Synthesis of amphiphilic pullulan-graft-poly(ε-caprolactone) via click chemistry

Chemical modification of natural polymers has been commonly employed for the development of new bio-based materials, aiming at adjusting specific properties such as solubility, biodegradability, thermal stability and mechanical behavior. Among all natural polymers, polysaccharides are promising materials, in which biodegradability, processability and bioreactivity make them suitable for biomedical applications. In this context, this work describes the synthesis and characterization of a novel amphiphilic pullulan-g-poly(ε-caprolactone) (Pull-g-PCL) graft copolymer. In a first step, pullulan was chemically modified with 2-bromopropionyl bromide to obtain bromo-functionalized pullulan (PullBr). Then, this precursor was modified with sodium azide, leading to azide pullulan (PullN3). In parallel, propargyl-terminated poly(ε-caprolactone) was prepared via ring-opening polymerization (ROP). These preliminary steps involved the synthesis of azide and alkyne compounds, capable of being linked together via alkyne-azide cycloaddition reaction catalyzed by copper (Cu (I)), which leads to Pull-g-PCL. The chemical structures of the polymers were assessed by Proton Nuclear Magnetic Resonance (1H NMR) and Fourier Transform Infrared (FTIR). •Amphiphilic copolymer based in pullulan was successful synthetized via click chemistry reaction.•The chemical modification was confirmed by different techniques, such as 1H NMR, FTIR, XPS, XRD and DSC.•The amphiphilic copolymer obtained is suitable to form core-shell nanoparticles.•Pullulan-g-poly(ε-caprolactone) is a promising candidate for drug delivery systems.