有机过氧化物与N,N-二(2-羟烷基)对甲苯胺体系引发烯类聚合及其机理的研究

STUDIES ON THE VINYL POLYMERIZATION AND ITS MECHANISM INITIATED WITH ORGANIC PEROXIDE AND N,N-DI(2-HYDROXYALKYL)-p-TOLUIDINE SYSTEMS

研究了有机过氧化物BPO,LPO分别与N,N-二(2-羟烷基)对甲苯胺DHET,DHPT组成的体系引发MMA的聚合。测定其聚合速度R_p,聚合表观活化能,聚合速度方程,聚合放热过程的温度与时间的关系。用自旋捕捉和ESR波谱技术,测定了上述体系反应产生的自由基中间体,同时通过聚合物端基分析证实DHET,DHPT组份产生的自由基能引发单体聚合。依据实验结果提出了这类体系的引发机理。

The polymerization of methyl methacrylate (MMA) initiated with organic peroxide, such as benzoyl peroxide (BPO), lauroyl peroxide (LPO), and N,N-di(2-hydroxyalkyl)-p-toluid-ine, such as N, N-di(2-hydroxyethyl)-p-toluidine (DHET), N, N-di(2-hydroxypropyl)-p-to-luidine (DHPT), or tertiary aromatic amine such as N, N-dimethyl-p-toluidine (DMT), N, N-dimethyl aniline (DMA) systems has been studied. The polymerization rate Rp, overall activation energy of polymerization Ea, and the rate equation of MMA polymerization in toluene were determined respectively. It was found that the order of Rp as follows: BPO-DHET> BPO-DHPT > BPO-DMT > BPO-DMA >BPO, and the values of Ea for BPO-Amine systems were always smaller than that of BPO alone. In the MMA curing reaction using the BPO-Amine initiation systems can decrease the curing time and shorten the time required to reach the peak temperature.From the ESR studies on the free radical intermediates produced from the BPO-Amine-MNP (2-methyl-2-nitrosopropane) systems, it reveals the formation of radicals 1-4 (see Table 5). The UV spectra of PMMA solutions reveal that the DHET and DHPT moieties are present as the end groups of polymer obtained by using BPO-DHET and BPO-DHPT initiation systems.Based on these results, the initiation mechanism for BPO-DHET and BPO-DHPT initiation systems were proposed.