Excellent Electroactive Shape Memory Performance of EVA/PCL/CNT Blend Composites with Selectively Localized CNTs

In this work, the binary blend of poly(ethylene vinyl acetate) (EVA)/poly(epsilon-caprolactone) (PCL) with different compositions were prepared and the shape memory behaviors were evaluated first. Then, carbon nanotubes (CNTs) were introduced into the composition that exhibited relatively better shape memory effect (SME) to prepare the ternary blend composites with electrically actuated SME. The morphologies of the blend and/or blend composites, the crystallization of the component, and the selective location states of CNTs in the blend composites were comparatively investigated. The results demonstrated that the binary EVA/PCL blends exhibit a typical seaisland structure at low PCL content, a quasi-cocontinuous structure at mediate PCL content and then the seaisland structure at high PCL content. Among these binary blends, the EVA/PCL (60/40) sample exhibits relatively better SME with not only high shape fixing ratio but also shape recovery ratio. The presence of the CNTs further induces the changes of morphology and crystallization behavior in the blend composites. Due to the largely reduced electrical resistivity promoting more Joule heat generation at applied voltage, the blend composites containing relatively high content of CNTs exhibited excellent electrically actuated SME. This work demonstrated that introducing CNTs into the immiscible blends and controlling the selective location of CNTs in one component, the electrically actuated SME could be achieved at relatively lower voltage and the shape recovery speed could also be greatly increased.