高分子英语unit5.docx

第五单元?Traditional?methods?of?living?polymerization?are?based?on?ionic,?coordination?or?group?transfer?mechanisms.?活性聚合的传统方法是基于离子，配位或基团转移机理。?Ideally,?the?mechanism?of?living?polymerization?involves?only?initiation?and?propagation?steps.?理论上活性聚合的机理只包括引发和增长反应步骤。?All?chains?are?initiated?at?the?commencement?of?polymerization?and?propagation?continues?until?all?monomer?is?consumed.?在聚合反应初期所有的链都被引发，然后增长反应继续下去直到所有的单体都被消耗殆尽。?A?type?of?novel?techniques?for?living?polymerization,?known?as?living?(possibly?use?“controlled”?or?“mediated”)?radical?polymerization,?is?developed?recently.?最近开发了一种叫做活性自由基聚合的活性聚合新技术。?The?first?demonstration?of?living?radical?polymerization?and?the?current?definition?of?the?processes?can?be?attributed?to?Szwarc.?第一个活性自由基聚合的证实及目前对这一过程的解释或定义，应该归功于Szwarc。?Up?to?now,?several?living?radical?polymerization?processes,?including?atom?transfer?radical?polymerization?(ATRP),?reversible?addition-fragmentation?chain?transfer?polymerization?(RAFT),?nitroxide-mediated?polymerization?(NMP),?etc.,?have?been?reported?one?after?another.?到目前为止，一些活性自由基聚合过程，包括原子转移自由基聚合，可逆加成-断裂链转移聚合，硝基氧介导聚合等聚合过程一个接一个被报道。?The?mechanism?of?living?radical?polymerization?is?quite?different?not?only?from?that?of?common?radical?polymerization?but?also?from?that?of?traditional?living?polymerization.?活性自由基聚合的机理不仅完全不同于普通自由基聚合机理，也不同于传统的活性聚合机理。?It?relies?on?the?introduction?of?a?reagent?that?undergoes?reversible?termination?with?the?propagating?radicals?thereby?converting?them?to?a?following?dormant?form：?活性自由基聚合依赖于向体系中引入一种可以和增长自由基进行可逆终止的试剂，形成休眠种：?The?specificity?in?the?reversible?initiation-termination?step?is?of?critical?importance?in?achieving?living?characteristics.?这种特殊的可逆引发-终止反应对于获得分子链活性来说具有决定性的重要意义。?This?enables?the?active?species?concentration?to?be?controlled?and?thus?allows?such?a?condition?to?be?chosen?that?all?chains?are?able?to?grow?at?a?similar?rate?(if?not?simultaneously)?throughout?the?polymrization.?可逆引发终止使活性中心的浓度能够得以控制。这样就可以来选择适宜的反应条件，使得在整个聚合反应过程中(只要没有平行反应)所有的分子链都能够以相同的速度增长。?This?has,