Stretchable and biodegradable chitosan-polyurethane-cellulose nanofiber composites as anisotropic materials

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Tissue Engineering

Background:

• Chitosan and polyurethanes are biocompatible polymers with diverse applications.
• Existing chitosan-polyurethane composites lack sufficient strength and stretchability.
• Cellulose nanofibers (CNFs) offer potential for material reinforcement.

Purpose of the Study:

• To develop novel chitosan-polyurethane composites with enhanced strength and stretchability.
• To create stretchable and anisotropic materials using cellulose nanofibers.
• To explore the potential of these composites in biomimetic and tissue engineering applications.

Main Methods:

• Synthesis of biodegradable polyurethane nanoparticles, end-capped with aldehyde (dialdehyde polyurethane, DP).
• Preparation of a DP-CNF composite crosslinker (DPF) by adding CNFs to DP nanoparticles.
• Formation of polyurethane-CNF-chitosan (DPFC) composites by blending DPF with chitosan.
• Characterization of hydrogel formation, elongation at break, and anisotropic properties via tension annealing and in situ SAXS/WAXS.

Main Results:

• DPFC composites formed hydrogels rapidly (~33 min) at room temperature, indicating effective crosslinking.
• Composite films exhibited high elongation (~420.2 %) at 60 °C.
• Tension annealing induced significant elastic anisotropy (anisotropic ratio ~4.9) with 200 % pre-strain.
• Microstructural rearrangement and alignment during tension annealing were confirmed by SAXS/WAXS.

Conclusions:

• Integrated cellulose nanofibers significantly improve the mechanical properties of chitosan-polyurethane composites.
• The developed anisotropic composite films demonstrate tunable properties for specific applications.
• These materials show potential for guiding neural stem cell growth, indicating promise for biomimetic and tissue engineering applications.