||To design pH-sensitive injectable hydrogel, we decided to use sulfadiazine which shows sharp charge transition around pH 6.5, dendrimer-shaped PEO (poly(ethylene oxide)) and glycol chitosan. 6-arm PEO was obtained by anionic polymerization and further synthesized using tris(hydroxymethyl)-aminomethane. As a result, dendrimer-shaped PEO has 18 hydroxyl groups on the surface and sulfadiazine oligomer was successfully attached to each hydroxyl group. Glycol chitosan was selected as a counter part of the blend system. When sulfadiazine containing PEO and glycol chitosan were mixed at pH 6.0, there are no interactions between them because sulfadiazine does not have negative charges. However, at pH 7.4 which is the same environment with physiological condition, sulfadiazine exhibits negative charges. Thus, it can interact with positive charges of glycol chitosan and, finally, the blend system can go physical crosslinking which is resulted to hydrogel formation, as we confirmed.