Preparation,Modification And Application Of Novel Graphene-Based Nanomaterials And Their Composites

Graphene consisting of single layer carbon atoms with a unique 2 dimensional structure,owns great research value and application potential in different fields such as energy storage and composite materials,due to the excellent characters.However,strong surficial chemical inertness and uncontrollability of the composite largely limit the development of graphene-like materials.Therefore,various methods to improve the applied properties of modified materials based on maintaining the advantages of graphene itself have become the research frontier and hotspot of material science.In order to develop applications of graphene,this thesis focuses on the preparation and modification of graphene-based polyvinyl alcohol hydrogels and novel epoxy resin corrosion protective coatings.In addition,the protection effect of graphene sheet towards molecular crystals and gold nanoparticles has been systematically discussed,which could contribute to the application and development of graphene in crystals filed.Based on the summary of the fabrication methods,experiment process and performance researches of garphene hydrogels,this paper proposes a new kind of GO-SPAN-PVA hydrogel,aiming at improving the mechanical property,moisture content,adsorption and desorption performance of the hydrogel.Excellent mechanical property is found in the obtained hydrogel,high elasticity and immutability have been verified as well.The results of moisture content test indicated that the highest moisture content of the hydrogel could reach 87.84% under an additional GO-SPAN dosage of 0.8wt%,which also showed the best adsorption effect.The results of desorption and renewability measurements indicated that the third adsorption amount could reach 100% after desorption,and the sixth adsorption amount could also reach over 80%,which illustrated the excellent adsorption capacity after multiple times desorption experiments.Additionally,results of fabricating process and measurement could contribute to the designing of more kinds of hydrogels in theoretical and experimental basis.Furthermore,as for epoxy resin corrosion protective coatings,GO-SAT was fabricated by chemical synthesis in our experiments for improving the corrosion protection of the coating based on the spin-coat technology of Q235 carbon steel.The synergistic effect between GO and SAT makes it easier for GO to disperse in epoxy resin and increases the corrosion protective performance.Moreover,the corrosion protective efficiency would reach 96.42% with 10 mg GO-SAT.The addition of GO-SAT composite makes the diffused path of the corrosive medium within coatings longer and more circuitous due to the excellent barrier effect of GO.The results of contact angle showed that the addition of GO-SAT in coatings could increase the contact angle from 77.9° to 106.2°,so the diffusion rate and number of the corrosion medium would be obviously decreased.Moreover,for a better understanding of the corrosion protective mechanism,VTA has been prepared to combine with rGO.Obviously,the addition of VTA could help rGO forming a uniform suspension solution,which could keep in a stable status in epoxy resin coatings.Results of electrochemical measurements showed that the addition of VTA-rGO could significantly improve the corrosion protection of epoxy resin coatings under 3.5wt% NaCl solution.The fabrication of the series of novel composite materials could not only enrich the methods of modifying graphene with various organics,but also develop the application of graphene-like materials in corrosion protective coatings.Finailly,as for molecular crystals and AuNP,the protection effect of graphene towards molecular crystals(including pyranine)and AuNP was investigated based on the excellent barrier effect of graphene sheet.And the pyranine crystals with good water solubility and pH-sensitivity could be covered underneath the graphene after the graphene transfer process.The optical results after dealing with different solvents explained that pyranine crystals underneath graphene sheet could stand on the glass slide due to the unique sheet structure and physical barrier effect of graphene itself.Based on the previous conclusion,this paper proposes an idea to cover the AuNP underneath graphene.Following,an effective protection from graphene sheet under severe experimental conditions and applied environment could be verified by the results of experiments.The conclusion of our experiments could provide important theoretical support and experiment evidence for the application of different molecular crystals and AuNP in various solvents,and also reveal the enormous potential of graphene sheet in crystal-scale field.