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Anomalous pH Actuation of a Chitosan/SWNT Microfiber Hydrogel with Improved Mechanical Property

Published online by Cambridge University Press:  01 February 2011

Su Ryon Shin
Affiliation:
sjk@hanyang.ac.kr, Hanyang University, Department of Biomedical Engineering, Seong Dong P.O. Box 55, Seoul, 133-605, Korea, Seoul, N/A, N/A, Korea, Republic of
Sang Jun Park
Affiliation:
sjpark92@ihanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
Seong Gil Yoon
Affiliation:
pandasky@ihanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
Chang Kee Lee
Affiliation:
withs@ihanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
Kwang Min Shin
Affiliation:
coolskm@ihanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
Bon Kang Gu
Affiliation:
bons1020@ihanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
Min Kyoon Shin
Affiliation:
masscsq@ihanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
Min Sup Kim
Affiliation:
kimins21@ihanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
Yu Jin Kim
Affiliation:
snow82@ihanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
Seon Jeong Kim
Affiliation:
sjk@hanyang.ac.kr, Hanyang University, Seoul, N/A, N/A, Korea, Republic of
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Abstract

Composite fibers composed of chitosan and single-wall carbon nanotubes (CNTs) have been fabricated using a wet spinning method. The dispersion was improved by the sonic agitation of the CNTs in a chitosan solution followed by centrifugation to remove tube aggregates and any residual catalyst. The mechanical behavior was investigated using a dynamic mechanical analyzer (DMA). The mechanical tests showed a dramatic increase in Young's modulus for the chitosan/CNT composite fibers fabricated using the improved dispersion method. The strain on the microfibers was determined from tensile load measurements during pH switching in acidic or basic electrolyte solutions. The microfibers showed a general actuation behavior of expanding at pH = 2 and contracting at pH = 7 under low tensile loads. However, a reverse of this actuation behavior was exhibited under high tensile loads. This anomalous pH actuation is both new and surprising. It was explained from an analysis of the differences in sample stiffness and Poisson’s ratio under tensile load in electrolyte solutions with different pH values.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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