侧链液晶高聚物的活性/可控自由基聚合

Synthesis of the polymers consisting of liquid crystalline by living/controlled radical polymerization

活性聚合最常见的增长链为离子,链端因为电荷的排斥作用而相互不发生反应,但是这种活性聚合方式仅仅适用于一部分单体,制约了所得聚合物的组成和结构。而自由基聚合虽然适用的单体种类较多,但由于增长链是自由基,比离子更容易互相结合而不易进行活性聚合。因此如何实现自由基的活性聚合,寻找类似于离子那样稳定的自由基,增长迅速、并且不会引发产生新的增长链是聚合物科学的迫切任务。本文主要介绍几种自由基的活性聚合方法Iniferter、氮氧化物调介聚合(NMP)和原子转移自由基聚合(ATRP)以及它们在合成侧链液晶高聚物方面的应用。

Living polymerization is most often observed in systems where the growing species are ions. In such systems the chain ends do not react to each other due to elestrostactic repulsion, but only to monomers allowing, this way, the control in structure of the formed polymer. Free radicals,which are the growing species in the radical polymerization, easely undergo combination and prevent a living radical polymerization. Thus,a great challenge to polymer science was in meeting a system that offered to the radical polymerization a radical stabilization alike in ionic polymerizations. at the same time,the radicals should undergo rapid propagation and should not be able to initiate new chains, in a controlled reaction.some succesfull techniques of living/controlled radical polymerization,such as iniferter,nitroxide mediated polymerization(NMP) and atom transfer radical polymerization (ATRP) will be overviewed here, as well as their application to the synthesis of liquid crystalline polymers.