J.B. Yadav

Properties of vacuum evaporated vapour chopped polyaniline thin film: effect of synthesis method

The paper reports optical properties and adhesion of polyaniline thin film prepared by vacuum evaporated polyaniline powder synthesized in acidic and nonacidic medium respectively. The effect of vapour chopping on its optical and adhesion properties is also studied. Maximum transmittance 85% and 90% was obtained for polyaniline thin film deposited from polyaniline powder synthesized from nonacidic and acidic medium respectively. Due to non-acidic medium, the film showed absorption peak at 420 nm, whereas due to acidic medium it shifts below 350 nm. Refractive index of PANI from nonacidic medium is higher than the refractive index from acidic medium. After vapour chopping the refractive index decreases and transmittance increases. Adhesion of the film measured by direct pull of method was higher due to acidic medium ~68 Kgf/cm2 After chopping adhesion of the film increases. Polyaniline thin film deposited from acidic polyaniline powder are more stable and gives lower refractive index with higher adhesion. Vapour chopping also improves the properties of these thin films.

Impact of low-pressure glow-discharge-pulsed plasma polymerization on properties of polyaniline thin films

This study reports on polyaniline thin films deposited on a glass substrate using a low-pressure glow-discharge-pulsed plasma polymerization method. The polyaniline thin film obtained by pulsed plasma polymerization has been successfully demonstrated as an optical waveguide with a transmission loss of 3.93 dB cm−1, and has the potential to be employed in integrated optics. An attempt has been made to investigate the effect of plasma OFF-time on the structural, optical as well as surface properties of polyaniline thin film. The plasma ON-time has been kept constant and the plasma OFF-time has been varied throughout the work. The plasma OFF-time strongly influenced the properties of the polyaniline thin film, and a nanostructured and compact surface was revealed in the morphological studies. The plasma OFF-time was found to enhance film thickness, roughness, refractive index and optical transmission loss, whereas it reduced the optical band gap of the polyaniline thin films. Retention in the aromatic structure was confirmed by FTIR results. Optical studies revealed a π-π* electronic transition at about 317 nm as well as the formation of a branched structure. As compared with continuous wave plasma, pulsed plasma polymerization shows better properties. Pulsed plasma polymerization reduced the roughness of the film from 1.2 nm to 0.42 nm and the optical transmission loss from 6.56 dB cm−1 to 3.39 dB cm−1.