Modeling of the θ(lower critical solution temperature) in polymer solutions using molecular connectivity indices

In this work, correlations for the estimation of the θ(lower critical solution temperature, LCST) for Polystyrene, Polyethylene, Polypropylene, Polybutene-1, Polypentene-1, Poly(4-methylpentene-1), Polydimethylsiloxane and Polyisobutylene solutions were proposed based on the molecular connectivity index. The correlations give satisfactory estimation of the θ(LCST), with the absolute error smaller than 20 K for most systems studied. Since the new correlations require only molecular connectivity indices of the solvent in the calculations, and the molecular connectivity indices can be calculated easily once the molecular structure of the substance concerned is known, they have better predictive capability and are easier to apply comparing with the existing methods and models.