The crystallization behavior of the blending system consists of homopolymer poly(ethylene oxide) (h-PEO) with different molecular weights, and polystyrene-block-poly (ethylene oxide)-block-polystyrene (PS-b-PEC-b-PS) triblock copolymer has been investigated by DSC measurements. The crystallization of PEO block (b-PEC) in block copolymer Occurs under much lower temperature than that of the h-PEO in the bulk (Delta T > 65 degrees C), which is attributed to the homogeneous nucleation crystallization behavior of the b-PEO microdomains. In both the "dry-brush" and the "wet brush" blending systems, the homogeneous nucleation crystallization temperature of PS-b-PEO-b-PS/h-PEO blends increases due to the increase of the domain size. The heterogeneous nucleation crystallization temperatures of h-PEO in the wet brush blending systems are higher than that of the corresponding h-PEO in the bulk. At the same time, the heterogeneous nucleation crystallization temperature of b-PEO10000 decreases from 43 degrees C to 30 degrees C and 40 degrees C in the h-PEO600 and h-PEO2000 blending systems, respectively, because of the stretching of the PEO chains in the wet brush. However, this kind of phenomenon does not happen in the dry brush blending systems. The self-seeding procedure was used to further ascertain the nucleation mechanism in the crystallization process. As a result, the self-seeding domains have been confirmed, and the difference between the dry brush and wet brush systems has been observed. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 907-915, 2009