Water Sorption Thermodynamics in Glassy and Rubbery Polymers: Modeling the Interactional Issues Emerging from FTIR Spectroscopy

Water sorption thermodynamics has been effectively investigated in rubbery and glassy polymers using, respectively, an equilibrium lattice fluid model, originally introduced by Panayiotou et al. [Panayiotou, C.; Tsivintzelis, I.; Economou, I.G. Ind. Eng. Chem. Res. 2007, 46, 2628], accounting for hydrogen bond (HB) interactions in the system (i.e., the nonrandom hydrogen bonding, NRHB, model), and an extension of this model to a nonequilibrium glassy state (i.e., nonequilibrium thermodynamics for glassy polymers (NETGP)) that follows the same line of thought adopted originally by Doghieri and Sarti [Doghieri, F.; Sarti, G.C. Macromolecules 1996, 29, 7885] to develop the NETGP approach. NRHB and NETGP-NRHB models have been used to interpret water sorption thermodynamics respectively in polycaprolactone and in polyimides. Model predictions in terms of self- and cross-HB established in the system are compared with quantitative information gathered from in situ infrared spectroscopy experiments, exploiting the wealth of information provided by proper elaboration of spectroscopy data by means of 2D correlation techniques.