Synthesis of a New Poly(ε-Caprolactone)-g-Chitosan Amphiphilic Graft Copolymer With a "Reverse" Structure.

Hydrophilic Chitosan (CHT) and hydrophobic Poly ε-caprolactone (PCL) are well-known biocompatible and biodegradable polymers that have many applications in the biomedical and pharmaceutical fields. But the mixtures of these two compounds are considered incompatible, which makes them not very interesting. To avoid this problem and to further extend the properties of these homopolymers the synthesis of a new graft copolymer, the fully biodegradable amphiphilic Poly(ε-caprolactone-g-Chitosan) (PCL-g-CHT) is described, with an unusual "reverse" structure formed by a PCL backbone with CHT grafts, unlike the "classic" CHT-g-PCL structure with a CHT main chain and PCL grafts. This copolymer is prepared via a copper-catalyzed 1,3-dipolar Huisgen cycloaddition between propargylated PCL (PCL-yne) and a new azido-chitosan (CHT-N 3 ). In order to obtain an amphiphilic copolymer regardless of the pH, chitosan oligomers, soluble at any pH, have been prepared and used. The amphiphilic PCL-g-CHT copolymer spontaneously self-assembles in water into nano-micelles that may incorporate hydrophobic drugs to give novel drug delivery systems. This article is protected by copyright. All rights reserved.