DYNAMICS OF H-BONDED LIQUIDS CONFINED TO NANOPORES

Broad-band dielectric spectroscopy (10(-2) Hz-10(7) Hz) is employed to study the molecular dynamics of three low-molecular-weight glass-form ing H-bonded liquids being confined in (dielectrically inactive) porou s glasses with pore sizes of 2.5 nm, 5.0 nm and 7.5 nm. From the relax ation time distribution of the dielectric spectra, a three-layer model is deduced, consisting of molecules having solid-like, interfacial an d bulk-like dynamics, respectively. The quantitative analysis of the d ifferent contributions shows that the bulk-like fraction scales with t he pore size, the interfacial and solid-like layers remaining relative ly unchanged. Our results restrict the possible existence of cooperati vely rearranging clusters in the system below nanometer scale.