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Stereo- and Temporally Controlled Coordination Polymerization Triggered by Alternating Addition of a Lewis Acid and Base
 
作者:Liu, Bo;Cui, Dongmei;Tang, Tao
关键字:coordination polymerization,Lewis acids, Lewis bases,polymerization, sequence-controlled polymers
论文来源:期刊
具体来源:http://onlinelibrary.wiley.com/doi/10.1002/anie.201605038/abstract;jsessionid=66E0869E98C176BD7A82BC
发表时间:2016年


Significant progress has been made with regard to temporally controlled radical and ring-opening polymerizations, for example, by means of chemical reagents, light, and voltage, whereas quantitative switch coordination polymerization is still challenging. Herein, we report the temporally and stereocontrolled 3,4-polymerization of isoprene through allosterically regulating the active metal center by alternating addition of Lewis basic pyridine to "poison" the Lewis acidic active metal species through acid-base interactions and Lewis acidic AliBu(3) to release the original active species through pyridine abstraction. This process is quick, quantitative, and can be repeated multiple times while maintaining high 3,4-selectivity. Moreover, this strategy is also effective for the switch copolymerization of isoprene and styrene with dual 3,4- and syndiotactic selectivity. Tuning the switch cycles and intervals enables the isolation of various copolymers with different distributions of 3,4-polyisoprene and syndiotactic polystyrene sequences.