Materials fromRenewableResources

Stephen J. Eichhorn and Alessandro Gandini,Guest Editors

without the intervention of humankind.These cycles appear to take place with relatively less energy consumption thanmost industrial processes. For instance,one example of a natural low-energyprocess is sequestration of carbon dioxideand its subsequent formation into longchain sugars, which form the structure ofplants; this process is fueled by the captureof light. The plant matter produced alsocan degrade and provide nutrients for successive plant life in a cycle that appears to consume little in the way of resources—neglecting usage ofland, modern farm machinery, and, morerecently, water. Annual planting and harvesting of crops could provide a signif-icant proportion of the total biomassrequired for fuel/energy (10–20%) andmaterials consumption,3 although we havenot yet developed this to its full extent.

Figure 1 summarizes the two processroutes to materials derived from naturaland oil-based resources, showing the pres-ence of significant energy inputs. Energyinputs into the production of oil arethought to be higher than from harvestingnatural feedstocks, although significantcosts are associated with the latter. Theprocessing of natural and oil-based feed-stocks could use similar technology, andboth require a significant energy input atthis stage. Any natural process that gener-ates material without the use of significantenergy input is likely to be competitive toeither of these processing routes. Oneenergy input not explicitly considered inthis summary is transportation. Anyenergy cost analysis on the relative bene-fits of using a renewable resource wouldhave to take this into consideration. It is,however, worth pointing out that thesequestration of carbon dioxide duringthe plant growth process could potentiallymake a significant contribution to climatechange. Some examples of products aregiven in the lower part of Figure 1, whereoften the competition between the usageof these materials is presently governedon the basis of price. However, this com-petition is likely to become less significantwith a dwindling oil supply. There is apoten tial for both renewable and oil-basedmaterials to be recycled, with an addi-tional option of degrading the formerin landfills. The presence of oil-basedmaterials in landfills, although posingimmense problems, could be viewed as arecycling resource if separation can beachieved.

There is a range of renewable resourcesthat has been extensively researched, particularly for use as polymers and composites.4 The materials that have been investigated include naturally occur-

IntroductionRecently, a large emphasis has been

placed on the need to better utilizeresources such as oil, mostly for energy pur-poses, but also for the generation of plastics.At present, the human race is thought to beat or near peak oil consumption, dependingon which theory is used.1 After peak oil con-sumption, it is predicted that the use of thisresource will decline dramatically as aresult of the dwindling supply. At the sametime, the price of oil is volatile, oftenincreasing dramatically at times of eco-nomic and/or supply uncertainty. It isenvisaged that as supplies decrease, the costwill increase. This places an onus on thehuman race to utilize other resources, evenif we just want to maintain our productivityand consumption at current levels. As theworldwide population continues to grow,more strain will be placed on declining oilresources due to increased consumption.

Oil is derived from plant material,which is formed under high pressure over

many millions of years, and so, in a sense,oil is renewable when viewed over a longperiod of time. This large time-disparitybetween the renewability of this resourceand the rapid industrial expansion andconsumption of oil has led to its furtherdepletion. Energy is the most consump-tive use of oil. The International EnergyAgency has warned that the demand forenergy will increase by 45% between nowand 2030, and this will put further pres-sure on this resource.

Typical levels of oil usage for chemicalsin the mid-1990s only reached about 7% ofthe total usage.2 Other sources of chemi-cals for materials from plants are availablethat have renewable timescales more in-tune with our consumption. Thesematerials can be derived from natural oilspresent in plants and the cellulosic mate-rial that they use structurally. Nature alsohas its own consumption and renewablematerials cycle, which would continue

AbstractThe drive for greater use of renewable materials is one that has recently gained

momentum due to the need to rely less heavily on petroleum. These renewable materialsare defined as such since they are derived from plant-based sources. Some renewablematerials also offer properties that conventional materials cannot provide: hierarchicalstructure, environmental compatibility, low thermal expansion, and the ability to bemodified chemically to suit custom-made applications. Nature’s materials, particularly fromplant- and animal-based polysaccharides and proteins, have hierarchical structures, andthese structures can be utilized for conventional applications via biomimetic approaches.This issue begins with an article covering renewable polymers or plastics that can beused to generate block copolymers (where two polymers with specific functions arecombined) as an alternative to conventional materials. Applications of renewablepolymers, such as cellulose from plants, bacteria, and animal sources, are also covered.Also presented are the use of bacterial cellulose and other plant-based nanofibers fortransparent electronic display screens and, in a wider sense, the use of cellulosenanofibers for composite materials, where renewable resources are required to generatelarger amounts of material. Finally, this issue shows the use of biomimetic approaches totake the multifunctional properties of renewable materials and use these concepts, or thematerials themselves, in conventional materials applications.

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ring polymers such as cellulose, chitin,starch, and numerous proteins (collagen,keratin, silk).

The first of these materials (cellulose) isthe most utilized, with traditional applica-tions as a building material in the form ofwood, in textiles from cotton, for packag-ing, and print media in the form of paper.Cellulose also is widely used for films andas a coating material, as a polyelectrolytematerial, as an emulsifier in food, and as adrug-delivery medium. The first-everplastic was formed from a derivatized cel-lulose (cellulose nitrate).2 Subsequent tothis, the development of cellulose acetate,

particularly for filter tow for cigarettes,has dominated the worldwide markets interms of production of cellulosics. In 2003,this production stood at 600,000 metrictons.5 Cellulose acetate also has been uti-lized for photographic film, although withthe advent of digital technology, this mar-ket is currently diminishing. Recently, thedemands for cellulose acetate have beenfor LCD flat screens.5 Other cellulosederivatives, such as hydroxypropyl cellu-lose, are used in the pharmaceuticalindustry. Non-derivatized grades, such asmicrocrystalline cellulose, however, alsoare used, constituting the major compo-

nent of solid dosage tableting. Cellulose iswidely used for bandaging and woundrepair materials, as a possible scaffold fortissue engineering, and as a severe burnrepair material.6

Chitin is mainly used in a derivatizedform as chitosan, in the biomedical indus-try, and as a dietary supplement material.Starch is mostly used in the food industry,although a major development in the areaof bioplastics has been the production ofpolylactic acid from starch. Polylactic acidis derived via bacterial fermentation ofcorn starch or sugarcane. Global produc-tion of this polymer has recently beenreported to exceed 250,000 tons per year.7Although initially very expensive, theprice of polylactic acid is coming down.Particular examples of recent commercialventures using polylactic acid have beenthe Cargill Natureworks’ Ingeo bioplastic(sole U.S. manufacturer), although Toyotaalso produces the polymer in Japan, as does PURAC in the Netherlands.Polylactic acid–derived polymers promiseapplications in biopackaging, with degra-dation properties that are not deemed tobe harmful to the environment.

Two forms of what can be termed “bacterial polymers” have recently gained prominence, mainly in researchlaboratories: bacterial cellulose and poly(hydroxyalkanoate)s, such aspoly(hydroxybutyrate). Bacterial celluloseis produced under culture conditions byaerobic bacteria and has many pote n -tial applications, albeit currently in specialized markets such as speakerdiaphragms and in the biomedical sector.6,8 Applications using poly(hydrox-yalkanoate)s are heavily restricted on thebasis of price, although it is envisaged thatthe cost will decrease as the drive touse polymers from renewable sourcesincreases.

Silk still has its traditional use in the textiles industry, but recent interest hasfocused on using it for tissue engineeringapplications.9 Silk, in essence, is a renew-able material, as proteins are essentially anabundant natural resource. Spiders recy-cle their silk, and given the aqueous processing of the material, it presents itselfas a potentially “green” material. The volume production of silk is sufficient forthe textile industry, but if structural appli-cations are to be realized, then this needsto increase significantly. In order to dothis, efforts have been made to produceartificial silks. Efforts to mimic silk fibers,however, have not been that successful.An example of one approach has been theseeding of human cells with proteinsfound in silk in order to produce fila-ments.10 Most, if not all, attempts to pro-

Processing

Polylactic acidPolyalkanoatesPaperCellulose Acetate

PolypropylenePolyestersPolystyrenePolycarbonate

Natural and Renewable Resource Oil

Processing

Figure 1. Summary of renewable materials versus oil production indicating stages ofsignificant energy input and some examples of products with their competition on price.

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Materials from Renewable Resources

introduces the five articles selected forthis issue.

Content of This IssueEach of the five articles reports on the

use of renewable materials in technologi-cal applications. The articles highlight therenewability of the materials and the benefits in terms of properties that theybring to the particular application. At thesame time, they represent the state-of-theart research that is taking place in this fieldand offer insight into how we might betterutilize renewable materials.

The first article by Robertson et al. dis-cusses the production and use of rene -wable block copolymers, which arehybrid macromolecules composed of twoor more covalently connected segments.These fascinating self-assembled materi-als are used in applications ranging fromfootwear to bitumen modification tomicroelectronics. The number of technolo-gies that utilize or could benefit fromblock copolymers is expanding at a rapidrate. This growth is due to the develop-ment of simple scalable synthetic tech-nologies, a deeper understanding of theirstructure-property relationships, and theireffectiveness as low-level additives. Asindustrial uses of block copolymer-basedmaterials become more prevalent, therewill be an increased focus on alternativepreparative approaches that do not rely on petroleum feedstocks. Therefore, thedevelopment of biorenewable blockcopolymers is an important researchendeavor. The article explores the synthe-sis, self-assembly, and properties ofrenewable block copolymers that containaliphatic polyesters, as well as segmentedpolyurethanes from bio-sources. Thesetwo classes of block copolymers are themost promising and practical candidatesfor implementation in the next generationof sustainable materials.

The second article by Berglund andPeijs concerns the challenges and oppor-tunities raised in using cellulose in biocomposite materials. Cellulose fibersare the key reinforcement phase in thecomposite structure of plant cell walls,which are present in the form of nanofib-rils. These nanofibrils can be exploited in avariety of materials applications, andsome of these are discussed. The problemsassociated with their extraction and interfacing with other materials also arecovered. A vast range of sizes of fibers isavailable from micron-sized fibers tonanowhiskers and nanofibrils. These rein-forcements can be arranged in the form of weaves, continuous fibers, and co-mingled matrix fibers, all of which are discussed in this article. Developments in

duce artificial silk have failed, mostly dueto the fact that this artificial material’sproperties did not match that of the natu-rally derived material. Nevertheless,much progress has been made on under-standing structure-property relationshipsof silk in spinning and how processingcould be the route for better silk fibers forengineering applications.11 There aremany challenges ahead for industry and the scientific community whendesigning technological applications thatuse materials from renewable resources.The next section addresses some of thesechallenges.

Challenges for the Use of Materials from RenewableResources

It is almost certain that industrial use ofrenewable materials will only take place ifthere is an economically good reason to doso. The expected rise in oil prices is astrong economic driver and will continueto direct industrial policy into renewabletechnology. The technology used to generate conventional polymers frompetroleum is less than 100 years old.Nevertheless, considerable progress has been made on the development ofhigh-performance polymers, and there-fore considerable investment in the production infrastructure (plants, knowl-edge base) has already taken place. One ofthe first challenges of the 21st century is touse non-petroleum feedstocks where tra-ditionally petroleum has been used, andthis may come at an additional cost to themanufacturer. New processes to controlvariability and mixed stream feedstocksfrom plant material will require additionalinvestment from industry. A rapid learn-ing process also will have to take place if these materials are to replace tra -ditional resources. The use of a “biorefin-ery concept” is now required, as has been explicitly outlined recently,12 where a con-tinuous loop of biofuels and materials canbe developed without depletion of naturalresources. This also will have to comewith the technological means to generateadvanced materials.

Renewable materials have to match upto the properties of existing materials andadd something in order to make themviable. In the first instance, the additionalproperty will be their renewability, but itis vital to ensure that this is trulyexploited. Some of the initial materials inthis area have promise, but actual renewa-bility must be addressed in order to meetour environmental targets. Additionalchallenges lie ahead in being able toexploit other properties of natural and renewable materials, such as a hierar-

chical structure. Controlling the inherentvariability in natural and renewable feed-stocks presents another challenge toindustrialists and academia in the genera-tion of a reliable product.

There are many technical challengesthat we will face over the use of renewablematerials, but this is not a complete picture. The challenge of using rene w -able feedstocks also brings nonscientificproblems, including the social and eco-nomic consequences of the use of foodcrops for biofuels and plastics. Recentrises in the price of corn, maize, and otherstaple food stuffs, because of their poten-tial use in biofuels (and therefore bioplas-tics), has been a cause for concern, whichcould be remediated through the use ofnonfood crops. The challenge, therefore, isto use nonfood crops where possible.

Efforts to investigate the production ofpetroleum precursors and liquid fuelsfrom biomass are reported in the litera-ture,13 and presumably a percentage ofthis could be returned to polymeric mate-rials, using the same model that hasworked for oil. The challenge is not tofall into the same trap where consumptionand demand exceed supply, where therenewable aspects of the materials maybe lost.

It has been recently recognized thattechnology solves problems through theuse of “energy,” whereas biology tends touse “information” and “structure.”14 Thisis true for a number of renewable materi-als when they remain in a biological cycle.The self-assembly of plant materials andproteins is less dependent on raw energyper se and more dependent on the use ofentropy (order and disorder). Conversely,large amounts of energy are expended toextract oil, from which polymers can thenbe synthesized with a relatively lowerenergy expense. Minimal use of energy asa whole to generate renewable materialsand chemical feedstocks needs to beaddressed in order to avoid high costs.Some methods of extraction of biomassfor natural materials use large amounts ofenergy, which is something that is largelyignored but will play a key role in deci-sion-making when technologicalapproaches are adopted. The question is,are there alternative methods for renew-able materials production that are lessenergy intensive? Perhaps the use of bio-mimetic methods of materials productionis a way forward, relying more on self-assembly, structure, and, in a wider con-text, information. Enzymatic and bacterialprocesses of materials production are twooptions that can, if carefully controlled,generate biomass in a more energy conser-vative way. The following section briefly

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Materials from Renewable Resources

modifying the fiber/matrix interfaceusing novel grafting agents are discussed,as well as the relatively recent work on all-cellulose composites, which have thepotential to be fully biodegradableand/or recyclable. In recent times, cellu-lose nanofibers have gained widespreadinterest. Nanofibrils of this type have beenproduced in a cost- effective manner usingenzymatic or chemical pretreatment fol-lowed by mechanical disintegration fromplant cells. The resulting nanocompositesshow much-improved properties in termsof mechanical strength, Young’s modulus,toughness, reduced thermal expansion,and optical transparency. All of theseaspects are covered as well as theoreticalmodeling studies, which demonstrate themolecular level mechanisms for suchobservations. The properties of specificmaterials, such as aerogels, where gels ofcellulose nanofibers are freeze-dried toform very low density networks, also arepresented. These aerogels are character-ized by mechanical robustness, low ther-mal conductivity, and high acousticdamping. The use of these materials astemplates for inorganic hybrids, such asmagnetic nanoparticle composites, also isdiscussed. By combining cellulose withstarch foams, materials with propertiessimilar to conventional polymers can beobtained. This means that foams can be generated from renewable materials(starch and cellulose), with propertiescompatible with the materials that are currently preferred by industry. Thefuture for cellulose fibers deserves morethan a simple blending with conventionaloil-based thermoplastics, and this isdemonstrated with specific recent devel-opments in the area.

The third article by Gatenholm andKlemm looks at cellulose from a bacterialsource for a new and exciting application.Nanofibers of bacterial cellulose are anemerging biomaterial with great potentialfor wound and burn dressings and forscaffolds for tissue regeneration. Bacterialcellulose has remarkable mechanicalproperties despite the fact that it is com-prised almost entirely of water. The water-retaining capacity of bacterial cellulose isthe most probable explanation for the factthat implants made of this material do not elicit any foreign body reactions.Moreover, the nanostructure and morpho-logical resemblance with collagen makesbacterial cellulose attractive for cell immo-bilization and support. The architecture ofbacterial cellulose can be engineered atdifferent length scales, from micro tonano, which makes this material an idealscaffold for tissue engineering. The factthat bacterial cellulose can be generated

chemical or thermal transformation of thenatural material—or by a virtual extractionof the materials concepts and their applica-tion to the fabrication of engineering mate-rials. The first route often is described as biotemplating and the second as biomimetic materials research. This finalarticle briefly describes the principles ofthese two approaches and gives some illus-trative examples.

Each article gives a tutorial overview ofan area of materials from renewableresources. To further support the verypremise of this theme, the technologies arepresented along with an explanation ofhow the materials are renewable and howthey will contribute in a meaningful wayto current and new applications. Forinstance, the use of plant-based materials(e.g., starch, furans) to generate a widerange of polymers, in particular block co-polymers, is given. It is also shownhow cellulose, derived from plants, canbe used in a number of technologicalapplications.

References1. A.R. Brandt, Energy Policy 35, 3074 (2007).2. N.G. McCrum, C.P. Buckley, C.B. Bucknall,Principles of Polymer Engineering (OxfordUniversity Press, Oxford, 2001).3. F. Cherubini, S. Uligiati, Applied Energy 87, 47(2010).4 N.M. Belgacem, A. Gandini, Eds., Monomers,Polymers and Composites from RenewableResources (Elsevier, Amsterdam, 2008).5. P. Rustemeyer, History of CA and Evolution ofthe Markets in Cellulose Acetates: Properties andApplications, P. Rustemeyer, Ed. (Wiley-VCH,Germany, 2004).6. W.K. Czaja, D.J. Young, M. Kawecki, R.M.Brown, Biomacromolecules 8, 1 (2007).7. A. Gandini, Macromolecules 41, 9491 (2008).8. M. Iguchi, S. Yamanaka, A. Budhiono,J. Mater. Sci. 35, 261 (2000).9. G.H. Altman, F. Diaz, C. Jakuba, T. Calabro,R.L. Horan, J.S. Chen, H. Lu, J. Richmond, D.L.Kaplan, Biomaterials 24, 401 (2003).10. A. Lazaris, S. Aridiacono, Y. Huang,Z.F. Zhou, F. Duguay, N. Chretien, E.A. Welsh,J.W. Soares, C.N. Karatzas, Science 295, 472(2002).11. F. Vollarth, D. Porter, Polymer 50, 5623 (2009).12. A.J. Ragauskas, C.K. Williams, D.H.Davison, G. Britovsek, J. Cairney, C.A.Eckert, W.J. Frederick, J.P. Hallett, D.J.Leak, C.L. Liotta, J.R. Mielenz, R. Murphy,R. Templer, T. Tschaplinski, Science 311, 484(2006).13. Y. Roman-Leshkov, C.J. Barrett, Z.Y. Liu,J.A. Dumesic, Nature 447, 982 (2007); E.L. Kunkes, D.A. Simonetti, R.M. West, J.C.Serrano-Ruiz, C.A. Gartner, J.A. Dumesic,Science 322, 471 (2008).14. J.F.V. Vincent, O.A. Bogatyreva, N.R.Bogatyrev, A. Bowyer, A.-K. Pahl, J. R. Soc.Interface 3, 471 (2008). ■■

readily in the laboratory using benign processing makes the material infinitelyrenewable. This article covers all therecent developments in this area.

The fourth article by Nakagaito et al.reports on another use of cellulosenanofibers. Flexibility is an essential char-acteristic not only for future electronicdevices such as flexible displays andsolar cells, but also for materials suitablefor forthcoming roll-to-roll productionprocesses. These processes enable the con-tinuous deposition of functional materialson a roll of optically transparent flexibleplastic. However, most plastics have largecoefficients of thermal expansion (CTE).Therefore the functional materials that aredeposited on the plastic substrates couldbe broken or damaged by the tempera-tures involved in the assembly andmounting processes due to the mismatchof the CTEs. Reinforcement of transparentplastics with nano-sized cellulose fiberscan overcome these difficulties, as rein-forcing elements with diameters less thanone-tenth of the wavelength of visiblelight are free from light scattering,enabling the formation of optically trans-parent composites. The advantages ofnano-sized reinforcements have beenexperimentally demonstrated using bun-dles of cellulose nanofibrils. The resultingnanocomposites are not only highly transparent but also exhibit a low CTE(due to the low CTE of cellulose) compa-rable to that of glass; they also havemechanical strengths comparable tomild steel. It is also shown how an electro-luminescent layer can be placed on thesetransparent cellulose nanocomposites,such that they can be used for displaydevices.

The final article by Paris et al. deals withbiomimetics and biotemplating of naturalmaterials. Natural materials have devel-oped a wealth of structures to fulfill manyfunctions. Hierarchical structuring is key tomultifunctionality and allows adaptationto the varying needs of the organism. As aconsequence, our natural environmentrepresents not only a direct and renewablesource of useful materials, such as wood,plant fibers, or even proteins of pharma-ceutical importance, but also an enormous“database” of structures with exceptionalmechanical, optical, and magnetic proper-ties. Rather than using the natural materi-als directly, the approach discussed in thisarticle extracts the structural principlesencoded in them and implements these inthe manufacture of artificial materials ofentirely different types and chemical com-positions. The required information maybe extracted in two ways, either by directcopying or templating—for example using

Materials from Renewable Resources

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Stephen J. Eichhorn,Guest Editor in this issueof MRS Bulletin, can bereached at the School ofMaterials, University of Manchester, UK; tel. +44-161-306-5982; fax +44-161-306-3586; and e-mail s.j.eichhorn@manchester.ac.uk.

Eichhorn is currently aReader in PolymerPhysics and Biomaterialsat the University ofManchester, UK. Hestudied physics at theUniversity of Leeds.From there, Eichhorncontinued his studies atthe University ofManchester Institute ofScience and Technologyon forestry and paperindustries technology,earning his master’s andPhD degrees. He joinedthe Materials ScienceCentre at the Universityof Manchester in 2002.Eichhorn is currently theprogram chair of theACS Cellulose andRenewable Materialsdivision. He has interestsin the use of naturalmaterials and hasparticular research skillsin the area of interfacialcharacterization usingspectroscopy and x-raydiffraction.

Alessandro Gandini,Guest Editor in this issueof MRS Bulletin, can bereached at the ChemistryDepartment, CICECO,University of Aveiro,Portugal; tel.

+351-234-370735; fax+351-234-370084; and e-mail:agandini@ua.pt.

Gandini is currentlyprofessor of chemistry atthe University of Aveiro,Portugal. He graduatedwith a PhD degree fromKeele University in 1965and has held researchand teaching positions inpolymer chemistry,photochemistry, andphysical chemistry inSwitzerland, Canada, theUnited States, Cuba,France, Brazil, andPortugal. Gandini alsohas had invitedprofessorships in theUnited Kingdom, Italy,Tunisia, Spain, Uruguay,Costa Rica, Argentina,Mexico, and Spain. His primary researchinterests includepolymers fromrenewable resourcesand the physicalchemistry of surfaces and interfaces. He is aDoctor Honoris Causa ofthe Saint Petersburg State Forest-TechnicalAcademy and HavanaUniversity.

Lars A. Berglund can be reached at theWallenberg WoodScience Centre, RoyalInstitute of Technology,SE-100 44 Stockholm,Sweden; tel. 46-8-790-6000; and e-mailblund@kth.se.

Berglund is a professorof wood and wood

composites at the RoyalInstitute of Technology(KTH) in Stockholm. He also is director ofWallenberg WoodScience Centre, a 10-yearprogram engagingaround 50 researchers atKTH and at ChalmersUniversity inGothenburg. Berglundholds degrees from the University ofMassachusetts atAmherst (in polymerscience and engineering)and LinkopingUniversity (inengineering materials)and has been a visitingscientist at StanfordUniversity and CornellUniversity. His researchinterests focus on newnanostructured materialsfrom trees, with anemphasis on composites.Berglund has won theInnovation Cup inSweden and is a memberof the Swedish Academyof Engineering Science.

Ingo Burgert can bereached at the MaxPlanck Institute ofColloids and Interfaces,Research Campus Golm,14424 Potsdam,Germany; tel. 49-331-567-9432; fax 49-331-567-9402;and e-mailingo.burgert@mpikg.mpg.de.

Burgert leads aresearch group on plantbiomechanics andbiomimetics in theDepartment of

Biomaterials at the MaxPlanck Institute ofColloids and Interfaces.He studied wood scienceand technology at theUniversity of Hamburg,where he also receivedhis PhD degree in woodscience in 2000.Following postdoctoralwork with the Instituteof Materials Science andPhysics at the Universityof Natural Resources andApplied Life Sciences,Vienna, Austria, hejoined the Max PlanckInstitute in 2003.Burgert’s researchfocuses on mechanicalproperties, stressgeneration capacities,and organ movements inplants with a view toextract design principlesfor biomimetic materials.

Peter Fratzl can bereached at the MaxPlanck Institute ofColloids and Interfaces,Research Campus Golm,14424 Potsdam,Germany; tel. 49-331-567-9400; fax 49-331-567-9402;and e-mailpeter.fratzl@mpikg.mpg.de.

Fratzl is director of theBiomaterials Departmentat the Max PlanckInstitute of Colloids andInterfaces in Potsdam,Germany, and is anhonorary professor ofphysics at Potsdam andat Berlin’s HumboldtUniversity. He receivedan engineering degree

from the EcolePolytechnique in Paris,France (1980), and adoctorate in physics fromthe University of Vienna,Austria (1983). Beforemoving to Potsdam in2003, Fratzl heldprofessor positions inmaterials physics at theUniversities of Viennaand of Leoben in Austria,and also was director of the Erich SchmidInstitute of MaterialsScience of the AustrianAcademy of Sciences.Fratzl’s lab studies therelation between(hierarchical) structureand mechanical behaviorof biological materials,such as bones, teeth, orplant cells, as well asbioinspired compositematerials. He haspublished more than 300 papers in journalsand books and is acorresponding memberof the Austrian Academyof Sciences. His honorsinclude severalinternational awards forhis work, including theMax Planck ResearchAward (2008) from theHumboldt Foundationfor pioneering work onbiological andbioinspired materials.

Paul Gatenholm can bereached at theWallenberg WoodScience Centre,Department of Chemicaland BiologicalEngineering, Chalmers

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Stephen J. Eichhorn Alessandro Gandini Lars A. Berglund Ingo Burgert Peter Fratzl

University of Technology,SE412 96 Göteborg,Sweden; tel. 46-3-17723407; fax 46-3-17723418; and e-mailpaul.gatenholm@chalmers.se.

Gatenholm receivedhis PhD degree inpolymer technology atChalmers University.Gatenholm has been avisiting professor at theUniversity ofWashington, NavalResearch Laboratory,USA, and the GeorgiaInstitute of Technology.He also was a professorof materials, science, andengineering at VirginiaPolytechnic Institute andState University (VirginiaTech) until 2009.Gatenholm is an adjunctprofessor of biomedicalengineering at VirginiaTech and at Wake ForestInstitute for RegenerativeMedicine. He iscofounder of Xylophane,Arterion, and BC Genesis.He is currently presidentof BC Genesis.

Marc A. Hillmyer can be reached at theDepartment ofChemistry, University ofMinnesota, Minneapolis,55455-0431, USA; tel.612-625-7834; and e-mail:hillmyer@umn.edu.

Hillmyer is a professorof chemistry at theUniversity of Minnesota(UMN). He earned a BSdegree in chemistry atthe University of Florida

(1989) and a PhD degreein chemistry at theCalifornia Institute ofTechnology (1994). Aftera postdoctoral position inchemical engineeringand materials science atUMN, Hillmyer joinedthe chemistry faculty in1997. He also is thedirector of the Center forSustainable Polymers atUMN and an associateeditor for Macromolecules.Hillmyer’s researchinterests includemultifunctional blockpolymers and renewableresource materials.

Dieter Klemm can bereached at Polymet Jena,Technology andInnovation Park,Wildenbruchstraße 15, D 07745 Jena, Germany;tel. 49-3641-548281; fax 49-3641-548289; ande-mailDieter.Klemm@uni-jena.de.

Klemm has been aprofessor of organicchemistry at theUniversity of Jena since1987. He received hisPhD degree from studieson steroids and hisHabilitation in 1977 afterconducting research insynthetic polymerchemistry. Klemm joinedthe University of Jenaafter working in thepharmaceutical industry.Currently, he is active inthe research anddevelopment of bacterialcellulose medical

implants. Klemm is anassociate editor ofCellulose, and his honorsinclude the AnselmePayen Award from theAmerican ChemicalSociety for thedevelopment of newcellulose-based materials(2004).

Anne-Cécile Mortametcan be reached by e-mailat chp07amm@shef.ac.uk.

Mortamet is a final-year PhD degree studentat the University ofSheffield working withProfessor Anthony Ryan.Mortamet graduatedwith a master’s degree inchemistry from theSchool of Chemistry,Physics, and Electronicsin Lyon, France, in 2007.She then spent a yearworking in industry atJohnson MattheyCatalysts in Billingham,UK. Conjointly to herFrench degree, Mortametwas awarded a MPhildegree in chemistry atStrathclyde University,Glasgow, UK, in 2009.Her research interestsinclude structure-property relations in bio-sourced polyurethaneelastomers.

Antonio NorioNakagaito can bereached at theDepartment of Chemistryand Biotechnology,Graduate School ofEngineering TottoriUniversity, 4-101

Koyama-cho Minami,Tottori; Japan; tel. andfax 81(857) 31-5592; ande-mail nakagaito@rish.kyoto-u.ac.jp. (e-mailstarting April 2010:norio.rm@gmail.com).

Nakagaito is aresearcher at theLaboratory of Active Bio-Based Materials,Research Institute ofSustainableHumanosphere, KyotoUniversity. He holds a BSdegree in physics and aMS degree in materialsscience and engineering,both from the Universityof Sao Paulo, Brazil.Nakagaito earned hisDrAgr degree in forestryand biomaterials sciencefrom Kyoto University,Japan. His researchinterests involve thedevelopment ofcellulose-basednanocomposites,especially those with thematrix phase alsoobtained fromsustainable resources.

Masaya Nogi can bereached at theDepartment of AdvancedInterconnectionMaterials, Institute ofScience and IndustrialResearch, OsakaUniversity, Ibaraki, Osaka 567-0047, Japan;tel. 81-6-6879-8521; fax 81-6-6879-8522; ande-mail nogi@eco.sanken.osaka-u.ac.jp.

Nogi is a an assistantprofessor at the Institute

of Science and IndustrialResearch, OsakaUniversity, Japan. He hasa MS degree in woodscience and a DrAgrdegree in biosphereresources science fromNagoya University,Japan. Nogi’s researchinterests involve thedevelopment ofadvanced opticallytransparent materialsusing natural nanofibers.

Oskar Paris can bereached at the Universityof Leoben, Austria; tel.43-3842-402-4600; fax 43-3842-402-4602; and e-mail oskar.paris@unileoben.ac.at.

Paris is a professor ofphysics and chair of theInstitute of Physics at theUniversity of Leoben,Austria. He received hisdoctoral degree inphysics from theUniversity of Vienna in1996 and his postdoctorallecture qualification(Habilitation) in materialsphysics from theUniversity of Leoben in2003. Paris was apostdoctoral researcherat the Swiss FederalInstitute of Technology inZurich, Switzerland(1996 to 1998), a seniorpostdoctoral researcherat the University ofLeoben, Austria (1998 to2003), and researchgroup leader at the MaxPlanck Institute ofColloids and Interfaces inPotsdam, Germany

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Paul Gatenholm Marc A. Hillmyer Dieter Klemm Anne-Cécile Mortamet Antonio NorioNakagaito

(2003–2009). Paris is anexpert in materialsstructure characterizationemploying synchrotronradiation and neutrontechniques. His currentresearch interests focuson the structure-functionrelationship in complexnatural and syntheticnanocomposites. He haspublished more than 80papers in refereedjournals and books.

Ton Peijs can be reachedby e-mail att.peijs@qmul.ac.uk.

Peijs is a professor ofmaterials at Queen MaryUniversity of London(QMUL) and a visitingprofessor at EindhovenUniversity of Technology,The Netherlands. Hisresearch interests are inall aspects of structure,processing, and propertyrelationships of polymer(nano)composites. Hisgroup has made notablecontributions to thedevelopment of eco-composites, includingwork on bio-basedcomposites and the

development of fullyrecyclable all-polymercomposites. In recentyears, Peijs has focusedmore on the utilization ofnanoscale architecturesin polymer composites.He is a director atNanoforce TechnologyLtd, a spin-out companywholly-owned by QMULthat is devoted tonanocomposites researchfor exploitation byindustry.

Megan L. Robertson canbe reached at theDepartment ofChemistry, University ofMinnesota, Minneapolis,55455-0431, USA; e-mail:rueg0011@umn.edu.

Robertson is apostdoctoral researchassociate at theUniversity of Minnesotain the Department ofChemistry working withProfessor Marc Hillmyer.She received a PhDdegree in chemicalengineering from theUniversity of California,Berkeley, in 2006,advised by Professor

Nitash Balsara.Robertson earned her BSdegree in chemicalengineering fromWashington Universityin St. Louis in 2001. Priorto her postdoctoralappointment, she spentone year at Rohm andHaas in Spring House,PA. Her researchinterests include polymerthermodynamics,nanostructuredpolymers, and renewablematerials.

Anthony J. Ryan can bereached at the Universityof Sheffield, UK; tel. +44-114-222-9761; ande-mail: tony.ryan@sheffield.ac.uk.

Ryan is the Pro-Vice-Chancellor for theFaculty of Science at theUniversity of Sheffield.He has BSc and PhDdegrees in polymerscience and technologyfrom the VictoriaUniversity of Manchesterand a DSc degree fromthe University ofManchester Institute ofScience and Technology

(UMIST). He started hisacademic career with alectureship in polymerscience at UMIST andmoved to serve as thechair of physicalchemistry at theUniversity of Sheffield,where he has been theICI Professor of PhysicalChemistry and directorof the Polymer Centre.Ryan’s research coversthe synthesis, structure,processing, andproperties of polymers,and he is widelyinvolved in the publicengagement of science.He presented the Royal InstitutionChristmas Lectures in2002 and was made anOfficer of the BritishEmpire in 2006.

Hiroyuki Yano can bereached at theLaboratory of Active Bio-Based Materials,Research Institute ofSustainableHumanosphere, KyotoUniversity, Gokasho, Uji,Kyoto 611-0011, Japan;tel. and fax 81-0774-38-

3669; and e-mailyano@rish.kyoto-u.ac.jp.

Yano is a professor atthe Laboratory of ActiveBio-Based Materials,Research Institute ofSustainableHumanosphere, at KyotoUniversity, Japan. He hasBS and MS degrees inwood science andtechnology, and a DrAgrdegree—all from KyotoUniversity. Yano’sresearch interestsinvolve the extraction ofnanofibers from bio-resources, such aswood and crab shell, and their applications for nanomaterials. ■■

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Masaya Nogi Oskar Paris Megan L. Robertson Anthony J. Ryan

Hiroyuki Yano

Ton Peijs