Surface Modification of Poly(Lactic Acid) Microspheres via Gamma Irradiation

Abstract

Irradiation technique is one of methods used in modification of polymer surface although it has been used in sterilization for decades. It allows establishing simple and compact technique, non-contaminated with residues of toxic initiators, crossing agents or other additives. This study is to evaluate the effects of different gamma (γ) irradiation doses on poly (lactic acid) (PLA) microsphere surface grafted with maleic anhydride (MAH). Source of γ-irradiation used is 60Co and dose irradiation used in this study is10, 30, 50, 70, 90 and 110 kGy. Characterization was performed on samples before and after irradiation by FTIR, SEM and DSC. Results of FTIR suggest maleic anhydride successfully grafted onto PLA microsphere. Data from DSC shows thermal property of PLA changed after irradiation where the crystallization is increased compared to neat PLA. SEM images showed the difference of the PLA microspheres before and after γ irradiation. Neat PLA microspheres had a smooth surface, while after irradiation, the surface become rough. Degradation of microspheres observed by SEM as in suggest that PLA microspheres is degrade by bulk degradation. Gamma irradiation not only modified the surface of PLA microspheres by successfully grafting the maleic anhydride and increase surface roughness, it also affected the bulk properties of PLA microspheres.