COMPOSITE LANGMUIR-BLODGETT (LB) FILMS OF POLYANILINE AND CADMIUM STEARATE

Composite monolayers of cadmium stearate and polyaniline processed wit h camphor sulphonic acid have been obtained at the air-water interface and subsequently transferred onto substrates as uniform Langmuir-Blod gett multilayers. Pressure-area (Pi-A) isotherm studies indicated that polyaniline molecules are not squeezed out of the cadmium stearate ma trix during compression or in the compressed state. Monolayer stabilit y is seen to decrease when the polymer content is increased beyond 60% (in weight) which is probably associated with the formation of microa ggregates that also affected the monolayer surface potential at large areas per molecule. With increasing amount of polyaniline in the mixtu re, a transition from Y-type to Z-type deposition has been observed. T ransferred multilayer LB films were characterized by UV-vis, FTIR, XRD , surface potential, and de electrical conductivity measurements. UV-v is results indicated that though the polyaniline was in the doped stat e in the spreading solution, the transferred films were in the emerald ine base state. FTIR studies revealed that the transferred films mainl y contained cadmium stearate salt in addition to polyaniline. XRD resu lts indicated that the stacking order is dependent on the polyaniline content in the composite films, the order was found to decrease upon i ncreasing the polymer amount. The uniformity of transferred films was confirmed by surface potential studies. A possible packing arrangement in these composite Langmuir and Langmuir-Blodgett films has been prop osed. (C) 1998 Elsevier Science Limited.