Design and property of thermoresponsive core-shell fluorescent nanoparticles via RAFT polymerization and suzuki coupling reaction

Abstract

The polymerization of a 2,7-dibromocarbazole-containing functional monomer, 6-(2,7-dibromo-9H-carbazol-9-yl)hexyl methacrylate (DBCzMA), was successfully carried out via the reversible addition-fragmentation chain transfer (RAFT) technology. The polymerization behavior possessed the feature of “living”/controlled radical polymerization, for example, the first-order kinetics, the linear increase of the molecular weight of the polymer with the monomer conversion and relatively narrow molecular weight distribution (Mw/Mn ≤ 1.27). The amphiphilic copolymers, poly(DBCzMAm-b-NIPAMn), with different chain length of poly(DBCzMA) and poly(N-isopropylacrylamide) (PNIPAM), were successfully prepared via RAFT chain-extension reaction, using poly(DBCzMA) as the macromolecular chain transfer agent (macro-CTA) and NIPAM as the second monomer. Modification of 2,7-dibromide groups in amphiphilic copolymer poly(DBCzMA-b-NIPAM) via Suzuki coupling reaction employed 2,7-bis(4′,4′,5′,5′-tetramethyl-1′,3′,2′-dioxaborolan-2′-yl)-N−9″-heptadecanylcarbazole as the other reaction material to afford a poly(2,7-carbazole)-containing crosslinked materials. The stable and uniform core–shell fluorescent nanoparticles were successfully prepared in water. The formed fluorescent nanoparticles showed good thermoresponsive properties, which is confirmed by dynamic light scattering observation. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4021–4030