SYNTHESIS AND CHARACTERIZATION OF AMPHIPHILIC MULTIBLOCK COPOLYMERS BASED ON POLY(p-DIOXANONE) AND POLY(ETHYLENE GLYCOL)

In order to overcome the defects of poly (p-dioxanone)(PPDO) due to its hydrophobicity, amphiphilic PPDO/poly(ethylene glycol) (PEG) multiblock copolymers were synthesized by coupling the dihydroxyl-terminated PPDO with dicarboxylic acid-terminated PEG. The structures and molecular characteristics of the resulting PPDO/PEG multiblock copolymers were studied by H-1-NMR and GPC. The crystallization and thermal stability of the copolymers were studied using DSC and TGA. DSC analysis showed that the PPDO blocks restrained the crystallization of PEG blocks. TGA showed that the multiblock copolymers underwent thermal degradation in two separate steps for the PPDO and PEG blocks, respectively from which the PPDO contents could be calculated, and the results were very close to the theoretical values. Polymeric nanoparticles were prepared in an aqueous medium by dialysis technique. The more the content of hydrophilic PEG in copolymers, the easier the formation of nanoparticles. Dynamic light scattering (DLS) was used to investigate the nanoparticles of copolymers, showing a mono-dispersed size distribution and hydrodynamic diameters of around 173 similar to 193 nm The novel PPDO/PEG multiblock copolymers may have a potential application in drug delivery systems.