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Transport of water in an epoxy network with high cross-link density was investigated at several water vapor activities by time-resolved FT-IR spectroscopy and gravimetric measurements. The analysis of the infrared spectra provided information about the molecular interactions occurring in the system. In particular, several interaction complexes were identified and their structures were proposed. An estimate was made of the concentration of the various water species present in the system, based on the knowledge of the respective molar absorptivities. An excellent agreement between the spectroscopic and gravimetric determinations of sorbed water was found throughout. The evolution of the different water species was monitored by resolving the complex profile of the water spectrum in the νOH frequency range. This information, coupled with the results of the gravimetric analysis, was used to evaluate the effect of polymer/penetrant H-bonding interactions on the diffusion process of water molecules. Transport of the different water species was found to follow a Fickian behavior characterized by an effective diffusion coefficient which increases with total water concentration.

Chemical sensors are generally based on the integration of suitable sensitive layers and transducing mechanisms. Although inorganic porous materials can be effective, there is significant interest in the use of polymeric materials because of their easy fabrication process, lower costs and mechanical flexibility. However, porous polymeric absorbents are generally amorphous and hence present poor molecular selectivity and undesired changes of mechanical properties as a consequence of large analyte uptake. In this contribution the structure, properties and some possible applications of sensing polymeric films based on nanoporous crystalline phases, which exhibit all identical nanopores, will be reviewed. The main advantages of crystalline nanoporous polymeric materials with respect to their amorphous counterparts are, besides a higher selectivity, the ability to maintain their physical state as well as geometry, even after large guest uptake (up to 10–15 wt%), and the possibility to control guest diffusivity by controlling the orientation of the host polymeric crystalline phase. The final section of the review also describes the ability of suitable polymeric films to act as chirality sensors, i.e., to sense and memorize the presence of non-racemic volatile organic compounds.