Unlike the other common polar conjugated monomers, the efficient and precise polymerization of semifluorinated methacrylates (SFMAs) by conventional anionic or coordination polymerization has remained an unmet challenge, despite the unique and intriguing characteristics of the resulting polymers. This contribution reports the first Lewis pair polymerization (LPP) of SFMAs that provides a viable and effective strategy for the efficient synthesis of semifluorinated polymethacrylates (SFPMAs) with precise control over molecular weight and stereospecificity. Among Lewis pair (LP) catalysts based on N-heterocyclic carbene (NHC) Lewis bases (LBs) and group 13 Lewis acids (LAs), a strongly nucleophilic 1,3-di-tert-butylimidazolin-2-ylidene (I^tBu) LB and a strongly Lewis acidic and sterically encumbered methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) [MeAl(BHT)₂] LA have stood out as the best LP catalyst in all aspects for SFMA LPP. Even at an exceptionally large excess of SFMA (e.g., 4500 equiv), quantitative monomer conversion can be achieved by this LP at room temperature within 60–180 min, affording ultrahigh-molecular-weight SFPMAs with very low dispersities (M_n up to 1300 kg/mol, Đ = 1.01–1.10). For the typical SFMAs of trifluoroethyl methacrylate (TFEMA) and hexafluorobutyl methacrylate (HFBMA), living characteristics of their LPPs have been unequivocally established, and a fundamental understanding of this living feature has also been gained by the mechanistic studies. Highly syndioregular PTFEMA, with a high syndiotacticity of [rr] up to 92.0% and a low Đ of 1.16, can be produced at low temperature, which readily forms a stereocomplex with isotactic poly(methyl methacrylate), thus affording a robust fluorinated-contained crystalline material with a high melting temperature up to 175 °C.

中文翻译：

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半氟化甲基丙烯酸酯的路易斯对聚合中分子量和立体特异性的精确控制：机理研究和立体复合物的形成

与其他常见的极性共轭单体不同，尽管所得聚合物具有独特而引人入胜的特性，但通过常规的阴离子或配位聚合反应进行有效且精确的半氟化甲基丙烯酸酯（SFMA）聚合仍是一项尚未解决的挑战。该论文报道了SFMA的第一个路易斯对聚合（LPP），它为有效合成半氟化聚甲基丙烯酸酯（SFPMA）提供了可行且有效的策略，并且可以精确控制分子量和立体特异性。在基于N杂环卡宾（NHC）Lewis碱（LBs）和13族Lewis酸（LAs）的Lewis对（LP）催化剂中，一种强亲核性的1,3-二叔丁基咪唑啉-2-亚烷基（I ^tBu）LB和强路易斯酸性且空间受限的甲基铝双（2,6-二叔丁基-4-甲基苯氧基）[MeAl（BHT）₂ ] LA在所有方面均是针对SFMA LPP的最佳LP催化剂。即使在一个非常大的过量SFMA（例如，4500当量）的，定量的单体转化率可以通过本LP在室温下60-180分钟内实现，得到超高分子量非常低的分散度SFPMAs（中号_Ñ可达1300千克/摩尔，Đ= 1.01-1.10）。对于典型的甲基丙烯酸三氟乙酯（TFEMA）和甲基丙烯酸六氟丁酯（HFBMA）的SFMA，已经明确地确定了它们的LPP的活性特征，并且通过机理研究也获得了对该活性特征的基本理解。高度syndioregular PTFEMA，与[高间规度RR ]高达92.0％和低Đ 1.16，可以在低温下，其容易形成与全同立构聚（甲基丙烯酸甲酯）的立构产生的，从而提供强大的氟化包含的熔点高达175°C的结晶材料。