Controlled synthesis of poly(ε-caprolactone)-grafted dextran copolymers as potential environmentally friendly surfactants

The combination of bioresorbable and biodegradable hydrophilic polysaccharides with biodegradable hydrophobic polyester chains to form totally biodegradable, nonionic brushlike amphiphilic graft copolymers useful as surfactants has been investigated. In fact, a totally controlled and original three-step procedure is described which gives access to a wide range of poly(ε-caprolactone)-grafted dextran copolymer compositions. It consists of the reversible protection of the hydroxyl groups of the polysaccharide backbone by silylation, followed by the ring-opening polymerization of ε-caprolactone initiated by the free remaining hydroxyl groups of the partially silylated dextran in the presence of aluminum and tin-based catalysts. The last step relies upon the removal of silylating groups under mild acidic conditions yielding the desired amphiphilic graft copolymers.