Preparation of hydrogel nanoparticles by atom transfer radical polymerization of N-isopropylacrylamide in aqueous media using PEG macro-initiator

• DOI: 10.1016/j.polymer.2005.02.009
• Publication Date: 2005-03-16T12:14:06Z
• Authors: Keon Hyeong Kim; Jungahn Kim; Won Ho Jo
• Keywords: Atom-transfer radical-polymerization; Poly(N-isopropylacrylamide); Precipitation polymerization; Chain transfer

Abstract PEG- b -PNIPAM block copolymers are synthesized by the atom transfer radical polymerization of NIPAM using PEG macro-initiator. When the polymerization temperature is 25 °C, the block copolymer is soluble in water, whereas the block copolymer is phase-separated to form micelles during polymerization as the polymerization temperature is raised to 50 °C, the temperature above the LCST of PEG- b -PNIPAM. To prepare stable hydrogel nanoparticles in water at room temperature, a small amount of N , N ′-ethylenebisacrylamide is added as a cross-linker to the reaction system, where the size of nanoparticles is controlled by the composition of mixed solvent.