LANGMUIR-BLODGETT MONOLAYER AND MULTILAYER ASSEMBLIES OF AMPHIPHILIC LIQUID-CRYSTALLINE NORMAL-ALKYL-4'-NORMAL-ALKOXYBIPHENYL-4-CARBOXYLATES .1.

Five n-Alkyl-4'-Alkoxy-biphenyl-4-carboxylates were investigated as Langmuir monolayers at the air/water interface and as Langmuir-Blodgett (LB) films on solid supports. All five compounds form stable monolayers at the air/water interface and can be transferred onto solid supports yielding LB-films, whose structures and kinetic behavior strongly depend on the headgroup. The structures of the LB-films were investigated by means of optical textures and X-ray diffraction and compared with the structures of the corresponding bulk phases which were investigated by means of Differential Scanning Calorimetry and X-ray powder diffraction. The LB-films of the acid and the two methyl esters exhibit bilayer lamellar structures which are very similar to the bulk crystalline phases at room temperature. The two ethyl esters show a mixture of two phases after transfer, a monolayer and a bilayer phase, the percentage of bilayer phase decreasing with time. For these two compounds the bilayer phase is a deposition enforced phase, which has not been observed in bulk material.