Determination of the Propagation Rate Coefficient (kp) and Termination Mode in the Free-Radical Polymerization of Methyl Methacrylate, Employing Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry for Molecular Weight Distribution Analysis
Determination of the Propagation Rate Coefficient (kp) and Termination Mode in the Free-Radical Polymerization of Methyl Methacrylate, Employing Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry for Molecular Weight Distribution Analysis
复制标题
采用基质辅助激光解吸电离飞行时间质谱法测定甲基丙烯酸甲酯自由基聚合的传播速率系数 (kp) 和终止模式进行分子量分布分析
DOI：
10.1021/ma9512925
复制
发表时间：
1996
期刊：
影响因子：
5.5
通讯作者：
D. Haddleton
中科院分区：
文献类型：
--
作者：
M. Zammit;T. P. Davis;D. Haddleton
介绍。脉冲激光聚合（PLP）已被证明是测定多基团自由基聚合中传播系数（kp）的最精确方法。1-7 PLP方法的成功和可靠性已经得到了IUPAC自由基聚合动力学建模工作组的认可，8这导致了PLP作为繁殖速率系数的主要实验方法的普遍认可。PLP技术包括以已知频率脉冲紫外激光通过添加合适光引发剂的单体溶液。通过对所得分子量分布（MWD）的分析，可以得到速率系数kp。这种方法的独特之处在于动力学分析在很大程度上不需要基于模型的假设。PLP的动力学分析可以简化为一个方程(1)。在这里，动力学链长（υ）与单体浓度，闪烁频率（t0）和传播速率系数成正比。因此，如果υ可以从实验中确定，kp可以计算。从以前的工作6链长，υ，可以最好地近似为GPC色谱上的低分子量拐点。因此，如果要获得可靠的kp值，精确的随钻测井分析是极其重要的。
Introduction. Pulsed laser polymerization (PLP) has been shown to be the most accurate method for determining the propagation coefficient (kp) in freeradical polymerization by a number of groups. 1-7 The success and reliability of the PLP method has been recognized by an IUPAC working party on modeling free-radical polymerization kinetics, 8 and this has led to a general recognition of PLP as the primary experimental approach to propagation rate coefficients. The PLP technique consists of pulsing UV-laser light at a known frequency through a solution of monomer with a suitable photoinitiator added. By analysis of the resulting molecular weight distribution (MWD), the rate coefficient kp can be found. This method is unique in that the kinetic analysis is largely free from modelbased assumptions. The kinetic analysis of PLP collapses into a single equation (1).Here the kinetic chain length (υ) is proportional to the monomer concentration, the flashing frequency (t0), and the propagation rate coefficient. Thus if υ can be determined from experiment, kp can be calculated. From previous work6 the chain length, υ, can be best approximated as the low molecular weight inflection point on a GPC chromatogram. Thus accurate MWD analysis is extremely important if reliable kp values are to be obtained.