Preparation of mesoporous MCM-41/poly(acrylic acid) composites using supercritical CO2 as a solvent

Abstract

The synthesis of host–guest composites consisting of entrapped poly(acrylic acid) (PAA) and inorganic host MCM-41 is described. The monomer acrylic acid (AA) and initiator azoisobutyronitrile (AIBN) were introduced into the channels of MCM-41 using supercritical CO₂ as a solvent at 35.0 °C, followed by free radical polymerization at a higher temperature, resulting in MCM-41/PAA composites. The composites were characterized using thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption and desorption, scanning electronic microscopy (SEM) and X-ray diffraction (XRD). It was confirmed that PAA was indeed entrapped in the pores of MCM-41, and that the structure of MCM-41 was not destroyed. Composites with different compositions were obtained by controlling the processing parameters, such as the absorbing time, the concentration of AA in the fluid phase, and the pressure of CO₂.