Neutron reflectivity studies of the interface between a small molecule liquid crystal and a polymer

In this report, we elucidate the structure of a small molecule liquid crystal/polymer interface using specular neutron reflectivity. More specifically, we have examined the interfacial transition zone width of a small molecule liquid crystal/polymer sample as a function of increasing temperature. The interface between a thin film (≈1000 Å thick) of the liquid crystal 4′-n-octyl-4-cyanobiphenyl (8CB) and a thin film (≈800 Å thick) of deuterated poly(methyl methacrylate) (d-PMMA) is broad and broadens with increasing temperature; it was also observed that the thin film geometry influences the mixing behaviour of the 8CB/d-PMMA system. These results may have implications for current theories of liquid crystal display devices formed by the phase separation of liquid crystal polymer mixtures.