Thermodynamics of water sorption in poly(epsilon-caprolactone): a comparative analysis of lattice fluid models including hydrogen bond contributions

Thermodynamics of water sorption in poly(epsilon-caprolactone) (PCL) has been interpreted by using three models based on compressible lattice fluid theories, addressing the issue of self- and cross-hydrogen bond interactions. The models, available in the literature, are of increasing complexity and consist of a compressible lattice fluid term which could account or not for nonrandomness of contacts and, in the case of two of the models, of a hydrogen bonding contribution. Models were analysed and compared in terms of fitting capability of the experimental sorption isotherms and, where appropriate, of predicted amount of self- and cross-hydrogen bonds which are established in the PCL-water mixture. Results confirm that, to obtain a satisfactory fitting of data, it is necessary to explicitly account for formation of hydrogen bonds.