Cameron Neil R, Lagrille Olivier, Lovell Peter A, Thongnuanchan Bencha
Department of Chemistry and Biophysical Sciences Institute, University of Durham, South Road, DH1 3LE, United Kingdom.
Materials Science Centre, School of Materials, The University of Manchester, Manchester, M13 9PL, United Kingdom.
ACS Macro Lett. 2012 Nov 20;1(11):1262-1265. doi: 10.1021/mz300464c. Epub 2012 Oct 12.
Factors underlying design of a new nitroxide, 2,2,5-trimethyl-4--butyl-3-azahexane-3-oxyl (TITNO), and its styrene alkoxyamine (Styryl-TITNO) for effecting nitroxide-mediated polymerization (NMP) at temperatures ≤90 °C are described. The rate coefficient, , for thermal dissociation of Styryl-TITNO was determined in the range 70-100 °C, giving Arrhenius parameters = 2.9 × 10 s and = 104.1 kJ mol. Due to the low value of , values of and the activation-deactivation equilibrium constant for NMP of -butyl acrylate (BA) and styrene are much lower at any given temperature than for alkoxyamines of more established nitroxides. Good control of molecular weight and dispersity, with negligible contributions from termination, is achieved at 90 °C for BA and at 70 °C for styrene, thus, eliminating the complicating contributions from styrene thermal initiation. Hence, TITNO and Styryl-TITNO offer new opportunities for controlled NMP at temperatures much lower than has previously been attainable.
描述了一种新型氮氧化物2,2,5-三甲基-4-丁基-3-氮杂己烷-3-氧基（TITNO）及其苯乙烯烷氧基胺（Styryl-TITNO）的设计背后的因素，这些因素用于在≤90°C的温度下实现氮氧化物介导的聚合反应（NMP）。在70 - 100°C范围内测定了Styryl-TITNO热解离的速率系数，得到阿伦尼乌斯参数 = 2.9 × 10 s和 = 104.1 kJ mol。由于 的值较低，在任何给定温度下，丙烯酸丁酯（BA）和苯乙烯NMP的 值以及活化-失活平衡常数都比更成熟的氮氧化物的烷氧基胺低得多。在90°C下对BA以及在70°C下对苯乙烯实现了良好的分子量和分散度控制，终止贡献可忽略不计，从而消除了苯乙烯热引发带来的复杂影响。因此，TITNO和Styryl-TITNO为在比以前所能达到的温度低得多的温度下进行可控NMP提供了新机会。
