Pettersson Torbjörn, Naderi Ali, Makuska Ricardas, Claesson Per M
Department of Chemistry, Surface Chemistry, Royal Institute of Technology, Drottning Kristinas väg 51, SE-10044 Stockholm, Sweden.
Langmuir. 2008 Apr 1;24(7):3336-47. doi: 10.1021/la703229n. Epub 2008 Feb 16.
The effect of side chain to charge ratio on the frictional properties of adsorbed layers formed by bottle-brush polyelectrolytes with poly(ethylene oxide) side chains has been investigated. The brush polyelectrolytes were preadsorbed from 0.1 mM NaNO(3) solutions onto mica and silica surfaces; the interfacial friction was then measured in polyelectrolyte-free solutions via AFM (with the silica surface acting as the colloidal probe). It was concluded that the decisive factor for achieving favorable lubrication properties is the concentration of nonadsorbing poly(ethylene oxide) side chains in the interfacial region. However, contrary to what may be expected, the results showed that an ideal brush layer structure with the adsorbed polymers adopting comb-like conformation is not necessary for achieving a low coefficient of friction in the asymmetric mica-silica system. In fact, the lowest coefficient of friction (<0.01) under applied pressures as high as 30 MPa was observed for a system with a side chain to charge ratio of 9:1, incapable of forming brush-like layers.
研究了侧链与电荷比 对由带有聚环氧乙烷侧链的瓶刷状聚电解质形成的吸附层摩擦性能的影响。将刷状聚电解质从0.1 mM硝酸钠溶液预吸附到云母和二氧化硅表面；然后通过原子力显微镜在无聚电解质溶液中测量界面摩擦力（以二氧化硅表面作为胶体探针）。得出的结论是，在界面区域实现良好润滑性能的决定性因素是非吸附性聚环氧乙烷侧链的浓度。然而，与预期相反，结果表明，在不对称云母-二氧化硅体系中，要实现低摩擦系数，吸附聚合物采用梳状构象的理想刷层结构并非必要。事实上，对于侧链与电荷比为9:1且无法形成刷状层的体系，在高达30 MPa的外加压力下观察到了最低摩擦系数（<0.01）。
