A solvent effect on the morphology of PMMA-coated polypyrrole surfaces

This paper reports on the morphology of poly (methyl methacrylate) (PMMA) films cast from chloroform (CHCl3) and tetrahydrofuran (THF) onto tosylate-doped polypyrrole (PPyTos) surfaces. We have examined the bare and PMMA-coated PPyTos by X-ray photoelectron spectroscopy (XPS) to determine the surface composition and by atomic force microscopy (AFM) to characterize the surface morphology. We have found that the polymer coating morphology depends significantly on the nature of the solvent. Indeed, the basic PMMA film cast from CHCl3 (an acidic good solvent) is much smoother than that cast from THF (a basic poor solvent). We interpret our results in terms of acid-base properties of the different species involved in the polymer film formation, i.e. the substrate, and the solute and solvent of the polymer solution.