Synthesis of PDON-b-PEG-b-PDON block copolymers and drug delivery system thereof

摘要

ABA-type block copolymers of poly(1,4-dioxan-2-one) (PDON) with poly(ethylene glycol) (PEG) were synthesized and characterized. From the results of differential scanning calorimetry and wide-angle X-ray diffraction, it was observed that the PDON blocks show similar crystallization behavior with homopolymer while the PEG blocks demonstrate lower melting temperature and crystallinity than PEG homopolymer. Their dynamic contact angles (theta(alpha)) decreased with the increase of PEG fraction in copolymers, indicating the hydrophilicity of PDON-b-PEG-b-PDON (PDPEPD) copolymers was improved gradually. The potential application of PDPEPD copolymers in the drug delivery system has been investigated. The release rate of Levonorgestrel (LNG) increased with the strengthening of hydrophilicity of copolymer samples. The burst effect of release of LNG is small in copolymers with short PDON blocks. When DON mole fraction in copolymers is high enough, no burst effect can be observed. In an experimental period of about 25 days, the release rate of LNG kept almost constant. (C) 1998 John Wiley & Sons, Inc. [References: 20]