Ultrasonic-Assisted Silanization of SiO₂ Using TMSPM: Surface Functionalization, Hydrophobicity Enhancement, and Structural Analysis

This study investigates the structural and chemical changes occurring upon ultrasonic-assisted silanization of SiO₂ nanoparticles. While traditional silanization often faces challenges in grafting uniformity, the application of ultrasonication in this work facilitates enhanced interfacial contact and rapid functionalization with 3-(trimethoxysilyl)propyl methacrylate (TMSPM). The concentration of TMSPM was varied to evaluate correlation between TMSPM concentration gradients, grafting density, and particle size of silanized SiO₂ under ultrasonic conditions. FTIR analysis confirmed the successful chemical bonding of TMSPM, evidenced by the intensified Si–O–Si absorption bands and the distinct appearance of methacrylate carbonyl groups. The results indicated that 10% TMSPM can be considered the most effective concentration for SiO₂ silanization, as indicated by the substantial increase in carbon content of 31% via EDS analysis and a maximum water contact angle of 128°. This significant shift from hydrophilic to hydrophobic behavior demonstrates the effectiveness of the ultrasonic-assisted approach in producing high-quality, silanized silica fillers. Furthermore, XRD analysis revealed that while the fundamental amorphous structure of SiO₂ is preserved, the modification process introduces subtle changes in the short-range structural order of the nanoparticles.