Tunable Polyaniline Chemical Actuators

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• 作者：Junbo Gao ; José ; -Marí ; a Sansiñ ; ena ; and Hsing-Lin Wang
• 刊名：Chemistry of Materials
• 出版年：2003
• 出版时间：June 17, 2003
• 年：2003
• 卷：15
• 期：12
• 页码：2411 - 2418
• 全文大小：321K
• 年卷期：v.15,no.12(June 17, 2003)
• ISSN：1520-5002

文摘

Polyaniline (PANI) porous asymmetric membranes were prepared using a phase-inversiontechnique, and their bending-recovery behavior induced by sorption and desorption ofchemical vapors was studied. It was found that the bending-recovery rates and maximumbending angles of the membranes were different in various vapors [hexane, ethyl ether,ethyl acetate, tetrahydrofuran (THF), and ethanol]. The undoped PANI membrane showedthe most extensive and the fastest bending-recovery movement in THF but no bending-recovery movement in hexane. We believe that the bending-recovery movement results fromthe asymmetric structure of the membrane's cross section. The dense side has a larger volumeexpansion than the more porous side after the absorption of organic vapors, and this largervolume causes a bending toward the porous side. Desorption of organic vapor from themembrane allows it to recover to its original position. The study of the effect of the membranestructure on membrane bending-recovery behavior shows that changing the PANI emeraldine base (EB) concentration of the solution used to cast the PANI porous asymmetricmembrane changes not only the mechanical properties of the membranes but also thebending-recovery rate of these membrane-based actuators. Lowering the EB concentrationleads to the formation of a more porous structure, which increases the diffusion rate of theorganic vapor into the membrane and thereby accelerates the bending-recovery movementinduced by sorption and desorption. Reversing the hydrophobicity by doping PANI with thesurfactant acid, dedecylbenzenesulfonic acid, allows the membrane to respond to less-polarorganic vapors such as hexane. Simplified mechanisms between both doped and undopedPANI and organic vapors are proposed to explain the above results.