Surfacehyphen;induced ordering of a liquid crystal in the isotropic phase. II. 4hyphen;methoxybenzylidenehyphen;4prime;hyphen;nhyphen;butylaniline (MBBA)

摘要

The boundary order parameter of the liquid crystal 4hyphen;methoxybenzylidenehyphen;4prime;hyphen;nhyphen;butylaniline (MBBA) in the isotropic phase has been deduced for several surface treatments by measuring the surfacehyphen;induced pretransitional birefringence. Results for the silane surface coupling agent, methylhyphen;3hyphen;aminopropyltrimethoxyhyphen;silane (MAP) were particularly interesting, indicating a negative surface order parameter. An analytic expression for the temperaturehyphen;dependent birefringence is derived from Landaursquo;s expanison in the order parameter. This expression shows that the value of the boundary order parameter determines the absolute minimum isotroic phase temperature.