Renewable carbon strategies for sustainable bioplastics integrating biomass valorization with carbon dioxide utilization and structural property relationships

The shift toward sustainable materials has fuelled the exploration of renewable carbon approaches to bioplastics, combining biomass valorization, the use of carbon dioxide (CO2), and polymer architecture. This review focuses on the valorization of second-, third-, and fourth-generation biomass, such as lignocellulosic residues, algal systems and industrial waste streams, in the context of integrated biorefinery systems. The importance of advanced pretreatment technologies is critically reviewed, but pretreatment is the most energy-consuming and cost-dominant process in biomass conversion and is one of the major determinants of process feasibility. Moreover, CO2 is considered a substitute for carbon feedstock, with catalytic polymerization pathways and new monomer platforms being prioritized. The sustainability of CO₂-derived polymers, however, largely relies on the efficiency of carbon capture and the use of renewable energy since energy-consuming activation and processing may negate environmental advantages when fossil-based energy is employed. This review also provides a correlation between biorefinery-based precursors and the relationships between the structure and properties of polymers, including the influences of monomer composition, crystallinity and material architecture on mechanical performance, thermal stability, and biodegradability. A comparative study of biorefinery generations explains the trade-offs between the availability of feedstock, complexity of the process and economic viability. Altogether, this piece offers a critical, integrative framework, which connects the selection of feedstock, conversion technologies, and material design, which highlights the design of a scalable and sustainable bioplastic system. Carbon-neutral materials can be made only when the processes of capturing and converting CO₂ are driven by renewable energy sources because the fossil-based energy source can neutralize the advantages of the use of CO₂ in the environment.