title: Synthesis, characterization, and morphology studies of biodegradable amphiphilic poly[(R)-3-hydroxybutyrate]-alt-poly(ethylene glycol) multiblock copolymers.
abstract: Novel biodegradable amphiphilic alternating block copolymers based on poly[(R)-3-hydroxybutyrate] (PHB) as biodegradable and hydrophobic block and poly(ethylene glycol) (PEG) as hydrophilic block (PHB-alt-PEG) were successfully synthesized through coupling reaction. Their chemical structures have been characterized by using gel permeation chromatography, (1)H nuclear magnetic resonance, and Fourier transform infrared spectroscopy. Differential scanning calorimetry (DSC) analysis revealed that both PHB and PEG blocks in PHB-alt-PEG block copolymers can crystallize to form separate crystalline phase except in those with a short PEG block (M(n) 600) only PHB crystalline phase has been observed. However, due to the mutual interference from each other, the melting transition of both PHB and PEG crystalline phases shifted to lower temperature with lower crystallinity in comparison with corresponding pure PHB and PEG. The crystallization behavior of PHB block and PEG block has also been studied by X-ray diffraction, and the results were in good agreement with those deduced from DSC study. The surface morphologies of PHB-alt-PEG block copolymer thin films spin-coated on mica have been visualized by atomic force microscopy with tapping mode, indicating formation of laterally regular lamellar surface patterns. Static water contact angle measurement revealed that surface hydrophilicity of these spin-coated thin films increases with increasing PEG block content.
authors.affiliation: Institute of Materials Research and Engineering, National University of Singapore, 3 Research Link, Singapore.
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Kerh Li
authors.initials: KL
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Eunice Phay Shing
authors.initials: EP
authors.lastname: Tan
authors.forename: Lee Meng
authors.initials: LM
authors.lastname: Chan
authors.forename: Chwee Teck
authors.initials: CT
authors.lastname: Lim
authors.forename: Suat Hong
authors.initials: SH
authors.lastname: Goh
mesh_terms: D002850:Chromatography, Gel; D009682:Magnetic Resonance Spectroscopy; D018625:Microscopy, Atomic Force; D011091:Polyesters / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D000094122:Polyhydroxybutyrates
chemical_list: D011091:Polyesters; D011092:Polyethylene Glycols; D011108:Polymers; C515859:poly(3-hydroxybutyrate)-alt-poly(ethylene glycol) multiblock copolymer; D000094122:Polyhydroxybutyrates