Synthèse d'agents RAFT macromoléculaires hydrophiles à base d'acide (méth)acrylique ou d'alginate pour l'élaboration de nanoparticules par polymérisation en émulsion

摘要

This work describes the synthesis of nanoparticles stabilized by polyelectrolytes from synthetic(poly((meth)acrylic acid)) or natural (alginate) source by controlled free radical polymerization (CRP),namely RAFT, in emulsion. This process is based on the use of a hydrophilic polymer prepared by RAFT (i.e. macroRAFT) which is reactivated in water for the polymerization of a hydrophobic monomer. The formation of amphiphilic block copolymers which self-assemble in situ leads to the formation of nanoparticles. Firstly, we tried to perform the whole process in water. The RAFT polymerization of acrylic acid and methacrylic acid was studied in this context. Well-defined homopolymers were obtained under a large range of conditions, and further used as macroRAFTs in emulsion polymerization of hydrophobic monomers. Stable nanoparticles composed of well-defined amphiphilic block copolymers were produced. It was shown that the control of the polymerization and the nucleation were strongly dependent on the pH. Nevertheless, a good colloidal stability wasobserved in all cases. This “one-pot” process was then extrapolated to the synthesis of particles stabilized by hydrophilic copolymers of N-acryloylmorpholine (NAM) and alginate macromonomer. Nano-objects with various morphologies were obtained. In order to better understand the formation of these morphologies, a model system using a hydrophilic copolymer of NAM and a polyNAM macromonomer obtained by RAFT polymerization was studied in styrene emulsion polymerization.