Influence of hydrolysis of polyvinyl alcohol on its lubrication for styrene-ethylene-butylene-styrene block copolymer

Poly(vinyl alcohol) (PVA) aqueous solution, as commonly seen in our daily life playing a role similar to artificial tears, is a type of lubricant. However, no study has been devoted to disclose whether and how the degree of hydrolysis (DH) affects its lubrication capability. In this work, it is found that stable while lower friction coefficient could be achieved even at a concentration as low as 0.02 wt% when partial DH-PVA is employed. In contrast, neither deionized water nor the solution of high DH-PVA could achieving comparable lubrication. It is proposed that such excellent lubrication effect is attributed to rapid adsorption of PVA chains to the substrate, forming a surface layer containing abundant water molecules upon movement of the friction pair.