双向形状记忆结晶聚合物及其复合材料的研究进展

形状记忆聚合物是一种典型的智能材料,具有质轻、形变量大、可对多种刺激进行响应等优点.根据形状记忆过程的可逆性进行分类,形状记忆效应可以分为2种:单向与双向形状记忆效应.与不可逆的单向形状记忆过程相比,双向形状记忆过程是可逆的,样品不需要使用者进行再次变形,就可以在原始形状与临时形状之间进行可逆转换,因此其具有极高的实用价值与广阔的应用前景,受到各国研究人员的广泛关注,成为当前的研究热点之一.本文总结了近年来所研究的双向形状记忆结晶聚合物及其复合材料,包括恒外力条件下(外力≠0)的准双向形状记忆结晶聚合物,无外力条件下的双向形状记忆结晶聚合物及其复合材料.具体来说,前者包括在恒外力作用下的化学或物理交联的结晶聚合物.后者包括双层或核-壳聚合物复合材料、由分步交联得到的双网络交联结晶聚合物、化学交联的双组分结晶聚合物、具有较宽熔融转变的化学交联结晶聚合物与物理交联的结晶聚合物.重点关注了这些材料的制备方法、影响因素及相应的双向形状记忆机理,并对其研究前景进行了展望.

Recent Progress in Two-way Shape Memory Crystalline Polymer and Its Composites

As a sort of intelligent material,shape memory polymer material is outstanding in various aspects,such as lower density,high recoverable strain,and in response to a vast array of external stimuli.According to whether the shape memory process is reversible or not,the shape memory effect could be classified into two categories:one-way shape memory effect and two-way shape memory effect.The one-way shape memory process is actually irreversible,in which the recovered permanent shape cannot revert back to the temporary shape by merely altering the external stimulus and a re-programming process is necessarily needed.On the contrary,the two-way one is fully reversible,meaning that the sample would be able to vary between distinguished shapes reversibly without external re-shaping process applied by user.As a consequence,two-way shape memory polymer materials have high practical values and broad application prospects,which have aroused wide attention and become one of the hot spots of current researches.This work presents a brief review of two-way shape memory crystalline polymer and its composites that have been investigated and developed in recent years,including quasi two-way shape memory crystalline polymer under constant external stress and two-way shape memory crystalline polymer plus its composites without external stress.More specifically,the former consists of chemically and physically cross-linked crystalline polymer with persistent extemal stress,while the latter is comprised of polymer laminates,polymer/elastomer core/shell composites,chemically cross-linked crystalline polymer possessing dual-cure network architectures,chemically cross-linked two-component crystalline polymer,chemically cross-linked crystalline polymer with a broad melting transition,and physically cross-linked crystalline polymer.More importantly,preparation methods,influencing factors and the corresponding two-way shape memory mechanism of the aforementioned materials are introduced and discussed in detail.In the end,the future developments and research directions of these polymer materials are proposed as well.