#elastomers

Researchers at North Carolina State University have successfully incorporated “photosensitizers” into a range of polymers, giving those materials the ability to render bacteria and viruses inactive using only ambient oxygen and visible-wavelength light. The new approach opens the door to a range of new products aimed at reducing the transmission of drug-resistant pathogens.

“The transmission of antibiotic-resistant pathogens, including so-called ‘superbugs,’ poses a significant threat to public health, with millions of medical cases occurring each year in the United States alone,” says Reza Ghiladi, associate professor of chemistry at NC State and co-corresponding author of a paper on the work. “Many of these infections are caused by surface-transmitted pathogens.

"Our goal with this work was to develop materials that are self-sterilizing, nontoxic and resilient enough for practical use. And we’ve been successful.”

“A lot of work has been done to develop photosensitizer molecules that use the energy from visible light to convert oxygen in the air into biocidal 'singlet’ oxygen, which effectively punches holes in viruses and bacteria,” says Richard Spontak, distinguished professor of chemical and biomolecular engineering, professor of materials science and engineering at NC State and co-corresponding author of the paper. “There is no resistance to this mode of action.

Researchers in the labs of Christopher Bates, an assistant professor of materials at UC Santa Barbara, and Michael Chabinyc, a professor of materials and chair of the department, have teamed to develop the first 3-D-printable “bottlebrush” elastomer. The new material results in printed objects that have unusual softness and elasticity—mechanical properties that closely resemble those of human tissue.

Conventional elastomers, i.e. rubbers, are stiffer than many biological tissues. That’s due to the size and shape of their constituent polymers, which are long, linear molecules that easily entangle like cooked spaghetti. In contrast, bottlebrush polymers have additional polymers attached to the linear backbone, leading to a structure more akin to a bottle brush you might find in your kitchen. The bottlebrush polymer structure imparts the ability to form extremely soft elastomers.

The ability to 3-D-print bottlebrush elastomers makes it possible to leverage these unique mechanical properties in applications that require careful control over the dimensions of objects ranging from biomimetic tissue to high-sensitivity electronic devices, such as touch pads, sensors and actuators.

For electric vehicles (EVs) to become mainstream, they need cost-effective, safer, longer-lasting batteries that won’t explode during use or harm the environment. Researchers at the Georgia Institute of Technology may have found a promising alternative to conventional lithium-ion batteries made from a common material: rubber.

Elastomers, or synthetic rubbers, are widely used in consumer products and advanced technologies such as wearable electronics and soft robotics because of their superior mechanical properties. The researchers found that the material, when formulated into a 3D structure, acted as a superhighway for fast lithium-ion transport with superior mechanical toughness, resulting in longer charging batteries that can go farther.  The research, conducted in collaboration with the Korea Advanced Institute of Science and Technology, was published Wednesday in the journal Nature.

Inconventional lithium-ion batteries, ions are moved by a liquid electrolyte. However, the battery is inherently unstable: even the slightest damage can leak into the electrolyte, leading to explosion or fire. The safety issues have forced the industry to look at solid-state batteries, which can be made using inorganic ceramic material or organic polymers.