Stain-Resistant Fabric Finish Inspired by Lotus Leaves

Innovation: Industry

GreenShield Finish

2008

Image: Isaac Chou / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Protect From Excess Liquids

While water is essential to life, too much water or other liquids can overwhelm living systems. Excess liquids can, for example, decrease a living system’s access to oxygen, promote excessive bacterial or fungal growth, or strip away soil and nutrients. To prevent the accumulation of excess liquids, living systems must control the movement of liquids across their boundaries or surfaces. They do so using waterproofing materials or structures, slowing flow, and/or facilitating flow to move the liquid away. Plant leaves, for example, commonly have waxy surfaces comprised of water-repelling chemicals to keep water from engorging the leaves or facilitating bacterial and fungal growth.

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Protect From Dirt/solids

When dirt and other small solids adhere to living systems, they can slow them down, create blockages, reduce their ability to carry out vital functions, or cause surface wear and tear. Due to electrostatic forces, it’s easy for dirt and other solids to adhere to surfaces, so living systems must overcome those forces. An earthworm, for example, uses a small electric current to keep soil particles from adhering to its body as it moves through the soil. This enables it to move more efficiently by reducing drag.

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Patents

US7879743B2
1.4 MB PDF

Keeping It Clean

Explore resources for teaching about superhydrophobicity and nanotechnology using the story of how super water‑repellent lotus leaves inspired self‑cleaning surface coatings.

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GreenShield from GreenShield Finish uses a nano-textured, self-cleaning surface to dramatically reduce the amount of fluorochemicals needed to repel water- and oil-based stains.

Benefits

Water, dirt, and oil repellent
Eco-friendly

Applications

Commercial and residential interiors
Automotive interiors
Marine applications
Outdoor gear

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure

The Challenge

Furniture and textiles are vulnerable to shorter lifetimes due to staining from liquids, including oil. To protect against these stains, products are coated with a continuous layer of polymer-based chemicals, often fluorochemicals. Fluorochemicals are bio-accumulative in living beings and persistent in the environment.

Innovation Details

GreenShield® fabric finishes are oil-repellent, water-repellant, and stain-repellent without the use of harmful fluorocarbons. It is made of amorphous silica nanoparticles (similar to those found in toothpaste and cosmetic creams) that permanently adhere to the fabric as a mesh network and prevent droplets from penetrating. Although this is slightly different from how lotus leaves repel water, the overall concept of preventing water droplets from forming (the ‘lotus effect’) is similar. The nanoparticles are listed as a GRAS material (Generally Recognized as Safe) by the FDA.

Fibers with Green Shield Finish contain silica nanoparticles that permanently adhere to the fabric as a mesh network, creating a repellent surface. Photo: GreenShield Finish.

Biological Model

Lotus plants stay dirt-free, an obvious advantage for an aquatic plant living in typically muddy habitats. The surface of the lotus leaf contains microscopic bumps that prevent water molecules from adhering to the surface. Instead, the water rolls right off, and picks up any dirt or oil on the surface of the lotus leaf along the way.

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Biological Strategy

Surface Allows Self-Cleaning

Sacred lotus

Leaves of the sacred lotus are self-cleaning thanks to hydrophobic microscale bumps.

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