How to build doughnuts with Lego blocks

December 21, 2011
This shows AFM tapping amplitude signal of a diblock ring in the late stages of annealing. A Plateau-Rayleigh-like instability has developed and the ring is showing the formation of four distinct droplets. The scan area is approximately 54 × 54 μm2. Credit: European Physical Journal E

Scientists have uncovered how nature minimises energy costs in rings of liquids with an internal nanostructure made of two chemically discordant polymers joined with strong bonds, or di-blocks, deposited on a silicon surface, in an article about to be published in European Physical Journal E.

Josh McGraw and his colleagues from McMaster University, Canada, and the University of Reading, UK, first created rings of di-block polymers that they liken to building doughnuts from Lego blocks due to the nature of the material used. This material has an discretised like Lego blocks, resulting in rings approximating the seamless shape of a doughnut (see photo of previously unseen nanoscale assemblies which illustrates this report).

McGraw and his colleagues measured the dynamics of interacting edges in ring structures that display asymmetric steps, i.e., different spacing inside and outside the ring, when initially created. They found that the interaction shaping the ring over time is the between edges. While the molecular details remain elusive, the source of this repulsion is intuitive: an edge is a defect which perturbs the surface profile with an associated cost to the .

The edge repulsion prevents two neighbouring edges from getting too near each other. As two isolated edges approach, the perturbation deviates further, thereby deforming the equilibrium edge structure and increasing the free energy. For rings solely subject to the repulsive edge interaction, the authors found that the equilibrium shape of their edges had to be symmetric.

These edges could be considered defects in a material with an otherwise perfect order at the nanoscale. Thus, research based on the elucidation of defect interactions could help scientists trying to eliminate such defects by understanding how these materials self-assemble. Such systems could also provide an ideal basis for creating patterns on the nanoscale, data storage, and nanoelectronics.

Explore further: Cassini Radio Signals Decipher Saturn Ring Structure

More information: McGraw J. D., Rowe I. D.W., Matsen M. W., and Dalnoki-Veress K. (2011). Dynamics of interacting edge defects in copolymer lamellae, European Physical Journal E (EPJ E) DOI 10.1140/epje/i2011-11131-7

Related Stories

Cassini Radio Signals Decipher Saturn Ring Structure

May 23, 2005

The Cassini spacecraft has obtained the most detailed look ever at Saturn's rings, including the B ring, which has eluded previous robotic explorers. Its structure seems remarkably different from its two neighbors, rings ...

Organic Hydrogen Storage

February 24, 2006

Fossil fuels are limited and polluting, hence the search for alternatives. One suitable and environmentally sound fuel would be hydrogen; unfortunately there are currently few technical possibilities for the construction ...

Physicists undo the 'coffee ring effect' (w/ video)

August 17, 2011

A team of University of Pennsylvania physicists has shown how to disrupt the "coffee ring effect" — the ring-shaped stain of particles leftover after coffee drops evaporate — by changing the particle shape. The ...

Forget exomoons. Let’s talk exorings

November 25, 2011

In an article earlier this month, I discussed the potential for discovering moons orbiting extrasolar planets. I’d used an image of an exoplant system with rings, prompting one reader to ask if those would be possible ...

Recommended for you

Physicists develop new technique to fathom 'smart' materials

November 26, 2015

Physicists from the FOM Foundation and Leiden University have found a way to better understand the properties of manmade 'smart' materials. Their method reveals how stacked layers in such a material work together to bring ...


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.