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A fast response, large deformation, excellent mechanical pH-responsive polyacrylonitrile/polyimide bilayer film

2020; Elsevier BV; Volume: 191; Linguagem: Inglês

10.1016/j.polymer.2020.122271

1873-2291

Xu Wang, Chengyong He, Longbo Luo, Daiqiang Chen, Xiangyang Liu, Jiaqiang Qin,

Dielectric materials and actuators

Here, we demonstrated pH responsive polyacrylonitrile/polyimide (PAN/PI) bilayer films with fast response, large deformation and excellent mechanical properties obtained by vertical-phase-separation. These films with concave/convex interface were composed by modified PAN (m-PAN) layer with nitrogen heterocyclic structure (pyridine ring) acting as responsive layer and PI as supporting layer. Attributing to the nitrogen heterocyclic structure being able to complex proton, m-PAN layer shows an acid-swelling behavior, exhibiting a completely different responsive behavior compared with traditional PAN responsive materials which are all of the alkali-swelling. The pH-induced bend and straight reciprocating motion occurs periodically with fast speed in acid and alkali solution alternatively, and the movement speed and size depend on the content of m-PAN, the pH value, the load and the relative stiffness and thickness of the two layers. Due to the excellent mechanical property of PI supporting layer, response strength of m-PAN and interface between PI and m-PAN, this soft polymer film actuator exhibited a tensile strength of 74 MPa and acted as an actuator for driving a high weight load of 1600 times its own weight.