The Behaviour of Contact Angles of Wetting for Liquid Crystalline Drops on Glass Near the Phase Transition

The experimental values of contact angles of wetting for pazoxyanisole - glass in the nematic and isotropic phase have been obtained. At the point the phase transition, a change in the value of contact angle of wetting is observed. The values of adhesion energy, have been calculated for different orientation of molecules with respect to the glass support.

It is well-known /I/that contact angles of drops on solid supports enable an information on interfacial energy γ_SL to be obtained. A change in the structure of liquid results in alteretion of the contact angle as it a has been shown recently for polymer solutions /2/. It seem to be quite possible that orientational ordering of liquid crystals has to affect the value of contact angles of wetting. Nevertheless, this value was not found to very upon phase transition from the isotropic to liquid crystalline state /3/.

We studied the behaviour of contact angle of wetting for a drop of a classical liquid crystalline compound p-azoxyanisole (PAA) in its nematic and isotropic phases.