University of Delaware researchers pioneer greener way to create interwoven polymers with blue light
A pair of engineers at the University of Delaware has developed a process to form interwoven polymer networks more easily, quickly and sustainably than traditional methods allow. Their secret ingredient? Blue light.
Abhishek Shete, graduate research assistant in materials science and engineering, and Christopher Kloxin, assistant professor in materials science and engineering and chemical and biomolecular engineering, describe their method in a paper featured on the cover of the 24th issue of Polymer Chemistry. The paper is titled "One-pot blue-light triggered tough interpenetrating polymeric network (IPN) using CuAAC and methacrylate reactions."
Polymers, which are materials made from chains of molecules, are found in everything from food to clothing to cars. Two or more types of polymer chains with different individual properties can also be linked together to form interpenetrating polymeric networks, materials that often combine favorable mechanical properties from each polymer such as high strength and toughness.
"These chemistries independently are used in a broad range of applications," from dental composites, automobile bumpers to drug delivery materials, Shete said.
However, the process of linking polymers is not simple. It requires two chemical reactions, which are typically initiated through either a lengthy two-step process or a one-step process induced at elevated temperatures and longer time spans.
The method Kloxin and Shete developed is one step and works rapidly at room temperature and ambient conditions.
They use 470-nanometer blue light, which is similar to blue LED light used to detect certain body fluids in crime scene investigations. This light triggers reactions with a photosensitizer called camphorquinone and an activator called amine. These materials are commonly utilized in polymeric dental composites for filling cavities.
The light irradiates the materials to photostimulate the two chemical reactions, but not simultaneously. First up is a reaction called the copper-catalyzed azide-alkyne cycloaddition (CuAAC) click polymerization. This reaction is facilitated by copper, and polymerization occurs in steps. Next is a reaction called the methacrylate polymerization, which forms a plastic-like material in a manner similar to adding links to a growing chain. "This is unique in the way the blue light induces sequential reactions," says Kloxin.
The end result is a material that Kloxin and Shete describe as a "glassy film," less brittle than pure methacrylate and stronger than pure CuAAC at higher temperature. The films made from this IPN material also exhibit shape memory-- when deformed, it can be returned to its original size and shape with 15 minutes of heating at 80 degrees Celsius.
This blue-light approach to form interpenetrating polymer networks saves time and energy, but those are not its only advantages. For one, this approach allows Kloxin and Shete to control the pair of chemical reactions with increased precision, allowing them to fashion the polymer networks into complex shapes. This rapid method also keeps the ingredients from separating in a way that could otherwise interfere with the formation of an interpenetrating polymer network.
In addition, the new process requires none of the solvents or additives commonly used in plastics manufacturing, often added to prevent brittle fracture. The materials reported by Kloxin and Shete exhibit enhanced toughness that overcomes this brittleness without any solvents or additives, also making it a greener synthetic approach.
The team has filed a provisional patent for the method described in the new paper. "These chemistries could be attached to other molecules," Kloxin said, and the team will test their applications to form hydrogels, dental materials and other polymer networks.
Peter Bothum | EurekAlert!
The stacked colour sensor
16.11.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt
Counterfeits and product piracy can be prevented by security features, such as printed 3-D microstructures
16.11.2017 | Karlsruher Institut für Technologie (KIT)
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses