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由N,N-二甲基苯胺(DMA)-氯化苄(BzCl)两者构成的混合物或其季铵盐,皆可引发乙烯型单体自由基聚合反应,并已应用于某些纤维的接枝共聚改性工作.本文为了进一步探讨DMA-BzCl体系的引发特性,采用膨胀仪法(高真空装置下聚合),以苯为溶剂,于60℃测定了该体系引发甲基丙烯酸甲酯(MMA)聚合的反应速率.求得聚合速率Rp∝[MMA],Rp∞[Ⅰ](当[DMA]=[BzCl]=[Ⅰ]时),Rp∞[BzCl]~1/2.(当[DMA]不变时),并推导得如下动力学方程式,R_p=-d[M]/dt=Kp(K_l/K_t)~(1/2)[DMA]~(1/2)[BzCl]~(1/2)[DMA].还研究了DMA苯环上取代基的效应.若为吸电子取代基时,使聚合速率降低,降低的程度符合于Hammett方程.
A mixture of both N, N-dimethylaniline (DMA) -benzyl chloride (BzCl) or its quaternary ammonium salt can initiate the free-radical polymerization of the vinylic monomer and has been applied to some fibers Grafting copolymerization.This paper is to further explore the initiation characteristics of DMA-BzCl system, using dilatometer method (high vacuum device polymerization), benzene as a solvent at 60 ℃ measured the system initiated methyl methacrylate MMA) was used to obtain the polymerization rate Rpα [MMA], Rp∞ [I] (when [DMA] = [BzCl] = [I]) and Rp∞ [BzCl] [DMA] is invariable), and the following kinetic equation is deduced: Rp = -d [M] / dt = Kp K_l / K_t ~ 1/2 [DMA] ~ (1/2) [DMA] The effect of the substituents on the benzene ring of DMA has also been studied, and for the electron-withdrawing substituent, the rate of polymerization is reduced to a degree corresponding to the Hammett equation.