Group Contribution Theory for the Gibbs Energy of Solutions of Polyethers

Abstract

The Gibbs energies of different oligoethers (oligomers of tetrahydrofuran and ethylene oxide and a block cooligomer of these ethers) with hydroxyl and acetyl end groups in tri- and tetrachloromethane are obtained by vapour pressure measurements. A group contribution theory, based on a quasichemical equilibrium between contacting segment surfaces, which was used so far only for calculating mixing enthalpies, is extended to Gibbs energies. The Gibbs energies predicted with this theoretical approach show a good agreement with the measured data of the tested polymer solutions. With this theory it is not only possible to describe but even to predict gaps in the mixing behaviour of polymer solutions.