Reactive-HALS III:ATMP光聚合动力学研究

Reactive-HALS Ⅲ: Photopolymerization Kinetics of ATMP

以受阻胺哌啶醇衍生物4 (丙烯酰氧基) 2,2,6,6 四甲基哌啶醇酯(ATMP)作为聚合单体,利用光差动热分析法(DPC)系统地研究了ATMP的光聚合反应活性和反应动力学规律。结果表明:反应体系的组成和聚合条件对ATMP光聚合动力学有显著的影响;在聚合初期,ATMP光聚合速率同引发剂浓度和辐照光强的平方根呈线性关系;利用DPC测定了ATMP光聚合过程的动力学参数(kp和kt),链终止速率常数kt远大于链增长速率常数kp,kt/kp=100.01～394.78;kt和kp均随着转化率的增大而减小,但kt的减小幅度大于kp;电子顺磁共振谱(EPR)定量结果表明:原位生成的微量[(2～6)×10-7mol/L]稳定氮氧自由基对ATMP的溶液光聚合过程的阻聚效应不明显。

By using DPC technique,we have systematically studied the photoinduced polymerization of ATMP in melted state and in solution state under different reaction conditions. The results show that the photoinduced polymerization of ATMP is greatly influenced by the reaction conditions such as the type and concentration of photoinitiator, reaction temperature, atmosphere as well as light intensity, and that the rate of photopolymerization of ATMP is directly proportional to the square root of photoinitiator concentration C0.5PI and incident light intensity I0.50, which is in accordance with he theoretical expectation. The kinetic parameters ( kp and kt) of the bulk photopolymerization of ATMP have been determined by photoDSC. The rate of propagation constant kp and the rate of termination constant kt increased with the increase of ATMP conversion, but kt is much larger than kp(kt/kp)= 100.01-394.78). By using EPR technique, we have monitored and estimated the concentration of the stable nitroxide radicals produced in situ during the photopolymerization of ATMP in the solution, and found that the content of the stable nitroxide radicals produced in the system is about the level of 10-7 mol/L, and that hadn't obviously influence on the rate and the conversion curves of ATMP photopolymerization.