Effect of surface modification and medium on the rheological properties of silica nanoparticle suspensions

The unmodified and 3-(trimethoxysilyl) propyl methacrylate (TPM) modified silica nanoparticles were synthesized via the modified Stöber method. The structure and chemical composition of silica nanoparticles were determined by scanning electron microscope (SEM), X-ray diffraction (XRD) characterization, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results demonstrate that silica nanoparticles with the diameter of 90   nm and amorphous state are successfully modified by TPM. The rheological test results demonstrated that surface modification of nanoparticles and medium exerted great influence on the rheological properties of silica particle suspension. Under high shear rate of about 250   s −1 , the viscosity of suspension comprising unmodified silica nanoparticles and deionized water , TPM-modified silica nanoparticles and deionized water, TPM-modified silica nanoparticles and polyethylene glycol , is about 0.4   Pa.s, 0.1   Pa.s and 30   Pa.s, respectively. The results are significant for preparing homogenous and stable silica nanoparticle suspension, and meaningful for ceramic processing .