The influence of hydrogen bond and electrostatic interaction on the mechanical properties of the WPU/modified SiO2 nanocomposites

A variety of nano SiO2 microspheres with negative charge or positive charge were prepared by hydrochloric acid treatment or/and γ-mercaptopropyltrimethoxysilane modification respectively. The obtained modified SiO2 with different content of -OH or -SH and different charges were physically introduced into water-borne polyurethane (WPU) dispersion to fabricate the WPU/modified SiO2 nanocomposites with interfacial interaction of hydrogen bond and electrostatic interaction. The influence of interfacial interaction (hydrogen bond and electrostatic interaction) between WPU and modified SiO2 on the interface structure and mechanical properties of the WPU/modified SiO2 nanocomposites were investigated. The results showed that when both hydrogen bond and electrostatic interaction were present between WPU and modified SiO2, the microstructure and the tensile strength of the WPU/modified SiO2 nanocomposite were mainly affected by the electrostatic interaction, while the elongation at break was mainly affected by the hydrogen bond interaction. Overall, a methodology of the combination of molecular dynamics simulation and experiment study was established to reveal the influence of surface characteristic of SiO2 on the interface interaction and mechanical properties of the WPU/modified SiO2 nanocomposites.