Binary Cellulose Nanocrystal Blends for Bioinspired Damage Tolerant Photonic Films.

Area of Science:

• Materials Science
• Nanotechnology
• Biomaterials

Background:

• Cellulose nanocrystals (CNCs) are promising for creating strong, tough composites.
• Existing methods using wood-derived CNCs (w-CNCs) struggle with mechanical performance due to poor shear transfer.
• Limited overlap lengths between w-CNCs hinder efficient shear transfer and overall material strength.

Purpose of the Study:

• To develop a novel strategy for fabricating superior helicoidal CNC films.
• To enhance mechanical properties and flexibility beyond current benchmarks for photonic CNC materials.
• To explore the use of length-bidisperse CNCs for improved composite performance.

Main Methods:

• Fabrication of helicoidal CNC films by co-assembling short w-CNCs with high aspect ratio tunicate-derived CNCs (t-CNCs).
• Characterization of mechanical properties, including in-plane strength and out-of-plane flexibility.
• Utilizing coarse-grained molecular dynamics simulations to understand the role of t-CNCs in property enhancement.

Main Results:

• Achieved simultaneous enhancement of all in-plane mechanical properties and out-of-plane flexibility.
• Demonstrated that t-CNCs increase interaction lengths and activate additional toughening mechanisms.
• Observed UV-reflecting behavior in films with >5% t-CNC content, indicating optical activity.

Conclusions:

• The co-assembly of length-bidisperse CNCs offers a simple yet effective strategy for superior material fabrication.
• The developed CNC films exhibit mechanical properties rivaling natural materials and advanced photonic CNC materials.
• These damage-tolerant, optically active materials are suitable for protective coatings, and the length-bidispersity approach is adaptable to other nanoparticle ensembles.