Pentacosa-10,12-diynoic acid/henicosa-2,4-diynylamine alternate-layer Langmuir-Blodgett films: Synthesis, polymerisation and electrical properties

Langmuir-Blodgett alternate-layer structures of pentacosa-10,12-diynoic acid mixed with tricos-22-enoic acid and henicosa-2,4-diynylamine mixed with 1-docosylamine, both in a 1:1 m/m ratio, have been prepared. The multilayers were polymerised via initiation by irradiation with ultraviolet light and the reaction was followed spectrophotometrically. A blue polymer was formed initially, which became red on further irradiation. Infrared spectroscopic investigations combined with film thickness determinations and polarised optical microscopy experiments have demonstrated that the polymerisation process is accompanied by a substantial reorganisation of the film structure. The pyroelectric coefficient of the unpolymerised film was 0.8 μC m^-2 K^-1 and that of the blue polymer film was 0.6 μC m^-2 K^-1; red films produced short-circuit devices. Direct-current electrical conductivity measurements yielded a maximum in-plane value of 2 x 10^-7 S cm^-1 for iodine-doped polymer structures in their red form.