Influence of microstructure on the upper and lower critical solution temperatures of poly(methylmethacrylate) solutions

Abstract

Upper and lower critical solution temperatures have been measured for both atactic and isotactic forms of poly(methylmethacrylate) in a number of solvents. Results have been analysed in terms of the Prigogine–Patterson–Flory theory and the critical solution temperatures, which are experimentally inaccessible, can be predicted from this theory. The two tactic forms can be distinguished by measuring the critical temperatures and the corresponding theta temperatures. In the upper critical region, θ_u values for isotactic and atactic poly(methylmethacrylate) differ when measured in the same solvent but no set pattern is observed, whereas the corresponding θ_L values for the atactic polymer are consistently higher than those for the isotactic material.