Published on April 15th, 2014 | By: April Gocha, PhD0
Self-assembly of zirconium phosphate nanoparticle films using an art supply spray gunPublished on April 15th, 2014 | By: April Gocha, PhD
Liquid crystals are like brunch—standing on the line between breakfast and lunch, sometimes leaning more towards breakfast, sometimes more towards lunch. Substitute crystalline solids and liquids for breakfast and lunch, and you get the picture.
These interesting states of matter have some really useful applications. Many of us spend hours every day staring at liquid crystal displays (LCDs) on our computer screens, calculators, phones, and lots of other electronics devices. Liquid crystalline phase solutions can even be spun into fibers, creating highly aligned fibers with high strength but low weight (plus other great functional properties)—like Kevlar.
Because of these properties, thin films of liquid crystalline materials are useful for a host of applications. But current techniques used to create these materials require highly technical processes and equipment (read, dollar signs), such as photolithography.
A new paper published in Nature Materials details the fast synthesis of highly-ordered 2D nanoparticle thin films without the complex, expensive, and laborious processes typically required to achieve such nanostructures.
The authors explain, in a Texas A&M University press release, “we have developed a simple approach of applying a surface coating of thin, flat nanoplatelets using a common spray gun, such as can be purchased off-the-shelf from an art supply store, to create a surface coating in which nanoplatelets spontaneously self-assemble into ‘nano-walls.’ “
The scientists made those films out of a suspension of zirconium phosphate nanoplatelets coated with polyoxyalkyleneamine oligomers. When sprayed onto thin polyimide films and allowed to dry, the nanoplatelets self-assemble into a highly-ordered smetic zirconium phosphate/epoxy layer.
The authors offer up a simple analogy: “To understand this process, imagine a bricklayer who dumps a barrow of bricks and the bricks spontaneously build up into a wall on their own. A similar process of ‘self-assembly’ occurs for the nanoplatelets to create nano-walls that increase the barrier efficiency of the film by more than twenty times.”
The authors extrapolate that similar methods could be used for a host of other “layered functional materials,” including transition metal oxides, dichalcogenides, and current hot topic graphene.
The anticipated application of the new technology is for barrier films for gas separation in industrial processes. The films show “excellent gas barrier properties at both low- and high humidity levels,” according to the paper’s abstract. In addition, the authors conclude in the paper’s discussion that “this technology promises to be of interest to fields as diverse as electronics, catalysts, environmental and composite materials.”
The paper is “Large-scale self-assembled zirconium phosphate smectic layers via a simple spray-coating process” (DOI: 10.1038/ncomms4589).
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