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首页> 外文期刊>ACS Macro Letters >Direct Chain End Functionalization of Living Polyisobutylene Using Phenoxyalkyl (Meth)acrylates
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Direct Chain End Functionalization of Living Polyisobutylene Using Phenoxyalkyl (Meth)acrylates

机译：使用（甲基）丙烯酸苯氧烷基酯对活性聚异丁烯的直接链端官能化

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Phenoxyallcyl acrylates and methacrylates were studied as quenching (capping) agents for living carbocationic polymerization of isobutylene (IB) at -70 degrees C in 40/60 (v/v) hexane/methyl chloride, catalyzed by TiCl4. Quenching reactions were carried out by reactivation by TiCl4 of preformed difunctional tert-chloride-terminated polyisobutylene (PIE) or by a one-step method in which IB polymerization and quenching were conducted sequentially in the same reactor. Chain-end concentrations ranged from 0.02 to 0.1 M, and quenchers were used at concentrations of 1.5-2.5 times the chain ends. The phenoxyalkyl (meth)ac-rylates were synthesized by reaction of (meth)acryloyl chloride with the corresponding phenoxyalkanol; alkylene tethers from two to eight carbons were examined. Quenched polymers were characterized by H-1 and C-13 NMR, MALDI-TOF mass spectrometry, and size exclusion chromatography (SEC). Alkylation was observed to occur exclusively at the para position of the phenoxy moiety, and SEC showed no coupling or molecular weight degradation as a result of quenching. For short tethers of two or three carbons, quenching was slow and incomplete due to competing loss of living chain ends presumably by carbocation rearrangement. For tethers of four, six, or eight carbons, quenching was much faster and yielded quantitative (meth)acrylate chain-end functionality (number-average functionality >= 1.98 by H-1 NMR). MALDI-TOF-MS results were consistent with the expected end group structures. The carbonyl group of the quencher consumes one equivalent of Lewis acid in formation of a 1:1 complex; thus, the highest rate of quenching at a given Lewis acid concentration is achieved by using only a modest excess of quencher relative to living chain ends.
机译：对丙烯酸苯氧基烯丙酯和甲基丙烯酸甲酯作为淬灭剂（封端剂）进行了研究，用于在TiCl4催化下于-70℃在40/60（v / v）己烷/氯甲烷中进行异丁烯（IB）的活性碳阳离子聚合。淬灭反应是通过预先形成的双官能叔氯化物封端的聚异丁烯（PIE）的TiCl4活化或通过一步法在同一反应器中依次进行IB聚合和淬灭来进行的。链端浓度为0.02至0.1 M，淬灭剂的使用浓度为链端的1.5-2.5倍。通过（甲基）丙烯酰氯与相应的苯氧基链烷醇反应合成（甲基）丙烯酸苯氧基烷基酯。检查了两个到八个碳的亚烷基系链。淬灭的聚合物通过H-1和C-13 NMR，MALDI-TOF质谱和尺寸排阻色谱（SEC）进行表征。观察到烷基化仅发生在苯氧基部分的对位，并且SEC未显示出由于淬灭而引起的偶联或分子量降低。对于两个或三个碳原子的短链，淬灭是缓慢且不完全的，这归因于活性链末端的竞争性损失，可能是由于碳正离子重排。对于4、6或8个碳的束缚链，淬灭要快得多，并产生定量的（甲基）丙烯酸酯链端官能度（H-1 NMR数均官能度> = 1.98）。 MALDI-TOF-MS结果与预期的端基结构一致。淬灭剂的羰基以1：1的配合物形式消耗一当量的路易斯酸。因此，在给定的路易斯酸浓度下，相对于活性链末端仅使用适度过量的淬灭剂即可达到最高的淬灭速度。

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