Friction of double‐network hydrogels against glass substrate in poly(vinyl alcohol) aqueous solution

Abstract The frictional coefficient of biological joint cartilage is extremely low. For this, many researchers are looking to develop materials that are similar to those in nature. We prepared a poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate)/polyacrylamide double‐network hydrogel, and tested the friction of the hydrogel in poly(vinyl alcohol) ( PVA ) aqueous solution, which imitates a biological environment, against glass substrate. Results show that there is a transition sliding velocity in the friction test, which decreases with an increase in PVA solution concentration. At low sliding velocities, the frictional stress exhibits a minimum at a PVA concentration of 2 c * , where c * is the overlap concentration. It is assumed that a separation layer of PVA has formed completely at this concentration, the thickness of which is calculated. In addition, the friction of the hydrogel is not sensitive to the normal pressure in PVA aqueous solution. © 2014 Society of Chemical Industry