Study on the Preparation of Hollow Silica Nanospheres and Their Heat Retention and Hydrophobicity in Paperboard Coatings

ABSTRACT This study developed hydrophobic hollow silica nanospheres and incorporated them into bio‐based coatings. These coatings were subsequently applied to the surface of E‐flute corrugated paperboard to create functional paperboard suitable for food heat retention packaging. Hollow silica nanospheres with a diameter of approximately 350 nm were prepared using a selective etching method, with methyl groups grafted onto their surface to impart hydrophobicity. An in‐depth performance analysis was then conducted to assess their microstructure, surface groups and specific surface area characteristics. To explore the effects of hydrophobic hollow silica nanospheres on paper‐based materials, they were incorporated into bio‐based coatings and applied to paper substrates. When the thickness of the CGDM coating (the bio‐based coating containing hydrophobic hollow silica nanospheres) was 10 μm, the water contact angle of the functional paperboard was measured to be 132.8°, indicating that the coating surface exhibited hydrophobicity. A thermal conductivity analysis of samples with varying coating thicknesses and compositions revealed that increasing the coating thickness helped reduce the thermal conductivity of paper‐based materials. Among the samples, CGDM@P (the bio‐based coated functional paperboard containing hydrophobic hollow silica nanospheres) demonstrated optimal heat retention performance across different coating thicknesses. The hydrophobic hollow silica nanospheres developed in this study address the limitations of paper‐based materials in terms of heat retention and hydrophobicity, thereby enhancing their potential for use in food packaging applications.