Thermally stimulated currents in LB films composed of molecules in which various polar groups are bonded to linear hydrocarbon chains

Thermally stimulated current (TSC) was investigated in as obtained and corona-charged multi-layer LB films, composed of molecules in which various polar groups, such as -COOCH₃, -CH₂NH₂, -CH₂OH and -CONH₂, were bonded to linear hydrocarbon chains, -(CH₂)₁₆CH₃. In the as obtained LB films of these materials, several TSC peaks were observed below and above the melting point of bulk materials. TSC peaks observed below the melting point were attributed to the pre-melting and the melting of two-dimensional LB layers. Peaks of TSC above the melting point of bulk materials may be caused by the aluminum oxide films formed on the electrode and by the reorientation of residual water molecules in the layers. In the corona-charged LB layers, the same types of TSC curves were obtained. However, the current values were larger and TSC were clearer. The activation energy for pre-melting peaks was obtained to be 135 kJ/mol in average and that of water in the one layer stearyl alcohol film was 77 kJ/mol. It is concluded that the head polar groups have an effect on the TSC appearance and peak position.