Nacre-Inspired Composite Coatings with Hierarchical Architecture for Durable Surface Protection

Area of Science:

• Materials Science
• Biomimetics
• Conservation Science

Background:

• Built cultural heritage faces degradation from environmental factors.
• Existing protective coatings often lack long-term durability and aesthetic compatibility.
• Nacre's hierarchical structure offers exceptional mechanical properties and protection.

Purpose of the Study:

• To develop a bioinspired multilayer coating for cultural heritage protection.
• To emulate the nacre's hierarchical architecture using sustainable materials.
• To assess the coating's mechanical, chemical, and aesthetic performance.

Main Methods:

• Fabrication via alternating deposition of calcium carbonate (CaCO3) and organic layers (chitosan, cellulose nanofibrils, polyacrylic acid).
• Utilized a CO2-controlled environment for CaCO3 layer formation and substrate adhesion.
• Characterized mechanical properties using nanoindentation and stiffness mapping.
• Evaluated durability under acidic conditions and assessed aesthetic compatibility (color change).

Main Results:

• Achieved stratified organization and mechanical properties comparable to natural nacre.
• Demonstrated enhanced hardness and modulus with increasing multilayers.
• Confirmed structural integrity and aesthetic compatibility (ΔEab < 5) under acidic conditions.
• Showcased effective stress dissipation and damage inhibition due to layered architecture.

Conclusions:

• The bioinspired multilayer coating provides effective protection for built cultural heritage.
• The developed material integrates mechanical resilience, chemical stability, and visual compatibility.
• This research lays the groundwork for advanced protective materials in cultural heritage conservation.