Improving PPy Adhesion by Surface Roughening

Conjugated polymers have found applications as “artificial muscles” because they undergo significant volume change upon electrochemical cycling. However, this large repeated strain also leads them to delaminate from the underlying electrode. Two methods of improving the adhesion of polypyrrole films to Au electrodes during extended electrochemical cycling were quantitatively characterized. Both involved roughening the Au surface, the first by electroplating and the second by etching. The extent of delamination was quantified using a tape test at regular intervals during switching between the fully oxidized and reduced states in an aqueous electrolyte, and the surfaces were characterized by scanning electron microscopy. Untreated smooth control surfaces were simultaneously monitored the same way. Without surface treatment, 3000 A thick polypyrrole films doped with dodecylbenzenesulfonate, PPy(DBS), delaminated unpredictably between 1 cycle and 20 000 cycles, with almost half the samples failing before 3000...

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