Abstract
Poly(ɛ-caprolactone)2-b-poly(L-lactide)2 miktoarm block copolymers were successfully synthesized via ring-opening polymerization using pentaerythritol as the initiator and a protection–deprotection procedure. 1H nuclear magnetic resonance (1H NMR) and size exclusion chromatography (SEC) were employed to characterize the miktoarm structure, molecular weight and molecular weight distribution. The microspheres of poly(ɛ-caprolactone)2-b-poly(L-lactide)2 ((PCL)2-b-(PLLA)2) were produced by an oil-in-water emulsion solvent extraction/evaporation method and studied with scanning electron microscopy (SEM). The hydrolytic degradation of microspheres with different architectures and compositions was performed at 37 °C in a phosphate-buffered saline solution (pH=7.4). The weight loss of the microspheres was strongly affected by the molecular architecture, chain length and composition. The compositional, or molar ratio, changes were monitored during the degradation using 1H NMR, SEC, differential scanning calorimetry and SEM, all of which suggested that the degradation proceeded from the surface to the interior and could be described using a combined degradation model with surface erosion and bulk degradation.
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Acknowledgements
This research was supported by the Fundamental Research Funds for the Central Universities (WD0913008, WD1014017), the ‘Shu Guang’ Project of Shanghai Municipal Education Commission, the Natural Science Foundation of Shanghai (11ZR1409200), the National Natural Science Foundation of China (51103041), the Shanghai Leading Academic Discipline Project (B502), the Shanghai Key Laboratory Project (08DZ2230500) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.
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Zhang, X., Xiao, Y. & Lang, M. Synthesis and degradation behavior of miktoarm poly(ɛ-caprolactone)2-b-poly(L-lactone)2 microspheres. Polym J 45, 420–426 (2013). https://doi.org/10.1038/pj.2012.166
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DOI: https://doi.org/10.1038/pj.2012.166
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