STUDY OF PHASE-SEPARATION OF A BINARY-FLUID MIXTURE IN CONFINED GEOMETRY

Small angle neutron scattering experiments were performed to measure t he structure factor S(q) for a binary fluid water/lutidine mixture imb ibed inside porous Vycor glass at concentrations both near and away fr om critical. In both cases, the results can be interpreted as a combin ation of a lutidine-rich wetting layer coating the internal surfaces o f Vycor and random single-phase domain growth with temperature. This r esult does not support the random field Ising model predictions for th e phase separation behavior, but is in good agreement with theories ba sed on pore confinement of the imbibed fluid mixture.