Chain-growth polycondensation: The living polymerization process in polycondensation
Chain-growth polycondensation: The living polymerization process in polycondensation
复制标题
DOI：
10.1016/j.progpolymsci.2006.08.001
复制
发表时间：
2007
影响因子：
27.1
通讯作者：
T. Yokozawa;A. Yokoyama
中科院分区：
文献类型：
--
作者：
T. Yokozawa;A. Yokoyama
综述了缩聚反应中活性聚合过程研究的历史发展。经典的缩聚反应是一个逐步增长的过程，但活性聚合缩聚反应必须通过链增长而不是逐步增长机制进行。早期的工作表明，有些缩聚反应不服从Flory的统计处理：例如，即使在低转化率下，也可以得到高分子量的聚合物。这意味着必须涉及链增长机制，无论有无逐步增长机制。近年来，人们对只通过链增长进行的缩聚反应（链增长缩聚反应）的理解有了巨大的发展。几种可能的机制是：（1）通过单体和聚合物之间取代基效应的变化来活化聚合物末端基团，例如芳香族聚酰胺、聚酯、聚醚、聚（醚砜）和聚（2）通过将催化剂转移到聚合物端基来活化聚合物端基，如聚噻吩;（3）将衍生自引发剂的反应性物质转移到聚合物端基，如聚亚甲基和聚磷腈;和（4）在由单体储存相和聚合相组成的两相中的相转移聚合，如脂肪族聚酯。这些链增长缩聚反应已被应用于合成具有各种结构的缩聚物：嵌段共聚物、星星聚合物、接枝共聚物等。
The historical development of research on the living polymerization process in polycondensation is reviewed. Classical polycondensation is a step-growth process, but a living polymerization polycondensation must proceed by a chain-growth rather than a step growth mechanism. Early work demonstrated that some polycondensations do not obey Flory's statistical treatment: for example, high molecular weight polymer may be obtained, even at low conversion. This means that a chain-growth mechanism must be involved, with or without a step-growth mechanism. Recent years have seen dramatic development in understanding of polycondensations that proceed only by chain-growth (chain-growth polycondensation). Several possible mechanisms are: (1) activation of the polymer end group by changed substituent effects between the monomer and the polymer, as with aromatic polyamides, polyesters, polyethers, poly(ether sulfone)s and poly(ether ketone)s; (2) activation of the polymer end group by transfer to it of the catalyst, as with polythiophenes; (3) transfer of the reactive species, derived from the initiator, to the polymer end group, as with polymethylenes and polyphosphazenes; and (4) phase-transfer polymerization in a biphase composed of a monomer storage phase and a polymerization phase, as with aliphatic polyesters. These chain-growth polycondensations have been applied to the synthesis of condensation polymers with various architectures: block copolymers, star polymers, graft copolymers, etc.