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Energy Storage

Croissants and Blenders

by Sam Lemonick
November 24, 2019 | A version of this story appeared in Volume 97, Issue 46


From croissants to capacitors

Photograph of cut croissant showing airy interior structure.
Credit: Shutterstock
Pastry meets polymers: The press-and-fold method used to make croissants can produce high-performing plastic capacitors.

Inspiration can strike anywhere, anytime. Even, apparently, in the stupor that follows a family Christmas meal.

“We were in the living room, sort of drugged by foods,” recalls Emiliano Bilotti, a polymer scientist at Queen Mary University of London. At the time, Bilotti had been trying to figure out a better way to disperse graphene nanoparticles in polymers, where they tend to warp and clump together. This limits their performance. The answer was in his mother’s rustici, savory vegetable-filled pastries.

Like a croissant, rustico dough is repeatedly flattened and folded to create an airy structure. Bilotti intuited that the same technique could evenly spread graphene nanoparticles between sheets of polymer. His group found the method isolated and protected the nanoparticles even at high weight percentages.

Bilotti’s team is now applying the press-and-fold method to capacitors, which can store and quickly discharge electrical energy. Rather than dispersing nanoparticles, the researchers used the technique to control crystallization in a poly(vinylidene fluoride) polymer. Their croissant-copycat capacitor has the highest reported energy storage value for polymer materials, meaning it could rival the performance of current capacitors while adding the benefits of a polymer’s mechanical properties (Nat. Commun. 2019, DOI: 10.1038/s41467-019-12391-3).

For now, Bilotti and his colleagues are folding their polymers by hand, just like his mother does when she makes her rustici. “It’s quite a time-consuming way,” he tells Newscripts. But commercial croissant-making machines exist, and Bilotti thinks he might be able to adopt their mechanics to produce his capacitors on larger scales.


A cover story

Plenty of teens dream of being on magazine covers. Gabrielle Chiong, a senior at Walnut Hills High School in Cincinnati, already has hers: the Sept. 11, 2019, issue of ACS Applied Materials and Interfaces.

Cover of ACS Applied Materials and Interfaces showing a laser hitting a lipid bilayer surface.
Credit: ACS Applied Materials and Interfaces
Art class: A high school student's interest in art and science came together for this journal cover.

Chiong spent this past summer working as a researcher in Laura B. Sagle’s bionanomaterials lab at the University of Cincinnati. Sagle would normally hire a graphic designer to make art to accompany an article, but knowing that Chiong was interested in illustration, Sagle asked the young woman to make a journal cover and table of contents image for a forthcoming paper (ACS Appl. Mater. Interfaces 2019, DOI:10.1021/acsami.9b09988).

Using the 3-D-modeling software Blender for the first time, Chiong built representations of the silica bead substrate, lipid bilayer, and other elements of the experiment. She continually consulted with Sagle to ensure scientific accuracy. One challenge, she says, was finding the right colors so that each object was visually distinct but the whole palette worked together. She played with a few different angles, too, before settling on one that portrays everything a bit skewed, which she likes.

Sagle says her group was floored when they saw what Chiong had made: “It was amazing.”

Chiong thinks art can help scientists and vice versa. “Since both deal with observing and interpreting,” she says, “being able to appreciate and understand both can allow you to approach problems and solutions with a different mind-set.”

As a senior, Chiong says she’s working on college applications and planning to major in bioengineering. But if she does want to keep making journal art, Sagle thinks she’ll have plenty of work—colleagues have been asking Sagle how to get hold of the artist.

Sam Lemonick wrote this week’s column. Please send comments and suggestions to


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