Effect of Added Block Copolymer on Phase-Separation Kinetics of a Polymer Blend. 1. A Light-Scattering Study.

摘要

A light-scattering study has been made to investigate the effect of added styrene-butadiene diblock copolymer on the phase-separation kinetics of blends of low molecular weight polystyrene and polybutadiene. The scattered light intensity was measured at 2 deg intervals up to 60 deg as a function of time from the beginning of phase separation into the late stage of Ostwald ripening. Various corrections, including the one for double scattering, were applied to the observed intensity. The effect of the added block copolymer was to retard the growth of phase-separated domains, as seen from the time evolution of q(max) and I(max) of the peak in the intensity curve. This can be explained in terms of the reduction in the interfacial tension between the demixed phases, resulting from accumulation of block copolymer there. The time-evolution exponents of q(max) and I(max), the invariant Q, and the superposition of scattering intensity curves all show the validity of dynamic scaling in the late ripening stage. (JS)