화학공학소재연구정보센터
Journal of Applied Polymer Science, Vol.128, No.1, 470-480, 2013
Surface Coated Iron Particles via Atom Transfer Radical Polymerization for Thermal-Oxidatively Stable High Viscosity Magnetorheological Fluid
A surface grafting technique for poly(2-fluorostyrene) onto iron particles via atom transfer radical polymerization (ATRP) is described. Grafted poly(2-fluorostyrene)-iron particles were synthesized by immobilizing 2-4(-chlorosulfonylphenyl)-ethyltrichlorosilane to the iron particles through the covalent bond of a silanol group, followed by the polymerization of 2-fluorostyrene monomer. The grafted polymer-iron particles display a higher thermal transition temperature compared to bulk polymer because the covalent bond between the polymer backbone and the surface of the iron particles restricts the molecular mobility. The molecular weight of the synthesized poly(2-fluorostyrene) has been measured and it has a narrow molecular weight distribution (M-w/M-n < 1.1). From thermogravimetric analysis, the thermal stability of poly(2-fluorostyrene) is superior to polystyrene. Also, the high viscosity magnetorheological fluid (HVMRF) prepared from surface coated iron particles has excellent thermo-oxidative stability, having nearly constant viscosity. These materials exhibit a large increase in shear yield stress for the off-and on-state as compared to a benchmark high viscosity magnetorheological fluid (HVMRF) and -coated iron particle HVMRF. In addition, this type of fluid eliminates iron particle settling which is a common problem found in traditional magnetorheological fluids (MRFs). (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 470-480, 2013