Preparation and pH-sensitive behavior of H-PAN/soy protein hydrogel fibers

The preparation of smart hydrogel fibers composed of polyacrylonitrile (PAN) and soy protein (SP) was presented. The spinning dope was prepared by heating the mixture of PAN and SP in the NaOH aqueous solution. It was extruded into coagulating bath containing saturated sodium sulfate with glutaraldehyde as crosslinkage and sulfuric acid, where the network was formed. The final hydrogel fibers exhibit an excellent reversible pH-sensitive behavior with an increase of the SP content. And when the hydrogel fiber was made from 40% (W-PAN:W-Total) of PAN, the shortest response times in elongation/contraction behavior were obtained, which were 9.3 and 1.6 s, respectively. The hydrogel fibers also show three discontinuous changes and the hysteresis loop oil pH by successive pH changes. The dynamical and static elongation/contraction behaviors were well reproducible.