This article will discuss natural polymer nanocomposites and their sources, addressing the applications that these sustainable sources of nanomaterials can advance.
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Polymers are macromolecules composed of simpler repeating structural units linked together by covalent bonds. Natural polymers exist in nature as biomolecules and compounds that make up the bodies of living things.
Many natural polymers such as cellulose or proteins form stable aggregates as fibers or cellular structures in the presence of water, similar to reversible hydrogen bonding.
How natural polymers are used in nanocomposites
Nanocomposites consist of a matrix. Charges are then shuffled into this matrix based on attributes that need to be upgraded.
Nanocomposites are classified as ceramic matrix nanocomposites, polymer matrix nanocomposites or metal matrix nanocomposites depending on the matrices used.
The structure of polymer nanocomposites is characterized by the presence of a particle size of up to 100 nanometers. The inclusion of nanoscale particles in a polymer can have two main consequences.
This leads on the one hand to a modification of the properties of the polymer matrix itself and, on the other hand, to the acquisition of new properties by the immobilized nanoparticles. The main properties of composites are significantly affected by the nature and characteristics of the polymer.
Applications of nanocomposites
Natural polymer nanocomposites have recently received more attention than synthetic polymers due to their non-toxicity, compatibility and biodegradability with cells and tissues.
These nanocomposites are well suited for a variety of industrial and biological applications. They not only meet the unique needs of businesses due to their superior thermal properties, specific strength, ease of separation, better energy recovery, recyclability and low cost availability.
By combining natural polymers with antimicrobial nanoparticles like gold, zinc, and copper, antimicrobial nanocomposites can be created that are useful in various industrial and medical applications.
For bone tissue engineering, biodegradable starch nanocomposites have been developed. Starch-based bone cement can provide immediate structural support and disintegrate on contact. Additionally, they can be combined with bioactive particles to promote bone production at the cement-bone interface.
How are natural polymer nanocomposites sourced and synthesized?
Nanocomposites can be obtained by different methods, and their properties will depend on the method used for their preparation. The most commonly used methods are solvent intercalation, in situ polymerization and fusion intercalation.
The mixing of the nanomaterial and the monomer in solution, where polymerization of the monomer occurs, is called in situ polymerization. Solvent intercalation occurs when the nanomaterial and the polymer interact in a solution. The polymer chains intercalate and migrate into the nanomaterial sheet in the solvent, creating the polymer nanocomposite by removal of the solvent.
During melt intercalation, the nanomaterial and polymer are joined above the melting point of the polymer and are held at that temperature for an extended period. Next, the material is subjected to shear or other conditions to stimulate intercalation of the nanomaterial.
Melt intercalation is the most desirable of these technologies due to its versatility and compatibility with existing polymer processing equipment, as well as its environmental friendliness due to the absence of solvents . Additionally, this procedure allows the use of polymers that do not lend themselves to in situ polymerization or solvent intercalation.
Main sources of natural polymer nanocomposites
Starch is a naturally renewable polymer and it has enormous potential due to its total compostability, biodegradability, biocompatibility and absence of hazardous residues. However, it has some drawbacks, such as high water sensitivity, poor mechanical properties and poor processability. The incorporation of nanofillers into starch nanocomposites leads to significant changes in the stability and applicability of starch-based nanocomposites.
One of the most important applications of starch-based nanocomposites is the creation of environmentally friendly biodegradable materials. Starch-based nanocomposites have a strong oxygen barrier and biodegradability, are relatively cheap and widely distributed in nature.
Cotton is the purest form of natural cellulose, and it is also one of the most common organic substances on the planet. The main component of paper made from tree wood and the supporting components of leaves and plants is cellulose. It is a polymer produced from glucose monomers.
Simple or pure cellulose can be processed using modern technologies to produce nanocellulose composites in various forms, such as cellulose acetate, bacterial nanocellulose, and cellulose nanofibers, all of which are high-tech materials. . Low manufacturing yields and economic constraints prevent these technologies from entering the market.
It is the second most common polymer in the world, created naturally by many living species. Chitin occurs naturally in nature as crystalline microfibrils found in the cell walls of fungi, yeasts, and arthropod exoskeletons. Chitin is used as a filler in a gelatin-based protein matrix to form natural polymer nanocomposites.
These composites are used in tissue engineering and bone regeneration. It can also be used to make fiber when mixed with a protein complex. Chitin can be easily made into beads, gels, nanofibers, sponges and scaffolds. In nanobiotechnology, cancer drugs, tissue engineering, and wound dressings, these forms have a wide range of applications.
Natural polymer nanocomposites have many uses, which are constantly expanding due to their unique characteristics, low cost and ease of fabrication. In the years to come, these are likely to have a significant impact on environmentally conscious strategies aimed at contributing to sustainable scientific practice.
Continue reading: Applications of natural polymer nanocomposites
References and further reading
João, CFC, Silva, JC and Borges, JP (2015). Chitin-based nanocomposites: biomedical applications. In Environmentally Friendly Polymer Nanocomposites (pp. 439-457). Springer, New Delhi. DO I: https://doi.org/10.1007/978-81-322-2473-0_14
Kalia, S., Dufresne, A., Cherian, BM, Kaith, BS, Avérous, L., Njuguna, J. and Nassiopoulos, E. (2011). Cellulose-based bio- and nanocomposites: a review. International Journal of Polymer Science, 2011. https://doi.org/10.1155/2011/837875
Medeiros, ES, Dufresne, A., & Orts, WJ (2010). Starch-based nanocomposites. Starches: Characterization, properties and applications, 205-251. Extract of https://www.researchgate.net/publication/216091637_Chapter_8_-_Starch-based_Nanocomposites
Tavares, MIB, Silva, EO d. , Silva, PR d. , & de Menezes, LR (2017). Polymer nanocomposites. In (Ed.), Nanostructured materials – From fabrication to applications. Intech Open. https://doi.org/10.5772/intechopen.68142