Pyroelectricity in polyurea thin film with oligothiophene segments in the main chain prepared by vapor deposition polymerization

A new polyurea thin film with oligothiophene segments in the main chain was fabricated in the form of a thin film by vapor deposition polymerization (VDP). The film was prepared by the reaction between 5,5‴-bis(ammomethyl)-2, 2′:5′,2Prime;:5″,2‴-quaterthiophene (BAQ) and 4,4′-diphenylinethane diisocyanate (MDI). Spectroscopic data indicate that the reaction occurs successfully and that the resulting thin film is orientated by corona poling. Because of the high crystallinity of the oligothiophene backbone, the film shows a high and stable pyroelectricity (26-220 μC/m ²·K) at 40-150°C compared with other aromatic polyurea films prepared by VDP and conventional bulk polymer such as polyvinylidene fluoride.