Poly(vinyl alcohol)/Silkworm Silk Composites With Spider Silk Behavior

Lin Gu (1,2), Yuanzhang Jiang(1), Jinlian Hu(*1)

1 Institute of Textiles & Clothing, The Hong Kong Polytechnic University, Hong Kong 999077, China; 2 Key Laboratory of Marine Materials and Related Technology, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China

Abstract: Besides the amazing mechanical properties, spider silks have another remarkable feature called supercontraction, which describes their dramatic shrinkage at high humidity. Moreover, supercontracted spider silks could exhibit typical water-sensitive shape memory behavior, and the mechanism can be explained by a switch-netpoint model as reported in our previous work. In the model, hydrogen bonding, within the amorphous regions of spider silk can be interpreted as a switch that is responsible for strain fixation, while β-sheet crystals act as netpoints to stabilize the permanent shape. Compared to spider silks, silkworm silks have also β-sheet structure, and could easily be obtained in large amounts. Here, we report silkworm silk/poly(vinyl alcohol) composites with spider silk behavior, displaying water-sensitive two-way shape memory effect, and demonstrate that β-sheet conformation could be formed and act as netpoints in the composites. These composites can be simply prepared, and are biocompatible and toxic, which possess great potential in biological, medical, textile, and toys applications. This work will lead to the establishment of water-sensitive SMP system, and provide a novel approach for designing smart materials.