Feng Quanyou, Tong Rong
Center for Molecular Systems and Organic Devices, Institute of Optoelectronic Materials, Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts and Telecommunications; Department of Chemical Engineering, Virginia Polytechnic Institute and State University.
Department of Chemical Engineering, Virginia Polytechnic Institute and State University;
J Vis Exp. 2017 Nov 21(129):56654. doi: 10.3791/56654.
Here, we describe an effective protocol that combines photoredox Ni/Ir catalysis with the use of a Zn-alkoxide for efficient ring-opening polymerization, allowing for the synthesis of isotactic poly(α-hydroxy acids) with expected molecular weights (>140 kDa) and narrow molecular weight distributions (Mw/Mn < 1.1). This ring-opening polymerization is mediated by Ni and Zn complexes in the presence of an alcohol initiator and a photoredox Ir catalyst, irradiated by a blue LED (400 - 500 nm). The polymerization is performed at a low temperature (-15 °C) to avoid undesired side reactions. The complete monomer consumption can be achieved within 4 - 8 hours, providing a polymer close to the expected molecular weight with narrow molecular weight distribution. The resulted number-average molecular weight shows a linear correlation with the degree of polymerization up to 1000. The homodecoupling H NMR study confirms that the obtained polymer is isotactic without epimerization. This polymerization reported herein offers a strategy for achieving rapid, controlled O-carboxyanhydrides polymerization to prepare stereoregular poly(α-hydroxy acids) and its copolymers bearing various functional side-chain groups.
在此，我们描述了一种有效的方案，该方案将光氧化还原镍/铱催化与使用锌醇盐相结合，用于高效的开环聚合反应，从而能够合成具有预期分子量（>140 kDa）且分子量分布窄（Mw/Mn < 1.1）的全同立构聚（α-羟基酸）。这种开环聚合反应由镍和锌配合物在醇引发剂和光氧化还原铱催化剂存在下介导，由蓝色发光二极管（400 - 500 nm）照射。聚合反应在低温（-15°C）下进行以避免不期望的副反应。在4 - 8小时内可实现单体的完全消耗，得到接近预期分子量且分子量分布窄的聚合物。所得的数均分子量与聚合度高达1000时呈线性相关。同核去耦氢核磁共振研究证实所得到的聚合物是全同立构的，没有差向异构化。本文报道的这种聚合反应提供了一种实现快速、可控的O-羧基酸酐聚合以制备立体规整的聚（α-羟基酸）及其带有各种功能性侧链基团的共聚物 的策略。
