Dually synergetic network hydrogels with integrated mechanical stretchability, thermal

responsiveness and electrical conductivity for strain sensors and temperature alertors

Zhiwen Wang, Hongwei Zhou, Weixing Chen, QiuZhao Li, Bo Yan, Xilang Jin, Aijie Ma, Hanbin Liu, and Weifeng Zhao

ACS Appl. Mater. Interfaces, Just Accepted Manuscript DOI: 10.1021/acsami.8b02060

Publication Date (Web): April 2, 2018

The first example of dually synergetic network hydrogel, which has integrated mechanical stretchability, thermal responsiveness and electrical conductivity, has been constructed by a versatile and topological co-crosslinking approach. Poly(N-isopropylacrylamide) (PNIPAAm) is introduced as the thermally responsive ingredient and polyaniline (PANI) is selected as the electrically conductive ingredient. PNIPAAm network is crosslinked by double bond end-capped Pluronic F127 (F127DA). PANI network is doped and crosslinked by phytic acid. These two ingredients are further mechanically interlocked. Due to the integrated multiple functionalities, the topologically co-crosslinked hydrogels, as will be mentioned as F-PNIPAAm/PANI hydrogels, can be fabricated into resistive-type strain sensors. The strain sensors can achieve a gauge factor of 3.92, response time of 0.4 s, and sensing stability at least for 350 cycles and can be further applied in monitoring human motions, including motion of two hands, bending of joints, even swallowing and pulse rate. Moreover, F-PNIPAAm/PANI hydrogels are utilized to construct efficient temperature alertors based on the disconnection of circuits induced by the volume shrinkage at high temperature.