有机过氧化物-芳叔胺体系引发甲基丙烯酸甲酯聚合的研究

以过氧化二酰(BPO、LPO)或有机过氧化氢物(TBH、CHP)和芳叔胺如DMA或对位具有不同取代基的衍生物组成的引发体系进行MMA聚合,研究过氧化物与胺的结构对聚合的影响。结果表明,过氧化二酰的活性要比有机过氧化氢物大,其顺序为BPO>LPO>CHP>TBH。对于BPO-芳叔胺或LPO-芳叔胺体系,芳叔胺中给电子取代基能提高聚合速度,而吸电子取代基能降低聚合速度。测定了MMA聚合的总活化能E_α,BPO-芳叔胺体系时E_α=36-54kJ/mole,LPO-芳叔胺体系时E_α=56-71kJ/mole;还研究聚合动力学。

STUDIES ON THE POLYMERIZATION OF METHYL METHACRYLATE INITIATED WITH ORGANIC PEROXIDEAMINE SYSTEMS

Radical polymerization of methyl methacrylate (MMA) initiated by various diacyl peroxide-amine systems were studied. Benzoyl peroxide (BPO) and lauroyl peroxide (LPO) were used as diacyl peroxide component, N, N-dimethyl aniline (DMA) and its para substituted derivatives, i.e., N, N-dimethyl-p-toluidine (DMT), p-hydroxymethyl-N, N-dimethyl aniline (HDMA), p-nitro-N, N-dimethyl aniline (NDMA) and p-dime-thylamino benzaldehyde (DMAB) were used as amine component. It was found that the diaeyl peroxide-DMT aystems always give higher rates of bulk polymerization Rp of MMA than the organic hydroperoxide-DMT systems with the following descending order: BPO-DMT>LPO-DMT>CHP (cumene hydroperoxide)-DMT>TBH (tertbutyl hydroperoxide)-DMT. The aromatic tertiary amines posses obvious structural effect on the RP values in the diacyl peroxide-amine system. Thus, the para-substituted electron-donating groups on the ring of the aromatic amine molecule increase Rp while the electron-withdrawing groups decreased it with the following descending order as DMT> HDMA>DMA>NDMA≈DMAB. The overall activation energies Ea of MMA polymerization were determined, the kinetics of polymerization of MMA initiated with BPO-DMT system were studied and its rate equation was determined as Rp=KBPO]0.5 DMT]0.5MMA].