Self-folding origami

June 23, 2017

Plastic with a thousand faces: A single piece of Nafion foil makes it possible to produce a broad palette of complex 3D structures. In the journal Angewandte Chemie, researchers describe how they use simple chemical "programming" to induce the foil to fold itself using origami and kirigami principles. These folds can be repeatedly "erased" and the foil can be "reprogrammed".

We have all seen the cranes and lotus flowers produced from a sheet of paper by practiced hands. Origami is the traditional Japanese art of folding that transforms paper into complex three-dimensional structures without the use of adhesive. Kirigami is a related technique in which the paper is strategically cut before folding. Both of these techniques have found application in modern technology.

Adebola Oyefusi and Jian Chen from the University of Wisconsin - Milwaukee (USA) have now presented a new variation on this technique. They chemically "programmed" Nafion foil so that heat causes it to fold itself into complex three-dimensional forms. The foil can also be "deprogrammed". Nafion is a polymer that can "remember" its shape, so that a stretched piece of foil will return to its initial form upon heating.

The secret to this trick is this: Nafion can be protonated in an acidic environment and deprotonated in a basic one. When protonated, stretched Nafion shrinks at temperatures over 100 °C, when deprotonated it must be heated over 260 °C. As long as the temperature remains within this range, only regions of the Nafion that are protonated will shrink. The deprotonated Nafion is "locked" and does not shrink. The researchers make use of this by programing the information required for folding in the form of a pattern of "unlocked" regions in a stretched piece of Nafion foil that has been "locked" with potassium hydroxide. The pattern is „painted" onto the sheet using hydrochloric acid. When heated above 100 °C, the sheet shrinks in the region of the lines and folds itself along these "creases".

The scientists made some simple and some complex structures, such as a bird and a zigzag rip pattern common in technical practice; solar panels for satellites, for example, are transported in a folded way and can be spread in just one movement. Simple acid-base chemistry and heating "erased" the structures and the nafion sheets could be coded and folded in a new fashion.

The 3D structures made from Nafion can be used as a master mold. This can be used to cast a secondary mold from plastics like polydimethylsiloxane, which can then be used to make molded components from a wide variety of materials, including polymers, ceramics, or metal. The reprogrammable master molds save time, money, and waste because they can be directly reused without a costly recycling process.
About the Author

Dr. Jian Chen is an Associate Professor of Chemistry at University of Wisconsin-Milwaukee. His current research interests focus on bio-inspired smart polymers and composites, and nanocarbon materials.


Related Origami Articles from Brightsurf:

SARS-CoV-2 uses 'genome origami' to infect and replicate inside host cells
Scientists at the University of Cambridge, in collaboration with Justus-Liebig University, Germany, have uncovered how the genome of SARS-CoV-2 - the coronavirus that causes COVID-19 - uses genome origami to infect and replicate successfully inside host cells.

Soft robots, origami combine for potential way to deliver medical treatments
Researchers have found a way to send tiny, soft robots into humans, potentially opening the door for less invasive surgeries and ways to deliver treatments for conditions ranging from colon polyps to stomach cancer to aortic artery blockages.

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Building mechanical memory boards using origami
Origami can be used to create mechanical, binary switches, and in Applied Physics Letters, researchers report the fabrication of such a paper device, using the Kresling pattern, that can act as a mechanical switch.

Origami microbots: Centuries-old artform guides cutting-edge advances in tiny machines
Origami principles can unlock the potential of the smallest robots, enhancing speed, agility and control in machines no more than a centimeter in size.

Origami metamaterials show reversible auxeticity combined with deformation recoverability
New research by Northwestern Engineering and Georgia Institute of Technology expands the understanding of origami structures, opening possibilities for mechanical metamaterials to be used in soft robotics and medical devices.

Engineers use 'DNA origami' to identify vaccine design rules
Using DNA origami as a virus-like scaffold, MIT researchers designed an HIV-like particle that provokes a strong response from human immune cells grown in the lab.

Kirigami/origami: Unfolding the new regime of advanced 3D micro-/nanofabrication with 'folding'
Emerging kirigami/origami techniques, neither subtractive nor additive, provide an automated fashion for 3D micro-/nanofabrication through folding, bending and twisting of 2D materials/structures.

Mechanical forces shape animal 'origami' precisely despite 'noise'
Researchers at the RIKEN Center for Biosystems Dynamics Research (BDR) in Japan have identified a new mechanism that helps animals to develop with precise and constant form.

Protecting DNA origami for anti-cancer drug delivery
Scientists coated octahedral-shaped DNA origami with peptoids that help protect the nanostructures in physiological environments relevant to biomedical applications including anti-cancer drug delivery.

Read More: Origami News and Origami Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to