Preparation And Characterization Of Nanolayered Organic-Silica Hybrid Materials

Lamellar structure organic-silica hybrid materials have become hot spots in recent years due to their excellent properties.According to reports in the literature,self-assembly of siloxane precursors and their hydrolysis and cross-linking reaction are currently used to prepare lamellar structure organic-silica hybrid materials.The structure of the precursor,the reaction conditions are important factors controlling the formation of the layered structure.However,most of the layered structures that have been prepared were thick layers with stacked layers.The preparation of thin-layer or single-layer organic-silica hybrid materials has rarely been reported.Based on the above background,we designed and prepared an amphiphilic precursor molecule that can be easily prepared,using the self-assembly properties of the amphipathic molecule and selecting the appropriate conditions for the hydrolysis cross-linking reaction,a few-layered organic-silica was successfully prepared and its structure and morphology were characterized.The main contents and research of this paper include the following aspects:1.We designed and synthesized an amphiphilic organosilane(PABI)containing phenyl urea and carboxyl group,and then investigated two-dimensional self-assembly and polymerization of the amphiphilic organosilane.The effects of precursor concentration,medium,catalyst amount,and precursor structure on the behavior of two-dimensional self-assembly polymerization were investigated.The results showed that when aqueous solution of tetramethylguanidine was used as the reaction condition,PABI could form few-layered organic-silica hybrid material by two-dimensional self-assembly and polymerization.The structure of the hybrid material were characterized by infrared spectrum(FT-IR)and the solid-state silicon spectrum.Transmission electron microscopy(TEM)can observe that the lateral dimension of the sheet is several hundred nanometers to several micrometers.Atomic force microscopy(AFM)test results show that the thickness of the sheet is 6-9 nm.These results are of great significance for preparation of few-layered or single-layered organic-silica hybrid nanomaterials.2.The resulting few-layered organic-silica hybrid material could reacts with halide at room temperature by using tetramethylguanidine promoted efficient esterification reaction,and introduce new groups at the end of the hybrid material.The results showed that the prepared hybrid material was successfully esterified with halide at room temperature and introduced alkyl chain,benzene ring,double bond,alkyne and other structures.This indicates that the obtained hybrid material can be further functionally modified.3.The effect of alkali species on the formation of layered hybrid materials was explored.An organic-silica hybrid material was prepared using aqueous solutions of triethylamine,sodium hydroxide and potassium hydroxide,respectively,as reaction conditions.The results showed that when using aqueous solution of triethylamine as a condition,a water-soluble thick layer hybrid M-TEA was prepared.When sodium hydroxide was used as a base,a water-insoluble layered hybrid material M-Na was obtained.When using aqueous solution of potassium hydroxide,a layered hybrid material cannot be obtained.In order to explore the influence of counter ions on the formation of thin-layer structures,M-Na was stripped with different types of bases and different salts to prepare thin-layer hybrid materials.The results show that the size of the counter ions will affect the stripping effect.