title: Poly(ethylene oxide) Mushrooms Adsorbed at Silica-Ionic Liquid Interfaces Reduce Friction.
abstract: The adsorbed layer conformation and lubricity of 35, 100, and 300 kDa PEO adsorbed to ionic liquid (IL)-silica interfaces from 0.01 wt % solutions have been investigated using colloid probe atomic force microscopy. The ILs used were propylammonium nitrate (PAN) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), which are protic and aprotic ILs, respectively. Normal force curves reveal steric interactions consistent with adsorbed polymer layers which are best fit using the mushroom model. Friction measurements show that the adsorbed polymer layer markedly reduces friction compared to surfaces sliding in the pure ILs and that lubricity increases with polymer length. When polymer is adsorbed to the sliding surfaces, friction is controlled by the creation and disruption of intermolecular interactions between entangled chains and the dragging of polymer chains through the interpenetration region. These experiments show that added polymer can reduce friction while maintaining the useful properties of ILs as lubricants.
authors: Priority Research Centre for Advanced Fluids and Interfaces, Newcastle Institute for Energy and Resources, The University of Newcastle , Callaghan, NSW 2308, Australia.
authors: James
authors: J
authors: Sweeney
authors: Priority Research Centre for Advanced Fluids and Interfaces, Newcastle Institute for Energy and Resources, The University of Newcastle , Callaghan, NSW 2308, Australia.
authors: Grant B
authors: GB
authors: Webber
authors: Priority Research Centre for Advanced Fluids and Interfaces, Newcastle Institute for Energy and Resources, The University of Newcastle , Callaghan, NSW 2308, Australia.
authors: Rob
authors: R
authors: Atkin