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구강희,이준혁,( Kin Liao ),김범준 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Design of surfactant is of great importance to precisely control the shape of nanostructured polymeric particles. Herein, we developed a new strategy to produce anisotropic shape of block copolymer particles using thermoresponsive surfactant based on Poly(N-isopropylacryamide) (PNIPAM). A dramatic transition of both the external shape and internal morphology of the particles of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) was induced by temperature change. When the temperature is lower than Lower Critical Solution Temperature (LCST) of PNIPAM, PNIPAM surfactant was preferentially localized at the interface between the P4VP domain and the surrounding water, producing unique convex lens-shaped BCP particles. Above the LCST of PNIPAM, PNIPAM surfactant was localized inside of the P4VP domain, which generated a morphological transition from cylinder to lamellar, producing unique striped-ellipsoid BCP particles.
Shape-controlled Janus Particles with pH-Responsive Surfactant Properties
구강희,장세규,( Kin Liao ),김범준 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Amphiphilic Janus particles can stabilize multiphasic fluids mixtures such as emulsions. In particular, the ability to control the shape and wetting properties of Janus particles provide a powerful strategy to control their surface activity. Herein, polystyrene/poly(2-vinylpyridine) (PS/P2VP) Janus particles were simply produced by oil-in-water emulsion technique, and applied to stabilize emulsions of toluene and water, where the surfactant properties were completely reversible in response to solution pH. One side of Janus particle is composed of hydrophobic styrene, whereas the other side is rich in a pH-sensitive hydrophilic P2VP. Therefore, these Janus particles allowed to stabilize different types of emulsions, and induce phase inversion of emulsions in response to changes in solution pH. Moreover, metal-loaded hybrid Janus particles were demonstrated by incorporating Au, Pd, Pt nanoparticles in the P2VP domain, making the particles useful for nanoreactors and molecule carriers.