Yoo Kwangho, Lee Gue Seon, Lee Hyo Won, Kim Byeong-Su, Kim Jeung Gon
Department of Chemistry, Research Institute of Physics and Chemistry, Jeonbuk National University, Jeonju 54896, Republic of Korea.
Department of Chemistry, Yonsei University, Seoul 03722, Republic of Korea.
Faraday Discuss. 2023 Jan 5;241(0):413-424. doi: 10.1039/d2fd00080f.
Mechanochemistry has been extended to various polymer syntheses to achieve efficiency, greenness, and new products. However, many fundamental polymerization reactions have not been explored, although anionic polymerization of vinyl compounds has been pursued under mechanochemical conditions. Two solid monomers, 4-biphenyl methacrylate and 4-vinyl biphenyl, representing methacrylate and styrenic classes, respectively, were reacted with secondary butyl lithium under high-speed ball-milling. The alkyl-anion-promoted polymerization process was established by excluding radical initiation and producing the expected polymers with good efficiency. However, the generally expected features of anionic polymerization, such as molecular weight control and narrow dispersity, were not observed. Analysis of the milling parameters, reaction monitoring, and microstructural analysis revealed that the mechanism of the mechanochemical process differs from that of conventional anionic polymerizations. The mechanical force fractured the newly formed polymer chains anionic initiation and generated macroradicals, which participated in the polymerization process. The anionic process governs the initiation step and the radical process becomes dominant during the propagation step.
机械化学已被应用于各种聚合物合成中，以实现高效、绿色和新产品的开发。然而，尽管在机械化学条件下对乙烯基化合物的阴离子聚合进行了研究，但许多基本的聚合反应尚未得到探索。两种固体单体，分别代表甲基丙烯酸酯类和苯乙烯类的甲基丙烯酸4-联苯酯和4-乙烯基联苯，在高速球磨下与仲丁基锂反应。通过排除自由基引发并高效制备预期聚合物，建立了烷基阴离子促进的聚合过程。然而，未观察到阴离子聚合通常预期的特征，如分子量控制和窄分散性。对研磨参数的分析、反应监测和微观结构分析表明，机械化学过程的机理与传统阴离子聚合不同。机械力使新形成的聚合物链断裂，引发阴离子聚合并产生大分子自由基，这些自由基参与了聚合过程。阴离子过程控制引发步骤，而自由基过程在增长步骤中占主导地位。
