Conducting hydrogels with enhanced mechanical strength

Mechanically strong triple-network (TN) hydrogels composed of poly(acrylic acid) (PAA) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been fabricated with conductive PEDOT-PSS hydrogel acting as the third network. As-prepared PAA/PEDOT-PSS TN hydrogels display a compressive fracture stress as high as 1.8 MPa and still keep the electrical functionality of the conducting component. The success of PEDOT-PSS hydrogel in strengthening the materials is ascribed to the entangled microstructure of the triple networks and the variable molecular structure of the conducting polymer. A preliminary strengthening mechanism is proposed based upon the experimental results and the DN and/or TN theories. In addition, the applicability of the TN hydrogels in electrosensors; and supercapacitors is briefly discussed. The present findings have successfully demonstrated the functionalization of mechanically strong hydrogels, and are of crucial significance in the development of DN and TN hydrogels both academically and practically. (C) 2009 Elsevier Ltd. All rights reserved.