Amino Acid Assisted Mechanochemical Modification Of Functional Materials:preparation And Properties

Mechanochemistry is a new synthesis method with simple process,low energy consumption and environmental protection.Therefore,mechanochemistry has been widely used in the preparation of various materials.Functional composites,while maintaining the excellent properties of each component,can also obtain comprehensive properties through the complementary performance of each component,which has a wide range of application values.Therefore,the design and synthesis of functional composites with excellent properties is a hot research topic.In terms of the above problems,in this thesis,mechanochemical methods were utilized to synthesize functional composites modified with various amino acids.The main contents were summarized as follows:1.A new method was proposed to modify boron nitride by mechanochemistry using amino acid as auxiliary reagent.During the mechanochemical exfoliating of boron nitride,Lewis acid-base interactions can occur between the electron-deficient boron atom in boron nitride and the amino group in the amino acid.Two amino acids grafted boron nitride nanoplatelets,Lys@BN and Glu@BN,were successfully prepared via ball-milling of h-BN with L-Lysine and L-Glutamic acid,respectively.It is found that,the dispersion state of Lys@BN and Glu@BN in water have been effectively stabilized.PVA hydrogel composites with Lys@BN and Glu@BN as functional fillers have been constructed and well-studied.With 11.3wt%Lys@BN incorporated,the thermal conductivity of Lys@BN/PVA hydrogel composite is up to 0.91 W·m^-1K^-1,increased by 78%,comparing to the neat PVA hydrogel.Meanwhile,the mechanical and self-healing properties of the composites are simultaneously largely enhanced.2.A simple method of preparing cathode materials for lithium-sulfur battery by mechanochemistry is proposed.The poly-levodopa modified sulfur(PDOPA@S)composites have been prepared by mechanochemical method using the auto polymerization of L-Dopa.Using PDOPA@S composite material as the cathode material for lithium-sulfur batteries,the electrochemical performance of the batteries was fully explored.When the mass ratio of elemental sulfur to L-Dopa was 7 to 3,the maximum discharge specific capacity was up to 1232 mAh·g^-1,under the current density of 0.1C and the voltage range of 1.7?2.8 V.After 100 cycles,the discharge capacity retention rate was still more than 70%,with the Coulomb efficiency was up to 97%,which indicated high stability and availability of sulfur.