that featured strong butreversible chemical bonds.The final result, Reverlinkself-healing elastomers, is atriumph of supramolecularchemistry."Reverlink technologybegan as a joint researchprogram [with chemistryprofessor Ludwik Leiblerof the Paris-based Écolesupérieure de physique etde chimie industrielles dela Ville de Paris]," says Dr.Michael E. Smith, techni-cal development managerfor Arkema. "It was part of our corpo-rate initiative for novel materials, ide-ally biobased materials. Most of whatis in a Reverlink self-healing rubber isbiosourced: 70% to 80%, dependingon the grade." While many researchers have pur-sued the concept of assembling largemolecular structures from smallerbuilding blocks-without necessarilyhaving them be permanent -[Leibler] "came up with the idea oftrying to simulate plastic and rubberstructures where you have a controllednumber of reversible connections,"Smith says.Based on hydrogen bonds that aresimilar to the link between the basepairs of amino acids in DNA strands,Arkema's Reverlink technology wascreated with the idea that a linkerstructure could allow the attachmentof complementary hydrogen bonds toplastics and rubbery materials. The results, Smith says, are promis-ing: "You can imagine you have seals,where you've got some sort of gasketor connection, and if some eventoccurs (and) you can design it proper-ly so the pieces stay in place-even ifthere's crack-ing-as long asthey are in con-tact with eachother, they willreform theirbonds. [Othertechnologies] arevaluable for things like coatings,where you have wear and tear andchipping and such; you bring it in tothe base and you can very quicklyreseal or recure the coating."In comparing self-healing technolo-gies, Smith notes that unlike those thatrequire an activator, Reverlink technol-ogy "does not require heating (or) anysort of (UV) light or anything else. Youjust need to bring the cut surfaces backinto contact within about an hour, andthe actual chemistry will allow the con-nections to form."Prospects for the adoption ofReverlink materials are in the earlystages. "At the moment, the quantitythat can be generated is large enoughto do hundreds of pounds, thousandsof pounds," Smith says. "You canmake real trials in real-world applica-tions; it's not a lab material where youcan only get a one-pound jar."Arkema and its partners are workingon potential applications in the mili-tary/defense and commercial sectors.The FutureThe trend toward exploring non-petroleum, biobased polymers(derived from vegetable oils or chemi-cal feedstock that comesfrom biomass) like polylac-tic acid will present contin-uing challenges for materialtoughness, Iowa State'sKessler predicts. "Some of the vegetableoil-based thermosets thathave been developed in the past sever-al years could have application (in therepair of significant infrastructure)"-competing with unsaturated polyestersand epoxy resins, he says.Meantime, the AFRL's Spicer says,commercial polymer development isthe primary focus of research stem-ming from the supersonic rain erosionstudies as well as the AFRL's other testcapabilities. "We have developed aCRADA (Cooperative Research andDevelopment Agreement), and thatallows third-party polymer developersto use this facility to evaluate theirpolymers such that they can thenclaim the performance and then comeback and sell it to DoD or the com-mercial world," he says. "With oursubsonic rain erosion-and we dohave a dust and particle erosion testcapability-we do a lot of work forcommercial companies that developmaterials for both DoD and (commer-cial uses), and they come through theCRADA and get the testing done."Noting that not even NASA has thetest capability of the AFRL, Spicersays: "We have some customers wait-ing in the queue. They are probablygoing to come in here [soon] to testmaterials to develop parameters fortest methods that we'll put into amaterial specification. We will eventu-ally be developing better polymersbecause we've got some applications(in which) polymers aren't performingas we would have hoped."www.4spe.org | OCTOBER 2011| PLASTICS ENGINEERING | 31Photos courtesy of PBI Performance Products.
. Dr. Tobin J. Marks,the VladimirN. Ipatieff Professor of CatalyticChemistry and Professor of MaterialsScience and Engineering atNorthwestern University (Evanston,Illinois, USA), is the recipient of the2011 Dreyfus Prize in the ChemicalSciences. Dr. Marks was cited for thedevelopment of major new industrialcatalysts and the fundamental under-standing of their chemical structuresand mechanisms of action.The prize,given biennially by the Camille andHenry Dreyfus Foundation,recog-nizes exceptional and originalresearch in a selected area of chem-istry that has advanced the field inmajor ways. The prize consists of amonetary award of $250,000-oneof the largest awards dedicated to thechemical sciences in the U.S.-a cita-tion, and a medal.The Dreyfus Foundation notes,"Catalysts accelerate the creation ofmolecules or materials without beingconsumed. This process, called cataly-sis, . ranges in scope from theactions of enzymes in biology toenabling the synthesis of therapeuticdrugs to the production of coatings,fertilizers, and plastics on a hugescale. Catalysis underlies manyaspects of the energy industry andmakes the creation of new materialspractical."[Dr.] Marks has been a worldleader in the understanding anddevelopment of new catalysts thatenable the production of recyclable,environmentally friendly, and sustain-ably produced plastics and elastomer-ic materials. His research has resultedin a far deeper understanding of therequirements to make and break spe-cific chemical bonds, thus giving sci-entists the ability to design new cat-alytic processes. His work has directlyled to multibillion-dollar industrialprocesses. Marks has also demonstrat-ed how metals from unusual parts ofthe periodic table, such as the rareearth elements, can be used as effi-cient catalysts with minimal forma-tion of undesired by-products.Enormous savings in energy andscarce resources have been directlyattributed to the fundamental knowl-edge and processes that have resultedfrom Marks's catalysis research."Tobin Marks holds a BS in chem-istry from the University of Marylandand a PhD in inorganic chemistryfrom the Massachusetts Institute ofTechnology; he has been on theNorthwestern faculty since 1970. Heis a recipient of the U.S. NationalMedal of Science and has been elect-ed into the National Academy ofSciences. From the AmericanChemical Society he has received theArthur K. Doolittle Award inPolymeric Material Science andEngineering, the Award inOrganometallic Chemistry, theAward in Inorganic Chemistry, theAward in the Chemistry of Materials,and the Arthur Cope Senior ScholarAward in Organic Chemistry.. David Inglefield,a PhD candidatepursuing a dual degree in chemistryand biomedical engineering atVirginia Polytechnic Institute &State University(Blacksburg,Virginia, USA), is the 2011-2012winner of the SPEAutomotiveComposites Conference &Exhibition(ACCE) graduate-levelscholarship in transportation compos-ites research. Mr. Inglefield won the$2000 scholarship for a research pro-ject involving the synthesis of func-tionalized carbon nanotubes for opti-mized properties in polymer compos-ites, a project that could have broadapplication in automotive compos-ites. He will report the results of hisresearch during the twelfth annualSPE ACCE, Sept. 11-13, 2012.Mr. Inglefield explains that sincethe discovery of carbon nanotubes(CNTs) in 1991, their use hasexpanded into areas as diverse as elec-tronics and bionanotechnology. Oneof their most promising areas ofusage is to improve the properties ofpolymer composites by increasingmechanical strength (without increas-ing resin weight or density, as mostreinforcements do) and conferringelectrical and thermal conductivity tomaterials that normally provide nei-ther property. However, wider usagehas been limited by many factors,including high production costs andthe difficulty of effectively dispersingthe nanoparticles into polymer matri-ces. Developing a functionalizedCNT that effectively interacts withthe resin in which it is incorporatedremains a significant challenge inexpanding usage of this technology."My work involves functionaliza-tion of multiwall carbon nanotubesfor more efficient incorporation intoindustryNEWS and NOTES32| PLASTICS ENGINEERING | OCTOBER 2011 | www.4spe.org Dr. Tobin J. Marks