Lignin‐Based Polyurethane: Recent Advances and Future Perspectives

Abstract

Polyurethane (PU), as a polymer material with versatile product forms and excellent performance, is used in coatings, elastomers, adhesives, and foams widely. However, the raw materials (polyols and isocyanates) of PU are usually made using petroleum‐derived chemicals. With the concern for depletion of petroleum resources and the associated negative impact on the environment, developing technologies that can use renewable raw materials as feedstock has become a research hotspot. Lignin, as an abundant, natural, and renewable organic carbon resource, has been explored as raw material for making polyurethanes because it possesses rich hydroxyl groups on its surface. Meanwhile, compared to vegetable oils, lignin does not compete with food supply and performance of the resulting products is superior. Lignin or modified lignin has been shown to impart the polyurethane material with additional functionalities, such as UV‐blocking ability, hydrophobicity, and flame retardancy. However, the utilization of lignin has encountered some challenges, such as product isolation, heterogeneity, aggregation, steric hindrance, and low activity. This paper summarizes recent research progress on utilizing lignin and modified lignin for bio‐based polyurethane synthesis with a focus on elastomers and foams. Opportunities and challenges for application of the lignin‐based polyurethanes in various fields are also discussed.

In Situ Polymerization and Flame Retardant Mechanism of Bio‐Based Nitrogen and Phosphorus Macromolecular Flame Retardant in Plywood

“…LOI test results are better than other phytic acid based biological flame retardants and other types of biological flame retardants. [ 27–30 ] The flame retardant results could effectively meet the flame retardant requirements. With the further increase of temperature, the flame retardant performance of flame retardant plywood did not further improve, and the LOI value of plywood decreased after the anti‐loss test.…”

Synthesis, Characterization and Properties of Antibacterial Polyurethanes

“…Polyurethanes (PUs) are one of the crucial classes of polymers with wide applications and properties, because their properties can easily be tailored by varying the components from which they are constructed [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. Polyurethanes offer excellent versatility in terms of their mechanical properties and are widely applied in many fields [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. In general, the synthesis of polyurethanes is carried out in two stages.…”

Viscoelastic polyurethane foams from unmodified kraft lignin dispersed into methoxy polyethylene glycol and palm kernel oil as partial substitutes of petroleum-based polyols

“…Large part of this KL (≈98%) is treated as waste material and burned for energy recovery in the paper and cellulose industry [7][8][9]. Many efforts have been made to transform low value KL to high-value products such as polyurethane foams, as a strategy to replace petroleum-based polyols [10][11][12][13][14][15][16][17][18]. However, there are several opportunities associated with the use, dispersion and incorporation of KL, as partial substitutes of petroleum-based polyols for VPF.…”