Beyond stain-resistant: New fabric coating actively shrugs off gunk

Apr 25, 2012
Beyond stain-resistant: New fabric coating actively shrugs off gunk

Scientists are reporting development and successful testing of a fabric coating that would give new meaning to the phrase "stain-resistant" -- a coating that would take an active role in sloughing off grease, dirt, strong acids and other gunk. The report, which shows that the coating is even more water-repellent than car wax or Teflon, appears in ACS' journal Langmuir.

Tong Lin and colleagues explain that a method called "layer-by-layer" (LbL) self-assembly produces films and coatings for sensors, drug-delivery devices and many other products. LbL involves setting down alternate layers of positively and negatively charged materials that are held together by electric charges. With this approach, coatings can be custom-designed for specific applications by selecting the composition of each layer. The downside: These multilayer films are not very stable and eventually come apart. Lin and colleagues wanted to develop a way to stabilize those layers with UV light to form a "superhydrophobic" coating, one that uses natural surface forces to highly repel water and other materials.

Laboratory tests showed that the new coating, applied to cotton fabric, repelled water, acids, bases and . The coating also was durable, remaining intact on the after 50 trips through a home washing machine. When the researchers applied several layers of the coating on the fabric, the contact angle (a measure of water-repellence) was about 154 degrees, making it even more repellent than car wax (90-degree contact angle), Teflon (95-degree contact angle) or products that repel rainwater from (110-degree ).

Explore further: Researchers develop new storage cell for solar energy storage, nighttime conversion

More information: “Photoreactive Azido-Containing Silica Nanoparticle/Polycation Multilayers: Durable Superhydrophobic Coating on Cotton Fibers” Langmuir, 2012, 28 (15), pp 6328–6335. DOI: 10.1021/la300281q

Abstract
In this study, we report the functionalization of silica nanoparticles with highly photoreactive phenyl azido groups and their utility as a negatively charged building block for layer-by-layer (LbL) electrostatic assembly to produce a stable silica nanoparticle coating. Azido-terminated silica nanoparticles were prepared by the functionalization of bare silica nanoparticles with 3-aminopropyltrimethoxysilane followed by the reaction with 4-azidobenzoic acid. The azido functionalization was confirmed by FTIR and XPS. Poly(allylamine hydrochloride) was also grafted with phenyl azido groups and used as photoreactive polycations for LbL assembly. For the photoreactive silica nanoparticle/polycation multilayers, UV irradiation can induce the covalent cross-linking within the multilayers as well as the anchoring of the multilayer film onto the organic substrate, through azido photochemical reactions including C–H insertion/abstraction reactions with surrounding molecules and dimerization of azido groups. Our results show that the stability of the silica nanoparticle/polycation multilayer film was greatly improved after UV irradiation. Combined with a fluoroalkylsilane post-treatment, the photoreactive LbL multilayers were used as a coating for superhydrophobic modification of cotton fabrics. Herein the LbL assembly method enables us to tailor the number of the coated silica nanoparticles through the assembly cycles. The superhydrophobicity of cotton fabrics was durable against acids, bases, and organic solvents, as well as repeated machine wash. Because of the unique azido photochemistry, the approach used here to anchor silica nanoparticles is applicable to almost any organic substrate.

Related Stories

Graphene is thinnest known anti-corrosion coating

Feb 22, 2012

New research has established the "miracle material" called graphene as the world's thinnest known coating for protecting metals against corrosion. Their study on this potential new use of graphene appears ...

Stay super-dry with Nokia's nanotechnology

Mar 07, 2012

What happens when a drop of water falls on a lotus leaf? It’s not a philosophical question, but a natural phenomenon scientists have been studying, and trying to make sense of, for hundreds of years. 

Recommended for you

Metal encapsulation optimizes chemical reactions

12 hours ago

The chemical industry consumes millions of tons of packing materials as catalytic sup- port media or adsorbents in fixed-bed reactors and heat storage systems. Fraunhofer researchers have developed a means of encapsulating ...

Fuel and chemicals from steel plant exhaust gases

13 hours ago

Carbon monoxide-rich exhaust gases from steel plants are only being reclaimed to a minor extent as power or heat. Fraunhofer researchers have developed a new recycling process for this materially unused carbon resource: They ...

Self-assembly of molecular Archimedean polyhedra

13 hours ago

Chemists truly went back to the drawing board to develop new X-shaped organic building blocks that can be linked together by metal ions to form an Archimedean cuboctahedron. In the journal Angewandte Chemie, the sc ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.