Shellac as a multifunctional biopolymer: A review on properties, applications and future potential

Abstract

Shellac is a physically refined form of lac resin, a natural biopolymer of animal origin obtained from tiny insects feeding on the sap of specific host trees. Shellac, in its basic form, is a polyester macromolecule composed of inter and intra esters of polyhydroxy aliphatic and sesquiterpene acids. It has been used in several industries for ages due to its exceptional properties such as film-forming, adhering, bonding, thermoplasticity, water-resistance and easy solubility in spirit and aqueous alkali solvents. From the beginning of the 21st century, due to increasing demand for natural products, a paradigm shift in the scope and applications of shellac has been witnessed, especially in green electronics, 3D printing, stealth technology, intelligent sensors, food and pharmaceutical industries. Shellac offers enormous potential for greener technologies as a natural and environmentally friendly material. This review provides an insight into the lac in detail, covering various forms of the lac, structure, properties, different applications of shellac and its future potential. This article would benefit the researchers involved in shellac research and others looking for natural and greener alternatives to synthetic polymers in various applications.