Abstract
Aerogels are nanoporous materials with excellent properties, especially super thermal insulation. However, owing to their serious high brittleness, the macroscopic forms of aerogels are not sufficiently rich for the application in some fields, such as thermal insulation clothing fabric. Recently, freeze spinning and wet spinning have been attempted for the synthesis of aerogel fibers. In this study, robust fibrous silica-bacterial cellulose (BC) composite aerogels with high performance were synthesized in a novel way. Silica sol was diffused into a fiber-like matrix, which was obtained by cutting the BC hydrogel and followed by secondary shaping to form a composite wet gel fiber with a nanoscale interpenetrating network structure. The tensile strength of the resulting aerogel fibers reached up to 5.4 MPa because the quantity of BC nanofibers in the unit volume of the matrix was improved significantly by the secondary shaping process. In addition, the composite aerogel fibers had a high specific area (up to 606.9 m2/g), low density (less than 0.164 g/cm3), and outstanding hydrophobicity. Most notably, they exhibited excellent thermal insulation performance in high-temperature (210 °C) or low-temperature (−72 °C) environments. Moreover, the thermal stability of CAFs (decomposition temperature was about 330 °C) was higher than that of natural polymer fiber. A novel method was proposed herein to prepare aerogel fibers with excellent performance to meet the requirements of wearable applications.
Highlights
Introduction published maps and institutional affilAerogels are materials with excellent features, such as large specific surface area (500–1200 m2 /g), high porosity (80–99.8%), and low density (0.003–0.5 g/cm3 ) [1], which make them readily applicable in adsorption [2,3], heat preservation [4,5], and catalysis [6,7]
Their morphology without shrinkage, even at low concentrations of silica precursors [40]. This could be because denser bacterial cellulose (BC) nanofibers could more effectively resist the shrinkage This could be because denser BC nanofibers could more effectively resist the shrinkage caused by capillary forces during the ambient pressure drying process
When the sheet temperature was −72 ◦ C, the creased further (CAF-4), the thermal insulation performance of composite aerogel fibers (CAFs)-4 decreased because absolute temperature difference |∆T| values of the one-layer aerogel fiber mat, silk fabric of the high content of the solid phase◦ and because heat is more transmitted within mat, and cotton thread mat were 59 C, 22 ◦ C, and 46 ◦ C, respectively
Summary
New the surface of theit gel skeleton, it to spring back during the the hydrophobic modification endowedmodification the CAFs with drying process. When the precursor concentration was improved further, the silica gel skeleton compact, as shown in CAF-4. Compared with our previous study, the higher density of the obtained BC nanofibers enables the samples to better retain study, the higher density of the obtained BC nanofibers enables the samples to better retain their morphology without shrinkage, even at low concentrations of silica precursors [40]. Their morphology without shrinkage, even at low concentrations of silica precursors [40] This could be because denser BC nanofibers could more effectively resist the shrinkage This could be because denser BC nanofibers could more effectively resist the shrinkage caused by capillary forces during the ambient pressure drying process.
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