OXYANIONS CATALYZE GROUP-TRANSFER POLYMERIZATION TO GIVE LIVING POLYMERS
OXYANIONS CATALYZE GROUP-TRANSFER POLYMERIZATION TO GIVE LIVING POLYMERS
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DOI：
10.1021/ma00220a002
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发表时间：
1990-09-03
期刊：
影响因子：
5.5
通讯作者：
SOGAH, DY
中科院分区：
文献类型：
--
作者：
DICKER, IB;COHEN, GM;SOGAH, DY
氧阴离子为丙烯酸单体的基团转移聚合（GTP）形成了一类新的催化剂。这类活性催化剂包括脂肪族和芳族羧酸盐、酚酸盐、亚磺酸盐、膦酸盐、磺胺酸盐、全氟烷氧化物、亚硝酸盐和氰酸盐。催化活性发现于共轭酸的p（在DMSO中）在4.5-23范围内的氧阴离子。在活性最高的催化剂的最低可操作浓度和中等活性催化剂的稍高浓度下，所得到的聚合物的活性和多分散性最好。生物氧阴离子（氧阴离子与其共轭酸的1:1配合物）也有活性，但与相应的单氧阴离子相比活性降低。它们比相应的单氧阴离子能更好地控制分子量。与较强的催化剂相比，较弱的催化剂在低于室温的温度下几乎没有活性。催化剂的相对效率与相应催化剂的共轭酸的pKa （DMSO）密切相关。用氧阴离子催化剂制备的PMMA的立体化学性质与用二氟化氢催化剂制备的PMMA的立体化学性质没有很大的不同。
Oxyanions form a new class of catalysts for group-transfer polymerization (GTP) of acrylic monomers. Active catalysts in this class include aliphatic and aromatic carboxylates, phenolates, sulfi-nates, phosphinates, sulfonamidates, perfluoroalkoxides, nitrite, and cyanate. Catalytic activity is found in oxyanions whose conjugate acids have a p (in DMSO) within the range 4.5-23. Best results in terms of livingness and polydispersity of the resulting polymers are obtained with the lowest operable concentrations of the most active catalysts and with somewhat higher concentrations of catalysts of moderate activity. Bioxy-anions (1: 1 complexes of oxyanions with their conjugate acids) also are active but show reduced activity compared to the corresponding monooxyanions. They give better control of molecular weight than is obtained with the corresponding monooxyanions. In contrast to the more potent catalysts, theweaker catalysts show little activity at temperatures substantially below room temperature. Relative catalyst efficiency correlates well with pKa (DMSO) of the conjugate acids of the corresponding catalysts. The stereochemistry of PMMA prepared with oxyanioncatalysts does not differ substantially from that of PMMA prepared with bifluoride catalysis.