Hydrophilic and anti-fouling HDPE/PE-b-PEG microporous membranes were prepared by blending high density polyethylene (HDPE) and amphiphilic copolymer polyethylene-block-poly(ethylene glycol) (PE-b-PEG) through the liquid-liquid thermally induced phase separation (L-L TIPS) process. Compared with pure HDPE membrane, HDPE/PE-b-PEG blend membranes exhibit larger water permeation flux due to the segregation of the hydrophilic PEG segments at the membrane surface, which was confirmed by X-ray photoelectronic spectroscopy (XPS) and contact angle measurements. The further investigation of the effects of PE-b-PEG content on the phase diagram of the HDPE/PE-b-PEG/DPE mixture system and membrane morphology showed that with increasing PE-b-PEG content, the cloud point of ternary system shifted to the higher temperature, while crystallization temperature did not change too much. Meantime. HDPE/PE-b-PEG membranes with higher PE-b-PEG content exhibited larger pore size, which is in consistent with the increased water flux. The improved separation performance and morphology of HDPE/PE-b-PEG membranes were explained by the viewpoint of droplet growth kinetics of L-L TIPS, i.e. the faster droplet growth rate and the longer droplet growth period result in the bigger droplet volume in HDPE/PE-b-PEG system, and thus the larger pore size in HDPE/PE-b-PEG membrane. (C) 2010 Elsevier B.V. All rights reserved.