#elastomers

Scientists solve 100-year-old mystery behind rubber that powers modern life

Every time you drive, board a plane or water your lawn, you're relying on a material that has quietly powered modern life for nearly a century—reinforced rubber. It's in car and aircraft tires, industrial seals, medical devices and countless everyday products. Yet despite its ubiquity and its central role in the $260 billion global tire industry, scientists have never fully understood why it works so well. Until now. Cracking rubber's long-standing mystery A research team led by University of South Florida engineering Professor David Simmons solved one of the oldest mysteries in materials science: How adding tiny particles known as carbon black transforms soft, stretchy rubber into something strong enough to support the weight of a fully loaded jet. Their findings, published this week in the journal Proceedings of the National Academy of Sciences, provide an answer and offer a new way of thinking about how to design safer, longer-lasting materials.

Credit: Felice Frankel. MIT engineers have designed a gel-like material that can be coated onto standard plastic or rubber devices.

1. By coating elastomer products such as catheters, intravenous lines and condoms in a layer of hydrogel, engineers at MIT, USA, could improve patient comfort, reduce friction and increase product safety.

2. The method of bonding the hydrogel to the elastomer involves dip-coating the devices, which have been treated to ensure they will adhere to the hydrogel polymers, into a hydrogel precursor solution. They are then exposed to UV light.

3. The thickness and composition of the hydrogel layers can be altered to change their rigidity.

4. The hydrogel laminates formed are impermeable, slippery, stretchable and durable – the team found that they could tolerate being bent and twisted.

5. The hydrogel laminates can have drugs integrated into them, which can be released to treat infection or, for example, a latex allergy.

From artificial organs to advanced batteries: A breakthrough 3D-printable polymer

A new type of 3D-printable material that gets along with the body's immune system, pioneered by a University of Virginia research team, could lead to safer medical technology for organ transplants and drug delivery systems. It could also improve battery technologies. The breakthrough is the subject of a new article published in the journal Advanced Materials, based on work done by the University of Virginia's Soft Biomatter Laboratory, led by Liheng Cai, an associate professor of materials science and engineering and chemical engineering. The paper's first author is Baiqiang Huang, a Ph.D. student in the School of Engineering and Applied Science. Their research shows a way to change the properties of polyethylene glycol to make stretchable networks. PEG, as it's known, is a material already used in many biomedical technologies such as tissue engineering, but the way PEG networks are currently produced—created in water by crosslinking linear PEG polymers, with the water removed afterward—leaves a brittle, crystallized structure that can't stretch without losing its integrity.

With AI, chemists create rubber-like materials in record time

Everyday items like car tires, plastic bags and foam cushions come from materials called polymers that can take years to develop and test. Researchers at Carnegie Mellon University and the University of North Carolina at Chapel Hill have developed a new approach to create better rubber-like materials more quickly by combining artificial intelligence with human expertise. Typically, when researchers make a material stronger, it becomes less flexible, while flexible materials tend to be weaker. To fix this problem, the team created a machine-learning model that works in tandem with human chemists. Machine learning—a subset of AI research—involves teaching an artificial intelligence to perform a specific task. In one experiment, the researchers collaborated with the AI tool to create a polymer that is both strong and flexible.

Wearable haptics get thinner: A flexible haptic patch lets you feel the virtual world

As virtual reality (VR) and augmented reality (AR) technologies rapidly evolve, the demand for more immersive, multisensory experiences grows alongside them. Among the key frontiers is tactile feedback—the ability to physically feel the virtual world. While wearable haptic suits equipped with vibrational motors or fluidic actuators have made strides in enhancing realism, delivering precise, diverse, and natural tactile sensations to the skin remains a major challenge. The limitation has largely stemmed from a lack of compact, lightweight, high-performance tactile actuators. That's where our research takes a bold step forward. My colleagues and I have developed a new class of thin, flexible tactile actuators designed to deliver rich, nuanced haptic feedback directly to the skin.

Programmable soft material bends, bounces and absorbs energy on demand

Scientists at Lawrence Livermore National Laboratory (LLNL) and their collaborators have created a new class of programmable soft materials that can absorb impacts like never before, while also changing shape when heated. The research—which includes collaborators from Harvard University, the California Institute of Technology (Caltech), Sandia National Laboratories and Oregon State University—opens the door to smarter, lighter and more resilient materials that respond to the world around them. The research is published in the journal Advanced Materials. Built from liquid crystal elastomers (LCEs)—rubbery polymers that shift in response to heat, light or stress—the team 3D-printed the materials into carefully engineered lattice structures. These lattices can be designed to absorb energy, stiffen, soften or even change shape, depending on their architecture and environmental conditions.

Novel kiri-origami structures enable high-performance stretchable electronics

Stretchable electronics are used in smartphones, smartwatches, curved displays, and wearable sensors. However, stretchable materials like elastomers have lower electrical performance than rigid materials such as metals or semiconductors, creating a trade-off between flexibility and function. To overcome this challenge, researchers have explored origami and kirigami, traditional Japanese paper folding (ori-) and cutting (kiri-) techniques, as strategies to achieve stretchability even when using non-stretchable electronic materials. Origami uses hinges to create flat, rigid-mountable panels by bending, while kirigami introduces slits for full-structure deformation and is better for large-area designs. However, kirigami is less suited for mounting rigid components. In a recent study, Professor Eiji Iwase and Mr. Nagi Nakamura from the Department of Applied Mechanics and Aerospace Engineering at Waseda University, Japan, developed an innovative hybrid technique using kiri-origami structures.

Electronic fiber with liquid metal droplets enables stretchable sensing

EPFL researchers have engineered a fiber-based electronic sensor that remains functional even when stretched to over 10 times its original length. The device holds promise for smart textiles, physical rehabilitation devices, and soft robotics. The phrase "liquid metal" may bring to mind something hazardous, like mercury or molten steel. But in the Laboratory of Photonic Materials and Fiber Devices (FIMAP) in EPFL's School of Engineering, it simply means a mixture of indium and gallium that is nontoxic, remains liquid at room temperature, and shows great promise for developing electronic fibers for wearables and robotic sensors. Unfortunately, as FIMAP head Fabien Sorin explains, liquid metals are extremely difficult to process, and it's especially hard to produce electronic fibers that combine high and stable conductivity with stretchability. Now, the lab has overcome this challenge using a technique called thermal drawing, which is traditionally used to engineer fiber optics.