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Friction

Keywords

superlubricity, hydrophilic polymer, protein, polysaccharide

Abstract

Hydrophilic polymer coatings can improve the surface characteristics of artificial implants. However, because they are used in vivo, they inevitably come into contact with biomolecules that affect their interfacial tribological properties. In this paper, the friction behaviors of poly(vinylphosphonic acid) (PVPA)-modified Ti6Al4V and polytetrafluorethylene balls were analyzed using albumin, globulin, aggrecan, and hyaluronic acid as lubricants. The interaction properties and dynamic adsorption characteristics of the biomolecules and PVPA molecules were explored by a quartz crystal microbalance to identify the cause of the friction difference. It was found that protein molecules disturbed the superlubricity of the PVPA-phosphate-buffered saline system because of the formation of a stable adsorption film, which replaced the interfacial characteristics of the PVPA coating. Polysaccharides, with their excellent hydration properties and polymer structure, had an unstable dynamic interaction or zero adsorption with PVPA molecules, and hardly changed the superlubricity of the PVPA and phosphate-buffered-saline system. The influence mechanism of the specific friction of proteins and polysaccharides was analyzed. Interactions were observed among different biomolecules. Polysaccharides can potentially reduce protein adsorption. The result of the synergistic regulation of the friction coefficient for PVPA-modified Ti6Al4V is approximately 0.017. The results of this study will provide a theoretical basis for the use of polymer coatings in vivo.

Publisher

Tsinghua University Press

Included in

Tribology Commons

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