Progress in Bio-Based Phenolic Foams: Synthesis, Properties, and Applications

Phenolic foams are widely used as insulation materials in construction, transportation, and spacecraft industries due to their flame retardancy, thermal stability, low toxicity, and low smoke generation. However, these foams are typically produced from non-renewable resources. With increasing environmental pollution, volatility in petrochemical prices, and depletion of petroleum resources, the demand for polymeric materials produced from renewable resources is ever-increasing. Numerous recent studies have introduced biomass as an alternative resource for petroleum-based raw materials for producing phenolic foams. In addition to their environmental benefits, bio-based phenolic foams exhibit properties similar or even superior to traditional phenolic foams. In this review, traditional phenolic foams are discussed. Recent progresses on synthesis of foams from bio-based resources, modification of the bio-alternatives, performance enhancements, and comparison with traditional phenolic foams are outlined. Challenges and methods to further improve performance characteristics of bio-based phenolic foams and their expanding range of applications are highlighted.