Raw materials, preparation methods, flame retardant properties and applications of bio-based flame retardant polyurethanes: Research progress and challenges

• Comprehensive Review of Bio-based Flame Retardant Polyurethane Materials. • Comprehensive Review of key bio-based raw materials. • Comprehensive Introduction to Application Areas. • Identification of key challenges and future research directions. Bio-based flame retardant polyurethane (BFRPU) is a green polymer functional material made from biomass. It retains the excellent properties of traditional flame-retardant polyurethane materials while possessing the sustainability and environmental protection characteristics of bio-based materials. In this paper, various types of bio-based raw materials for the preparation of flame-retardant polyurethanes are reviewed, including bio-based isocyanates, bio-based polyols, bio-based flame retardants, which are specifically related to polysaccharides, lignin, vegetable oils, and agricultural wastes, etc., and the characteristics and advantages of the biomass raw materials are analyzed in depth. The preparation process of various advanced bio-based flame retardant polyurethanes is discussed, the flame retardant properties of various bio-based flame retardants are reviewed, and the typical applications of bio-based flame retardant polyurethanes in different fields are listed, to provide practical guidance and theoretical insights for the researchers who are dedicated to the development of all-bio-based polyurethane materials. By systematically sorting out the current research focuses and comprehensively analyzing the challenges and problems, it is expected to provide researchers with a clear research idea so that they can more effectively grasp the research direction in future research work, and thus promote technological breakthroughs, innovative development, and practical applications of all-biobased polyurethane materials.