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(a) Friction coefficient μ between planar surfaces decorated by PE brushes (solid lines) and neutral brushes with the same degree of chain polymerization N and grafting density ρ (dotted lines) as a function of distance D between surfaces in logarithmic coordinates. (b) Ratio of friction coefficients μbrush/μbare for PE brush-decorated and bare surfaces with the same surface charge density in logarithmic coordinates. The region of enhanced lubrication by PE brushes is shadowed pink.
