A Nitroxide for Effecting Controlled Nitroxide-Mediated Radical Polymerization at Temperatures 鈮?0 掳C

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• 作者：Neil R. Cameron ; Olivier Lagrille ; Peter A. Lovell ; Bencha Thongnuanchan
• 刊名：ACS Macro Letters
• 出版年：2012
• 出版时间：November 20, 2012
• 年：2012
• 卷：1
• 期：11
• 页码：1262-1265
• 全文大小：274K
• 年卷期：v.1,no.11(November 20, 2012)
• ISSN：2161-1653

文摘

Factors underlying design of a new nitroxide, 2,2,5-trimethyl-4-tert-butyl-3-azahexane-3-oxyl (TITNO), and its styrene alkoxyamine (Styryl-TITNO) for effecting nitroxide-mediated polymerization (NMP) at temperatures 鈮?0 掳C are described. The rate coefficient, k_d, for thermal dissociation of Styryl-TITNO was determined in the range 70鈥?00 掳C, giving Arrhenius parameters A_d = 2.9 脳 10¹² s^鈥? and E_d = 104.1 kJ mol^鈥?. Due to the low value of E_d, values of k_d and the activation鈥揹eactivation equilibrium constant for NMP of n-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 掳C for BA and at 70 掳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.