Spontaneous pinning of domain growth during spinodal decomposition of offhyphen;critical polymer mixtures

摘要

Spinodal decomposition of offhyphen;critical mixtures of poly(styrenendash;randomndash;butadiene) copolymer with polyisoprene or polybutadiene was investigated as a function of the compositionwof the mixtures and of the phase separation temperatureTby timehyphen;resolved light scattering. The coarsening behavior of the mixtures was characterized in terms of the time change of the maximum intensityImand that of the magnitude of the scattering vectorqmat which the intensity becomes maximum. It was found that the time changes ofImandqmfor the offhyphen;critical mixtures studied here are effectively pinned at a certain time defined here as the lsquo;lsquo;pinningrsquo;rsquo; time. This spontaneous pinning of the growth of the unmixing structure was found to occur earlier whenwis biased toward 0 or 1 at a givenTand when the phase separation temperature is raised at a givenw, for these systems which seemingly have upper critical solution temperature behavior.