Abstract
In the present work, poly(ethylene glycol)-block-poly(γ-benzyl L-glutamate)-graft-poly(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.
Highlights
It is well known that polypeptide science is a growing field of interest for both academic and commercial reasons.[1,2,3,4,5,6,7,8,9,10,11,12] Because of the unique structures and properties, synthesized polypeptides and their copolymers have been investigated widely in the fields of protein simulation, macromolecular conformational study, catalysis, drug delivery, nanoreactors etc.[13,14,15,16,17,18,19,20,21,22,23]Recently, much interest has been focused on the self-association behavior of the copolymers composed of hydrophobic polypeptide segments and hydrophilic polymer chains.[1,7,8,9,10,11,12,13] Cho et al.[9] have reported the formation of polymeric micelles composed of poly(γ-benzylL-glutamate) and poly(ethylene oxide) in aqueous medium and the drug delivery system based on the core-shell nanoparticles with PBLG as the hydrophobic inner core and PEO as the hydrophilic outer shell
The molecular weights of PBLG-block-PEG copolymers and the grafting percentage of PEG-b-PBLG-g-PEG copolymer were estimated by nuclear magnetic resonance (NMR) measurements (Avance 550)
fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy (AFM) analysis proved that PEG-b-PBLG-g-PEG copolymer is composed of both PEG and PBLG segments
Summary
It is well known that polypeptide science is a growing field of interest for both academic and commercial reasons.[1,2,3,4,5,6,7,8,9,10,11,12] Because of the unique structures and properties, synthesized polypeptides and their copolymers have been investigated widely in the fields of protein simulation, macromolecular conformational study, catalysis, drug delivery, nanoreactors etc.[13,14,15,16,17,18,19,20,21,22,23]Recently, much interest has been focused on the self-association behavior of the copolymers composed of hydrophobic polypeptide segments and hydrophilic polymer chains.[1,7,8,9,10,11,12,13] Cho et al.[9] have reported the formation of polymeric micelles composed of poly(γ-benzylL-glutamate) and poly(ethylene oxide) in aqueous medium and the drug delivery system based on the core-shell nanoparticles with PBLG as the hydrophobic inner core and PEO as the hydrophilic outer shell. Few experimental works have been reported on the effects of reaction conditions on the grafting percentage of poly(ethylene glycol)-blockpoly(γ-benzyl L-glutamate)-graft-poly(ethylene glycol) copolymer. Effects of Reaction Conditions on the Grafting Percentage of PEG-b-PBLG-g-PEG Copolymer
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