MMaterialsgateNEWS vom 11.07.2016

Verwandte MaterialsgateCARDS

Researchers demonstrate tunable wetting and adhesion of graphene

Researchers from the University of Illinois at Urbana-Champaign have demonstrated doping-induced tunable wetting and adhesion of graphene, revealing new and unique opportunities for advanced coating materials and transducers.

"Our study suggests for the first time that the doping-induced modulation of the charge carrier density in graphene influences its wettability and adhesion," explained SungWoo Nam, an assistant professor in the Department of Mechanical Science and Engineering at Illinois. "This work investigates this new doping-induced tunable wetting phenomena which is unique to graphene and potentially other 2D materials in complementary theoretical and experimental investigations."

Graphene, being optically transparent and possessing superior electrical and mechanical properties, can revolutionize the fields of surface coatings and electrowetting displays, according to the researchers. A material's wettability (i.e. interaction with water) is typically constant in the absence of external influence and are classified as either water-loving (hydrophilic) or water-repelling (hydrophobic; water beads up on the surface). Depending on the specific application, a choice between either hydrophobic or hydrophilic material is required. For electrowetting displays, for example, the hydrophilic characteristics of display material is enhanced with the help of a constant externally impressed electric current.

"What makes graphene special is that, unlike conventional bulk materials, it displays tunable surface wetting characteristics due to a change in its electron density, or by doping," said Ali Ashraf, a graduate student researcher and first author of the paper, "Doping-Induced Tunable Wettability and Adhesion of Graphene," appearing in Nano Letters. "Our collaborative research teams have discovered that while graphene behaves typically as a hydrophobic material (due to presence of strongly held air-borne contamination on its surface), its hydrophobicity can be readily changed by changing electron density.

"Our study shows for the first time that graphene demonstrates tunable wettability -- switchable hydrophobic and hydrophilic behavior -- when its electron density is changed by subsurface charged polymers and metals (a.k.a. doping)," Ashraf added. "This finding sheds lights on previous unclear links between quantum-level charge transfer and macroscopic surface wettability for graphene. This exciting finding opens new doors of possibility for tunable surface coating and electrowetting displays without continuous external electric current supply, which will translate into significant energy savings."

"In addition, we investigated another closely related property -- surface adhesion," Nam said. "We observed changes in electron density of graphene leads to a change in adhesion, which determines how graphene interacts with other hydrophobic and hydrophilic molecules, which is important for graphene-based chemical and biosensors. Our finding suggests that it is possible to make reusable, self-cleaning graphene sensors that can first interact with hydrophobic molecules for detection, and then separates from them (i.e. cleans itself) by enhanced hydrophilicity via electron density modulation."

Source: University of Illinois College of Engineering – 07.07.2016.

Recherchiert und dokumentiert von:

Dr.-Ing. Christoph Konetschny, Inhaber und Gründer von Materialsgate
Büro für Material- und Technologieberatung
Die Recherche und Aufbereitung der in diesem Dokument genannten Daten erfolgte mit größter Sorgfalt.
Für die Richtigkeit, Gültigkeit, Verfügbarkeit und Anwendbarkeit der genannten Daten übernehmen wir zu keinem Zeitpunkt die Haftung.
Bitte diskutieren Sie die Verwendung und Eignung für Ihren konkreten Anwendungsfall mit den Experten der genannten Institution.

Sie wünschen Material- und Technologierecherchen zu diesem Thema?

Materialsgate steht für hochwertige Werkstoffberatung und innovative Materialrecherchen.
Nutzen Sie unseren Beratungsservice

MMehr zu diesem Thema

Researchers from the Tata Institute of Fundamental Research, Mumbai, have demonstrated the ability to manipulate the vibrations of a drum of nanometre scale thickness - realizing the world's smallest and most versatile drum.

This work has implications in improving the sensitivity of small detectors of mass - very important in detecting the mass of small molecules like viruses. This also opens the doors to probing exciting new aspects of fundamental physics. The work, recently published in the journal Nature Nanotechnology, made use of graphene, a one-atom thick wonder material, to fabricate drums that have highly tunable mechanical frequencies and coupling between various modes. Coupling between the modes was shown to be controllable which led to the creation of new, hybrid modes and, further, allowed amplification of the vibrations. The experiment consisted of studying the mechanical vibrational modes, or... mehr mehr lesen

An interdisciplinary team of scientists at the U.S. Naval Research Laboratory (NRL), Electronics Science and Technology and Materials Science and Technology Divisions, has demonstrated hyperthermal ion implantation (HyTII) as an effective means of substitutionally doping graphene — a hexagonally-arranged single-atomic thickness carbon sheet — with nitrogen atoms.

The result is a low-defect film with a tunable bandstructure amenable to a variety of device platforms and applications. The research shows that the HyTII method delivers a high degree of control including doping concentration and, for the first time, demonstrates depth control of implantation by doping a single monolayer of graphene in a bilayer graphene stack. This further demonstrates that the resulting films have high-quality electronic transport properties that can be described solely by changes in bandstructure rather than the defect-dominated behavior of graphene films doped or functionalized using other methods. “Since the discovery that a single atomic layer of sp2 bonded carbon... mehr mehr lesen

A Korean research team developed an ideal electrode structure composed of graphene and layers of titanium dioxide and conducting polymers, resulting in highly flexible and efficient OLEDs

The arrival of a thin and lightweight computer that even rolls up like a piece of paper will not be in the far distant future. Flexible organic light-emitting diodes (OLEDs), built upon a plastic substrate, have received greater attention lately for their use in next-generation displays that can be bent or rolled while still operating. A Korean research team led by Professor Seunghyup Yoo from the School of Electrical Engineering, KAIST and Professor Tae-Woo Lee from the Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH) has developed highly flexible OLEDs with excellent efficiency by using graphene as a transparent electrode (TE) which... mehr mehr lesen

In an article published in Carbon, Dr Aravind Vijayaraghavan and Dr Maria Iliut from Manchester have shown that adding a very small amount of graphene, the world's thinnest and strongest material, to rubber films can increase both their strength and the elasticity by up to 50%.

Thin rubber films are ubiquitous in daily life, used in everything from gloves to condoms. In their experiments, the scientists tested two kinds of rubbery materials - natural rubber, comprised of a material called polyisoprene, and a man-made rubber called polyurethane. To these, they added graphene of different kinds, amounts and size. In most cases, it they observed that the resulting composite material could be stretched to a greater degree and with greater force before it broke. Indeed, adding just one tenth of one percent of graphene was all it took to make the rubber 50% stronger. Dr Vijayaraghavan, who leads the Nano-functional Materials Group, explains "A composite is a... mehr mehr lesen

MaterialsgateNEWSLETTER

Partner der Woche

Suche in MaterialsgateNEWS

Bücher und Produkte

MaterialsgateANSWERS

MaterialsgateFAIR:
LASSEN SIE SICH INSPIRIEREN