Biodegradable polymers: from synthesis methods to applications of lignin-graft-polyester

Abstract

The issue of non-degradable petroleum-based plastic waste is a global challenge that requires urgent attention due to its harmful impact on humans and the environment. Biomass-based materials have garnered significant attention to address this challenge in recent times. Lignin, with its abundance, low price, and rich aromatic groups, is not only essential biomass but also a crucial material that can be utilized to produce biodegradable polymers. This review paper provides comprehensive knowledge of the synthesis and applications related to lignin, polyester, and lignin–polyester copolymers with a specific focus on organic polymer synthesis techniques and diverse applications. Beginning with lignin, the review explores various extraction methods from raw biomass resources aimed at enhancing its compatibility with polyester matrices. Next, we discuss lignin chemical modification methods that alter its chemical structure and properties, ultimately enhancing its integration with polyesters. Subsequently, the synthesis of polyester is examined, encompassing condensation polymerizations and ring-opening polymerizations. These methods are evaluated for their scalability and capability in producing tailored polymer chains suitable for copolymerization with lignin. The copolymerization strategies involving lignin and polyester are explored in detail, including graft-onto and graft-from approaches. Each method is discussed for its ability to control copolymer composition and properties, which are crucial for achieving desired material characteristics. In terms of applications, the review highlights the wide-ranging utility of lignin–polyester copolymers across industries such as packaging, construction, and separation. These polymers offer improved biodegradability, thermal stability, and mechanical strength compared to conventional polyesters, making them perfect candidates for novel sustainable materials. Overall, this review provides valuable insights into the synthesis methods and applications of lignin, polyester, and lignin–polyester copolymers offering a comprehensive overview of their potential for addressing environmental concerns and expanding the scope of lignin-derived materials in various industrial applications.