Body temperature triggers newly developed polymer to change shape

February 9, 2016
A time-lapse photo of a new shape-memory polymer reverting to its original shape after being exposed to body temperature. Credit: Adam Fenster/University of Rochester

Polymers that visibly change shape when exposed to temperature changes are nothing new. But a research team led by Chemical Engineering Professor Mitch Anthamatten at the University of Rochester created a material that undergoes a shape change that can be triggered by body heat alone, opening the door for new medical and other applications.

The material developed by Anthamatten and graduate student Yuan Meng is a type of shape-memory polymer, which can be programmed to retain a temporary shape until it is triggered—typically by heat—to return to its original shape.

"Tuning the trigger temperature is only one part of the story," said Anthamatten. "We also engineered these to store large amount of elastic energy, enabling them to perform more during their shape recovery"

The findings are being published this week in the Journal of Polymer Science Part B: Polymer Physics.

The key to developing the new polymer was figuring out how to control crystallization that occurs when the material is cooled or stretched. As the material is deformed, polymer chains are locally stretched, and small segments of the polymer align in the same direction in small areas—or domains—called crystallites, which fix the material into a temporarily deformed shape. As the number of crystallites grows, the polymer shape becomes more and more stable, making it increasingly difficult for the material to revert back to its initial—or "permanent"—shape.

The video will load shortly

The ability to tune the trigger temperature was achieved by including molecular linkers to connect the individual polymer strands. Anthamatten's group discovered that linkers inhibit—but don't stop—crystallization when the material is stretched. By altering the number and types of linkers used, as well as how they're distributed throughout the polymer network, the Rochester researchers were able to adjust the material's stability and precisely set the melting point at which the is triggered.

Heating the new polymer to temperatures near 35 ?C, just below the body temperature, causes the crystallites to break apart and the material to revert to its permanent shape.

"Our shape-memory polymer is like a rubber band that can lock itself into a new shape when stretched," said Anthamatten. "But a simple touch causes it to recoil back to its original shape."

The video will load shortly

Having a polymer with a precisely tunable trigger temperature was only one objective. Of equal importance, Anthamatten and his team wanted the material to be able to deliver a great deal of mechanical work as the shape transforms back to its permanent shape. Consequently, they set out to optimize their polymer networks to store as much elastic energy as possible.

"Nearly all applications of shape memory polymers will require that the material pushes or pulls on its surroundings," said Anthamatten. "However, researchers seldom measure the amount of mechanical work that are actually performing."

Anthamatten's shape-memory polymer is capable of lifting an object one-thousand times its weight. For example, a polymer the size of a shoelace—which weighs about a gram—could lift a liter of soda.

Anthamatten says the -memory could have a variety of applications, including sutures, artificial skin, body-heat assisted medical dispensers, and self-fitting apparel.

Explore further: New self-stretching material developed

Related Stories

New self-stretching material developed

February 13, 2015

Although most materials slightly expand when heated, there is a new class of rubber-like material that not only self-stretches upon cooling; it reverts back to its original shape when heated, all without physical manipulation.

New polymer can shape-shift into multiple forms (w/ video)

January 11, 2016

(Phys.org)—A team of researchers with Zhejiang University in China has developed a new type of polymer that can be caused to revert to multiple different forms on demand. In their paper published in the journal Science ...

Turning vapors into foam-like polymer coatings

October 11, 2013

the essential component of plastics—are found in countless commercial, medical, and industrial products. Polymers that are porous are called foam polymers and are especially useful because they combine light weight with ...

'Smart' medical material aims to unfurl at 98.6 degrees

November 22, 2013

(Phys.org) —Mechanical Engineering Professor Lih-Sheng (Tom) Turng has a simple office demonstration of how shape-memory polymers work. He takes the material, which is formed into a compact flower bud, drops the bud in ...

Recommended for you

Scientists develop first catalysed reaction using iron salts

January 20, 2017

Scientists at the University of Huddersfield have developed a new chemical reaction that is catalysed using simple iron salts – an inexpensive, abundant and sustainable alternative to costlier and scarcer metals. The research ...

Chemists cook up new nanomaterial and imaging method

January 20, 2017

A team of chemists led by Northwestern University's William Dichtel has cooked up something big: The scientists created an entirely new type of nanomaterial and watched it form in real time—a chemistry first.

Gecko inspired adhesive can attach and detach using UV light

January 19, 2017

(Phys.org)—A small team of researchers at Kiel University in Germany has developed new technology that emulates the way a gecko uses its toes to cling to flat surfaces. In their paper published in the journal Science Robotics, ...

Treated carbon pulls radioactive elements from water

January 19, 2017

Researchers at Rice University and Kazan Federal University in Russia have found a way to extract radioactivity from water and said their discovery could help purify the hundreds of millions of gallons of contaminated water ...

0 comments

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.