Department of Chemical Engineering, Faculty of Engineering, University of Maragheh , Maragheh 55181-83111, Iran.
ACS Appl Mater Interfaces. 2017 Jul 19;9(28):24061-24070. doi: 10.1021/acsami.7b02259. Epub 2017 Jul 3.
This work aimed to develop a facile and broadly applicable method for fabricating multistimuli responsive triple-shape memory polymers (SMPs). Hence, herein the SMPs were prepared through the simple physical blending of two commercially available biopolymers, poly(lactic acid) (PLA) and poly(vinyl acetate) (PVAc), in the presence of robust and conductive graphene nanoplatelets. Interestingly, atomic force microscopy observations and thermal analyses revealed that the presence of nanofillers led to phase separation and appearance of two well-separated transition temperatures in the blend of these two miscible polymers. Consequently, shape memory results showed that the unfilled blend of PLA/PVAc with a single thermal transition can only show moderate heat triggered dual-shape memory behavior. While, PLA/PVAc/graphene nanocomposite blends demonstrated excellent thermally and electrically actuated triple-shape memory effects besides their remarkable dual-shape memory behavior. In addition, electrical conductivity of the blend was enhanced by ∼14 orders of magnitude in the presence of graphene. More interestingly, electroactive shape recovery experiments exhibited that depending on the applied voltage, temporary shapes in each region of sample can be either individually or simultaneously recovered.
本工作旨在开发一种简便且具有广泛适用性的方法来制备多刺激响应型三重形状记忆聚合物（SMPs）。因此，本文通过在两种市售的生物聚合物聚乳酸（PLA）和聚醋酸乙烯酯（PVAc）的简单物理共混中加入坚固且导电的石墨烯纳米片来制备 SMPs。有趣的是，原子力显微镜观察和热分析表明，纳米填料的存在导致了相分离，并在这两种可混溶聚合物的共混物中出现了两个明显分离的转变温度。因此，形状记忆结果表明，具有单一热转变的未填充 PLA/PVAc 共混物只能表现出适度的热触发双形状记忆行为。而 PLA/PVAc/石墨烯纳米复合材料共混物除了具有显著的双形状记忆行为外，还表现出优异的热和电致动三重形状记忆效应。此外，在存在石墨烯的情况下，共混物的电导率提高了约 14 个数量级。更有趣的是，电活性形状恢复实验表明，根据施加的电压，可以单独或同时恢复样品各区域的临时形状。
