Carter Steven R, England Richard M, Hunt Barry J, Rimmer Stephen
The Polymer and Biomaterials Chemistry Laboratories, Department of Chemistry (Polymer Centre), Brook Hill, University of Sheffield, Sheffield, South Yorkshire, S3 7HF, UK.
Macromol Biosci. 2007 Aug 7;7(8):975-86. doi: 10.1002/mabi.200700108.
A series of NIPAM/4-vinyl benzyl chloride copolymers were substituted with 4(5)-imidazole dithioic acid or N-pyrrole dithioic acid to form multi-functional linear dithioate-functional polymers, which can be used as macromolecular transfer agents in a controlled radical polymerisation (RAFT) process. The presence of imidazole dithioate or N-pyrrole dithioate units along the NIPAM copolymer was determined by (1)H NMR, which showed broad CH-imidazole or CH-N-pyrrole resonances. Subsequent reaction of these multi-branch point polymers to produce graft polymers was achieved by reaction with NIPAM in the presence of AIBN. The graft polymers are produced as mixtures containing the desired product and linear polymer. The linear polymer is produced following transfer to the pendant dithioate group. Some of the branched polymers formed from the imidazole dithioate polymers were insoluble in water whilst others were found to be water soluble only in the presence of copper(II) ions. The use of N-pyrrole dithioate groups was found to substantially increase the solubility of the branched polymers in conventional solvents.
一系列NIPAM/4-乙烯基苄基氯共聚物用4(5)-咪唑二硫代酸或N-吡咯二硫代酸进行取代，以形成多功能线性二硫代酸酯官能化聚合物，其可在可控自由基聚合（RAFT）过程中用作大分子转移剂。沿NIPAM共聚物存在的咪唑二硫代酸酯或N-吡咯二硫代酸酯单元通过¹H NMR确定，其显示出宽的CH-咪唑或CH-N-吡咯共振。这些多支化点聚合物随后通过在AIBN存在下与NIPAM反应来制备接枝聚合物。接枝聚合物作为含有所需产物和线性聚合物的混合物产生。线性聚合物是在转移到侧链二硫代酸酯基团后产生的。由咪唑二硫代酸聚合物形成的一些支化聚合物不溶于水，而其他一些仅在铜(II)离子存在下可溶于水。发现使用N-吡咯二硫代酸酯基团可大幅提高支化聚合物在常规溶剂中的溶解度。
