Self-organized properties of conductive Langmuir-Blodgett films

Langmuir-Blodgett films were fabricated from mixed monolayers containing stearic acid (SA) and various Head-to-Tail poly(3-alkylthiophene)s (HT-PATs : alkyl = hexyl (HT-PHT), decyl (HT-PDT), octadecyl (HT-PODT)). The HT-PATs could form stable monolayers on the air-water interface with stearic acid, and could be deposited onto solid substrates as Y-type films by vertical dipping method. The structure of HT-PATs/SA LB films were investigated by transmission and reflection-absorption FT-IR measurements. By comparison of transmission and reflection FT-IR spectra, the tilt angles of alkyl side-chains of HT-PATs could be estimated. These results shows that self-organized properties and molecular orientation of HT-PATs were affected by the length of alkyl-side chains. HT-PDT was found to form more planar conformation because of the optimized length of alkyl-side chains.