原位合成引发剂引发原子转移自由基及衰减链转移同步聚合

在甲基丙烯酸甲酯(MMA)单体中,以偶氮二异丁腈(AIBN)与I2反应原位合成α-碘代异丁腈(IIBN),进一步作为原子转移自由基聚合引发剂分别与CuCl、FeCl2.4H2O等催化剂,MA5-DETA、PMDETA等络合剂相匹配引发MMA的ATRP,同时又作为衰减链转移聚合(DT)的可逆链转移剂同步进行DT聚合。实验结果表明:所得聚合物分子量可控,分子量分布(PDI)很窄(1.05～1.25),引发剂效率较高。动力学的研究结果显示:分子量随转化率而增长;由Ln[M]0/[M]t对时间作图,呈现良好的线形关系,表明聚合过程中增长自由基浓度是一个恒定值,证明由IIBN引发的聚合是典型的活性自由基聚合;这种方法克服了极不稳定的在α-位带有吸电子基团的碘化物的购运和储存的困难。不失是一种简单,快捷,方便的方法。

The atom transfer radical polymerization and degenerative transfer polymerization initiated by initiator formed in situ

A novel initiator α-iodoisobutyrontrile （HBN）, synthesized from the reaction of I2 with 2,2＇ -azobisisobutyronitrile （AIBN） in methyl methacrylate （MMA） is used as initiator for atom transfer radical polymerization （ATRP） and simultaneity as a transfer agent for degenerative transfer polymerization （DT） of MMA, using CuCI, FeCI2·4H2O etc. as catalysts and MA5-DETA, PMDETA etc. as ligands. Results exhibit： polymerization is well-controlled, results polymer with low polydispersities （ PDI： 1.05-1.25） initiator efficiency of HBN is rather high. The linearity of the semilogarithmic plot ofLn （[M]o/[M]） vs. polymerization time indicates the polymerizations were first-order, concentration of the growing radicals remaine constant throughout reaction time. This method refrains from using expensive, toxic unstable iodides. Direct employment of KBN as an initiator for ATRP and DT is a simple, effective and convenience method.