Surface coated iron particles via atom transfer radical polymerization for thermal–oxidatively stable high viscosity magnetorheological fluid

Abstract

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).

A facile controllable coating of carbonyl iron particles with poly(glycidyl methacrylate): a tool for adjusting MR response and stability properties

“…The ATRP system consists of alkyl halide as an initiator, metal halide as a catalyst and a ligand complexing the metal halide catalyst and thus improving its solubility in a polymerization mixture and fine tuning its catalytic efficiency. 35 So far, only two polymers poly(butyl acrylate) 25 and poly(2-fluorostyrene) 34 with molecular weights above 15 000 g mol À1 were grafted using surface-initiated ATRP (SI-ATRP) in order to prepare core-shell CI-polymer particles for MR suspensions. 35 So far, only two polymers poly(butyl acrylate) 25 and poly(2-fluorostyrene) 34 with molecular weights above 15 000 g mol À1 were grafted using surface-initiated ATRP (SI-ATRP) in order to prepare core-shell CI-polymer particles for MR suspensions.…”

The chemical stability and cytotoxicity of carbonyl iron particles grafted with poly(glycidyl methacrylate) and the magnetorheological activity of their suspensions

“…In EDS measurements, the electron beams are only able to penetrate a few nanometers deep into the sample surface[37]. In EDS measurements, the electron beams are only able to penetrate a few nanometers deep into the sample surface[37].…”

Superparamagnetic Molecularly Imprinting Polymers for Adsorbent and Separation Pentapeptides by Surface ATRP

“…Since atom transfer radical polymerization (ATRP) was introduced by Matyjaszewski's group (5) and was widely used to synthesize polymers that have controlled morphologies, functionality, polydispersities, and predictable molecular weights. A wide range of monomers can be polymerized using ATRP either at mild conditions (6). Biomacromolecule imprinting requires mild preparation conditions to keep specific structure.…”