Electrochemical properties and characterisation of novel polyurethane/polyindene, poly(ethylene terephthalate)/polyindene and poly(vinyl chloride)/polyindene conducting composites

Abstract

This study covers the synthesis of conducting polyindene (PIn) homopolymer, polyurethane/polyindene (PU/PIn), poly(ethylene terephthalate)/polyindene (PET/PIn) and poly(vinyl chloride)/polyindene (PVC/PIn) composites. Polyindene and composites were synthesised electrochemically by cationic mechanism using LiClO4 as an initiator. From Fourier transform infrared spectroscopy spectra of polymers, it was revealed that the polymerisation reaction occurred by one to two mechanisms. The conductivities of polymers were also measured by four-probe technique, and it was found that PIn had the highest conductivity with 7·86×10−4 S cm−1 among the homopolymer and composites;the conductivity values of PU/PIn, PET/PIn and PVC/PIn composites were 4·23×10−5, 4·34×10−5 and 3·87×10−5 S cm−1 respectively. Magnetic properties of the polymers were analysed by Gouy scale measurements, and it was found that their conducting mechanisms are of polaron and bipolaron natures. Thermal stability of polymers was investigated by thermogravimetric analysis, and the initial degradation temperatures were found to be 271, 420, 390 and 465°C for PIn, PU/PIn, PET/PIn and PVC/PIn respectively. Scanning electron microscopy was used for microstructural analysis, and when the morphologies of PET/PIn, PVC/PIn composites and PIn, PU/PIn were compared, it was observed that PET/PIn and PVC/PIn composites have smoother layers and are more compact than PIn and PU/PIn composite. X-ray diffraction spectra showed that the crystallisation degree of PET and PVC increased after polymerisation of PIn; degrees of crystallinity of PIn, PU/PIn, PET/PIn and PVC/PIn were obtained as 14·6, 18·8, 19·3 and 20·2% respectively.