Lignin defined ordered hard domains toward mechanically robust, long-term weather resistant bio-elastomer

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• High-performance elastomers are crucial for harsh environments but face significant challenges in durability.
• Existing polyurethanes (PU) often lack sufficient mechanical strength, toughness, and long-term weather resistance.
• Developing sustainable and robust materials from renewable resources like lignin is an ongoing area of research.

Purpose of the Study:

• To develop a mechanically robust, highly stretchable, and weather-resistant polyurethane bio-elastomer using lignin.
• To investigate the structure-property relationships of lignin-mediated polyurethane (LPU) materials.
• To demonstrate the potential of LPU as a green engineering material for challenging applications.

Main Methods:

• Incorporation of polyphenol lignin as a structural and functional monomer in polyurethane synthesis.
• Utilizing lignin-mediated covalent (carbamate bonds) and non-covalent (hydrogen bonding) interactions to form ordered hard domains.
• Characterization of thermal, mechanical, and long-term weather resistance properties of the synthesized LPU.

Main Results:

• Lignin-derived polyurethane (LPU) showed significantly enhanced thermal stability, with a 75°C increase in initial decomposition temperature compared to PU.
• LPU with 70% lignin substitution exhibited remarkable mechanical properties: 60.39 MPa tensile strength, 532.52% elongation at break, 235.71 MPa elastic modulus, and 183.24 MJ/m³ toughness.
• LPU demonstrated excellent long-term weather resistance after exposure to UV irradiation, seawater corrosion, and heat aging, maintaining structural integrity and mechanical tolerance.

Conclusions:

• Lignin integration via covalent and non-covalent assembly creates ordered hard domains, leading to super-strong and intrinsically weather-resistant polyurethane elastomers.
• The developed LPU offers a promising alternative to conventional elastomers for applications in harsh environments.
• This work highlights a novel strategy for utilizing lignin in the development of sustainable and high-performance green engineering materials.