A LIGHT-SCATTERING STUDY OF POLY(2-ALKYL-2-OXAZOLINE)S - EFFECT OF TEMPERATURE AND SOLVENT TYPE

Solutions of poly(2-ethyl-2-oxazoline), PEOX, and poly(2-methyl-2-oxaz oline), PMOX, in water and PEOX solutions in several alcohols were cha racterized by light scattering. The second virial coefficients in wate r were found to decrease with increasing temperature, reflecting lower critical solution behaviour due to hydrogen bonding. This resulted in negative values of the excess enthalpy DELTAh(E) and entropy of dilut ion DELTAs(E) for PEOX and PMOX in water. The magnitudes of DELTAh(E) and DELTAs(E) were higher for PMOX than for PEOX. The magnitudes of DE LTAh(E) and DELTAs(E) for PEOX increased with molecular weight. The se cond virial coefficients of PEOX in water were systematically lower th an in ethanol, isopropanol and n-butanol.