In situ solution-phase polymerization and chemical vapor deposition of polyanilne on microporous cellulose ester membranes: AFM and electrical conductivity studies Muhammad Aamir Shehzad, Asif A. Qaiser *, Atif Javaid, Farhan Saeed Department of Polymer and Process Engineering, University of Engineering and Technology, Lahore 54890, Pakistan A R T I C L E I N F O Article history: Received 6 July 2014 Received in revised form 6 December 2014 Accepted 9 December 2014 Available online xxx Keywords: Polyaniline Composite membranes Chemical oxidative polymerization Chemical vapor deposition AFM characterization XRD studies A B S T R A C T 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. ã 2014 Elsevier B.V. All rights reserved. 1. Introduction Intrinsically conducting polymers (ICPs) have attracted a great interest of scientists due to their potential technological applica- tions such as conductive coatings, rechargeable batteries, ﬂexible electronics, anodic passivation, light emitting diodes (LEDs), electrochemical displays, etc. [1–3]. ICPs also have been employed in membrane separation processes mainly due to their high electrical conductivity, electrochemical activity and switchability between various oxidation and doping states [4]. Pristine ICP or ICP-polymer composite membranes have been trialed in various separation processes such as pervaporation [5], gas separation [6,7], and electrochemical based separation processes [8]. In addition, ICPs have been used in non-membrane applications where barrier properties of ICPs play signiﬁcant role. These applications include ICP coatings for corrosion prevention of metals, responsive packaging, chemical, electrochemical and biological sensors [9,10]. In membrane separation processes, microporous membranes are used to ﬁlter microorganisms and other micrometer sized particles based on size exclusion principle [11]. In addition to these conventional ﬁltration applications, highly permeable porous membranes have been developed where the pore surface of base microporous membrane was functionalized by depositing various functional materials such as metals and carbon nanotubule, polyaminoacids and polymeric dendrites [12–14]. These function- alized membranes provide the permeation of electrolyte under the inﬂuence of induced electrostatic and steric interactions with membrane wall. This pore functionalization yielded highly permeable membranes operating at much lower pressures as compared to that in ultra- and nano-ﬁltration processes with acceptable levels of selectivity [12,13,15]. Similarly, the base microporous membranes have been modiﬁed with ICPs such as polyaniline, polypyrrole, polythiophene to enhance * Corresponding author. Tel.: +92 3063798108. E-mail address: asifaliqaiser@uet.edu.pk (A.A. Qaiser). http://dx.doi.org/10.1016/j.synthmet.2014.12.011 0379-6779/ ã 2014 Elsevier B.V. All rights reserved. Synthetic Metals 200 (2015) 164–171 Contents lists available at ScienceDirect Synthetic Metals journal homepage: www.else vie r.com/locat e/synme t