Polymeric films based on long-chain acetylenes as sensors for iodine vapour

Conducting polymeric thin films can be used as sensors to detect and identify volatile organics. Practically valuable possibilities of obtaining thin conducting layers with a definite topology in the substrate plane are ensured by Langmuir–Blodgett procedure. Orientation of monomer molecules is provided by the procedure of transferring the molecules from the subphase onto the substrate. It is shown that the UV-mediated polymerization of multimolecular layers of the acetylenic alcohol tetracosin-2-ol-1 (C21H43CCCH2OH) results in the trans-configuration with respect to the double bonds formed in polymerization. The conductivity of thus obtained layers is shown to depend on the partial pressure of molecular iodine in the gas phase. A mechanism is proposed that explains a non-linear increase in conductivity accompanying adsorption of iodine vapour.