The incorporation of polymeric components into aerogels based on clay produces a significant improvement in the physical and thermal properties of the aerogels. In this study, clay-based aerogels were produced from a ball clay by incorporation of angico gum and sodium alginate using a simple, ecologically acceptable mixing method and freeze-drying. The compression test showed a low density of spongy material. In addition, both the compressive strength and the Young’s modulus of elasticity of the aerogels showed a progression associated to the decrease in pH. The microstructural characteristics of the aerogels were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The chemical structure was studied by infrared spectroscopy with Fourier transform (FTIR). The TGA curves from a non-oxidizing atmosphere indicated that the clay had a mass loss of 9% above 500 °C and that due to the presence of polysaccharides, the aerogels presented a decomposition of 20% at temperatures above 260 °C. The DSC curves of the aerogels demonstrated a displacement in higher temperatures. In conclusion, the results showed that aerogels of ball clay with the incorporation of polysaccharides, which are still minimally studied, have potential application as thermal insulation considering the mechanical and thermal results obtained.

Tree-exuded gums are natural polymers that represent an abundant raw material in the food and pharmaceutical industries. The cashew gum can be obtained by exudation of trees of the genus Anacardium, a native species of the Brazilian northeast; its polymer consists of monosaccharide units propitious to the action of chemical reactions that tend to improve their intrinsic characteristics among them, as the degree of hydro-solubility. The objective of this work was to modify the exudate gum of Anacardium occidentale (cashew gum (CG)) through an amine reaction. The modification was confirmed by Nuclear Magnetic Resonance (¹H NMR), infrared spectroscopy (FTIR), gel permeation chromatography (GPC), zeta potential, and thermogravimetric analysis (TG). In addition, the chemical modification altered the molar mass and surface charge of the CG, and the amino group binding to the CG polymers was confirmed by FTIR spectra. In addition, cytotoxicity tests were performed where cell viability was estimated by an MTT assay on RAW 264.7 macrophages. Through these tests, it was found that the amine caused an increase in the thermal stability of the amino compounds and did not present cytotoxic potential at concentrations below 50.0 mg/L.

Introduction.Aerogel composed of a polymer/clay dispersion is a material with great potential for application in several areas. This unique structure gives it properties, low density, very high porosity,and remarkable thermal resistance, making it ideal for applications ranging from thermal insulation to air pollutant absorption. Objective. This work aimed to review the main parameters that influence the improvement of mechanical properties of polymer/clay aerogels over the last ten years. Methodology.The research was conducted in December2023 through a wide electronic consultation of scientific literature using the databases of Web of Science, Scopus,and Scielo: Results and Discussion. Efforts have been made to improve aerogels' physical and thermal properties usingvarious natural and synthetic polymers, such as casein, pectin, alginate, xanthan gum, polyvinyl alcohol cellulose materials, etc. In addition, parameters such as freezing temperature, chemical crosslinking, viscosity of dispersions, gamma radiation,and pH control have been studied in the literature in recent years. Final Considerations. This study highlighted that chemical and radiation crosslinking improves mechanical properties of aerogels, but faces economic and safety challenges. PVA’s resistance to moisture and flammability limits its application, while MMT and kaolinite are the most promising clays. The pH adjustment, the use of calcium ions,and the control of the freezing temperature were effective in improvingthe mechanical properties of aerogels.