Opportunity
The development of high-performance biodegradable polymers for biomedical and environmentally friendly applications faces a significant challenge: balancing mechanical strength with flexibility and toughness while ensuring rapid degradation. Existing synthetic polymers, such as conventional poly(γ-benzyl L-glutamate) (PBLG), typically possess only a single type of secondary structure, like β-sheet, which provides strength but limited extensibility. This results in materials that are either strong but brittle or flexible but weak, failing to mimic the superior toughness found in natural proteins like spider silk, which combines α-helix structures for extensibility with β-sheet structures for strength. Furthermore, many current biodegradable polymers have low biomass content, leading to slow degradation rates, which limits their utility in applications requiring timely absorption or environmental breakdown, such as medical implants, drug delivery systems, and disposable packaging. There is a clear market and technological need for a synthetic material that can replicate the synergistic mechanical properties of natural biomolecules while being composed predominantly of biodegradable components to ensure a swift and complete degradation profile, addressing both performance and sustainability requirements in advanced material science.
Technology
This patent discloses an innovative degradable polylactic acid-based-polypeptide polyurethane. The core technological advancement lies in the synthesis of a novel PBLG that simultaneously incorporates both α-helix and β-sheet secondary structures, achieved by precisely controlling the polymerization degree (14-15) of γ-benzyl L-glutamate N-carboxyanhydride using a specific initiator like ethylenediamine and a controlled monomer-to-initiator ratio. This dual-structure PBLG is then used as a key building block. The material is synthesized via a multi-step polymerization process: first, a prepolymer is formed by reacting a diisocyanate (e.g., isophorone diisocyanate) with a polylactic acid-polycaprolactone diol (PLA-co-PCL diol) using a catalyst like dibutyltin dilaurate. Subsequently, this prepolymer is chain-extended by reacting with the specially synthesized dual-structure PBLG. The final copolymer integrates the PLA-co-PCL soft segments, the diisocyanate linker, and the polypeptide hard segments (PBLG). The α-helix domains within the PBLG segments impart high extensibility and elasticity, while the β-sheet domains provide exceptional tensile strength. Their combination within a single polymer chain creates a synergistic effect, yielding a material with remarkable toughness. Furthermore, because the primary components (PLA-co-PCL and PBLG) are derived from or mimic biological building blocks, the final polyurethane has a very high biomass content (80-95%), which directly contributes to its excellent and rapid biodegradability under controlled composting conditions.
Advantages
- Exceptional Mechanical Properties: Achieves an optimal balance of strength and flexibility, with a toughness of 150-300 MJ/m³, tensile strength of 60-150 MPa, and elongation at break of 200-1000%.
- Biomimetic Structure: Successfully mimics the dual secondary structure (α-helix and β-sheet) of natural tough proteins like spider silk, providing a synthetic route to achieve similar performance.
- High Biodegradability: Exhibits a very high biodegradation rate (85-91% under standard composting tests) due to its high biomass content (80-95%).
- Tailorable Synthesis: The polymerization process allows for control over key parameters (e.g., molar ratios, polymerization degree of PBLG) to fine-tune the final material's properties for specific needs.
- Good Processability: The specially designed PBLG with a controlled, lower molecular weight exhibits good solubility in common organic solvents, facilitating its incorporation into the polymerization reaction and subsequent processing.
Applications
- Biomedical Implants: Such as biodegradable screws, pins, plates, and scaffolds for tissue engineering (e.g., bone, cartilage) that require initial strength and gradual absorption by the body.
- Drug Delivery Systems: As a carrier for controlled-release pharmaceuticals, where the degradation rate of the polymer dictates the release profile.
- Surgical Sutures and Meshes: For wound closure and support that need to be strong, flexible, and fully absorbable over time.
- Advanced Biodegradable Packaging: For high-value or specialty products where mechanical robustness is required alongside compostability.
- Base Material for Composites: Can be blended or compounded with other polymers or fillers to create bio-based composite materials with enhanced toughness for various industrial applications.
