聚苯乙烯大分子单体与醋酸乙烯酯接枝共聚物的合成及表征

<正> 用大分子单体与小分子单体共聚是七十年代初才出现的合成接枝共聚物的一种新方法。通过共聚合反应而不是接枝反应同时形成主干及支链。这种接枝共聚物由于形成支链的大分子单体是预先合成的,其分子量分布较窄,又可调节控制,所以合成的接枝共聚物支链长短比较均一,副反应较少,链结构比较明确,因此也易于表征。

SYNTHESIS AND CHARACTERIZATION OF COMB-COPOLYMER OF POLYSTYRENE MACROMER WITH VINYL ACETATE

With BPO as an initiator in solution; the comb-copolymer of PSt macromer and vinyl acetate was synthesized. The composition and branching degree of comb-copolymer were deter mined by IR spectroscopy. It is suggested that a reasonably accurate estimate of components and branching degree would be given by the equations respectively:A700/A1740=0.4194Cst/CVAC+ 0.1469 and A700/A1740 = 0.12n + 0.0155. When Mn of Macromer is not the standard 20000, the branching degree of graft copolymer is n'=n (20000/Mn), where Mn is the numeral average molecular weight of macromer used in the process of copolymerization, n' is branching degree per 1000 VAC units.From the experimental evidence available, it was found that branching degree of graft co polymer depends on Mn of macromer. When the monomer feed ratio and Mn of macromer changed slightly, the branching degree did not change basically; when Mn of macromer was reduced, the branching degree of graft copolymer was increased. The styrene macromer feed ratio changed from 5 to 8% then the styrene contents of copolymer increased to ≥55%. It was shown that macromer is more active than vinyl acetate in the process of copolymerization.