The new plastic-like material can be soft and stretchy or hard and rigid depending on whether or not it is illuminated with visible light during synthesis with a catalyst. Image: UT Austin.Inspired by living things, researchers at the University of Texas at Austin (UT Austin) set out to create a plastic that is 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 – resulted in a new material that is 10 times as tough as natural rubber and could lead to more flexible electronics and robotics. The researchers report their work in a paper in Science.
“This is the first material of its type,” said Zachariah Page, assistant professor of chemistry at UT Austin and corresponding author of 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. But when using a mix of different synthetic materials to mimic these attributes, materials often fail, coming apart and ripping at the junctures between the different materials.
“Oftentimes, when bringing materials together, particularly if they have very different mechanical properties, they want to come apart,” Page said. As an alternative approach, he and his team tried to control and change the structure of a plastic-like material, using light to alter how firm or stretchy the material would be.
The researchers started with a monomer, a small molecule that binds with others like it to form a polymer. After testing a dozen catalysts, they found one that, when added to their monomer and shown visible light, created a semicrystalline polymer similar to those that make up existing synthetic rubber. Even more impressively, the catalyst created a harder and more rigid version of the polymer in the areas illuminated by visible light, and a soft, stretchy version in unlit areas.
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 the researchers used inexpensive blue LEDs as the light source in the experiment. The reaction also takes less than an hour and minimizes the use of hazardous waste, making the process rapid, inexpensive, energy efficient and environmentally benign.
The researchers will next seek to produce more objects with the material to further 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 that the material could be used as a flexible foundation to anchor electronic components in medical devices or wearable tech. In robotics, materials that are both strong and flexible are desirable for improving movement and durability.
This story is adapted from material from the University of Texas at Austin, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.