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The enrichment of poly(ethylene glycol) (PEG) on the surface of poly(ethylene glycol)/polypropylene (PEG/PP) blends was investigated by using attenuated total reflection infrared spectroscopy (ATR‐FTIR), contact angle measurement (CDA), and scanning electron microscopy (SEM). The preferred aggregation of the PEG component on the film surface of PP/PEG blends was affected mainly by the content, the molecular weight, and the segregated domains of PEG. Lower content and dies with higher surface energy favored the surface enrichment of PEG. The PEG with higher molecular weights was distributed in PP with larger phase domains, which resulted in a lower tendency toward preferred aggregation and surface enrichment. J. VINYL ADDIT. TECHNOL, 2008. © 2008 Society of Plastics Engineers

A novel macromolecular surface modifier, polypropylene-grafted-poly(ethylene glycol) copolymer (PP-g-PEG), was synthesized by coupling polypropylene containing maleic anhydride with monohydroxyl-terminated poly(ethylene glycol). The effects of the reaction condition on the graft reactions were studied. The copolymers were characterized by IR, 1 H NMR, thermogravimetry (TG) and differential scanning calorimetry (DSC). The results indicated that the graft reactions were hindered by increasing the molecular weight of PP or PEG. The graft copolymer was found to have a higher initial thermal degradation temperature and lower crystallization capacity as compared with pure PP, and the side chain of PEG hindered the PP chain from forming a perfect b crystal. The thermal stability of PP-g-PEG decreased with the increasing content or molecular weight of PEG. The copolymers were blended with polypropylene to modify the surface hydrophilicity of the products. The results of attenuated total reflectance FTIR spectroscopy (ATR-FTIR) showed that PP-g-PEG could diffuse preferably onto the surface of the blends and be suitable as an effectual macromolecular surface modifier for PP.