Enthalpic stabilization in nonaqueous media

Abstract It is shown that polyacrylonitrile latexes stabilized by polyisobutylene in 2-methylbutane (isopentane) flocculate on heating to the θ-point for the stabilizing chains in free solution. This demonstrates unequivocally that the latexes are enthalpically stabilized, at least just below the critical flocculation temperature; the latexes represent the first quantitative documentation of enthalpic stabilization in nonaqueous media. The occurrence of enthalpic stabilization in nonaqueous media is attributed to the difference in free volume between the polymeric stabilizing chains and the dispersion medium.