Graphene scavenges free radicals to synergistically enhance structural properties in a gamma-irradiated polyethylene composite through enhanced interfacial interactions

Abstract

A unique strategy for scavenging free radicals in situ on exposure to gamma irradiation in polyethylene (PE) nanocomposites is presented. Blends of ultra-high molecular weight PE and linear low-density PE (PEB) and their nanocomposites with graphene (GPEB) were prepared by melt mixing to develop materials for biomedical implants. The effect of gamma irradiation on the microstructure and mechanical properties was systematically investigated. The neat blend and the nanocomposite were subjected to gamma-ray irradiation in order to improve the interfacial adhesion between PE and graphene sheets. Structural and thermal characterization revealed that irradiation induced crosslinking and increased the crystallinity of the polymer blend. The presence of graphene further enhanced the crystallinity via crosslinks between the polymer matrix and the filler on irradiation. Graphene was found to scavenge free radicals as confirmed by electron paramagnetic resonance spectroscopy. Irradiation of graphene-containing polymer composites resulted in the largest increase in modulus and hardness compared to either irradiation or addition of graphene to PEB alone. This study provides new insight into the role of graphene in polymer matrices during irradiation and suggests that irradiated graphene-polymer composites could emerge as promising materials for use as articulating surfaces in biomedical implants.

Graphene oxide enhanced, radiation cross-linked, vitamin E stabilized oxidation resistant UHMWPE with high hardness and tensile properties

“…This may be that the mobility of chain scission is hindered by the strong interface binding force between GO and VE/UHMWPE matrix. In addition, Gonçalves et al 28 and Kolanthai et al 29 demonstrate that GO/graphene has ability to scavenge free radicals to some extent. As a result, the incorporation of GO further reduces the crosslink density of GO/VE/UHMWPE nanocomposite.…”

“…Irradiation could result in cleavage of C-C and C-H bond, and generates free radicals which can recombine with each other to form molecular bonds and increases the interface interactions. Moreover, Kolanthai et al 29 investigates the effect of graphene on the mechanical properties of UHMWPE/LLDPE (linear lowdensity polyethylene)/graphene. The results show that both irradiation and the ller of graphene could enhance the interfacial interactions between graphene and UHMWPE/LLDPE matrix.…”

“…Perez and Vanderhart 37 also report that irradiation induced crosslink formation and produced Y-type branches and H-type branches. In addition, Kolanthai et al 29 reports that GO could gra on polymer chains during the irradiation process, and then the interactions at polymer-graphene interface are enhanced. Anson-Casaos et al 38 reports that graphene materials could role as radical scavengers and crosslinking generators.…”

“…The conjugated double bonds which consist in carbon nanostructures give carbon nanomaterials a great ability of electron donor-acceptor. 29,39 Therefore, irradiation crosslinking treatment not only enables UHMWPE molecule to form reticular structure, but also causes the broken C-C bonds of GO to react with the broken C-C bonds of UHMWPE to form new C-C bonds, as shown in Fig. 9b.…”

Hydrophilic Carbon Nanomaterials: Characterisation by Physical, Chemical, and Biological Assays

“…[6][7][8] Despite the benefits that carbon nanomaterials can provide to medicine, their intrinsic therapeutic potential, comingf rom their antioxidant and radical scavenging capabilities in biological systems, has not been extensively investigated. The antioxidant properties of carbon-basedm aterials, such as carbon nanotubes, graphene and graphene oxide, have been broadly recognised, [9][10][11][12][13] although they have only found utility for the protection of polymericm atrices against oxidative degradation, [14][15][16][17] and not in the biomedical field due to their toxicity and low bioavailability. [18,19] Because carbon dots are known to have good water-solubility,b iocompatibility and low cytotoxicity,t hey would be good candidates for therapeutic applicationsi ft hey displayed antioxidant andr adical scavenging capabilities.…”