Ultra-robust polyurethane/lignin elastomers based on multiscale structural orientation induced by pre-stretching.

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Polyurethane elastomers are versatile materials.
• Developing robust polyurethane elastomers with enhanced mechanical properties is crucial for advanced applications.
• Incorporating bio-based crosslinkers like lignin nanoparticles offers sustainable alternatives.

Purpose of the Study:

• To develop a simple yet effective method for designing ultra-robust polyurethane elastomers.
• To investigate the impact of pre-stretching on the mechanical properties and microstructure of polyurethane/lignin elastomers.
• To explore the role of lignin nanoparticles (LNP) as a biomacromolecular crosslinker.

Main Methods:

• Synthesis of polyurethane/lignin elastomers using polytetramethylene ether glycol (PTMG), hexamethylene diisocyanate (HDI), 4,4'-dihydroxydiphenyl ether (DO), and LNP.
• Application of pre-stretching to the synthesized elastomers at various ratios (λ).
• Characterization of mechanical properties (tensile strength, toughness) and structural changes (interphase distance, crystal distance, Herman orientation factor).

Main Results:

• Pre-stretching polyurethane/lignin elastomers at λ = 14 significantly improved mechanical properties.
• Tensile strength increased from 32.4 MPa to 116.2 MPa, and toughness enhanced from 298.7 MJ m⁻³ to 501.3 MJ m⁻³.
• Structural analysis revealed decreased interphase distance, increased interplanar crystal distance, and a higher Herman orientation factor, indicating dense cross-linked networks.

Conclusions:

• A novel and simple strategy for enhancing polyurethane elastomer performance via pre-stretching has been presented.
• The combined effects of pre-stretching on multiscale structural orientation and stress-induced crystallization are key to achieving ultra-robust properties.
• This approach offers a promising route for developing high-performance, bio-inspired polyurethane elastomers.