Synthesis and Characterization of Biocompatible PEG-based Block Copolymers

Abstract

A series of poly(ethylene glycol) (PEG)-based biocompatible tri-block copolymers, poly(ε-caprolactone-co-lactide)-poly(ethylene glycol)-poly(ε-caprolactone-co-lactide) (PCLA-PEG-PCLA) and poly(D,L-lactide)-poly(ethylene glycol)-poly(D,L-lactide) (PLA-PEG-PLA) were synthesized via ring opening polymerization of D,L-lactide and ε-caprolactone, respectively, and reacted with PEG of different molecular weights. Aqueous solutions of these block copolymers have shown a sol-gel transition behavior at approximately body temperature (37°C). The tri-block copolymers were further coupled with sulfamethazine oligomer at both ends to create five-block copolymers that are more sensitive to external stimuli. The products were confirmed by Fourier transform infrared spectra (FT-IR), 1H-NMR. Their porous morphology was observed by scanning electron microscopy (SEM). Microcrystalline cellulose was used in an attempt to improve the mechanical properties of block copolymers. The sol-gel transition behavior of gels made at different concentrations was observed and recorded within a range of different temperatures and pH values. The observed properties suggest that these block copolymers are potential candidates for use as biocompatible, and possibly injectable hydrogels in biomedical and pharmaceutical applications.