Morphological control of porous membranes based on aromatic polyether/water soluble polymers Denise Karamessini, 1,2 Georgia Ch. Lainioti, 1,2 Valadoula Deimede, 1 Joannis K. Kallitsis 1,2 1 Department of Chemistry, University of Patras, Patras GR-26504, Greece 2 Foundation for Research and Technology-Hellas (FORTH)/Institute of Chemical Engineering Sciences (ICE-HT), P.O. Box 1414, Rio, Patras GR-265 04, Greece Correspondence to: J. K. Kallitsis (E-mail: j.kallitsis@upatras.gr) ABSTRACT: This work describes the development of porous membranes based on blends of an aromatic polyether bearing main and side chain pyridine units (AP) with hydrophilic ionic polymers, like poly(sodium 4-styrenesulfonate) (PSSNa) and its acid form (PSSH), or non-ionic like polyvinylpyrrolidone and polyethylene glycol. Porous membranes were obtained after the removal of the water soluble polymers from the respective blend. The effect of various parameters such as water soluble polymer used (pore former), blend composition, casting solvent, and solvent evaporation level on porous structure formation was studied thoroughly. Specifically, SEM examination for the aforementioned systems indicated various porous morphologies depending on experimental conditions as well as thermodynamic and kinetic parameters occurring during their formation. The thermal properties of the membranes were influenced by the kind of the pore former, as revealed by thermogravimetric analysis. Special attention was paid to the systems AP/ PSSNa and AP/PSSH to evaluate their miscibility via dynamic mechanical analysis and ATR-FTIR spectroscopy. AP/PSSNa mem- branes have been preliminary used to test the water permeability for water purification. The tests revealed high water flux values at increased PSSNa concentrations. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44539. KEYWORDS: blends; hydrophilic polymers; membranes; morphology; porous materials Received 14 May 2016; accepted 3 October 2016 DOI: 10.1002/app.44539 INTRODUCTION Membranes and membrane processes have rapidly gained con- siderable attention due to their high potentiality for a variety of applications, especially in the last years. 1 Their utilization in membrane distillation, 2 membrane gas absorption and gas sepa- ration, 3 water purification and wastewater treatment, food proc- essing, biological applications, 4,5 as well as separators for lithium-ion batteries, 6 established them as an innovative and rapidly developing field across science and engineering. Mem- branes have been evolved into promising separation systems due to their attractive features including high energy efficiency, high stability, simplicity in design, low cost operations, and pro- tection of the natural ecosystem. Growing interest in the separation area motivated the develop- ment of inorganic and polymeric membranes. Inorganic mem- branes, although they may provide the desired material properties for different separation processes, their performance, and higher cost compared to polymeric membranes may cause difficulties in industrial applications. On the other side, regard- ing the polymeric membranes and depending on different applications, a wide variety of new polymers is available to form different membranes with specific morphologies and transport properties suitable to the desired separation processes. Polymeric membranes can be either porous or dense. In both cases, the development of a new class of advanced membranes with controlled pore architectures is important for the achieve- ment of more efficient and cost effective purification processes. Common techniques for the preparation of polymer-based porous membranes are: extrusion-stretching, 7 sintering, 8 irradia- tion, 9 template-leaching, gas foaming, emulsion freeze-drying, 10 and phase separation techniques. 11–13 The final morphology of the membranes obtained will vary greatly, depending on the properties of the materials and the process conditions. Phase inversion technique has been one of the most important control- ling procedures to obtain porous structures, including different approaches: (1) thermally induced phase separation: precipitation by cooling, 14 (2) vapor induced phase separation: precipitation by absorption of non-solvent (water) from the vapor phase, 15 (3) non-solvent induced phase separation: immersion precipitation in a non-solvent (typically water), 16,17 and (4) evaporation induced phase separation: dry casting-solvent evaporation. 18 V C 2016 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2017, DOI: 10.1002/APP.44539 44539 (1 of 11)