PARTIAL MOLAR HEATS OF MIXING OF SMALL MOLECULES WITH POLYMERS BY GAS-CHROMATOGRAPHY

Partial molar heats of mixing (ΔH1∞) of small molecule probes have been determined with a variety of synthetic polymers by the gas chromatographic method. For normal, alkanes from Cs to Cu, ΔH1∞ is of the order of a few hundred calories for solution in polyethylene, polypropylene, and poly(l-butene). The inclusion of minor amounts of polar groups such as ketone or ester carbonyl in polyethylene has a negligible effect on the heat of mixing. With more polar substrates such as polystyrene, poly(methyl acrylate), polyvinyl chloride), or poly(N-isopropylacrylamide) the values of ΔH1∞ are substantially greater, ranging from 1 to 4 kcal mol-1. Factors involved in the determination are discussed. © 1978, American Chemical Society. All rights reserved.