Miscibility windows for poly(styrene- co-vinyl phenol) blends with poly(n-butyl methacrylate) and poly(n-hexyl methacrylate): a comparison of theoretical predictions with Fourier transform infra-red experimental data

Abstract

Employing parameters recently derived from studies of miscible poly(4-vinyl phenol) (PVPh) blends with poly(ethyl methacrylate) and poly(n-propyl methacrylate), spinodal phase diagrams and ‘miscibility windows’ have been calculated for blends of styrene- co-vinyl phenol (STVPh) copolymers with poly(n-butyl methacrylate) (PBMA) and poly(n-hexyl methacrylate) (PHMA) using an association model. Theoretical calculations predict that STVPh copolymers containing 0-∼97% styrene are miscible with PBMA at ambient temperature. In contrast, PVPh is immiscible with PHMA at ambient temperature, but a miscibility window extending from ∼32–94% styrene was predicted. Five random copolymers of STVPh were synthesized containing 75, 43, 25, 8 and 2 wt% vinyl phenol (VPh) and experimental studies were performed on blends of these copolymers with PBMA and PHMA. Quantitative analyses of the fraction of hydrogen-bonded carbonyl groups were obtained by Fourier transform infra-red spectroscopy and the data compared to the theoretical predicted values for miscible systems. In addition, the hydroxyl stretching region of the spectrum was compared qualitatively to the theoretical distribution of hydroxyl-hydroxyl, hydroxyl-carbonyl and ‘free’ hydroxyl groups that would be present in a miscible blend. PVPh and the STVPh copolymers containing 75, 43, 25 and 8 wt% VPh were found to be miscible with PBMA, while the corresponding copolymer containing 2 wt% VPh was found to be immiscible. For the PHMA blends, PVPh and the two STVPh copolymers containing 75 and 2 wt% VPh were found to be immiscible with PHMA, while the corresponding copolymers containing 43, 25 and 8 wt% VPh were found to be miscible. These experimental results are in excellent accord with the theoretical predictions and lend support to the general validity of our association model approach.