Effects of reaction conditions on the grafting percentage of poly(ethylene glycol)-block-poly(γ-benzyl L-glutamate)-graft-poly(ethylene glycol) copolymer

Abstract

a cadeia PEG. A estrutura e propriedades do copolímero PEG-b-PBLG-g-PEG foram investigadas por spetroscopia no infravermelho (FT-IR), microscopia de força atômica (AFM), microscopia eletrônica de varredura (SEM) e calorimetria diferencial de varredura (DSC). Foram investigados os efeitos de temperatura de reação, tempo de reação, e extensão da cadeia dos segmentos PBLG na porcentagem de enxerto do copolímero PEG-b-PBLGg-PEG. Os resultados experimentais demonstraram que a porcentagem de enxerto do copolímero PEG-b-PBLG-g-PEG aumentarou com o aumento do tempo e temperatura de reação, enquanto que o aumento do comprimento da cadeia de segmentos PBLG no copolímero bloco diminuiu a porcentagem de enxerto.In the present work, poly(ethylene glycol)-block-poly(γ-benzyl L-glutamate)-graftpoly(ethylene glycol) (PEG-b-PBLG-g-PEG) copolymer was synthesized by the ester exchange reaction of PEG-block-PBLG copolymer with PEG chain. Structure and properties of PEG-b-PBLG-g-PEG copolymer were investigated by fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), scanning electron microscopy (SEM), and differential scanning calorimeter (DSC). The effects of reaction temperature, reaction time, and the chain length of PBLG segments on the grafting percentage of PEG-b-PBLG-g-PEG copolymer were studied. Experimental results demonstrated that the grafting percentage of PEG-b-PBLG-g-PEG copolymer increased with the increase of both reaction temperature and reaction time, while the increase of the chain length of PBLG segments in block copolymer decreased the grafting percentage.