**1. Introduction**

Here, the polymeric properties of naturally existing lignin and its potential in the field of many chemical industries have been focused. The structure of lignin is considered as the cross-linking of various polyphenols containing methoxy groups and aldehyde functionality at terminal position. Lignin is the second most naturally existing polymer with full of aromatic functionality. Despite being its abundance in nature lignin, utilization is not seen in relevant areas such as polymers, adhesives, and rubber industries.

With exponential growth of population and their energy demands, there is a strong urge to incline our dependency on sustainable approaches [1]. The recent researches are focusing on the development of methods which are dependent on sustainable or renewable sources. Lignin is a nonedible polymer with carbon-neutral concept and is found in plenty of quantities from agriculture and forestry residues [2]. For the low utilization of these lignin resources and considering its potential in various chemical industries, the researchers are continuously working to develop methods for isolation of lignin (high-quality technical) for further transformation to various value-added chemicals [2].
