Until now, polymers with temperature-controlled shape memory could only change form once. Biomaterial researchers have recently developed plastics that can repeatedly change from one shape to another and then back again when temperatures fluctuate within a selected range. The material is dubbed “polymer actuators” by its creators in Germany.
Today’s options for high-performance fibers, include Kevlar, Spectra, Dyneema and Zylon. They have been the strongest synthetics in the world. But Marilyn Minus, an asst. prof. of engineering at Northeastern Univ., has developed a type of fiber that is stronger than the first three commercial products mentioned above, and in its first generation approaches the strength of Zylon.
Introductory chemistry students learn that oil and water repel each other. So do other hydrophobic substances, which carry no electric charge, and hydrophilic substances, which carry an electric charge that allows them to mix with water. In a recent study, a group of bioengineers have found a way to strongly adhere hydrogels to hydrophobic silicone substrates, an innovation that provides a valuable new tool for microscale biotechnology.
Designers of buildings typically have no choice but to use black or bluish-gray colored solar panels. With the help of thin-film technologies, however, researchers in Germany have now added color to solar cells. Optics specialists have changed physical thickness of the transparent conductive oxide layer, modifying its refractive index.
In a new study, a “bioadhesive” coating developed at Brown Univ. significantly improved the intestinal absorption into the bloodstream of nanoparticles that someday could carry protein drugs such as insulin. Such a step is necessary for drugs taken by mouth, rather than injected directly into the blood.
Electrolysis is often used to produce hydrogen that can be used for a storable fuel. Modified solar cells with highly efficient architecture can use this method to obtain hydrogen from water with the help of catalysts. But these solar cells rapidly corrode in aqueous electrolytes. By embedding the catalysts in an electrically conducting polymer, researchers have prevented this corrosion while maintaining competitive efficiency.
Sandia National Laboratories researchers want airports, border checkpoints and others to detect homemade explosives made with hydrogen peroxide without nabbing people whose toothpaste happens to contain peroxide. That’s part of the challenge faced in developing a portable sensor to detect a common homemade explosive called a FOx mixture, made by mixing hydrogen peroxide with fuels.
Space scientists from the Univ. of New Hampshire and the Southwest Research Institute report that data gathered by NASA’s Lunar Reconnaissance Orbiter show lighter materials like plastics provide effective shielding against the radiation hazards faced by astronauts during extended space travel. The finding could help reduce health risks to humans on future missions into deep space.
Using star-shaped block co-polymer structures as tiny reaction vessels, researchers have developed an improved technique for producing nanocrystals with consistent sizes, compositions and architectures—including metallic, ferroelectric, magnetic, semiconductor and luminescent nanocrystals. The technique relies on the length of polymer molecules and the ratio of two solvents to control the size and uniformity of colloidal nanocrystals.
Rice Univ. researchers have for the first time detailed the molecular mechanism that makes a particular combination of cement and polymer glue so tough. The theoretical research led to a fine picture of how hydrogen bonds control the properties of hybrid organic-inorganic materials. The finding has implications for understanding the interface bonding that is often a roadblock to improved composite properties.
Are teeth the latest victims of bisphenol A (BPA)? Yes, according to the conclusions of a team lead by researchers in France. They have shown that the teeth of rats treated with low daily doses of BPA could be damaged the chemical.
The potential energy available via solar power might seem limitless on a sunny summer day, but all that energy has to be stored for it to be truly useful. If you see a solar panel on a rooftop, a bulky battery or supercapacitor is hidden just out of sight, receiving energy from the panel through power lines. However, that's a storage method that doesn't scale well for solar-powered devices with no space for a battery pack.
A chemical that’s often the key ingredient in improvised explosive devices can be quickly and safely detected in trace amounts by a new polymer created by a team of Cornell Univ. chemists. The polymer, which potentially could be used in low-cost, handheld explosive detectors and could supplement or replace bomb-sniffing dogs, was invented in the lab of William Dichtel, assistant professor of chemistry and chemical biology.
A rabbit sculpture, the size of a typical bacterium, is one of several whimsical shapes created by a team of Japanese scientists using a new material that can be molded into complex, highly conductive 3D structures with features just a few micrometers across. The new resin holds promise for making customized electrodes for fuel cells or batteries, as well as biosensor interfaces for medical uses.
Human scabs have become the model for development of an advanced wound dressing material that shows promise for speeding the healing process, scientists are reporting. The team explains that scabs are a perfect natural dressing material for wounds. In addition to preventing further bleeding, scabs protect against infection and recruit the new cells needed for healing.
A new version of solar cells created by laboratories at Rice and Pennsylvania State universities could open the door to research on a new class of solar energy devices. The photovoltaic devices are based on block copolymers, self-assembling organic materials that arrange themselves into distinct layers. They easily outperform other cells with polymer compounds as active elements.
Nearly everyone is familiar with the polytetrafluoroethylene (PTFE), otherwise known as Teflon. Famous for being “non-sticky” and water repellent, PTFE is a dry lubricant used on machine components everywhere. Recently, engineering researchers at the University of Arkansas found a way to make the polymer even less adhesive.
In a quest to develop low-friction components for ever smaller mechanical systems, a team of physicists in Germany has recently discovered a previously unknown type of friction that they call “desorption stick.” The researchers examined how and why single polymer molecules in various solvents slide over or stick to certain surfaces. They found that an unexpected factor was responsible for the friction they observed.
Amid concerns over the potential health effects of existing flame retardants for home furniture, fabrics and other material, are reporting development of an “exceptionally” effective new retardant that appears safer and more environmentally friendly. The key is a nanocoating made with a relatively benign polymer that creates a “gas blanket,” preventing oxygen from fueling a fire.
Cells are the basic unit of life and are separated from the outside world by a thin organic membrane. A major function of this membrane is to allow certain molecules to enter or leave the cell whilst other molecules are blocked from the cell interior. This allows metabolic processes to take place. Controlling membrane permeability is therefore a key challenge when building artificial cells in the form of enclosed chemical systems.
A polymer thin film solar cell (PSC) produces electricity from sunlight by the photovoltaic effect. Though light and inexpensive, PSCs currently suffer from a lack of enough efficiency for large scale applications and they also have stability problems. Researches in Korea have designed and added multi-positional silica-coated silver nanoparticles that have greatly improved stability and performance of these cells.
A team led by Lawrence Berkeley National Laboratory Materials Sciences Division’s Jeffrey Urban and Rachel Segalman have discovered highly conductive polymer behavior occurring at a polymer/nanocrystal interface. The composite organic/inorganic material is a thermoelectric—a material capable of converting heat into electricity—and has a higher performance than either of its constituent materials.
Methanol to formaldehyde: This reaction is the starting point for the synthesis of many everyday plastics. Using catalysts made of gold particles, however, formaldehyde could be produced without the environmentally hazardous waste generated in conventional methods. But just how a gold catalyst could work has only recently been discovered by researchers.
Coating medical supplies with an antimicrobial material is one approach that bioengineers are using to combat the increasing spread of multidrug-resistant bacteria. A research team in Singapore has now developed a highly effective antimicrobial coating based on cationic polymers. The coating can be applied to medical equipment, such as catheters.
U.S. Naval Research Laboratory scientists have developed a second-generation, cost-effective polyetheretherketone (PEEK)-like phthalonitrile-resin demonstrating superior high-temperature and flammability properties for use in marine, aerospace, and domestic applications. The resin can be used to make composite components by established industrial methods and automated composite manufacturing techniques.