the total uptake of pll 375 g 5 6 peg 5 on several oxides surfaces showing the dependence of the amount of uptake on the isoelectic point of the oxide surface lubrication of steel pin against glass with pll g peg copolymers sliding geometry two different architectures of pll peg pll 20 g 3 4 peg 2 and pll 20 g 3 4 peg 5 were dissolved in hepes at a concentration of 0 25 g liter and used to lubricate a couple consisting of a steel pin and glass the steel is covered with its native oxide the contact geometry for testing lubricant formulations is shown in fig5 the lubricant was placed on the surface of the glass and the steel pin was then placed on top of the glass and the glass disk rotated to create a sliding motion between the two surfaces the glass and the pin were also tested in a polymer free buffer in fig6 the sliding friction reduction effect of the added polymer is seen when the polymer containing solution is compared to the polymer free buffer the friction coefficient u03bc of buffer 0 28 is reduced to a value of 0 13 for pll 20 g 3 4 peg 2 and to a value of 0 11 for pll 20 g 3 4 peg 5 thus a friction reducing effect is observed these results also indicate that the reduction in friction increases as the length of.