Study on adhesion of thin film coatings of polypyrrole on glass substrate for mechanical durability of sensor devices

Thin film coatings of polypyrrole have been extensively used as gas sensors in chemiresistors where the films are deposited on insulating substrates. These polypyrrole films have also been used as coatings to glass optical fiber as a chemo-chromic transducer for gas sensing. For long term mechanical durability of these sensing films, their adhesion to the substrate is very important. Adhesion between polypyrrole films and glass slide substrates is investigated for solution deposited polypyrrole films. The substrate surface is investigated in terms of addition of silane coupling agents and substrate surface roughness, for enhancement of the film substrate adhesion. The adhesion test is performed by the standard ASTM D - 4541 Pull-off Test Method. The films deposited on as-received slides are characterized for their electrical conductivity and optical transmission for their use in both chemiresistor and optical fiber sensor applications for nerve agent DMMP (di-methylmethylphosphonate) sensing.