A Biomimetic Actuator Based on an Ionic Networking Membrane of Poly(styrene‐alt‐maleimide)‐Incorporated Poly(vinylidene fluoride)

A novel electro‐active polymer actuator employing the ionic networking membrane of poly(styrene‐alt‐maleimide) (PSMI)‐incorporated poly(vinylidene fluoride) (PVDF) was developed to improve the electrical and mechanical performance of the artificial muscles. The main drawback of the previous ionic polymer‐metal composite actuator was the straightening‐back and relaxation under the constant voltage excitation. The present ionic networking membrane actuator overcomes the relaxation of the ionic polymer‐metal composite actuator under the constant voltage and also shows much larger tip displacement than that of the Nafion‐based actuator. Under the simple harmonic stimulus, the measured mechanical displacement was comparable to that of the Nafion‐based actuator. The excellent electromechanical response of the current polymer actuator is attributed to two factors: the inherent large ionic‐exchange capacity and the unique hydrophilic nano‐channels of the ionic networking membrane. The electro‐active polymer actuator of PSMI‐incorporated PVDF can be a promising smart material and may possibly diversify niche applications in biomimetic motion.     

Switching Light Transmittance by Responsive Organometallic Poly(ionic liquid)s: Control by Cross Talk of Thermal and Redox Stimuli

A novel organometallic poly(ionic liquid) with both redox‐ and thermoresponsive properties is synthesized from a poly(ferrocenylsilane) (PFS) via a one‐step Strecker sulfite alkylation reaction by using tetraalkylphosphonium sulfite as an effective and versatile nucleophile. This dual‐responsive polymer is composed of a PFS backbone and quaternary phosphonium sulfonate side groups and exhibits a concentration‐dependent lower critical solution temperature (LCST)‐type phase transition in aqueous solution. Furthermore, the LCST‐type phase behavior of the polymer can be switched between the “off” state and “on” state by chemical or electrochemical oxidation and reduction on the ferrocene units in the polymer main chain. As a consequence, a classical LCST‐type phase transition, as well as an “isothermal” redox‐triggered phase transition can be induced by using thermal and electrochemical triggers without changing the composition of the system. On the basis of this dual responsiveness, a “smart window” device is fabricated. The optical characteristics of this device are completely unaltered after 100 thermal and/or redox cycles.