Robust Silica-Cellulose Composite Aerogels with a Nanoscale Interpenetrating Network Structure Prepared Using a Streamlined Process

Abstract

Silica aerogels can be strengthened by forming a nanoscale interpenetrating network (IPN) comprising a silica gel skeleton and a cellulose nanofiber network. Previous studies have demonstrated the effectiveness of this method for improving the mechanical properties and drying of aerogels. However, the preparation process is generally tedious and time-consuming. This study aims to streamline the preparation process of these composite aerogels. Silica alcosols were directly diffused into cellulose wet gels with loose, web-like microstructures, and an IPN structure was gradually formed by regulating the gelation rate. Supercritical CO2 drying followed to obtain composite aerogels. The mechanical properties were further enhanced by a simple secondary regulation process that increased the quantity of bacterial cellulose (BC) nanofibers per unit volume of the matrix. This led to the production of aerogels with excellent bendability and a high tensile strength. A maximum breaking stress and tensile modulus of 3.06 MPa and 46.07 MPa, respectively, were achieved. This method can be implemented to produce robust and bendable silica-based composite aerogels (CAs).

Silica-Bacterial Cellulose Composite Aerogel Fibers with Excellent Mechanical Properties from Sodium Silicate Precursor

“…Each wet fiber-like BC matrix (8 cm long) was immersed in the silicate solutions (SS-1, SS-2, SS-3, and SS-4) at room temperature for varying amounts of time [ 38 ]. Then, the samples that had been soaked for different times were placed in an oven to dry (at 80 °C for 20 min).…”

“…According to Figure 7 a, with the increase in silica precursor concentration, the thermal insulation performance of the corresponding CAF-2 and CAF-3 gradually improved, because more and denser gel skeletons were formed with the increase in the solid concentration in the aerogels. However, CAF-4, which had the highest concentration, did not match this trend, because the solid content of CAF-4 was too high; heat was more likely to transfer along the solid phase, resulting in inferior insulation performance [ 38 , 42 ]. To further investigate the stability of the CAF insulation performance, the dynamic temperature changes on the surface of the hot plate (T h ) and aerogel fibers (CAF-3) during the heating-cooling cycle ( Figure 7 d) were evaluated.…”

Elastic Agarose Nanowire Aerogels for Oil–Water Separation and Thermal Insulation

“…Recently, aerogels have attracted significance attention in the fields of oil–water separation and thermal insulation because of their extremely low density (0.003–0.5 g/cm 3 ), high porosity (80–99.8%), and large specific surface area (500–1200 m 2 /g). − Nevertheless, traditional inorganic aerogels with pearl-necklace-like network structures, such as SiO 2 or Al 2 O 3 aerogels, , cannot be used for these purposes because of their high brittleness and weak mechanical strength. , To date, many carbon-based aerogels with excellent mechanical properties have been developed, such as carbon nanotubes and graphene aerogels. , Unfortunately, the practical application of these aerogels is challenging due to disadvantages such as their high manufacturing cost (e.g., resulting from the expensive equipment and complex technologies) …”

Ambient Pressure Drying to Construct Cellulose Acetate/Benzoxazine Hybrid Aerogels with Flame Retardancy, Excellent Thermal Stability, and Superior Mechanical Strength Resistance to Cryogenic Temperature

“…specific surface area, and high porosity. 11 Therefore, this green nanoporous material has a great application potential in thermal insulation, 12 adsorption separation, 13 biomedical field, 14 and as a carrier. 15 However, cellulose aerogels possess poor mechanical properties such as low strength of skeleton, 16,17 flammability, 18 and poor thermal stability, 19,20 which hinder their applications.…”

“…Cellulose aerogels have attracted extensive interest as a novel kind of green biodegradable nanoporous material. − Cellulose aerogels combine the environmental friendliness, biocompatibility, and biodegradability of cellulose and the characteristics of traditional aerogel materials such as low density, high specific surface area, and high porosity . Therefore, this green nanoporous material has a great application potential in thermal insulation, adsorption separation, biomedical field, and as a carrier …”