Synthesis and characterization of inorganic-organic composite materials with anion-exchange groups based on mesoporous silicates

Abstract

Mesoporous materials functionalized with quaternary ammonium groups have been prepared by the surface modification of the MCM-41 mesoporous material with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride. The specific surface area, pore volume, and pore diameter were determined from nitrogen adsorption and desorption isotherms at 77 K. It was revealed that modification in toluene and water leads to a higher pore diameter. Based on this fact, it can be supposed that the nonhomogeneous filling of the inorganic matrix by the modification agent or partial changes in the hexagonal structure of the above-mentioned samples takes place. Modification in methanol presumably proceeds without structural changes in the silicate backbone of the mesoporous material. IR spectra were used to control the modification. The structural changes during sample heating to 150–250°C have been shown by DRIFT. The TGA/DTA method revealed the thermostability of composite materials. The loss of mass of the modified materials due to the destruction of the organic layer starts from 180°C, which corresponds to IR data. The degree of grafting is 13–51%.