Journal of Membrane Science 249 (2005) 103–112 Development and characterization of novel hydrophilic surface modifying macromolecule for polymeric membranes D. Rana a , T. Matsuura a,∗ , R.M. Narbaitz b , C. Feng a a Industrial Membrane Research Institute, Department of Chemical Engineering, University of Ottawa, 161 Louis Pasteur St., Ottawa, Ont., Canada KIN 6N5 b Industrial Membrane Research Institute, Department of Civil Engineering, University of Ottawa, 161 Louis Pasteur St., Ottawa, Ont., Canada KIN 6N5 Received 26 March 2004; received in revised form 26 August 2004; accepted 1 September 2004 Available online 19 December 2004 Abstract A hydrophiLic Surface Modifying Macromolecule (LSMM) was synthesized, characterized, and blended into the casting solution of polyethersulfone (PES) membranes. Ultra-filtration membranes were prepared by the phase inversion technique. The membranes were then characterized by contact angle measurements and a solute transport study using poly(ethylene glycol) (PEG) and poly(ethylene oxide) (PEO) solutes of different molecular weights. Pore size and pore size distribution of the membranes were determined by using PEG and PEO separation data. The Ottawa River water was treated by the membranes. The LSMM blended PES membranes showed higher fouling resistance and long-term stability than the PES membrane without LSMM. © 2004 Elsevier B.V. All rights reserved. Keywords: Hydrophilic surface modifying macromolecule; Polyethersulfone; Contact angle; Ultra-filtration; Fouling resistance 1. Introduction The control of surface properties is of scientific and technological importance in many academic and industrial research areas. One such area is the modification of the mem- brane surfaces as they have an important role in membrane separation processes. There are several techniques to modify the surface, e.g., blending, coating, grafting, chemical mod- ification, plasma treatment, etc. [1–6]. For example, Erbil et al. described a superhydrophobic coating using commercially available isotactic polypropylene to form a gel-like layer with a porous surface [1]. Another example is argon plasma treat- ment followed by poly(acrylic acid) grafting in vapor phase to achieve complete and permanent hydrophilic modification of the membrane surface [2]. ∗ Corresponding author. Tel.: +1 613 562 5800x6114; fax: +1 613 562 5172. E-mail address: matsuura@eng.uottawa.ca (T. Matsuura). It is well known that polymer blend miscibility is rare oc- currence from the thermodynamically point of view [7]. If a solution with blended polymers is equilibrated in the air, the polymer with the lowest surface energy (hydro-phobic or -philic) will migrate and concentrate at the air interface reduc- ing the interfacial energy as a consequence. Many researchers have observed the preferential adsorption of a lower surface tension component at the surface for miscible polymer blend systems [8–13]. Steiner et al. observed in a polyolefin blend system that there was a tendency for the more highly branched component to segregate at the surface compared to the less branched component as the former one had a lower surface tension than the latter one [8]. Although blending is the classical technique for mem- brane surface modification, only recently much attention has been paid to hydrophobic surface modifying macro- molecule (SMM) blending as a surface modifying approach [14–23]. It was proven that SMM blended membranes had a better performance in the separation of volatile or- ganic compounds from aqueous solutions by pervaporation, 0376-7388/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2004.09.034