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 Zhang1,2
1
School of Materials Science & Engineering, Beijing Institute of Technology, Beijing
100081, P. R. China
2
Suzhou Institute of Nano-tech & Nano-bionics, Chinese Academy of Sciences,
Suzhou, 215123, P. R.China
3
College of Chemistry, Chemical Engineering & Material science, Soochow
University, Suzhou, 215123, P. R. China
[†] These authors contribute equally to this work
Email: zhangxtchina@yahoo.com
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.
Intensity (a.u.)
(a)
1450
1540 1300
1040 783
1170 893
(b)
1450
1540
2400
2000
1600
1300
1040 783
1170 893
1200
800
400
Wavenumber (cm )
-1
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.
Intensity (a.u.)
1315
1588
1244 1407
930
(a)
1046
(b)
500
750 1000 1250 1500 1750 2000
Wavenumber (cm )
-1
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.
(a)
(b)
(c)
Compress
Release
Compress
Release
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.
6
E' (), E"() (Pa)
(a) 10
Aging for 1 day:
10 days:
20 days:
E'
E'
E'
E"
E''
E''
5 days:
15 days:
30 days:
E'
E'
E'
E"
E''
E"
5
10
4
10
3
10
2
10
1
10
100
-1
(rad s )
4
4
3x10
-1
E'(=10 rad s ) (Pa)
(b) 4x10
4
2x10
4
1x10
0
0
5
10
15
20
25
30
Aging times (days)
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).
Figure SI6 SEM images of PPy sponge without (a, b) and with (c, d) compression..
4
Compression strain 50 %
R/R0 (%)
3
2
1
0
-1
0
25
50
75
100
125
150
175
Time (s)
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
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).