Germanium- And tin-catalyzed living radical polymerizations of styrene and methacrylates
Germanium- And tin-catalyzed living radical polymerizations of styrene and methacrylates
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DOI：
10.1002/masy.200750213
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发表时间：
2007-02
影响因子：
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通讯作者：
A. Goto;H. Zushi;Norihiro Hirai;Tsutomu Wakada;Y. Kwak;T. Fukuda
中科院分区：
文献类型：
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作者：
A. Goto;H. Zushi;Norihiro Hirai;Tsutomu Wakada;Y. Kwak;T. Fukuda
开发了Ge和Sn（非过渡金属）催化活性自由基聚合。在相当短的时间内以相当高的转化率获得了具有预测分子量的低多分散性（Mw/Mn = 1.1-1.3）聚苯乙烯、聚（甲基丙烯酸甲酯）、聚（甲基丙烯酸缩水甘油酯）和聚（甲基丙烯酸2-羟乙酯）。苯乙烯/凝胶4（催化剂）体系的准一级活化速率常数k act足够大，即使使用少量凝胶4，也足以解释为什么该体系从聚合的早期阶段提供低多分散性聚合物。苯乙烯/凝胶4体系中观察到的聚合速率的延迟在动力学上被证明主要是由于与凝胶3的传播自由基之间的交叉终止。Ge和Sn催化剂的吸引人的特征包括它们的高反应性，因此在温和条件（在60-80 °C）下需要少量（1-5 mM），在没有配体的有机介质中的高溶解度，对空气不敏感，因此允许在空气中制备样品，以及轻微的颜色和气味。Ge催化剂也可能因其低毒性而具有吸引力。
Ge and Sn (non-transition-metal) catalyzed living radical polymerizations were developed. Low-polydispersity (Mw/Mn∼ 1.1-1.3) polystyrenes, poly(methyl methacrylate)s, poly(glycidyl methacrylate)s, and poly(2-hydroxyethyl methacrylate) with predicted molecular weights were obtained with a fairly high conversion in a fairly short time. The pseudo-first-order activation rate constant k act for the styrene/Gel 4 (catalyst) system was large enough, even with a small amount of Gel 4 , to explain why the system provides low-polydispersity polymers from an early stage of polymerization. The retardation in the polymerization rate observed for the styrene/Gel 4 system was kinetically proved to be mainly due to the cross-termination between the propagating radical with Gel 3 . Attractive features of the Ge and Sn catalysts include their high reactivity hence small amounts (1-5 mM) being required under a mild condition (at 60-80 °C), high solubility in organic media without ligands, insensitivity to air hence sample preparation being allowed in the air, and minor color and smell. The Ge catalysts may also be attractive for their low toxicity.