Characterization,simulation And Conductivity Test Of Histidine Intercalated Hydrotalcite-montmorillonite Composite

This paper studied around two kinds of layered materials with opposite charges,hydrotalcites(LDHs)and montmorillonite(MMT).Amphiphilic compound histidine(His)was selected as the interlaminar guest and assembled to obtain a new composite layered material��histidine intercalated hydrotalcite-montmorillonite complex(His-LDHs-MMT).The structure and properties of the complex were systematically explored,and the His-LDHs-MMT structural model was constructed.The stable configuration and interaction of the complex were studied by quantum chemical method.The main works were as follows:1.The histidine intercalated zinc-aluminum hydrotalcites(His-Zn2Al-LDHs)was prepared by coprecipitation method and exfoliated of its layered structure with formamide;histidine intercalated montmorillonite(His-MMT)was prepared by ion exchange method and fully swelled with deionized water.The stripped His-Zn2Al-LDHs and the swollen His-MMT were combined in different ratios to obtain the His-LDHs-MMT complex.The XRD and TEM results showed that when the mass ratio of His-Zn2Al-LDHs to His-MMT was 4/1-6/1,a composite with both characteristic diffraction peaks and obvious layered structure can be obtained.The FT-IR determined the composition of complex by the absorption peak of characteristic functional group.The TGA results showed that the composite has higher thermal stability than the components;the EIS test showed that the composite has good conductivity potential.2.The supramolecular structure model of His-Zn2Al-LDHs,His-MMT and His-LDHs-MMT were constructed by Materials Studio8.0(MS8.0).The spatial geometry of the models were optimized by using the GGA/PW91 method and the DND basis set of density functional theory(DFT)with Dmol3 module.The calculation results indicated that the monolayer histidine was inserted between the hydrotalcite and the montmorillonite laminate in a nearly flat manner,and formed a stable structure with the laminate through hydrogen bonding and electrostatic interaction.The experimental and theoretical simulation XRD spectra correspond well to each other.3.It was found that the intercalation assembly of composite material can effectively improve the conductivity,so lithium modification was performed to improve the conductivity.The His-LiAI-LDHs and Li-MMT were prepared by the coprecipitation method and the ion exchange method,the lithium-modified His-LDHs-MMT was prepared by composite assembly of the two materials.A series of characterization were carried out on the composites.It was found that when the mass ratio of LiAl-LDHs to Li-MMT was 1/1-1/5 can obtain a composite with both characteristic diffraction peaks.The ionic conductivity of the composite can reach 10-4 S/cm order of magnitude at room temperature.