Construction And Lubrication Of Triton X-100/Imidazole Ionic Liquid/Graphene/Silica Composite Lamellar Liquid Crystals

Surfactants can form a variety of molecular ordered structures and play an important role in life,information,energy and materials.Lamellar liquid crystals(LLCs),as one of the most important types of molecular assembly ordered structure,have been widely studied and applied in the fields of material preparation,microchemical reaction,lubrication and life science.Traditional LLCs are formed by surfactants,cosurfactants(usually linear alcohols of medium carbon chain length)and water.Ionic liquid,as a kind of green solvent,has good lubrication performance and its amphiphilic structure also provides an opportunity for forming LLCs.Nanoparticles usually have some lubricating properties due to their small size.For example,graphene nanosheets and silica nanoparticles can be used as additives in both water-based and oil-based lubricants,which can effectively improve their lubrication performance.In this paper,composite LLCs of Triton X-100/imidazole ionic liquid/graphene/silicon were prepared with ionic liquid as co-surfactant,graphene and silicon as additives,which effectively improved the molecular order of surfactant in LLCs and improved the lubrication performance of the LLCs system.The research content of this paper is mainly divided into the following five parts:Ionic liquids/LLCs with good lubrication performance were prepared by addition of amphiphilic 1-alkyl-3-methylimidazolium hexafluorophosphate(CnmimPF6,n=8,12)and 1-alkyl-3-methylimidazole ditrifluorosulfimide salt(CnmimNTf2,n=8,12)into TritonX-100/n-C10H21OH/H2O LLCs.The influence of the concentration and the alkyl chain lengths of ionic liquids on the microstructures and the tribological properties of lamellar liquid crystals were investigated via the small-angle X-ray scattering(SAXS)technique and friction and wear tester.The relationship between the microstructure of LLCs and their tribological properties is established.Ionic liquids CnmimNTf2 has amphiphilic molecular structure and good self-lubrication performance,which can be used as cosurfactants to from Triton X-100/CnmimNTf2/H2O LLCs.The effect of the content and long chain alkyl chain n of CnmimNTf2 on the microstructure of Triton X-100/CnmimNTf2/H2O LLCs has been determined by polarized light microscopy,small angle X-ray scattering and 2H NMR,and their rheological and tribological properties with different concentration of CnmimNTf2 and the length of alkyl chain in the LLCs were investigated.Graphene is used as a high-performance lubricant additive with its ultra-thin lamellar structure,excellent mechanical properties and self-lubrication.In this chapter,Graphene was added into Triton X-100/CnmimNTf2/H20 to prepare Graphene/Triton X-100/CnmimNTf2/H2O composite LLCs and studied the influence of graphene concentration on the microstructure and lubrication performance of Triton X-100/CnmimNTf2/H2O LLCs.The distribution mechanism of graphene in LLCs structure is discussed.The rotational rheometer was used to test the change and creep recovery ability of Graphene/Triton X-100/CnmimNTf2/H2O LLCs during shear process.The graphene LLCs system with the best lubrication performance was found by tribological property test.The abrasive surface elements were analyzed by Raman spectroscopy and photoelectron spectroscopy.The lubrication mechanism of Graphene/Triton x-100/CnmimNTf2/H2O LLCs was proposed between the structural parameters of LLCs and the lubrication performance.Silica nanoparticles,as an economical and environmentally friendly nano material,have attracted extensive attention in tribology,especially in its application as lubricant additive.In this chapter,SiO2/Triton X-100/CnmimNTf2/H2O LLCs were prepared by adding silica nanoparticles into Triton X-100/CnmimNTf2/H2O LLCs.The influence of concentration and particle size of silica nanoparticles on the structure of LLCs is discussed.The lubrication performance of SiO2/Triton X-100/CnmimNTf2/H2O LLCs system was tested by friction and wear test to find the optimum particle size and concentration of Siv2 LLCs.The lubrication mechanism of SiO2/Triton X-100/CnmimNTf2/H2O LLCs was proposed by analyzing the chemical state of elements on the surface of abrasive surface with photoelectron spectroscopy.Graphene/SiO2/Triton X-100/CnmimNTf2/H2O LLCs was prepared by combining graphene,silica nanoparticles and Triton X-100/CnmimNTf2/H2O LLCs to integrate their lubrication advantages.The effect of graphene concentration and the silica particle size on the structural parameters,order parameter and the tribological performance of were systematically studied Combined with the light electronic energy spectrum,Raman spectrum,the lubrication mechanism of composite LLCs was analyzed,which provides a new way and idea for the design of a new type of ionic liquid based composite lamellar liquid crystal lubricant.