Synchrotron SAXS study of mean field and Ising critical behavior of poly(2-chlorostyrene)/polystyrene blends

Abstract

Synchrotron SAXS of poly(2-chlorostyrene)/polystyrene (P2C1S/PS) blends in the immediate neighborhood of the critical mixing point can be achieved by first locating the critical mixing point precisely. By combining a phase volume method with SAXS, the critical mixing point for P2ClS (M w = 2.33×10 5 , M w /M n = 1.19)/PS(M w = 3.7×10 4 , M w /M n <1.06) in the presence of 22.6 wt% di-n-butyl phthalate was found to have a critical weight fraction of PS, W PS,c = 0.52. A lower critical mixing temperature T c = 134.30°C, where W PS + W P2ClS was set to equal one, could clearly reveal a crossover in the static susceptibility and the correlation length from mean field to Ising-like behavior, with critical exponents γ changing from 1.00 (mean field) to 1.23 (Ising) and ν changing from 0.50 (mean field) to 0.63 (Ising)