End-functionalized oligo(α-methylstyrene)s with a definite number of perfluoroalkyl (Rf) groups(1-4) were successfully synthesized by a living anionic oligomerization and the quantitative end-functionalization reactions. Surface characterization of the resulting oligomer films were investigated by using X-ray photoelectron spectroscopy (XPS) and contact angle measurement. Swelling behavior of Rf3 and Rf4 films were observed under supercritical carbon dioxide (scCO_2 ) conditions, suggesting that scCO_2 innmerses into Rf domain formed by micro-phase separation. Interestingly, collapsed nano porous structures were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Key Words : scCO 2 process, perfluorooctyl group, swelling ratio, oligomer, surface characterization.