关于甲基丙烯酸甲酯本体聚合链长依赖性终止的固相脉冲激光光泵浦-电子顺磁共振研究

SP-PLP-EPR Investigations into the Chain-Length-Dependent Termination of Methyl Methacrylate Bulk Polymerization.

作者信息

Barth Johannes, Buback Michael

机构信息

Institute for Physical Chemistry, University of Göttingen, Tammannstraße 6, D-37077 Göttingen, Germany.

出版信息

Macromol Rapid Commun. 2009 Nov 2;30(21):1805-11. doi: 10.1002/marc.200900335. Epub 2009 Aug 13.

DOI:10.1002/marc.200900335

PMID:21638457

Abstract

Termination kinetics of methyl methacrylate (MMA) bulk polymerization has been studied via the single pulsed laser polymerization-electron paramagnetic resonance method. MMA-d(8) has been investigated to enhance the signal-to-noise quality of microsecond time-resolved measurement of radical concentration. Chain-length-dependent termination rate coefficients of radicals of identical size, k ti,i, are reported for 5-70 °C and up to i = 100. k ti,i decreases according to the power-law expression $k_{\rm t}^{i,i} = k_{\rm t}^{{\rm 1,1}} \cdot i^{ - \alpha }$. At 5 °C, k(t) for two MMA radicals of chain-length unity is k t1,1 = (5.8 ± 1.3) · 10(8) L · mol(-1) · s(-1) . The associated activation energy and power-law exponent are: E(A) (k t1,1) ≈ 9 ± 2 kJ · mol(-1) and α ≈ 0.63 ± 0.15, respectively.

摘要

通过单脉冲激光聚合 - 电子顺磁共振方法研究了甲基丙烯酸甲酯（MMA）本体聚合的终止动力学。研究了MMA - d(8)以提高自由基浓度微秒时间分辨测量的信噪比。报告了在5 - 70°C以及i高达100时相同大小自由基的链长依赖性终止速率系数k ti,i。k ti,i根据幂律表达式$k_{\rm t}^{i,i} = k_{\rm t}^{{\rm 1,1}} \cdot i^{ - \alpha }$降低。在5°C时，链长为1的两个MMA自由基的k(t)为k t1,1 = (5.8 ± 1.3) · 10(8) L · mol(-1) · s(-1) 。相关的活化能和幂律指数分别为：E(A) (k t1,1) ≈ 9 ± 2 kJ · mol(-1) 和α ≈ 0.63 ± 0.15。