Spatial Dynamics of Water Molecules Confined in Deuterated Epoxies by Quasi-Elastic Neutron Scattering

The relationship between the water within polymer materials and their material properties is key to expanding their application scope. This study conducted quasi-elastic neutron scattering (QENS) measurements of fully carbon-deuterated epoxies to elucidate the molecular dynamics of water confined in the nanometer-scale voids (nanovoids) of epoxies, focusing on spatial information. The QENS measurements of epoxies with different stoichiometries revealed that the motion space of mobile water molecules in stoichiometric epoxy was more than twice the average size of nanovoids in the epoxy, indicating the broad distribution across multiple nanovoids. In contrast, the extents of oxirane-excess and amine-excess epoxies were close to the nanovoid size. The spatial dynamics of water and its relationship to the chemical structure will help in understanding the water diffusion mechanism and designing epoxy materials with excellent water-related properties, such as water resistance or transport.