Available online at www.sciencedirect.com Separation and Purification Technology 61 (2008) 1–8 Preparation of hydrophilic poly(vinyl butyral)/Pluronic F127 blend hollow fiber membrane via thermally induced phase separation Yun-Ren Qiu a,b , Nasrul A. Rahman b , Hideto Matsuyama b,∗ a School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China b Department of Chemical Science and Engineering, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan Received 7 April 2007; received in revised form 7 September 2007; accepted 11 September 2007 Abstract Poly(vinyl butyral) (PVB)/surfactant with high molecular weight (Pluronic F127) blend hollow fiber membranes were prepared via thermally induced phase separation (TIPS) from PVB/Pluronic F127/diluent (PEG200) system. The phase diagram of PVB/PEG200 system was obtained and the addition of Pluronic F127 to this system led to the decrease of the cloud point. In order to know the kinetic property in the membrane preparation process, a light scattering experiment was carried out in cooling process of the PVB solution. The result indicated that the initial interphase periodic distance formed from the phase separation of PVB/Pluronic F127/PEG200 system was smaller than that of PVB/PEG200 system and its growth rate was lower in the former system. The properties of the hollow fiber membranes such as water permeability, particle rejection and hydrophilicity were investigated. The air gap distance in the membrane preparation condition highly influenced the water permeability. © 2007 Elsevier B.V. All rights reserved. Keywords: Thermally induced phase separation; Hollow fiber membrane; Blend membrane; Poly(vinyl butyral); Hydrophilic membrane 1. Introduction Microfiltration and ultrafiltration are widely used in diver- sified fields as biotechnology, biomedicine, drinking water and wastewater treatment [1–4]. However, membrane fouling is a major obstacle to the widespread applications due to deposi- tion of retained colloidal and macromolecular material on the membrane surface or pore wall, which results in deterioration of membrane performance and decrease of membrane life. There are some methods to reduce membrane fouling. One of the effec- tive methods to suppress membrane fouling is to increase the hydrophilicity of membrane [5–9]. Poly(vinyl butyral) (PVB) has been extensively used in lam- inated safety glass and surface treatments. It is prepared by reacting polyvinyl alcohol (PVA) with butyraldehyde in an acid medium. Its structural formula is shown in Fig. 1 [10]. Substan- tial amounts of unreacted vinyl alcohol units typically remain in the chain, so PVB is regarded as a random copolymer of vinyl butyral and vinyl alcohol units. The vinyl alcohol unit is polar and hydrophilic and the vinyl butyral unit is hydrophobic. ∗ Corresponding author. Tel.: +81 78 803 6180; fax: +81 78 803 6180. E-mail address: matuyama@kobe-u.ac.jp (H. Matsuyama). In addition to an innocuous and tasteless polymeric material, PVB can endure the low temperature, light, change in humidity, bacteria, microorganism, alkali and diluent acid [11]. Moreover, it reveals some hydrophilicity because of its hydroxyl groups. Therefore, PVB seems to be an attractive material for preparing the membrane, though very few literatures have been reported on the preparation of PVB microfiltration and ultrafiltration mem- branes [11–13]. Pluronic F127, representative of the copolymer surfac- tant, contains poly(ethylene oxide) (EO) and poly(propylene oxide) (PO) units with an approximate molecular formula (EO) 106 (PO) 70 (EO) 106 . Pluronic F127 is an amphiphilic copoly- mer. Since the PEO segment of Pluronic is highly hydrophilic, Pluronic has been widely investigated in biomedical applications for reducing protein adsorption [14–16]. Wang et al. [16] studied the blend membrane of Pluronic F127 and PES, and showed that the addition of Pluronic F127 can increase the membrane hydrophilicity and fouling-resistant ability. Pluronic F127 can exist in blend membranes stably, and the introduction of Pluronic F127 has minor affect on the mechanical strength. Thermally induced phase separation (TIPS) is one of the most useful technologies to prepare the porous membranes. In the TIPS process, a polymer is dissolved in a diluent at high tem- perature and then by cooling the solution, phase separation is 1383-5866/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2007.09.014