai Cao1, Haitao Guo1, Yongyi Zhang2, Qingwen Li2, Ziqiang
Shao1, Yulin Cui3, Xuetong Zhang1,2
1School of Materials Science & Engineering, Beijing Institute of Technology, Beijing
100081, P. R. China2Suzhou Institute of Nano-tech & Nano-bionics, Chinese Academy of Sciences,
Suzhou, 215123, P. R.China3College of Chemistry, Chemical Engineering & Material science, Soochow
University, Suzhou, 215123, P. R. China
[†] These authors contribute equally to this work
Email: [email protected]
Dated: April, 2014
Figures
Figure SI1 Photographs of various conducting polymer hydrogels under compression, from
all of which elasticity cannot be observed: (a) polyaniline (PAni) hydrogel reported
elsewhere1; (b) PEDOT-S hydrogel reported in our previous study2 (c) polypyrrole nanotube
hydrogel reported elsewhere3.
Figure SI2 FT-IR spectra of PPy oxidized by equimolar amount of Fe(NO3)3 without (a) and
with (b) aging process. The bands at 1540 cm-1 corresponds to the pyrrole ring vibration. The
bands at 1450 cm-1 correspond to the =CH in-plane vibration and the peaks at 893 cm -1 and
783 cm-1 are due to the =CH out-of-plane vibration. The stretching vibration of C-N bonds
shows a band at 1300 cm-1 and the band at 1170 cm-1 corresponds to the C-C stretching. A
very intense band at 1040 cm-1 is assigned to in-plane deformation of C-H and N-H bonds of
pyrrole ring4. In comparison with the FT-IR spectra of PPy before and after aging process,
there are no obvious changes in band positions. It can be inferred that the aging process only
concerns about hydrogel network morphological changes resulting in the slow oxidization
step instead of the rearrangement of molecular chains. The absence of absorbing bands at
1210 cm-1 and 800 cm-1 has indicated the low doping level caused by the deficient oxidation.
2400 2000 1600 1200 800 400
(b)
Inte
nsity
(a.u
.)
Wavenumber ( cm-1)
1540
1450
1300
11701040
893783
1540
14501300
11701040
893783
(a)
Figure SI3 Raman spectra of PPy oxidized by equimolar amount of Fe(NO3)3 before (a) and
after (b) aging process. The bands at 930 and 1046 cm -1 are due to C-H out-of-plane and in-
plane deformation, respectively. The bands at 1244 cm-1 corresponds to N-H in-plane
deformation. The pyrrole ring stretching shows bands at 1315 and 1407 cm -1. The band at
1588 cm-1 shows the low doping level of PPy chains5. There are no obvious changes in Raman
spectra before and after aging of the PPy hydrogel oxidized by equimolar amount of
Fe(NO3)3.
500 750 1000 1250 1500 1750 2000
(b)Inte
nsity
(a.u
.)
Wavenumber ( cm-1)
(a)
930
1046
12441315
1407 1588
Compress Release(b)
Compress Release(c)
(a) Compress Release
Figure SI4 Photographs of polypyrrole hydrogels, synthesized by deficient Fe(NO3)3 without
aging (a), sufficient Fe(NO3)3 without aging (b) and deficient FeCl3 with aging for 30 days at
room temperature (c) respectively, under compression and release process.
Figure SI5 Dynamic rheology behaviors of PPy hydrogel during aging procedure. The curves
of storage modulus (Eʹ) and loss modulus (Eʺ) vs. angular frequency (a) and the curve of Eʹ at
=10 rad/s vs. aging time (b).
1 10 100102
103
104
105
106
Aging for 1 day: E' E" 5 days: E' E" 10 days: E' E'' 15 days: E' E'' 20 days: E' E'' 30 days: E' E"
E' ()
, E"(
) (P
a)
( rad s-1)
(a)
0 5 10 15 20 25 300
1x104
2x104
3x104
4x104
E'(
=10
rad
s-1)
(Pa)
Aging times (days)
(b)
Figure SI6 SEM images of PPy sponge without (a, b) and with (c, d) compression..
Figure SI7 The changes of electrical resistance for the PPy sponge sensor during compression
and release circles. The electrical response of the PPy sponge to the external stimulations
0 25 50 75 100 125 150 175-1
0
1
2
3
4
R/R
0 (%
)
Time (s)
Compression strain 50 %
exhibits good stability.
References
1. Pan, L. et al. Hierarchical nanostructured conducting polymer hydrogel with high electrochemical activity. PNAS 109, 9287-9292 (2012).
2. Du, R., Xu, Y., Luo, Y., Zhang, X. & Zhang, J. Synthesis of conducting polymer hydrogels with 2D building blocks and their potential-dependent gel-sol transitions. Chem. Commun. 47, 6287-6289 (2011).
3. Wei, D. et al. Controlled growth of polypyrrole hydrogels. Soft Matter 9, 2832-2836 (2013).
4. Zhang, X. et al. Single-walled carbon nanotube-based coaxial nanowires: sythesis, characterization, and electrical properties. J. Phys. Chem. B. 109, 1101-1107 (2005).
5. Liu, Y.-C., Hwang, B.-J., Jian, W.-J. & Santhanam, R. In situ cyclic voltammetry-surface-enhanced Raman spectroscopy: studies on the doping–undoping of polypyrrole film. Thin Solid Films 374, 85-91 (2000).
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