Constructing tough bilayer hydrogel with excellent lubrication performance for load-bearing application

Numerous strategies have been proposed to improve the strength and stiffness of hydrogels, which significantly sacrificed water content, thereby compromising lubrication properties. Hence, it remains challenging to develop elastic and strong hydrogels with excellent lubrication properties for a wide range of applications. Inspired by the stratified structure of natural bio-tissues, the mechanically strong bilayer hydrogels comprising of soft lubricating layer and hard load-bearing layer were prepared. The top porous structure could trap water molecules to achieve low friction (COF-0.009) under a heavily loaded condition of 5 N (contact stress-2.5 MPa), while the bottom layer provided excellent load-bearing capacity. The bilayer hydrogel with high mechanical strength, superior lubrication and excellent wear-resistance properties has considerable potential in joint replacement and tissue scaffold.