Plant Surfaces: Structures and Functions for Biomimetic Innovations

Area of Science:

• Plant biology
• Bionics
• Surface science

Background:

• Biological species have evolved highly complex, multifunctional surfaces over 3.5 billion years.
• Superhydrophobicity, a key evolutionary step for terrestrial habitats, is primarily found in living organisms.
• Plants, as dominant sessile organisms, possess large, multifunctional surfaces with intriguing features.

Purpose of the Study:

• To provide an overview of plant surface structures, their evolution, chemistry, architecture, and functions.
• To explore possible biomimetic applications inspired by plant surfaces.
• To highlight the significance of superhydrophilicity and superhydrophobicity in plant surfaces.

Main Methods:

• A survey of plant surface structures and functions based on examinations of nearly 20,000 species.
• Detailed description of hierarchical surface features, from polymer cuticle and epicuticular wax to cellular structures.
• Categorization of plant surface functions into six groups: mechanical properties, radiation interaction, water relations, adhesion/non-adhesion, drag modification, and gas exchange.

Main Results:

• Superhydrophobic plant leaves cover approximately 50% of the Earth's surface area (estimated 250 million km²).
• A fundamental difference in surface chemistry and architecture exists between aquatic non-vascular and land-living vascular plants.
• Plant surface functions include mechanical properties, spectral radiation influence, water management, adhesion/non-adhesion, drag modification, and gas exchange.

Conclusions:

• Plant surfaces exhibit remarkable hierarchical structures and functionalities, surpassing abiotic surfaces.
• Global environmental change poses a threat to biodiversity, leading to the loss of valuable biological role models for biomimetics.
• The durability of nanocoatings remains a major challenge for engineers and materials scientists in developing biomimetic applications.