Structural effect of emulsifiers on the emulsion stability of a water/benzene mixture

Abstract

Core–shell-type microspheres with microphase-separated shells of polystyrene (PS) and poly(ethylene glycol) (PEG) (microsphereblock: molar ratio: PS/PEG 49.1/45.9 mol %; Mw: PS chain: 1.07 × 104, PEG chain 1.0 × 104; the ratio of arm numbers of PEG to PS: 1.0; microspheregraft: molar ratio: PS/PEG 33.8/55.9 mol %; Mw: PS chain: 1.54 × 104, PEG chain 1.0 × 104, the ratio of arm numbers of PEG to PS: 2.55) were synthesized by crosslinking of spherical domains of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(4-vinyl pyridine) (P4VP) of the microphase-separated films of poly(ethylene glycol)-block-poly(2-hydroxyethyl methacrylate)-block-polystyrene triblock terpolymer (Mn: 2.18 × 104; molar ratio: PS 49.1 mol %, PHEMA 5.0 mol %, PEG 45.9 mol %) and polystyrene-block-[poly(4-vinyl pyridine)-graft-poly(ethylene glycol)] block–graft copolymer (Mn: 4.56 × 104; molar ratio: PS 33.8 mol %, P4VP 10.3 mol %, PEG 55.9 mol %; branch number of PEG: 2.55), respectively. The structures of microphase-separated films were investigated by transmission electron microscopy and small-angle X-ray scattering. The effects of the arm number ratio of PS to PEG and the total arm number on the stability of the water/benzene emulsion were investigated. The emulsion stability of oil in water was improved by using the microsphere synthesized with the microspheregraft. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 321–331, 2004