Proton spin-spin relaxation study of hydration of a model nanopore

The hydration pattern of controlled pore glass, with pore diameter of 237 Å, was investigated using nuclear magnetic resonance. Water proton spin–spin relaxation decay curves were monitored and modeled as two-component exponential decays as a function of hydration. The results are consistent with a geometric model involving a surface water layer and a bulk-like liquid fraction in the form of a plug. The amount of surface water increases as the sample hydrates, until hydration reached approximately a monolayer, at which point a water plug starts to form in the pore, and grow in length at the expense of the surface layer. The results are also analyzed in terms of, and compared to, a recently developed puddle pore-filling model S.G. Allen, et al. J. Chem. Phys. 106 (1997) 7802–7809].