Boron-catalyzed polymerization offers unique C3-polymer structures because, in contrast to 1,4-polydienes, each double bond is separated by only one methylene group. However, the geometrical regularity of such unique C3-structures was less discussed, and their properties have not been reported. In this work, well-defined poly(2-methyl-propenylene)s with different molecular weights are prepared in the gram scale by boron-catalyzed polymerization of 2-methylallyl arsonium ylide. ¹H NMR, ¹³H NMR, and two-dimensional ¹H–¹³C heteronuclear single quantum coherence NMR spectra confirm the high selectivity toward trans-configuration (>99%) and C3 monomeric insertion (>98%). Density functional theory (DFT) calculations at the wb97xd/tzvp level (solvent = tetrahydrofuran) explain the high trans/C3. Furthermore, the thermal parameters, T_c, T_m, T_g, ΔH_c, ΔH_m, and crystallinity degree, of poly(2-methyl-propenylene)s are determined by differential scanning calorimetry (DSC), fast scanning chip calorimetry (Flash DSC), and Wide Angle X-ray Scattering (WAXS) for the first time and are compared with those of trans-polyisoprene.

中文翻译：

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硼催化烯丙基Ar鎓硼化物的高反选择性及其对C3-聚合物热性能的贡献

硼催化的聚合反应提供独特的C3聚合物结构，因为与1,4-聚二烯相反，每个双键仅被一个亚甲基隔开。但是，这种独特的C3结构的几何规律性讨论较少，并且尚未报道其性质。在这项工作中，通过硼催化的2-甲基烯丙基ar内鎓盐的聚合反应，以克为单位制得了分子量明确的聚（2-甲基丙烯）。¹ H NMR，¹³ H NMR和二维¹ H– ¹³ C异核单量子相干NMR光谱证实了对反式的高选择性-构型（＞ 99％）和C 3单体插入（＞ 98％）。wb97xd / tzvp水平（溶剂=四氢呋喃）的密度泛函理论（DFT）计算可解释高反式/ C3。此外，通过差示扫描量热法（DSC），快速扫描芯片确定了聚（2-甲基丙烯）的热参数T _c，T _m，T _g，ΔH _c，ΔH _m和结晶度。量热法（Flash DSC）和广角X射线散射（WAXS）首次与反式聚异戊二烯进行了比较。