Precise Synthesis of Miktoarm Star Polymers by Using a New Dual-Functionalized 1,1-Diphenylethylene Derivative in Conjunction with Living Anionic Polymerization System

The general utility of a 1,1-diphenylethylene (DPE) derivative substituted with trimethylsilyl- and tert-butyldimethylsilyl-protected hydroxyl functionalities, as a new dual-functionalized core agent in conjunction with a living anionic polymerization system, has been demonstrated by the successful synthesis of various well-defined 3-arm ABC and 4-arm ABCD mu-star polymers. Two different protected hydroxyl functionalities were progressively deprotected to generate hydroxyl groups, followed by conversion to alpha-phenyl acrylate (PA) functions at separate stages, and the PA functions were reacted with appropriate living anionic polymers to result in the above mu-stars. In order to further synthesize mu-star polymers with five or more arms, a new iterative methodology using a functional DPE anion derived from the above DPE derivative has been developed. The reaction system of this methodology is designed in such a way that the PA function used as the reaction site is regenerated after the introduction of an arm segment in each reaction sequence, and this sequence, consisting of arm introduction and regeneration of the PA reaction site, is repeatable. With this methodology, a series of new well-defined mu-star polymers up to a 5-arm ABCDE type, composed of all different methacrylate-based polymer segments, were successfully synthesized for the first time.