In situ synthesis of thermo-responsive ACB triblock terpolymer nanoparticles through seeded RAFT polymerization

Abstract

Seeded RAFT polymerization is proposed to prepare thermo-responsive ACB triblock terpolymer nanoparticles of poly[N,N-(dimethylamino) ethyl methacrylate]-block-polystyrene-block-poly(N-isopropylacrylamide) (PDMAEMA-b-PS-b-PNIPAM) containing a middle hydrophobic C block and two thermo-responsive blocks A and B. Following this seeded RAFT polymerization, the nanoparticles of the AC diblock copolymer containing a thermo-responsive block of poly[N,N-(dimethylamino) ethyl methacrylate] (PDMAEMA) are prepared through the macro-RAFT agent mediated dispersion polymerization, and then the in situ synthesized AC diblock copolymer nanoparticles are used as seed in the RAFT polymerization, onto which the other thermo-responsive B block of poly(N-isopropylacrylamide) (PNIPAM) is introduced. The synthesized triblock terpolymer nanoparticles contain a hydrophobic core of the middle polystyrene (PS) block and a mixed corona of two thermo-responsive PNIPAM and PDMAEMA blocks. The thermo-response of the PDMAEMA-b-PS-b-PNIPAM nanoparticles is checked, and the morphology of the triblock terpolymer nanoparticles during the thermo-responsive phase transition is detected. The proposed seeded RAFT polymerization is believed to be a valid method to prepare ACB triblock terpolymer nanoparticles containing two thermo-responsive blocks.