We demonstrate that an isotropic-genesis polydomain nematic elastomer (I-PNE) exhibits a large strain reaching 35% as well as a polydomain-to-monodomain transition at a nominal electric-field strength of 25 MV m À1 . The I-PNE has no ferroelectricity, and the maximum electrical strain observed is larger than the reported values for the ferroelectric chiral smectic elastomers. The I-PNE was obtained by cross-linking the mesogens in the high-temperature isotropic state and then by cooling the elastomer to the temperatures in the nematic state. The pronounced E-field responsivity originates from the softness regarding the director rotation specific to the isotropic-genesis polydomains.
We have found that a polypyrrole (PPy) film with anisotropy of conductivity and morphology bends in a regular direction and reverts during redox cycles. That is, the anisotropic PPy film acts as an actuator or a “bending machine”. The PPy film can be prepared electrochemically as a fiber in a slender Teflon pipe. The response speed of the PPy fiber actuator depends on the speed and amount of dopant insertion and extraction; namely, it becomes faster when the reduction potential is more negative or the electrolyte concentration is higher. The bending behavior strongly depends on the type of supporting salt in the electrolyte solutions, suggesting that cation transport into and out of PPy plays a key role in the bending behavior and that the size of the cation is also a critical factor. A bending behavior mechanism based on cation insertion and extraction, as well as on the anisotropic volume change upon doping/undoping, is proposed.
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