梯度共聚物的可控制备及其性能

Controlled synthesis and properties of gradient copolymers

梯度共聚物是近年来伴随着活性聚合方法而发展起来的一种新型共聚物,其特点在于单体单元组成沿着分子链方向逐渐变化,链结构界于常见的无规共聚物和嵌段共聚物之间。本文从梯度共聚物的结构特点入手,总结了其可控制备方法、表征手段、物化性质以及应用前景。基于共聚动力学模型控制单体加料速率的半连续活性/可控自由基聚合可实现梯度共聚物的结构定制,基于多步单体进料方式的RAFT乳液聚合则由于其简单和高效将成为梯度共聚物可控制备的重要方法。梯度共聚物的自组装行为和微观聚集态不同于嵌段共聚物,表现出独特的界面活性、热学特性和力学性能,组成梯度结构有望成为调控高分子材料性能的新参数,梯度共聚物有望在乳化剂、相相容剂、阻尼材料、多形状记忆材料等领域得到应用。

Gradient copolymer is a new kind of polymers emerging with the living polymerization techniques. The unique structural feature is the gradual variation of monomeric compositions along the polymeric chains, distinguishing from random and block copolymers. The current paper reviews the preparation techniques, characterization methods, physical properties and potential applications of gradient copolymers. Kinetic model-based monomer feeding policy in controlled/living radical polymerization presents a sophisticated method to precisely synthesize gradient copolymers by design, while many-shot monomer feeding policy in RAFT emulsion polymerization is a facile and efficient technique to tailor-make compositional gradient copolymers. Compared random and block copolymers, gradient copolymers exhibit different self-assembly behaviors in both solution and bulk, resulting in unique interfacial, thermal and mechanical properties. Composition gradient is expected to be a new parameter to finely tune the properties of polymers. Gradient copolymers have shown promising applications in the phase compatibilizers, damping materials and multi-shape memory materials.