Graft copolymers containing nonpolar main chains and polar side chains capable of acid-base interaction show surface property variations depending on the sample preparation methods. A series of polypropylene-graft-poly(ethylene glycol)s were synthesized and their surface property variations were studied using surface analysis techniques, such as surface contact angle measurement and X-ray photoelectron spectroscopic analysis. Molding against various substrates, dip-coating, vacuum annealing, and water-contact techniques were employed for the experiment. Different surfaces were obtained depending on the degree of acid-base interaction between the polymer surface and interfacing phase. These surface property variations were concluded to be the result of minimum interfacial free energy formation.