| 초록 |
Based on the macro initiators of Pluronic® F68((EO)75(PO)30(EO)75) and F108((EO)141(PO)54(EO)141) triblock copolymers having PEO-PPO-PEO blocks, Poly(lactic-co-glycolic acid) (PLGA) were attached to both ends to synthesize a PLGA-PEO-PPO-PEO-PLGA pentablock copolymers. Ratio of PLGA blocks were controlled and six kinds of pentablock copolymers with different PLGA block lengths were synthesized using Stannous octoate (Sn(Oct)2) catalyst for ring opening reaction of Cyclic D,L- lactide and glycolide. Opened Lactide and glycolide monomers were grafted randomly on hydroxyl group present at both ends of the F68 and F108 polymers. PLGA-F68-PLGA and PLGA-F108-PLGA pentablock copolymers were characterized by 1H-NMR and TGA. The molecular weight of the products identified by NMR was 11,000-35,000g/mol and the weight fraction of the PLGA block was 0.2-0.5. Weight fraction of PLGA blocks in pentablock copolymers also calculated by thermal decomposition analysis using TGA instrument. TGA results obtained by removing PLGA block selectively also matched with 1H-NMR results. |
