Radically Initiated Group Transfer Polymerization of Methacrylates by Titanium Amino-Phenolate Complexes

Radical initiation of methyl methacrylate polymerizations mediated by titanium amino-phenolate complexes gave exceptional control without the need for any cocatalyst or activator. The polymerization proceeds not by a classical controlled radical or coordination insertion mechanism but via a unique bimetallic group transfer process. Detailed experimental and computational studies support a polymerization mechanism with a titanium­(IV)-enolate complex and a second titanium­(III) complex that delivers an activated monomer and provides new insight into both titanium-mediated radical reactions and polymerizations.由氨基酚钛配合物介导的甲基丙烯酸甲酯聚合自由基引发体系可实现优异的聚合控制，且无需任何助催化剂或活化剂。该聚合反应并非遵循经典的可控自由基或配位插入聚合机理，而是通过一种独特的双金属基团转移过程进行。详尽的实验与计算研究证实，该聚合反应的机理涉及四价钛-烯醇盐配合物与另一三价钛配合物，其中三价钛配合物可传递活化单体，这一发现为钛介导的自由基反应与聚合领域均提供了全新的认知视角。