Research On Constructing Carbon Material Functional Coating Using Hydrolyzed Tannin Molecular Aggregates As Water Phase Transfer And Immobilization Factor

While preparing functional coatings,the use of nano-conjugated carbon materials,such as carbon nanotubes,graphene and Polyaniline,poses several challenges.For instance,hydrophilic modification can destroy the conjugated structure of carbon,leading to poor compatibility between the coatings and substrates.Such issues ultimately hinder the development of nano-carbon coatings.To overcome these limitations,it is imperative to find a non-covalent bond aqueous dispersion that can maintain the original properties and nanometer scale of carbon materials while improving the compatibility between the coating and substrate.Hydrolyzed tannic acid and ellagic acid have gained popularity due to their rich functional groups and ability to form stable water-dispersed ligands with nano-carbon materials throughπ-πaccumulation.In this study,hydrolyzed tannin aggregates with a high branching degree and accessible area were constructed using hydrolyzed tannin molecules（tannic acid and ellagic acid）to reinforce theπ-πinteraction between hydrolyzed tannins and nano-carbon materials.Meanwhile,the remaining"free"polyphenol branched chains of hydrolyzed tannin on the surface of the hydrolyzed tannin aggregate/nano-carbon material ligand react with the substrate to achieve the transfer and immobilization of nano-carbon material in an aqueous phase.Finally,a functional nano-conjugated carbon material coating was synthesized in an aqueous phase while preserving the original chemical structure and nano-dispersion size of nano-carbon material.The main research contents are as follows:（1）By controlling the molar ratio of Fe^III ions to tannic acid and the environmental p H value,dimeric and trimeric tannic acid/Fe^III complexes were formed.These complexes effectively bind with nano-carbon materials（carbon nanotubes and graphene）throughπ-πstacking interactions,yielding a dispersion of tannic acid/Fe^III/nano-carbon material.Through optimization of preparation conditions,the tannic acid/Fe^III trimeric complex was found to have the optimum dispersing effect on nano-carbon materials,with a particle size in the range of 450-700 nm when the mass ratios of tannic acid to carbon nanotubes and graphene were 0.5 and 1,respectively.Molecular dynamics simulations revealed that the main force between the TA/Fe^III complex and nano-carbon materials wasπ-πstacking,which was proportional to the accessible surface area（SASA）of the solution.Furthermore,conductivity tests were carried out on the carbon coating synthesized from the tannic acid/Fe^III/nano-carbon material dispersion in an aqueous phase demonstrating a fault-free and smooth coating on the hydrogel when the p H exceeded 7.The compression cycle experiment revealed stable normalized resistance strength.Finally,the tannic acid/Fe^III/nano-carbon material was evaluated as an anode material for a lithium battery,showcasing higher specific capacity.（2）To further increase the accessible surface area of the solution,ellagic acid with Gallic acid diploid was used as the dispersant matrix to construct an ellagic acid/Fe^III triple complex with Fe^IIIions for improvedπ-πstacking interaction with nano-carbon materials.After optimizing the preparation conditions,it was found that when the mass ratio of ellagic acid to nano-carbon material was 1,the particle size of the dispersion ranged from 300 to 600 nm.Electrical conductivity tests were carried out on the carbon coating synthesized from the ellagic acid/Fe^III/nano-carbon material dispersion in an aqueous phase,revealing that the coating could form a dense and conductive layer on the substrate surface and effectively improve its electrical conductivity.Finally,cyclic voltammetry tests were conducted on the ellagic acid/Fe^III/nano-carbon material as a battery anode material,showing higher specific capacity.（3）Compared toπ-πstacking interaction,organic cation-πinteraction can lead to higher bond energy between tannic acid/nano-conjugated carbon material ligands.To improve the dispersing effect of tannic acid on nano-carbon materials,the tannic acid/cation/nano-carbon material ligand with cation-πinteraction was constructed by introducing organic cations between tannic acid and nano-conjugated carbon materials.Optimization of the type and amount of organic amine cations in the dispersion of tannic acid/amine cations/nano-carbon materials revealed that the smallest particle size for the dispersion of amine cations/tannic acid/nano-carbon material prepared using cetyltrimethylammonium bromide（CTAB）was achieved at a mass ratio of 0.5 CTAB/tannic acid,with an average particle size of 448 nm.Further reduction of the particle size to 100-300 nm was achieved by adjusting the molar ratio of CTAB/tannic acid to 0.05 FT-IR results showed that CTAB enhanced the organic cation-πinteraction between tannic acid/nano-carbon material,resulting in a red-shift,and increased the dispersing effect of tannic acid.The conductivity test of the carbon coating synthesized from CTAB/tannic acid/nano-carbon material in an aqueous phase revealed that it could form a dense and conductive layer on the substrate surface,thereby effectively improving the electrical conductivity of the substrate.