October_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | O C T O B E R 2 0 1 7 1 4 SURFACE ENGINEERING A LOVE/HATE RELATIONSHIP WITH WATER Researchers at the Energy Safety Research Institute at Swansea Univer- sity, UK, developed a new class of non- toxic nanomaterials with tunable wet- tability that could replace the pricey, dangerous substances currently used in waterproofing and antifouling/antifog- ging applications. The new materials— which can be applied via spray or spin coating—provide texture to surfaces regardless of the substrate and allow them to be altered from hydrophobic to hydrophilic based on chemical func- tionality. To create the coatings, re- searchers synthesized aluminum oxide nanoparticles using hydrocarbon linear and branched carboxylic acids with dif- ferent surface energies. Nanoparticles with the methoxy (-OCH 3 ) functionality exhibit high surface energy and, con- sequently, possess superhydrophilic properties. Conversely, branched hy- drocarbons reduce surface energy and limit contact with water droplets, al- lowing them to slide off. The research demonstrates that subtle changes in the organic chain enable control of sur- face wettability and energy, roughness, and the ability of nanoparticles to be- have as surface ac- tive agents. In addition to potentially serving as an affordable, en- vironmentally frien- dly replacement for the fluorocarbons commonly used in superhydrophobic applications, the new materials could also reduce the interfacial tension of various oil-water emulsions by behav- ing as surfactants. Understanding the relationships between superhydropho- bic and superhydrophilic nanoparticles and the resulting oil stability, emulsion properties, and interfacial tension at the oil-water boundary could lead to greater efficiency in enhanced oil recov- ery methods. www.swansea.ac.uk . SLIP INTO SOMETHING MORE COMFORTABLE Engineers at the Massachusetts Institute of Technology (MIT), Cam- bridge, designed a gel-like material that can be coated onto standard plastic or rubber medical devices such as cathe- ters, providing a surface that not only reduces friction, but can also monitor and medicate infection. To create the material, the team attaches a layer of hydrogel—a polymer consisting most- ly of water—to common elastomers such as latex, rubber, and silicone, after treating the surfaces with benzophe- none, a molecular solution that facil- itates strong chemical bonding when MIT engineers designed a gel-like ma- terial that can be coated onto standard plastic or rubber devices, providing a so er, more slippery exterior that can ease patient discomfort during surgery. Courtesy of Felice Frankel. exposed to ultraviolet light. The result is a hydrogel laminate —a layer of elas- tomer sandwiched between two layers of hydrogel. To evaluate the material, the team adhered layers of hydrogel onto vari- ous elastomer-base medical devices, such as intravenous tubing. A battery of mechanical tests revealed that the structure remained strongly bonded, without tearing or cracking, even when stretched to multiple times its original length, and that coated devices exhib- ited much less friction than standard uncoated devices. Further experiments show that the laminate’s elastomer layer rendered the structure highly impermeable—much more so than the hydrogel alone—while other tests confirm that pH-sensing molecules or timed-release drugs could be embed- ded in the hydrogels. In other applica- tions, the new material performed well when tested on condoms, and could de- liver embedded medication for suffer- ers of latex allergy. mit.edu . BRIEF PPG, Pittsburgh, will acquire The Crown Group, Warren, Mich., a coatings application business, from High Road Capital Partners, New York, and Charter Oak Capital Partners, West Port, Conn. Crown serves the automotive, agriculture, construction, heavy truck, and alternative energy industries, applying coatings to manufactured parts and assembled products at 11 U.S. sites. In addition, the company provides assembly, warehousing, and sequencing services. The transaction is slated to close in late 2017. ppg.com . Schematic of nanoparticle functionalization and photographic im- ages of water droplets on spray-coatedmicroscope slides. Courtesy of Shirin Alexander/University of Swansea.