Cellulose Mineralization as a Route for Novel Functional Materials

Abstract

Cellulose possesses excellent properties, but its performance characteristics do not satisfy human requirements completely, which has soured a constant effort to improve its features. Currently, cellulose is combined with inorganics in a process called mineralization that results in a novel type of materials referred to as bio-nanocomposites. There are many examples of mineralized tissues with superior properties in living nature. This circumstance gives us a reason to biomimic them by compounding biopolymers with inorganics. Here, the main mineralization techniques, properties, structure, functionality, and application of mineralized cellulose are the focus. Cellulose can be combined with inorganics through the vapor phase or by the methods of wet chemistry. Much attention has been paid to sol-gel chemistry, which is of first importance in cellulose mineralization. Inorganics can protect polysaccharides, regulate hydrophilicity-hydrophobicity, and impart self-cleaning, antimicrobial and conducting properties, which not only improves them but results in bio-nanocomposites with novel functionalities and performance, not known before for cellulosic materials. Further calcination and carbonization of mineralized cellulose under mild conditions give nanosized metals, metal oxides, and their nanocomposites with carbon, which are often unavailable by conventional methods. Therefore, mineralization is used to develop innovative textiles, oil absorbent and oil/water separating membranes, catalysts and photocatalysts, solar cells, conductors, supercapacitors, transistors and batteries for flexible electronics, and energy storage devices. These nontraditional and highly promising areas for applications have caused an intense interest in cellulose that resembles its rediscovery.

Chitosan Hydrogels and Bionanocomposites Formed through the Mineralization and Regulated Charging

“…Chitosan macromolecules along with other polysaccharides are appropriate for the mineralization ,,,. THEOS possesses an additional preference over TEOS.…”

Dimensionally Stable Cellulose Aerogel Strengthened by Polyurethane Synthesized In Situ

“…Despite its excellent properties, man has long sought to improve its functionality because of serious limitations. One restriction consists in a sharp drop of mechanical strength after water absorption due to high hygroscopicity . Moisture and water absorption cause swelling and dimensional instability .…”

“…The MFC, which forms jelled mass, is more appropriate for the preparation of aerogels. They possess dimensional stability that opens up possibilities for various treatments of cellulose . Here we are using a dimensionally stable MFC aerogel for coating with polyurethane.…”

“…They serve to engineer such novel high-performance cellulosic materials as free-standing films, nanopaper, membranes, coatings, bionanocomposites, and aerogels. [17,21,22,[43][44][45][46][47][48][49] Advantages of the latter are low or ultra-low density up to 0.004 g cm −3 , large specific surface area, and a pore volume that sometimes reaches 99.8%. [50][51][52][53][54] Kistler, who prepared the first aerogels from regenerated cellulose in 1931, [55] found that they were not mechanically strong, ductile, and dimensionally stable.…”

Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis

“…When the template source contains significant inorganic components to produce its structure (e.g., silica frameworks), then the inorganic template remains in the final structure or it must be removed using strongly acidic or basic media. Natural cellulose structures have been extensively used as supports for metal oxide growth [29].…”