In situ solution-phase polymerization and chemical vapor deposition of polyanilne on microporous cellulose ester membranes: AFM and electrical conductivity studies

This study elucidates the effects of physical parameters involved in PANI deposition on microporous cellulose ester membranes using various in solution-phase polymerization techniques and chemical vapor deposition technique. PANI layering at the surface was achieved using single- and two-step solution-phase polymerization, and chemical vapor deposition techniques. The effects of different reactant-substrate contacting patterns in these techniques and polymerization time on various properties of the membranes have been elaborated in detail. PANI deposition content in the membranes, extent of surface layering and surface morphology were characterized using gravimetric method, Fourier-transform infrared spectroscopy and atomic-force microscopy, respectively whereas the extent of crystallinity was studied using X-ray diffraction (XRD) technique. The chemical vapor deposition technique showed the highest PANI deposition content, surface homogeneity and crystallinity that yielded the composite membranes with highest electrical conductivity value (∼0.98 S cm−1). In solution-phase polymerization, the soaking time of membranes in monomer solution prior to the onset of polymerization strongly influenced PANI deposition extent, and thickness and roughness of the deposited surface layer. This study shows that the contacting patterns of the reactants with the substrate and soaking and/or polymerization time significantly influence the extent of PANI deposition as a surface layer and its homogeneity. The variation of PANI deposition content and morphology resulted from different techniques and parameters also influenced the electrical conductivity values.