Evaluation of the styrene/n-butyl methacrylate binary interaction energy density

The phase behavior of blends of S–nBMA copolymers with monodisperse PS homopolymers was studied at three temperatures: 120, 150 and 180 °C. Quantitative evaluation of the binary interaction energy density between styrene (S) and n-butyl methacrylate (nBMA), BS/nBMA, was made at each temperature by analyzing the miscibility data using the copolymer/critical molecular weight method. The temperature dependence of BS/nBMA is interpreted by the Sanchez–Lacombe lattice fluid theory using a constant bare interaction energy ΔPS/nBMA∗. The BS/nBMA values determined in this study were much larger than those reported by others. Deuteration effects may be the reason for this difference.