Abstract
Graphene oxide (GO) was incorporated into polyvinyl alcohol (PVA) hydrogel to improve its mechanical and tribological performances for potential articular cartilage replacement application. The compressive mechanical properties, creep resistance, and dynamic mechanical properties of PVA/GO hydrogels with varied GO content were studied. The frictional behavior of PVA/GO hydrogels under stationary and migrating contact configurations during reciprocal and unidirectional sliding movements were investigated. The effects of load, sliding speed, diameter of counterface, and counterface materials on the frictional coefficient of PVA/GO hydrogels were discussed. PVA/0.10wt%GO hydrogel show higher compressive modulus and creep resistance, but moderate friction coefficient. The friction coefficient of PVA/GO hydrogel under stationary and migratory contact configurations greatly depends on interstitial fluid pressurization and tribological rehydration. The friction behavior of PVA/GO hydrogels shows load, speed, and counterface diameter dependence similar to those observed in natural articular cartilage. A low friction coefficient (~ 0.03) was obtained from PVA/0.10wt%GO hydrogel natural cartilage counter pair.Graphical Schematic diagrams of internal structure of PVA and PVA/GO hydrogel
Highlights
Hydrogels have been investigated as cartilage alternatives for decades [1,2,3,4,5,6,7]
The atomic force microscope (AFM) image of graphene oxide (GO) indicates the results of less aggregation, and its thickness is about 1.48 nm (Fig. 1b), which is within the thickness range of the single-layer GO sheets [38]
It is recognized that the friction behaviors of polyvinyl alcohol (PVA)/GO hydrogel under varied movements and contact modes greatly depend on the tribological rehydration, while the biphasic lubrication of hydrogels is guaranteed by the rehydration for interstitial liquid
Summary
Hydrogels have been investigated as cartilage alternatives for decades [1,2,3,4,5,6,7]. Among hydrogels developed for biomedical applications, polyvinyl alcohol (PVA) hydrogel has attracted great attentions as a potential articular cartilage substitute due to its non-toxicity, high water content, good lubrication. Pure PVA hydrogel lacks sufficient load-bearing capacity and wear resistance, which hinders its development [12]. Incorporation of graphene oxide (GO) in PVA matrix is considered as one of the effective ways to reinforce hydrogel. The good dispersion of GO in water is vital for the nanofiller to function at its best [13,14,15]. Liang et al [16] has confirmed the efficient load transfer between the graphene and PVA matrix. The water-locking and cross-linking effects of GO had been demonstrated in our previous study [17]
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