Effect of Silica Nanotube Surface Modification on the Physical Properties of Nanocomposites with Poly(methyl methacrylate)

Poly(methyl methacrylate) (PMMA)/silica nanotube (SNT) nanocomposites were prepared by a melt dispersion method using a twin screw extruder and a chloroform-based solvent dispersion method. After removing the template by calcination or organic solvent treatment, the SNT surface was modified by methacryloxypropyl trimethoxysilane (MPMA). The effects of SNT template removal, surface modification, and nanocomposite preparation method on the physical properties of PMMA/SNT nanocomposites were analyzed. The dispersion of SNTs in PMMA was analyzed using transmission electron microscopy. The thermal properties were evaluated using differential scanning calorimetry and thermogravimetric analysis. The mechanical properties of the nanocomposites were analyzed using a universal testing machine and the light transmittance of the nanocomposites was measured using UV-VIS-NIR spectrophotometry. As the SNT increased, the flexural modulus of SNT/PMMA nanocomposites increased. In particular, the surface modified SNT nanocomposite with 5% content by solvent dispersion method showed 49% improvement in flexural modulus compared to virgin PMMA. The tensile strength of nanocomposites decreased with the increase of SNT content. Nanocomposite containing surface modified SNT was higher in tensile strength than that of SNT without surface modification. The dispersion of SNT in the nanocomposite was better by surface modification of SNT, regardless of the preparation method (melt or solvent) of the nanocomposite. However, the light transmittance was more dependent on the SNT template removal method than the SNT surface modification, and ethanol extraction showed higher light transmittance than the calcination method.