SPINODAL DECOMPOSITION INDUCED BY CROSS-LINKING REACTION IN A BINARY POLYMER MIXTURE

Phase separation of a binary polymer mixture of droxy-1-trifluoromethy lethyl-alpha-methylstyrene]} (PS(OH)) and poly[(methyl methacrylate)-c o-(glycidyl methacrylate)] (PMMA(G)) upon cross-linking reaction was s tudied using time-resolved light scattering (TRLS) and optical microsc opy. The blends of PS(OH)/PMMA(G), in which PMMA(G) containing 1.4 mol -% epoxy groups can be selectively cross-linked with the multifunction al agent 4,4'-methylenebis(o-chloroaniline) (MOCA) and PS(OH) contains 1.8 mol-% of the strongly proton-donating group -C(CF3)(2)OH, exhibit a lower critical solution temperature (LCST). The cross-linking react ion was carried out for two compositions of PS(OH)/PMMA(G)/MOCA, 50/50 /0.7 and 40/60/0.8 (w/w/w), at various temperatures located in the one -phase region between the coexistence curve and the glass transition t emperature of the blends. TRLS investigation shows that the phase sepa ration takes place via spinodal decomposition (SD) induced by the incr ease in the molecular weight of PMMA(G) during the cross-linking react ion. A modulated phase structure with the characteristic features of p eriodicity and dual connectivity of the phases was developed in this c ase. The dynamics of SD were investigated in terms of changes of the p eak scattering vector q(m)(t) as a function of time. They are dependen t on the reaction temperature and composition. A scaling relation q(m) (t) proportional to t(-alpha)f(x) describing the behavior of the evolu tion of phase separation upon reaction was supported by the experiment s.