Lignin‐based polymers via graft copolymerization

Abstract

Lignin is an important source of synthetic materials because of its abundance in nature, low cost, stable supply, and no competition to the human food supply. Lignin, a crosslinked phenolic polymer, contains a large number of aromatic groups that can be used as a substitute for petroleum-based aromatic fine chemicals. However, modification of lignin is necessary for its application in advanced materials due to its chemically inert nature and structural complexity. Polymeric modification of lignin via graft copolymerization represents an important avenue for modification because this method forms stable covalent bond linkages between lignin and synthetic functional polymers. In this review, we discuss recent synthetic strategies toward polymeric modification of lignin using graft copolymerization and the special properties and applications of the produced lignin copolymers.

Unmodified kraft lignin isolated at room temperature from aqueous solution for preparation of highly flexible transparent polyurethane coatings

“…18,19 Current lignin research strategies follow two main routes: rst, a direct utilization without chemical modication and second, pre-treatment including chemical modication, functionalization and/or fractionation (degradation) to generate a wide range of intermediates, ne chemicals and polymers. [20][21][22] In between, lignin-derived polymers and composites are also studied as potential materials for biomedical applications such as tissue engineering and drug release. [23][24][25] Due to the large number of hydroxyl groups, lignins are intensively studied as candidates to substitute fossil based alcohol and polyol components in polyurethanes, polyesters, epoxides and phenol-formaldehyde resins.…”

Lignin‐Based Micro‐ and Nanomaterials and their Composites in Biomedical Applications

“…Aside from lignin self‐association, lignin can also be easily modified chemically because of the presence of many functional groups, such as aromatic groups, phenolic hydroxy groups, alcoholic hydroxy groups, and carbon–carbon double bonds. After appropriate chemical modifications, lignin derivatives can be used in many different areas . The chemical modification of lignin can be classified into three main categories: 1) fragmentation or depolymerization to use lignin as a carbon source or to cleave the lignin structure into aromatic macromers; 2) modification by creating new chemical active sites; 3) chemical modification of hydroxy groups.…”

Increased expansion ratio, cell density, and compression strength of microcellular poly(lactic acid) foams via lignin graft poly(lactic acid) as a biobased nucleating agent

“…Owing to its formation of a stable covalent bond between lignin and synthesized polymer, graft copolymerization is considered as one of the most effective methods for lignin modification, which can improve the adhesion of two incompatible phases 36 . Liu et al 37 reported on the excellent biocompatibility between PLA and lignin graft copolymers synthesized using different chiral lactide monomers.…”