Electrochemical applications of the bending beam method. 1. Mass transport and volume changes in polypyrrole during redox

We introduce the bending beam method to studies of the electrochemistry of polyrrole (PPy) electrodes, where a bipolymer strip made of a PPy layer and a polyethylene layer bound together responds, by bending, to volume changes in the PPy layer during its electrochemical doping and undoping. A correlation between the local linear strain and the curvature change of the strip is developed. Upon reduction (undoping) in an aqueous solution of LiClO 4 , a tosylate-doped PPy undergoes initial rapid swelling and subsequent rapid skrinking and continuous slow shrinking