Facile Syntheses of Surface-Functionalized Micelles

ABSTRACT: Block copolymer micelles and shell cross-linked nanoparticles (SCKs) pre-senting Click-reactive functional groups on their surfaces were prepared using two sep-arate synthetic strategies, each employing functionalized initiators for the controlled radical polymerization of acrylate and styrenic monomers to afford amphiphilic block copolymers bearing an alkynyl or azido group at the a-terminus. The first route for the synthesis of the azide-functionalized nanostructures was achieved via sequential nitro-xide-mediated radical polymerization (NMP) of tert-butyl acrylate and styrene, originat-ing from a benzylic chloride-functionalized initiator, followed by deprotection of the acrylic acids, supramolecular assembly of the block copolymer in water and conversion of the benzylic chloride to a benzylic azide. In contrast, the second strategy utilized an alkynyl-functionalized reversible addition fragmentation transfer (RAFT) agent directly for the RAFT-based sequential polymerization of tetrahydropyran acrylate and styrene, followed by selective cleavage of the tetrahydropyran esters to give the a-alkynyl-func-tionalized block copolymers. These Click-functionalized polymers, with the functionality located at the hydrophilic polymer termini, were then self-assembled using a mixed-mi