On the origin of the solution behaviour of ethyleneoxide containing polymers

Abstract

This chapter discusses the origin of the decreased solubility (clouding) of several ethyleneoxide containing polymers at elevated temperatures using available data both from theoretical and experimental investigations. It is found that the clouding process is closely related to the conformational equilibrium of the ethyleneoxide chains, and that this equilibrium depends on the properties of the free ethyleneoxide chain, the solvation of the chain, but also to a large extent on the effect that the ethyleneoxide chain has on the effective water–water interaction. Naturally, it is not possible to establish the exact origin behind the clouding behavior from the simulations discussed. This would require simulations of systems containing many fairly long polyethyleneoxide (PEO) molecules, a study that is completely out of reach with today's computer resources. However, the computer simulations have revealed an interesting interplay between conformational equilibrium, increased water–water interaction and the direct water–polymer interaction. If the experimentally obtained information is analyzed together with the information from the computer simulations, a fairly clear picture emerges, which suggests that there is a link between the preferred conformation of the polyethyleneoxide (PEO) chain and the solubility of the PEO molecules in water and other polar solvents, and that this conformational equilibrium is strongly influenced by the properties of the solvent and the temperature.