The synergistic effect of layer charge density of Na-montmorillonite (Na-MT), the carbon chain length and the dosage of alkyl ammonium on the microstructure and gel properties of single chain alkyl ammonium intercalated Na-MT was systematically studied by using X-ray diffraction (XRD), molecular dynamics simulation and small-scale experiment. The results of Z-axis density distribution and radial distribution function (RDF) shows that with the increase of the dosage of alkyl ammonium, the distribution pattern is gradually changed from layered to inclined winding and stacking distribution. The results of the self-diffusion coefficient show that the higher the layer charge density of Na-MT, the shorter the length of alkyl ammonium carbon chain, the lower the diffusivity of each component in the inter-layer. With the increase of the dosage of alkyl ammonium, the diffusivity of alkyl ammonium in the inter-layer increases firstly and then decreases. The results of gel properties show that with the increase of the dosage of alkyl ammonium, the colloidal ratio of the alkyl ammonium/Na-MT in xylene gradually increases, while the apparent viscosity in xylene-ethanol increases firstly and then decreases. Furthermore, the longer the carbon chain of alkyl ammonium, the lower the layer charge density of MT, the better the gel properties of the prepared alkyl ammonium/Na-MT.

This paper studied the adsorption characteristics and mechanism of four kinds of ionic liquids (ILs) with different carbon chain lengths in montmorillonite (Mt). The results of isothermal adsorption at 25 °C show that the adsorption of four kinds of IL in Mt conforms to the Modified‐Langmuir model, and the adsorbance of IL in Mt is positively correlated with the dosage and the carbon chain length of IL. The dynamics research results show that the adsorption of IL in Mt fits well with the quasi‐second‐order dynamics equation. The reaction constant k is negatively correlated with the dosage of IL but positively correlated with the carbon chain length. The thermodynamics results show that the adsorption of IL in Mt is exothermic. The carbon chain length and the dosage of IL have a cross effect on the adsorption capacity of Mt for IL and the structure of the adsorption products. The adsorption capacity of Mt increases first and then decreases with the increase of dosage, and it increases with the increase of carbon chain length. The dosage of IL has little effect on the d(001) of IL/Mt with the short carbon chain, but the d(001) of IL/Mt with the long carbon chain increases with the increase of the dosage of IL. The carbon chain length has little effect on the d(001) of IL/Mt with a low dosage of IL, however, when the dosage of IL is high, the d(001) of IL/Mt increases with the increase of carbon chain length. The specific surface area, pore volume and the most probable radius of IL/Mt decrease with the increase of the dosage and carbon chain length, but excessive amounts of IL will still increase the most probable radius. Molecular dynamics simulation results show that when the dosage of IL is 0.3CEC, four ILs with different carbon chain lengths are arranged in a monolayer between Mt layers, N (N in IL) coordinates with Ot (O on the tetrahedral surface) at a distance of 3.0 Å, and the coordination strength increases with the increase of the carbon chain length of IL.