Controllable Synthesis of Hollow Silica Nanoparticles Using Layered Double Hydroxide Templates and Application for Thermal Insulation Coating.

The innovative hollow silica nanoparticle (HSN) material possesses substantial potential for application in the insulation field. The size and shell thickness of HSN are crucial factors in determining their inherent properties, which, in turn, impact their applicability. This research presents a facile approach to synthesizing HSN in which sodium silicate (NaSiO) was utilized as the silica precursor that can be directly deposited onto layered double hydroxide (LDH) nanoparticles without the utilization of any surfactant. A subsequent acid treatment was used to eliminate the templates, resulting in the formation of an HSN devoid of mesopores in silica shells. By utilizing various sizes of LDH cores, obtainable via coprecipitation followed by hydrothermal treatment, we were capable of successfully synthesizing the hollow particles with adjustable diameters ranging from 50 to 200 nm. In addition, the shell thickness is varied from 6.8 to 22.5 nm by varying the silicate solution concentration. Results demonstrate that prepared HSNs have low thermal conductivity and high reflectance in the UV-vis-NIR range (averaging 82.1%). These findings suggest that HSN can be utilized as an effective inorganic filler in the formulation of reflective and thermally insulating coatings.