Isospecific Polymerization of Halide- and Amino-Substituted Styrenes Using a Bis(phenolate) Titanium Catalyst
作者：Qiyuan Wang , Zhen Zhang, Yang Jiang, Yanfeng Zhang, Shihui Li* and Dongmei Cui*
關鍵字：isospecific polymerization，halostyrene，amino-substituted styrene，titanium complex
論文來源：期刊
發表時間：2022年
Isospecific polymerization of polar styrenes is a challenge of polymer science. Particularly challenging are monomers bearing electron-withdrawing substituents or bulky substituents. Here, we report the coordination polymerization of halide- and amino-functionalized styrenes including para-fluorostyrene (pFS), para-chlorostyrene (pClS), para-bromostyrene (pBrS), and para-(N,N-diethylamino)styrene (DMAS) using 2,2'' -sulfur-bridged bis(phenolate) titanium precursor(1). The combination of 1 and [Ph3C][B(C6F5)4] and AliBu3 provides crystalline poly(pFS)s with perfect isotacticity (mmmm > 95%) and high molecular weights (≤16.0×104 g mol-1). Upon activation with a large excess of DMAO, 1 reaches polymerization activity of 5.58×105 g mol Ti-1h-1 producing isotactic poly(pFS)s featuring higher molecular weights (≤39.6 104 g mol-1). The distinguished performance of the 1/DMAO system has been extended to the polymerization of pClS and pBrS, both usually involve halogen abstraction during the polymerization, to produce isotactic and high molecular weight (Mn = 32.2×104 vs. 13.7×104 g mol-1) polymers in good activities (2.18×105 vs. 1.31×105 g molTi-1h-1). Surprisingly, 1/DMAO is nearly inactive for DMAS polymerization, on contrary, the system 1/[Ph3C][B(C6F5)4]/Ali Bu3 displays isoselectivity (mmmm > 95%) albeit in a moderate activity.