Tag Archives: Marshall J. Allen

Bioinspired ‘smart’ materials a step towards soft robotics and electronics

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An October 13, 2022 news item on Nanowerk describes some new work from the University of Texas at Austin,

Inspired by living things from trees to shellfish, researchers at The University of Texas at Austin set out to create a plastic much like many life forms that are hard and rigid in some places and soft and stretchy in others.

Their success — a first, using only light and a catalyst to change properties such as hardness and elasticity in molecules of the same type — has brought about a new material that is 10 times as tough as natural rubber and could lead to more flexible electronics and robotics.

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An October 13, 2022 University of Texas at Austin news release (also on EurekAlert), which originated the news item, delves further into the work,

“This is the first material of its type,” said Zachariah Page, assistant professor of chemistry and corresponding author on the paper. “The ability to control crystallization, and therefore the physical properties of the material, with the application of light is potentially transformative for wearable electronics or actuators in soft robotics.”

Scientists have long sought to mimic the properties of living structures, like skin and muscle, with synthetic materials. In living organisms, structures often combine attributes such as strength and flexibility with ease. When using a mix of different synthetic materials to mimic these attributes, materials often fail, coming apart and ripping at the junctures between different materials.

Oftentimes, when bringing materials together, particularly if they have very different mechanical properties, they want to come apart,” Page said. Page and his team were able to control and change the structure of a plastic-like material, using light to alter how firm or stretchy the material would be.

Chemists started with a monomer, a small molecule that binds with others like it to form the building blocks for larger structures called polymers that were similar to the polymer found in the most commonly used plastic. After testing a dozen catalysts, they found one that, when added to their monomer and shown visible light, resulted in a semicrystalline polymer similar to those found in existing synthetic rubber. A harder and more rigid material was formed in the areas the light touched, while the unlit areas retained their soft, stretchy properties.

Because the substance is made of one material with different properties, it was stronger and could be stretched farther than most mixed materials.

The reaction takes place at room temperature, the monomer and catalyst are commercially available, and researchers used inexpensive blue LEDs as the light source in the experiment. The reaction also takes less than an hour and minimizes use of any hazardous waste, which makes the process rapid, inexpensive, energy efficient and environmentally benign.

The researchers will next seek to develop more objects with the material to continue to test its usability.

“We are looking forward to exploring methods of applying this chemistry towards making 3D objects containing both hard and soft components,” said first author Adrian Rylski, a doctoral student at UT Austin.

The team envisions the material could be used as a flexible foundation to anchor electronic components in medical devices or wearable tech. In robotics, strong and flexible materials are desirable to improve movement and durability.

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Here’s a link to and a citation for the paper,

Polymeric multimaterials by photochemical patterning of crystallinity by Adrian K. Rylski, Henry L. Cater, Keldy S. Mason, Marshall J. Allen, Anthony J. Arrowood, Benny D. Freeman, Gabriel E. Sanoja, and Zachariah A. Page. Science 13 Oct 2022 Vol 378, Issue 6616 pp. 211-215 DOI: 10.1126/science.add6975

This paper is behind a paywall.

Is there a supercapacitor hiding in your tree?

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I gather the answer is: Yes, there is a supercapacitor in your tree as researchers at Oregon State University (OSU) have found a way to use tree cellulose as a building component for supercapacitors. From an April 7, 2014 news item on ScienceDaily,

Based on a fundamental chemical discovery by scientists at Oregon State University, it appears that trees may soon play a major role in making high-tech energy storage devices.

OSU chemists have found that cellulose — the most abundant organic polymer on Earth and a key component of trees — can be heated in a furnace in the presence of ammonia, and turned into the building blocks for supercapacitors.

An April 7, 2014 OSU news release (also on EurekAlert), which originated the news item portrays great excitement (Note: Links have been removed),

These supercapacitors are extraordinary, high-power energy devices with a wide range of industrial applications, in everything from electronics to automobiles and aviation. But widespread use of them has been held back primarily by cost and the difficulty of producing high-quality carbon electrodes.

The new approach just discovered at Oregon State can produce nitrogen-doped, nanoporous carbon membranes – the electrodes of a supercapacitor – at low cost, quickly, in an environmentally benign process. The only byproduct is methane, which could be used immediately as a fuel or for other purposes.

“The ease, speed and potential of this process is really exciting,” said Xiulei (David) Ji, an assistant professor of chemistry in the OSU College of Science, and lead author on a study announcing the discovery in Nano Letters, a journal of the American Chemical Society. The research was funded by OSU.

“For the first time we’ve proven that you can react cellulose with ammonia and create these N-doped nanoporous carbon membranes,” Ji said. “It’s surprising that such a basic reaction was not reported before. Not only are there industrial applications, but this opens a whole new scientific area, studying reducing gas agents for carbon activation.

“We’re going to take cheap wood and turn it into a valuable high-tech product,” he said.

The news release includes some technical information about the carbon membranes and information about the uses to which supercapacitors are put,

These carbon membranes at the nano-scale are extraordinarily thin – a single gram of them can have a surface area of nearly 2,000 square meters. That’s part of what makes them useful in supercapacitors. And the new process used to do this is a single-step reaction that’s fast and inexpensive. It starts with something about as simple as a cellulose filter paper – conceptually similar to the disposable paper filter in a coffee maker.

The exposure to high heat and ammonia converts the cellulose to a nanoporous carbon material needed for supercapacitors, and should enable them to be produced, in mass, more cheaply than before.

A supercapacitor is a type of energy storage device, but it can be recharged much faster than a battery and has a great deal more power. They are mostly used in any type of device where rapid power storage and short, but powerful energy release is needed.

Supercapacitors can be used in computers and consumer electronics, such as the flash in a digital camera. They have applications in heavy industry, and are able to power anything from a crane to a forklift. A supercapacitor can capture energy that might otherwise be wasted, such as in braking operations. And their energy storage abilities may help “smooth out” the power flow from alternative energy systems, such as wind energy.

They can power a defibrillator, open the emergency slides on an aircraft and greatly improve the efficiency of hybrid electric automobiles.

Besides supercapacitors, nanoporous carbon materials also have applications in adsorbing gas pollutants, environmental filters, water treatment and other uses.

“There are many applications of supercapacitors around the world, but right now the field is constrained by cost,” Ji said. “If we use this very fast, simple process to make these devices much less expensive, there could be huge benefits.”

Here’s a link to and a citation for the paper,

Pyrolysis of Cellulose under Ammonia Leads to Nitrogen-Doped Nanoporous Carbon Generated through Methane Formation by Wei Luo, Bao Wang, Christopher G. Heron, Marshall J. Allen, Jeff Morre, Claudia S. Maier, William F. Stickle, and Xiulei Ji. Nano Lett., Article ASAP DOI: 10.1021/nl500859p Publication Date (Web): March 28, 2014
Copyright © 2014 American Chemical Society

The article is behind a paywall.

One final observation, one of the researchers, William F. Stickle is affiliated with HewLett Packard and not Oregon State University as are the others.