Dual functionalized telechelic block copolymers with reproducible block sizes prepared by microwave assisted RAFT polymerization

Abstract

This work demonstrates the preparation of amphiphilic block copolymers with remarkable reproducibility of each block and the dual functionalization of the chain ends with a targeting unit and a fluorescent moiety. The size of the resulting micelles can be controlled between 17 and 55 nm by tuning the size of the hydrophobic block. The polymerization of the diblock was carried out by microwave assisted reversible addition fragmentation chain transfer (RAFT) polymerization and results in a very high degree of reproducibility of the number of repeat units of each block. The hydrophilic block of the polymer comprised of poly(2-hydroxyethyl acrylate) (pHEA) while the hydrophobic block was made of poly(2-ethylhexyl acrylate) (pEHA). Folic acid, a folate receptor targeting moiety, was tethered to the α end of the polymer while anthracene was covalently linked to the ω end. The ω end covalent attachment is via a redox cleavable disulfide bond, which is optimal for controlled drug delivery systems. High efficiencies of α- and ω-conjugations were obtained as determined by UV and NMR measurements.