丙酮对MMA-St无皂乳液聚合速率的影响

Effect of Acetone on the Emulsifier-free Emulsion Copolymerization Rate of Methylmethacrylate and Styrene

运用溶剂热法,以丙酮-水为分散介质,过硫酸钾为引发剂引发甲基丙烯酸甲酯(MMA)和苯乙烯(St)共聚,制备了P(MMA-St)。讨论了丙酮含量对MMA,St均聚和MMA-St共聚的影响。实验结果表明:随着丙酮含量的增加,MMA成核速率先减小后增大,聚合速率先减小后增大再减小;St成核速率先增大后减小再增大,聚合速率先增大后减小;丙酮含量对MMA-St共聚的聚合速率的影响与单体比例有关,当V(MMA)∶V(St)=1∶1时,聚合速率随丙酮的增加逐渐降低,当V(MMA)∶V(St)=1∶3和3∶1时,聚合速率随丙酮的增加先增大后逐渐减小;当丙酮含量高于40%后,MMA,St各自均聚和共聚的反应速率均明显减小。

Emulsifier-free poly(styrene-methylmethacrylate)[P(MMA-St)] copolymer were synthesized in acetone-water medium using potassium persulfate(KPS) as a initiator by solvothermal method. The effects of acetone amount on the emulsifier-free emulsion homopolymerization rate of MMA, St and the copolymerization rate was discussed. The results indicated that in the acetone-water system, with the concentration of acetone increasing, the nucleation rate of MMA decreased firstly and then increased, the homopolymerization rate of MMA decreased at beginning then increased and decreased in the end; the nucleation rate of St increased firstly then decreased and increased finally, the homopolymerization rate of St increased early and then decreased. The effect of acetone on the copolymerization rate of MMA-St varied at different volume ratios of MMA to St. When the ratio is (1 ∶1,) the copolymerization rate decreased with the increase of acetone concentration; when the ratio is 1 ∶3 or 3 ∶1, the polymerization rate increased firstly and then decreased. When the acetone volume fraction is more than 40%, the homopolymerization rate of MMA, St and the copolymerization rate of MMA-St decreased remarkably.