Bioinspired Polyurethane Using Multifunctional Block Modules with Synergistic Dynamic Bonds.

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Nature utilizes hierarchical structures for high-performance biomaterials like spider silk.
• Synthetic polymers struggle to replicate the stiffness, strength, and toughness of natural materials.
• Mussel byssus proteins inspire the use of iron-catecholate complexes in material design.

Purpose of the Study:

• To design novel polymer materials with enhanced mechanical properties, self-healing, and reprocessability.
• To mimic the multiblock backbone and H-bonding strategies found in spider silk.
• To integrate reversible iron-catechol cross-links and quadruple H-bonds into a polymer structure.

Main Methods:

• Incorporation of iron-catechol (DOPA-Fe3+) cross-links and 2-ureido-4-[1H]-pyrimidinone (UPy) dimers into a polyurethane backbone.
• Utilizing urethane and semicrystalline polycaprolactone (PCL) blocks.
• Characterization using Solid-State Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

• The dual dynamic cross-linking network (DOPA-Fe3+ and UPy) enhanced toughness and breaking elongation through energy dissipation.
• DOPA-Fe3+ complexes promoted PCL crystallization, significantly improving Young's modulus and tensile strength.
• Solid-state NMR confirmed the formation of quadruple H-bonds and DOPA-Fe3+ complexes, restricting chain mobility and increasing PCL crystallinity.

Conclusions:

• A novel molecular design strategy for bio-inspired polymers was successfully developed.
• The resulting materials exhibit a balanced enhancement of stiffness and toughness.
• The materials demonstrate excellent self-healing ability and reprocessability, offering a feasible route for advanced functional materials.