Porous Polyphenylene Sulfide Membrane with High Durability Against Solvents by the Thermally Induced Phase-Separation Method Huaiyu Ding, 1,2 Yiming Zeng, 1 Xiangfu Meng, 1 Ye Tian, 2 Yanqiao Shi, 1 Qingze Jiao, 2 Shimin Zhang 1 1 Institute of Chemistry, The Chinese Academy of Science, Beijing 100080, P. R. China 2 School of Chemical Engineering and Environment Science, Beijing Institute of Technology, Beijing 100081, P. R. China Received 21 July 2005; accepted 15 March 2006 DOI 10.1002/app.24535 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Porous polyphenylene sulfide membranes were prepared as new solvent-resistant membranes by the thermally induced phase-separation (TIPS) method. Porous structures were either formed by solid–liquid phase sep- aration (polymer crystallization) or liquid–liquid phase sep- aration. The effects of solvents, cooling rates, and polymer concentrations on the porous structures were investigated. Various characteristics of pore structure can be obtained with suitable diluents and cooling rates using the TIPS method. Ó 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2959–2966, 2006 Key words: polyphenylene sulfide; porous membranes; thermally induced phase separation; chemical resistance INTRODUCTION Porous membranes have been widely applied in var- ious areas such as the food industry, oil–water se- paration, and water and wastewater treatment. Nowadays, porous membranes are mainly used for aqueous separation. 1 In this field, organic separation is an important aspect which attracts much work to research the porous membranes that have high dura- bility against solvents. Iwama and Kazuse 2 have investigated the solvent-resistant polyimide mem- brane, which showed excellent stability to common organic solvents, even at elevated temperature. The membrane in their work was made by the immer- sion-precipitation method. In this method a homoge- neous polymer solution was first prepared before it was solidified to be a porous membrane in a non- solvent bath. This meant that the membrane had no durability against the solvents in membrane prepara- tion solutions. Polyphenylene sulfide (PPS) is a common semi- crystalline polymer that has high glass transition and high melting temperatures (T g is 103.98C and T m is 265.68C). The properties of commercial available PPS have excellent solvent resistance and thermal stability. However, PPS is generally regarded as being insoluble in most common solvents; thus, the immer- sion-precipitation method cannot be used for PPS because of solubility problems. Vaorbach et al. 3 investigated an approach to pre- pared PPS porous membrane. The material was first melted at a high temperature, and then the melted PPS was extruded out to be a hollow fibre filament. When the filament was cooled to a special tempera- ture, it was stretched to be a porous membrane. The pores in their samples were too small. The stretch forming method had its shortcoming to enlarge the pore structure. Some groups have investigated the phase-separation mechanism and effecting factors of microporous membrane formation, and many different materials have been used. According to their research, the phase- separation mechanism can be elucidated through view of thermodynamics. That is, membrane is formed by solid–liquid phase separation or liquid– liquid phase separation via TIPS, and nucleation and growth mechanism and spinodal decomposition mechanism are two mechanisms of liquid–liquid phase separation. Douglas R. Lloyd et al. 4–11 first re- searched the microporous membrane with use of PP, PE, PVDF, ethylene-acrylic acid compolymers. Fur- thermore, Hideto Matsuyama et al. 16–22 investigated some other materials (cellulose acetate, EVAL, etc.). Recently, Doo Sung Lee et al. 23–26 prepared PLGA membranes as biodegradable material. However, these polymeric material in previous research studies do not have sufficient durability against solvents; Correspondence to: Yanqiao Shi (Gwchen@iccas.ac.cn). Journal of Applied Polymer Science, Vol. 102, 2959–2966 (2006) V V C 2006 Wiley Periodicals, Inc.