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

Thermodynamics of water sorption in poly(ɛ-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 non-randomness 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.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Thermodynamics of water–PCL mixtures need accounting for hydrogen bonding. ► PS and NRHB lattice models supply the same qualitative results. ► Quantitative differences between PS and NRHB are only in cross-HB entropic parameter. ► Prevailing water–polymer HB interaction are established with carbonyl on PCL.