Preparation Of Modified Sericite And Biomass Carbon Quantum Dots Using Silane Coupling Agent(KH550)

As a silane coupling agent,γ-Aminopropyltriethoxysilane（KH550）has rich groups:nitrogen and silicon oxide groups.It is often used to modify hydrophobic of sericite However,the modification efficiency and application range of KH550 still need to be increased.Based on the unique structure of KH550,this paper has proposed a new method for hydrophobic modification of sericite and has applied KH550 to the preparation of biomass carbon quantum dots.The main work is as follows:1.Sericite is hydrophilic and easy to agglomerate in insoluble reagents,which hinders the application of sericite in composite materials.In this paper,the surface modification process of sericite was optimized,including reaction temperature and KH550 hydrolysis time,and so on.In addition,dichloromethane（DCM）was used as a coupling reaction promoter for the hydrophobic modification of sericite for the first time in this paper.DCM can make the reaction system formed an oil-water interface,which result in KH550 to extend and arrang directionally on the oil-water interface,and increase the density of silane coupling agent silanol groups on the water side of the interface.Therefore,the addition of DCM significantly promoted the reaction of KH550 and the silico hydroxy of activated sericite.It promoted the hydrophobic modification effect of sericite and increased the contact angle of modified sericite from 0°to 88.90°.Furthermore,polystyrene（EPS）particles with uniform size can be prepared by adding modified sericite into styrene suspension polymerization,Addition of sericite has reduced the thermal conductivity of EPS by 15%.This research has provided an effective mean for the study of surface modification of sericite,and has supplied a deeper insight for the preparation of clay-polymer composite system.2.In this research,carbon quantum dots（C-CDs）possesses bright blue fluorescence emission,which synthesized by hydrothermal method.The raw materials of carbon quantum dots are cow nail and KH550.Thereinto,KH550 endows C-CDs with rich surface groups,causing it have sensitive fluorescence response to Pd²⁺.C-CDs is spherical with a diameter of about 3 nm and possesses excellent dispersion.It maintains good fluorescence stability in different Na Cl concentration and different p H.The concentration of Pd²⁺is 0-10μmol/L,the fluorescence intensity of C-CDs is linear with the concentration of Pd²⁺,and the detection limit is 2.304×10^-5μM.The quenching mechanism of Pd²⁺on C-CDs is dynamic quenching.C-CDs was used to detect Pd²⁺in actual water samples.The results showed that C-CDs can be potentially applied to detect Pd²⁺ions.Moreover,due to the excellent luminous efficiency of C-CDs（quantum yield up to 39.32%）and the high capacity of polyvinyl alcohol（PVA）to accommodate C-CDs,C-CDs doped PVA film has bright blue emission,which possesses potential applications in the field of solid-state lighting.