Thermal insulation of water-based acrylic coatings reinforced with APTES-functionalized silica fume nanoparticles

This study used pure silica fume nanoparticles (SF NPs) and 3-APTES-functionalized silica fume (F-SF) to improve the thermal properties of water-based acrylic paint. First, the NPs were synthesized and then their structural, chemical, and morphological studies were performed using infrared spectroscopy (FT-IR) to identify functional groups and confirm the functionalization reaction, X-ray diffraction (XRD) to determine the phase and crystal structural changes, scanning electron microscopy (SEM) to study the surface and overall morphology, energy dispersive X-ray spectroscopy/ elemental mapping (EDX/ Mapp), and transmission electron microscopy (TEM) to examine the particle size and dispersion. The addition of F-SF to water-based acrylic paint significantly improved the coating adhesion (up to 5B), hardness, and gloss, which is due to the higher dispersion of NPs and stronger interfacial interactions in the matrix. After confirming the above factors, NPs were added to water-based acrylic paint at 0.5-1.5 Wt.%. The thermal conductivity (K) properties of the samples were measured to investigate the thermal insulation performance. The K values ​​of the different samples as base coating, FS-0.5, FS-1, FS-1.5, F-FS-0.5, F-FS-1, and F-FS-1.5 were obtained as 0.420, 0.356, 0.326, 0.342, 0.337, 0.281, and 0.300 W/mK, respectively. The analysis showed that pure SF NPs reduced the paint's K by 22% and F-SF NPs by 33%. This decrease in K is due to the creation of porosity and increased thermal circulation paths in the paint structure, which prevents easy energy transfer and helps increase thermal insulation properties. Also, functionalization with 3-APTES improves the adhesion and dispersion of NPs in the paint matrix due to the higher decrease in K compared to pure SF, the difference in surface structure, and its effect on heat transfer. Overall, the results indicate the high potential of these NPs to improve the thermal insulation performance of acrylic paints and industrial applications in thermal protective coatings.