Facile Preparation of Ordered Macroporous Carboxyl Group Functionalized Polymer@SiO2 Composites and Their Adsorption Performance Towards Proteins

Abstract

Ordered macroporous carboxyl group functionalized polymer@silica composites (3DOM SiO2–COOH) were prepared by grafting a polymer layer onto the pore walls in the ordered macroporous thiol group functionalized silica hybrids (3DOM SiO2–SH). Acrylic acid was used as the functional monomer and glycerol 1,3-diglycerolate diacrylate as the cross-linker. The pore structure was characterized by FTIR and Raman spectrometer, SEM, Brunauer–Emmet–Teller measurement, DSC and TGA. The results show that the 3DOM SiO2–COOH had a uniform interconnected macroporous structure, a high porosity and a high mechanical strength. Batch adsorption tests towards lysozyme show that the adsorption performance was good and the adsorption process was apparently dominated by the internal diffusion. Several isothermal adsorption and kinetic models were applied to discuss their adsorption behaviors. The results show that the inferred parameters such as maximum adsorption amount (qm), adsorption equilibrium constant (Kl) and adsorption energy (E) were similar for the particles range from 65 to 225 µm. However, for the large particles of 550 µm, such parameters were different from the smaller particles due to the deep sites being not completely accessible for the proteins. Moreover, lysozyme had a higher desorption rate than the adsorption rate. The results show that 3DOM SiO2–COOH materials can be used as weak cation exchangers for proteins. Furthermore, 3DOM structured materials may be an ideal model for the theoretical research on the adsorption behaviors.