Polysaccharide-based aerogels have emerged as a promising class of sustainable materials due to their biodegradability, low environmental footprint, and excellent thermal insulation properties. This study presents the development of a flexible, lightweight, and flame-retardant composite aerogel derived from a ternary blend of sodium alginate (SA), carboxymethyl cellulose (CMC), and chitosan (CS), fabricated through a simple freeze-drying and post-cross-linking process. The integration of 1,2,3,4-butanetetracarboxylic acid (BTCA) and sodium hypophosphite (SHP) enabled eco-friendly ester cross-linking and phosphorylation, significantly enhancing both mechanical strength and fire resistance. The resulting material, designated SCC-B2, exhibited remarkable flexibility, structural stability, and exceptional thermal performance under extreme heat exposure.
The preparation began with the homogeneous mixing of SA, CMC, and CS in deionized water, followed by the addition of BTCA and SHP as co-additives. After 2 hours of mechanical stirring, the solution was rapidly frozen using liquid nitrogen and then subjected to vacuum freeze-drying at 50 °C for 24 hours. Subsequent thermal curing at 170 °C for 3 minutes under vacuum facilitated esterification between hydroxyl groups of the polysaccharides and BTCA, while SHP promoted phosphorylation. This dual-functional reaction not only improved intermolecular bonding but also contributed to the formation of a stable, thermally resistant carbonaceous char layer during combustion.
Scanning electron microscopy (SEM) revealed that SCC-B2 possessed a well-defined, hierarchical honeycomb-like porous structure with interconnected channels, which is ideal for minimizing heat transfer. Compared to the uncross-linked SCC-B0, SCC-B2 displayed a denser, more compact morphology with layered features resembling fish scales, indicating effective network reinforcement.SARS-CoV-2 S1 Protein (HEK293)medchemexpress FTIR spectroscopy confirmed the presence of new ester carbonyl absorption at 1625 cm⁻¹ and characteristic P–H and C–O vibrations at 812 cm⁻¹ and 1236 cm⁻¹, respectively, providing direct evidence of successful cross-linking and phosphorylation. XRD analysis further supported the structural modifications induced by chemical treatment.
Mechanical testing demonstrated that SCC-B2 could withstand repeated bending and twisting without fracture, showcasing high flexibility. Unlike SCC-B0, which disintegrated upon immersion in water, SCC-B2 remained intact even after prolonged soaking and drying cycles, indicating excellent hydrophobicity and durability. Compressive stress-strain curves showed that the cross-linked aerogel exhibited gradual deformation up to 60% strain, confirming reduced brittleness and enhanced ductility.PINCH Antibody Cancer At 80% strain, the specific compressive strength reached 0.PMID:34911591 09 MPa, and the material could bear a 100 g load without collapse, highlighting its practical load-bearing capability.
Thermal stability was evaluated using thermogravimetric analysis (TGA) under both nitrogen and air atmospheres. SCC-B2 exhibited a higher onset decomposition temperature (Tonset) and peak degradation temperature (Tpeak) than SCC-B0, with Tpeak shifting from approximately 260 °C to 300 °C. In nitrogen, the maximum weight loss rate decreased from 46.3% (SCC-B0) to 49.0% (SCC-B2), while the residual mass at 800 °C increased significantly, suggesting enhanced char formation. TG-FTIR analysis revealed suppressed CO₂ emission during pyrolysis, attributed to the release of non-flammable gases that diluted oxygen and inhibited flame propagation.
Kinetic analysis via the Kissinger method yielded an activation energy (E) of 19.06 kJ/mol, while the Flynn-Wall-Ozawa method provided an average E of 32.07 kJ/mol, indicating improved thermal resistance across multiple stages of decomposition. Cone calorimetry results showed that PHRR and THR were reduced to 19.35 kW/m² and 10 kJ/g, respectively, compared to SCC-B0 values of 30 kW/m² and 15 kJ/g. The LOI value of SCC-B2 reached 37.7%, confirming its non-flammable nature. Vertical burning tests confirmed self-extinguishing behavior with no afterglow, demonstrating superior flame retardancy.
Thermal insulation performance was assessed using an alcohol lamp and infrared imaging. After 200 seconds of heating, the backside temperature of SCC-B2 remained below 200 °C, whereas SCC-B0 reached 330 °C. When exposed to a butane torch (~1100 °C), SCC-B2 maintained structural integrity, while SCC-B0 was punctured and fragmented. The second-degree burn time, measured via TPP testing under 11.3 kW/m² radiant heat, was extended to 87.1 seconds—significantly longer than the 56.2 seconds observed for SCC-B0—providing crucial protection time for firefighters.
Antibacterial evaluation against *E. coli* and *S. aureus* showed inhibition rates of 55% and 68%, respectively, attributed to the cationic nature of chitosan, which disrupts bacterial cell membranes and inhibits metabolic activity. The mechanism involves electrostatic binding, membrane destabilization, and intracellular interference, offering additional functional benefits.
In summary, the developed SCC-B2 aerogel combines sustainability, flexibility, and high-performance fire resistance with excellent thermal insulation and antibacterial properties. Its scalable fabrication process and renewable raw materials make it a strong candidate for use in protective clothing, building insulation, and other high-demand applications where safety, comfort, and environmental responsibility are paramount.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
