CONJUGATED POLYMERS AS SMART MATERIALS, GAS SENSORS AND ACTUATORS USING BENDING BEAMS

In conjugated polymers small volume changes occur in response to various external stimuli. We find that the bending beam method provides an effective and sensitive way to detect and make use of these volume changes. Bipolymer strips, bending beams, made up of a conjugated polymer layer and a substrate polymer layer bound together are prepared. Through appropriate choice of materials, these strips can be used to detect the presence of certain gases, including ammonia gas and iodine vapor, by observing the bending behavior of the strips. The underlying nature could be doping/undoping of the conjugated polymers or merely some form of gas adsorption/desorption, and associated mass transport and conformational changes. These sensors are smart as they not only sense, but also actuate. We also report the application of the bending beam method to study in situ conformational change or phase transition in conjugated polymers during gas doping or undoping.