Mimicking a sweet solution to mop up pollution

May 11, 2018, King Abdullah University of Science and Technology
Mimicking a sweet solution to mop up pollution
A transmission electron microscopy (TEM) image shows that the spherical compartments are interconnected through nanochannels. Credit: S. Nunes

A fast, safe method to prepare a 3-D porous material that mimics the shape of a honeycomb could have broad applications in catalysis, drug delivery, or for filtering air to remove pollutants or viruses.

Both the lattice of a honeycomb and the symmetry of a diatom are complex living structures comprising patterns and shapes that have long provided inspiration for scientists. One recent application is to develop artificial hierarchical porous materials that are stable, yet have a and the ability to selectively extract materials. It has been difficult however to build these structures at the nanoscale due to their complexity and pattern repeatability across scales from the individual compartments to the whole .

A team from KAUST, led by Suzana Nunes, has proposed a simple that, in just five minutes, can produce a flexible film with a complex hierarchical structure that has repeating patterns of interconnected, regularly shaped pores.

With experts in the Imaging and Characterization Core Lab, the team used the block copolymer called polystyrene-b-poly (tertbutyl acrylate) (PS-b-PtBA) to demonstrate this method. They tested various concentrations of PS-b-PtBA with different solvent mixtures, cast the resulting solutions on glass plates and evaporated them for different time periods to promote the nucleation and growth of cavities with highly porous interconnecting walls. The resulting film was then immersed in water to rinse off the solvent and halt the phase separation.

"By using this method we create an important platform to design artificial porous that replicate highly ordered porous and complex systems mimicking nature," explains research scientist and lead author Stefan Chisca. "These have potential use for separations, such as virus filtration, and for biological scaffolds, such as those used for bone regeneration."

The repeating regular hierarchical structures are shown by scanning electron microscopy (SEM) images that illustrate how the honeycomb structure has formed at the surface of the material. Credit: S. Nunes

The study is published today in Science Advances.

The repeating regular hierarchical structures are shown by scanning electron microscopy (SEM) images that illustrate how the honeycomb structure has formed within the material. Credit: S. Nunes

Explore further: How the topology of a porous material influences the phase separation of binary mixtures

More information: "Artificial 3-D hierarchical and isotropic porous polymeric materials" Science Advances, advances.sciencemag.org/content/4/5M/eaat0713

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