Examine individual changes

[ 0 => '{{short description|Synthetic ultralight material}}', 1 => '{{Quote box', 2 => '| title = [[International Union of Pure and Applied Chemistry|IUPAC]] definition', 3 => '| quote = '''Aerogel''': [[Gel]] {{sic|comprising |hide=y}} a microporous solid in which the dispersed phase is a gas.<ref>{{cite book|author1=R. G. Jones|author2= J. Kahovec|author3= R. Stepto|author4= E. S. Wilks|author5= M. Hess|author6= T. Kitayama|author7= W. V. Metanomski|title=IUPAC. Compendium of Polymer Terminology and Nomenclature, IUPAC Recommendations 2008 (the "Purple Book")|date=2008|publisher=RSC Publishing, Cambridge, UK|url=https://www.iupac.org/cms/wp-content/uploads/2016/07/ONLINE-IUPAC-PB2-Online-June2014.pdf}}</ref><ref>{{cite journal|title=Terminology of polymers and polymerization processes in dispersed systems (IUPAC Recommendations 2011)|journal=[[Pure and Applied Chemistry]]|year=2011|volume=83|issue=12|pages=2229–2259|doi=10.1351/PAC-REC-10-06-03|url=https://www.degruyter.com/downloadpdf/j/pac.2011.83.issue-12/pac-rec-10-06-03/pac-rec-10-06-03.pdf|last1=Slomkowski|first1=Stanislaw|last2=Alemán|first2=José V.|last3=Gilbert|first3=Robert G.|last4=Hess|first4=Michael|last5=Horie|first5=Kazuyuki|last6=Jones|first6=Richard G.|last7=Kubisa|first7=Przemyslaw|last8=Meisel|first8=Ingrid|last9=Mormann|first9=Werner|last10=Penczek|first10=Stanisław|last11=Stepto|first11=Robert F. T.}}</ref>', 4 => '', 5 => 'Note 1: Microporous silica, microporous glass, and zeolites are common examples of aerogels.', 6 => 'Note 2: Corrected from ref.,<ref>{{cite book|author1=A. D. McNaught|author2= A. Wilkinson.|title=IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book").|date=1997|publisher=Blackwell Scientific Publications|location=Oxford|edition=XML on-line corrected version|doi=10.1351/goldbook|isbn=978-0-9678550-9-7}}</ref> where the definition is a repetition of the incorrect definition of a gel followed by an inexplicit reference to the porosity of the structure.', 7 => '', 8 => '| align = right', 9 => '| width = 30%', 10 => '}}', 11 => '', 12 => '{{Use dmy dates|date=July 2016}}', 13 => '[[File:Aerogel hand.jpg|right|thumb|A block of aerogel in a hand]]'''Aerogel''' is a [[Manufacturing|synthetic]] porous [[ultralight material]] derived from a [[gel]], in which the [[liquid]] component for the gel has been replaced with a [[gas]] without significant collapse of the gel structure.<ref name="goldbook007">{{cite book|date=2007|title=Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)|url=http://goldbook.iupac.org/A00173.html|journal=[[Pure and Applied Chemistry]]|volume=79|issue=10|pages=1801–1829|doi=10.1351/goldbook.A00173|isbn=978-0-9678550-9-7|url-status=live|archiveurl=https://web.archive.org/web/20121130224939/http://goldbook.iupac.org/A00173.html|archivedate=30 November 2012|df=dmy-all}}</ref> The result is a solid with extremely low [[density]]<ref name="GuinnessRecord">{{cite web|url=http://stardust.jpl.nasa.gov/news/news93.html|title=Guinness Records Names JPL's Aerogel World's Lightest Solid|date=7 May 2002|publisher=Jet Propulsion Laboratory|work=NASA|accessdate=25 May 2009|archiveurl=https://web.archive.org/web/20090525181226/http://stardust.jpl.nasa.gov/news/news93.html|archivedate=25 May 2009|url-status=live}}</ref> and extremely low [[thermal conductivity]]. Nicknames include ''frozen smoke'',<ref name="Times081907">{{cite news|url=http://www.timesonline.co.uk/tol/news/uk/science/article2284349.ece|title=Scientists hail 'frozen smoke' as material that will change world|last=Taher|first=Abul|date=19 August 2007|work=News Article|publisher=Times Online|location=London|accessdate=22 August 2007|url-status=live|archiveurl=https://web.archive.org/web/20070912234840/http://www.timesonline.co.uk/tol/news/uk/science/article2284349.ece|archivedate=12 September 2007|df=dmy-all}}</ref> ''solid smoke'', ''solid air'', ''solid cloud'', ''blue smoke'' owing to its [[transparency (optics)|translucent]] nature and the way [[light]] [[Scattering|scatters]] in the material. Silica aerogels feel like fragile [[expanded polystyrene]] to the touch, while some polymer-based aerogels feel like rigid foams. Aerogels can be made from a variety of chemical compounds.<ref name="Aerogels Handbook">{{cite book|title=Aerogels Handbook|last=Aegerter|first=M.A.|date=2011|publisher=Springer publishing|isbn=978-1-4419-7477-8|author2=Leventis, N. |author3=Koebel, M. M. }}</ref>', 14 => '', 15 => 'Aerogel was first created by [[Samuel Stephens Kistler]] in 1931, as a result of a bet<ref>{{cite book|url = https://books.google.com/?id=exRjDAAAQBAJ&pg=PA41&dq=kistler+charles+learned|title = Cryogenic Heat Transfer|edition = 2nd|first1 = Randall F.|last1 = Barron|first2 = Gregory F.|last2 = Nellis|publisher = [[CRC Press]]|year = 2016|page = 41|isbn = 9781482227451|url-status=live|archiveurl = https://web.archive.org/web/20171122171437/https://books.google.com/books?id=exRjDAAAQBAJ&pg=PA41&dq=kistler+charles+learned&hl=en&sa=X&redir_esc=y|archivedate = 22 November 2017|df = dmy-all}}</ref> with Charles Learned over who could replace the liquid in "jellies" with gas without causing shrinkage.<ref>{{cite journal|date=1931|title=Coherent expanded aerogels and jellies|journal=[[Nature (journal)|Nature]]|volume=127|issue=3211|page=741|bibcode=1931Natur.127..741K|doi=10.1038/127741a0|author=Kistler, S. S.}}</ref><ref>{{cite journal|date=1932|title=Coherent Expanded-Aerogels|journal=[[Journal of Physical Chemistry]]|volume=36|issue=1|pages=52–64|doi=10.1021/j150331a003|author=Kistler, S. S.}}</ref>', 16 => '', 17 => 'Aerogels are produced by extracting the liquid component of a gel through [[supercritical drying]] or [[freeze-drying]]. This allows the liquid to be slowly dried off without causing the solid matrix in the gel to collapse from [[capillary action]], as would happen with conventional [[evaporation]]. The first aerogels were produced from [[silica gel]]s. Kistler's later work involved aerogels based on [[alumina]], [[Chromium(III) oxide|chromia]] and [[tin dioxide]]. [[Carbon]] aerogels were first developed in the late 1980s.<ref>{{Cite journal|last=Pekala|first=R. W.|title=Organic aerogels from the polycondensation of resorcinol with formaldehyde|journal=Journal of Materials Science|language=en|volume=24|issue=9|pages=3221–3227|doi=10.1007/BF01139044|issn=0022-2461|bibcode=1989JMatS..24.3221P|year=1989}}</ref>', 18 => '', 19 => '==Properties==', 20 => '[[File:Aerogelflower_filtered.jpg|right|thumb|A flower is on a piece of aerogel which is suspended over a flame from a [[Bunsen burner]]. Aerogel has excellent insulating properties, and the flower is protected from the flame.]] Despite the name, aerogels are solid, rigid, and dry materials that do not resemble a gel in their physical properties: the name comes from the fact that they are made ''from'' gels. Pressing softly on an aerogel typically does not leave even a minor mark; pressing more firmly will leave a permanent depression. Pressing extremely firmly will cause a catastrophic breakdown in the sparse structure, causing it to shatter like glass (a property known as ''[[friability]]''), although more modern variations do not suffer from this. Despite the fact that it is prone to shattering, it is very strong structurally. Its impressive load-bearing abilities are due to the [[Dendrite (metal)|dendritic]] microstructure, in which [[spherical]] particles of average size 2–5&nbsp;[[Nanometre|nm]] are fused together into clusters. These clusters form a three-dimensional highly [[Porosity|porous]] structure of almost [[fractal]] chains, with pores just under 100&nbsp;nm. The average size and density of the pores can be controlled during the manufacturing process.', 21 => '', 22 => 'Aerogel is a material that is 99.8% air. Aerogels have a porous solid network that contains air pockets, with the air pockets taking up the majority of space within the material.<ref>{{cite web|url=http://www.azom.com/article.aspx?ArticleID=6499|title=What is Aerogel? Theory, Properties and Applications|date=12 December 2013|publisher=azom.com|accessdate=5 December 2014|url-status=live|archiveurl=https://web.archive.org/web/20141209123257/http://www.azom.com/article.aspx?ArticleID=6499|archivedate=9 December 2014|df=dmy-all}}</ref> The dearth of solid material allows aerogel to be almost weightless.', 23 => '', 24 => 'Aerogels are good [[Thermal insulation|thermal insulators]] because they almost nullify two of the three methods of [[heat transfer]] – conduction (they are mostly composed of insulating gas) and convection (the microstructure prevents net gas movement). They are good [[Heat conduction|conductive]] insulators because they are composed almost entirely of gases, which are very poor heat conductors. (Silica aerogel is an especially good insulator because silica is also a poor conductor of heat; a metallic or carbon aerogel, on the other hand, would be less effective.) They are good [[Convective heat transfer|convective]] inhibitors because air cannot circulate through the lattice. Aerogels are poor [[Thermal radiation|radiative]] insulators because infrared radiation (which transfers heat) passes through them.', 25 => '', 26 => 'Owing to its [[hygroscopic]] nature, aerogel feels dry and acts as a strong [[desiccant]]. People handling aerogel for extended periods should wear gloves to prevent the appearance of dry brittle spots on their skin.', 27 => '', 28 => 'The slight color it does have is due to [[Rayleigh scattering]] of the shorter [[wavelength]]s of [[visible light]] by the nano-sized dendritic structure. This causes it to appear smoky blue against dark backgrounds and yellowish against bright backgrounds.', 29 => '', 30 => 'Aerogels by themselves are [[hydrophilic]], and if they absorb moisture they usually suffer a structural change, such as contraction, and deteriorate, but degradation can be prevented by making them [[hydrophobic]], via a chemical treatment. Aerogels with hydrophobic interiors are less susceptible to degradation than aerogels with only an outer hydrophobic layer, even if a crack penetrates the surface.', 31 => '', 32 => '== Knudsen effect ==', 33 => 'Aerogels may have a [[thermal conductivity]] smaller than that of the gas they contain. This is caused by the [[Knudsen number|Knudsen effect]], a reduction of thermal conductivity in gases when the size of the cavity encompassing the gas becomes comparable to the [[mean free path]]. Effectively, the cavity restricts the movement of the gas particles, decreasing the thermal conductivity in addition to eliminating convection. For example, thermal conductivity of air is about 25&nbsp;mW/m·K at STP and in a large container, but decreases to about 5&nbsp;mW/m·K in a pore 30 nanometers in diameter.<ref>Berge, Axel and Johansson, Pär (2012) [http://publications.lib.chalmers.se/records/fulltext/local_159807.pdf Literature Review of High Performance Thermal Insulation] {{webarchive|url=https://web.archive.org/web/20141121114200/http://publications.lib.chalmers.se/records/fulltext/local_159807.pdf |date=21 November 2014 }}. Department of Civil and Environmental Engineering, Chalmers University of Technology, Sweden</ref>', 34 => '', 35 => '== Structure ==', 36 => 'Aerogel structure results from a [[sol-gel]] [[polymerization]], which is when [[monomers]] (simple molecules) react with other monomers to form a sol or a substance that consists of bonded, cross-linked [[macromolecules]] with deposits of liquid solution among them. When the material is critically heated, the liquid [[evaporates]] and the bonded, [[cross-linked]] macromolecule frame is left behind. The result of the polymerization and critical heating is the creation of a material that has a porous strong structure classified as aerogel.<ref>[https://str.llnl.gov/str/Foxhighlight.html Aerogel Structure] {{webarchive|url=https://web.archive.org/web/20141225170824/https://str.llnl.gov/str/Foxhighlight.html |date=25 December 2014 }}. Str.llnl.gov. Retrieved on 31 July 2016.</ref> Variations in synthesis can alter the surface area and pore size of the aerogel. The smaller the pore size the more susceptible the aerogel is to fracture.<ref>{{cite web|url=http://www.aerogel.org/?p=16|title=Silica Aerogel|last=|first=|date=|website=Aerogel.org|access-date=|url-status=live|archiveurl=https://web.archive.org/web/20160404111603/http://www.aerogel.org/?p=16|archivedate=4 April 2016|df=dmy-all}}</ref>', 37 => '', 38 => '== Waterproofing ==', 39 => 'Aerogel contains particles that are 2–5&nbsp;nm in diameter. After the process of creating aerogel, it will contain a large amount of [[hydroxyl groups]] on the surface. The hydroxyl groups can cause a strong reaction when the aerogel is placed in water, causing it to catastrophically dissolve in the water. One way to waterproof the [[hydrophilic]] aerogel is by soaking the aerogel with some chemical base that will replace the surface hydroxyl groups (–OH) with non-polar groups (–O''R''), a process which is most effective when ''R'' is an [[aliphatic]] group.<ref>[http://www.vsl.cua.edu/cua_phy/images/c/cf/Aerogel_Aerlon_SilicaAerogels.pdf The Surface Chemistry of Silica Aerogels] {{webarchive|url=https://web.archive.org/web/20141201035010/http://energy.lbl.gov/ECS/aerogels/sa-chemistry.html |date=1 December 2014 }}. Energy.lbl.gov. Retrieved on 31 July 2016.</ref>', 40 => '', 41 => '== Porosity of aerogel ==', 42 => 'There are several ways to determine the porosity of aerogel: the three main methods are gas [[adsorption]], mercury porosimetry, and scattering method. In gas adsorption, nitrogen at its boiling point is adsorbed into the aerogel sample. The gas being adsorbed is dependent on the size of the pores within the sample and on the partial pressure of the gas relative to its [[saturation pressure]]. The volume of the gas adsorbed is measured by using the Brunauer, Emmit and Teller formula ([[BET theory|BET]]), which gives the specific [[surface area]] of the sample. At high partial pressure in the adsorption/desorption the Kelvin equation gives the pore size distribution of the sample. In mercury porosimetry, the [[Mercury (element)|mercury]] is forced into the aerogel porous system to determine the pores' size, but this method is highly inefficient since the solid frame of aerogel will collapse from the high compressive force. The scattering method involves the angle-dependent deflection of radiation within the aerogel sample. The sample can be solid particles or pores. The radiation goes into the material and determines the fractal geometry of the aerogel pore network. The best radiation wavelengths to use are X-rays and neutrons. Aerogel is also an open porous network: the difference between an open porous network and a closed porous network is that in the open network, gases can enter and leave the substance without any limitation, while a closed porous network traps the gases within the material forcing them to stay within the pores.<ref>[https://pamelanorris.wordpress.com/resources/pore-structure-of-silica-aerogels/ Pore Structure of Silica Aerogels] {{webarchive|url=https://web.archive.org/web/20141201064113/http://energy.lbl.gov/ECS/aerogels/sa-pore.html |date=1 December 2014 }}. Energy.lbl.gov. Retrieved on 31 July 2016.</ref> The high porosity and surface area of silica aerogels allow them to be used in a variety of environmental filtration applications.', 43 => '', 44 => '== Materials ==', 45 => '[[File:Aerogelbrick.jpg|thumb|A 2.5 kg [[brick]] is supported by a piece of aerogel with a mass of 2&nbsp;g.]]', 46 => '', 47 => '=== Silica Aerogel ===', 48 => '', 49 => 'Silica aerogel is the most common type of aerogel, and the most extensively studied and used. It is [[silica]]-based and can be derived from [[silica gel]] or by a modified [[Stober process]]. The lowest-density silica nanofoam weighs 1,000&nbsp;g/m³,<ref name="terms">[https://web.archive.org/web/20050718075757/http://www.llnl.gov/IPandC/technology/profile/aerogel/Terms/index.php Aerogels Terms]. LLNL.gov</ref> which is the evacuated version of the record-aerogel of 1,900&nbsp;g/m³.<ref name="llnl03">{{cite web|url=http://www.llnl.gov/str/October03/NewsOctober03.html|title=Lab's aerogel sets world record|date=October 2003|publisher=LLNL Science & Technology Review|url-status=live|archiveurl=https://web.archive.org/web/20061009154049/http://www.llnl.gov/str/October03/NewsOctober03.html|archivedate=9 October 2006|df=dmy-all}}</ref> The density of [[air]] is 1,200&nbsp;g/m³ (at 20&nbsp;°C and 1&nbsp;atm).<ref>Groom, D.E. [http://pdg.lbl.gov/2007/reviews/atomicrpp.pdf Abridged from Atomic Nuclear Properties] {{webarchive|url=https://web.archive.org/web/20080227212418/http://pdg.lbl.gov/2007/reviews/atomicrpp.pdf |date=27 February 2008 }}. Particle Data Group: 2007.</ref> {{as of|2013}}, [[aerographene]] had a lower density at 160&nbsp;g/m³, or 13% the density of air at room temperature.<ref>{{cite web|url=http://www.zju.edu.cn/c165055/content_2285977.html|title=Ultra-light Aerogel Produced at a Zhejiang University Lab-Press Releases-Zhejiang University|date=19 March 2013|publisher=Zju.edu.cn|accessdate=12 June 2013|url-status=dead|archiveurl=https://web.archive.org/web/20130523111001/http://www.zju.edu.cn/c165055/content_2285977.html|archivedate=23 May 2013|df=dmy-all}}</ref>', 50 => '', 51 => 'The silica solidifies into three-dimensional, intertwined clusters that make up only 3% of the volume. Conduction through the solid is therefore very low. The remaining 97% of the volume is composed of air in extremely small nanopores. The air has little room to move, inhibiting both convection and gas-phase conduction.<ref>{{cite web|url=http://www.aerogel.com/resources/about-aerogel/|title=About Aerogel|publisher=ASPEN AEROGELS, INC.|accessdate=12 March 2014|url-status=live|archiveurl=https://web.archive.org/web/20140526131958/http://www.aerogel.com/resources/about-aerogel/|archivedate=26 May 2014|df=dmy-all}}</ref>', 52 => '', 53 => 'Silica aerogel also has a high optical transmission of ~99% and a low refractive index of ~1.05.<ref name=":0">{{Cite journal|last=Gurav|first=Jyoti L.|last2=Jung|first2=In-Keun|last3=Park|first3=Hyung-Ho|last4=Kang|first4=Eul Son|last5=Nadargi|first5=Digambar Y.|date=11 August 2010|title=Silica Aerogel: Synthesis and Applications|journal=Journal of Nanomaterials|language=en|volume=2010|pages=1–11|doi=10.1155/2010/409310|issn=1687-4110|df=dmy-all|doi-access=free}}</ref>', 54 => '', 55 => 'This aerogel has remarkable thermal insulative properties, having an extremely low [[thermal conductivity]]: from 0.03&nbsp;[[Watt|W]]/(m·[[Kelvin|K]])<ref>"Thermal conductivity" in {{RubberBible86th}} Section 12, p. 227</ref> in atmospheric pressure down to 0.004&nbsp;W/(m·K)<ref name="terms" /> in modest vacuum, which correspond to [[R-value (insulation)|R-values]] of 14 to 105 (US customary) or 3.0 to 22.2 (metric) for {{convert|3.5|in|mm|0|abbr=on}} thickness. For comparison, typical wall insulation is 13 (US customary) or 2.7 (metric) for the same thickness. Its [[melting point]] is {{convert|1473|K|C F|0|abbr=on}}.', 56 => '', 57 => 'Until 2011, silica aerogel held 15&nbsp;entries in ''[[Guinness World Records]]'' for material properties, including best insulator and lowest-density solid, though it was ousted from the latter title by the even lighter materials [[aerographite]] in 2012<ref>{{cite journal|last=Mecklenburg|first=Matthias|date=July 2012|title=Aerographite: Ultra Lightweight, Flexible Nanowall, Carbon Microtube Material with Outstanding Mechanical Performance|journal=Advanced Materials|volume=24|issue=26|pages=3486–90|doi=10.1002/adma.201200491|pmid=22688858}}</ref> and then [[aerographene]] in 2013.<ref>Whitwam, Ryan (26 March 2013). [http://www.geek.com/articles/chips/graphene-aerogel-is-worlds-lightest-material-20130326/ Graphene aerogel is world's lightest material] {{webarchive|url=https://web.archive.org/web/20130327134015/http://www.geek.com/articles/chips/graphene-aerogel-is-worlds-lightest-material-20130326/ |date=27 March 2013 }}. gizmag.com</ref><ref>Quick, Darren (24 March 2013). [http://www.gizmag.com/graphene-aerogel-worlds-lightest/26784/ Graphene aerogel takes world's lightest material crown] {{webarchive|url=https://web.archive.org/web/20130325182654/http://www.gizmag.com/graphene-aerogel-worlds-lightest/26784/ |date=25 March 2013 }}. gizmag.com</ref>', 58 => '', 59 => '=== Carbon ===', 60 => '[[Carbon]] aerogels are composed of particles with sizes in the [[nanometer]] range, [[Covalent bond|covalently bonded]] together. They have very high [[porosity]] (over 50%, with pore diameter under 100&nbsp;nm) and surface areas ranging between 400 and 1,000&nbsp;m²/g. They are often manufactured as composite paper: non-woven paper made of [[carbon fiber]]s, impregnated with [[resorcinol]]–[[formaldehyde]] aerogel, and [[Pyrolisis|pyrolyzed]]. Depending on the density, carbon aerogels may be electrically conductive, making composite aerogel paper useful for electrodes in [[capacitor]]s or deionization electrodes. Due to their extremely high surface area, carbon aerogels are used to create [[supercapacitor]]s, with values ranging up to thousands of [[farad]]s based on a capacitance density of 104&nbsp;F/g and 77&nbsp;F/cm³. Carbon aerogels are also extremely "black" in the infrared spectrum, reflecting only 0.3% of radiation between 250&nbsp;nm and 14.3&nbsp;µm, making them efficient for [[Solar thermal energy|solar energy]] collectors.', 61 => '', 62 => 'The term "aerogel" to describe airy masses of [[carbon nanotube]]s produced through certain [[chemical vapor deposition]] techniques is incorrect. Such materials can be spun into fibers with strength greater than [[Kevlar]], and unique electrical properties. These materials are not aerogels, however, since they do not have a monolithic internal structure and do not have the regular pore structure characteristic of aerogels.', 63 => '', 64 => '=== Metal oxide ===', 65 => '[[Metal oxide]] aerogels are used as catalysts in various chemical reactions/transformations or as precursors for other materials.', 66 => '', 67 => 'Aerogels made with [[aluminium oxide]] are known as alumina aerogels. These aerogels are used as catalysts, especially when "doped" with a metal other than aluminium. [[Nickel]]–alumina aerogel is the most common combination. Alumina aerogels are also being considered by [[NASA]] for capturing hypervelocity particles; a formulation doped with [[gadolinium]] and [[terbium]] could [[fluoresce]] at the particle impact site, with the amount of fluorescence dependent on impact energy.', 68 => '', 69 => 'One of the most notable differences between silica aerogels and metal oxide aerogel is that metal oxide aerogels are often variedly colored.', 70 => '', 71 => '{| class="wikitable"', 72 => '|-', 73 => '! Aerogel !! Color', 74 => '|-', 75 => '| [[Silica]], [[alumina]], [[Titanium dioxide|titania]], [[zirconia]] || Clear with Rayleigh scattering blue or white', 76 => '|-', 77 => '| [[Iron oxide]] || Rust red or yellow, opaque', 78 => '|-', 79 => '| [[Chromium(III) oxide|Chromia]] || Deep green or deep blue, opaque', 80 => '|-', 81 => '| [[Vanadia]] || Olive green, opaque', 82 => '|-', 83 => '| [[Neodymium oxide]] || Purple, transparent', 84 => '|-', 85 => '| [[Samarium(III) oxide|Samaria]] || Yellow, transparent', 86 => '|-', 87 => '| [[Holmium(III) oxide|Holmia]], [[Erbium(III) oxide|erbia]] || Pink, transparent', 88 => '|}', 89 => '<ref>{{cite web|url=http://www.aerogel.org/?p=44|title=Metal Oxide Aerogels|publisher=Aerogel.org|accessdate=12 June 2013|url-status=live|archiveurl=https://web.archive.org/web/20130812045126/http://www.aerogel.org/?p=44|archivedate=12 August 2013|df=dmy-all}}</ref>', 90 => '', 91 => '=== Other ===', 92 => 'Organic polymers can be used to create aerogels. [[SEAgel]] is made of [[agar]]. AeroZero film is made of [[polyimide]]. Cellulose from plants can be used to create a flexible aerogel.<ref>{{cite journal|last2=Saito|first2=Tsuguyuki|last3=Isogai|first3=Akira|date=2014|title=Aerogels with 3D Ordered Nanofiber Skeletons of Liquid-Crystalline Nanocellulose Derivatives as Tough and Transparent Insulators|journal=Angewandte Chemie International Edition|volume=53|issue=39|pages=10394–7|doi=10.1002/anie.201405123|last1=Kobayashi|first1=Yuri|lay-url=http://www.rsc.org/chemistryworld/2014/07/plant-material-aligns-make-tough-aerogels-nanocellulose|laysource=Royal Society of Chemistry|laydate=11 July 2014|pmid=24985785}}</ref>', 93 => '', 94 => 'GraPhage13 is the first graphene-based aerogel assembled using [[graphene oxide]] and the [[M13 bacteriophage]].<ref>Passaretti, P., et al. (2019). "Multifunctional graphene oxide-bacteriophage based porous three-dimensional micro-nanocomposites." Nanoscale 11(28): 13318-13329. https://doi.org/10.1039/C9NR03670A</ref>', 95 => '', 96 => '[[Chalcogel]] is an aerogel made of [[chalcogen]]s (the column of elements on the periodic table beginning with oxygen) such as sulfur, selenium and other elements.<ref>Biello, David [http://www.scientificamerican.com/article/heavy-metal-filter-made-largely-from-air/ Heavy Metal Filter Made Largely from Air.] {{webarchive|url=https://web.archive.org/web/20150226102809/http://www.scientificamerican.com/article/heavy-metal-filter-made-largely-from-air/ |date=26 February 2015 }} ''Scientific American'', 26 July 2007. Retrieved on 2007-08-05.</ref> Metals less expensive than platinum have been used in its creation.', 97 => '', 98 => 'Aerogels made of [[cadmium selenide]] [[quantum dots]] in a porous 3-D network have been developed for use in the semiconductor industry.<ref>{{cite journal|date=2008|title=Engineering Strength, Porosity, and Emission Intensity of Nanostructured CdSe Networks By Altering The Building Block Shape|journal=[[Journal of the American Chemical Society]]|volume=130|issue=15|pages=5054–5055|doi=10.1021/ja801212e|pmid=18335987|last1=Yu|first1=H|last2=Bellair|first2=R|last3=Kannan|first3=R. M.|last4=Brock|first4=S. L.}}</ref>', 99 => '', 100 => 'Aerogel performance may be augmented for a specific application by the addition of [[dopants]], reinforcing structures and hybridizing compounds. Aspen Aerogels makes products such as Spaceloft<ref>{{cite web|url=http://www.aerogel.com/products/pdf/Spaceloft_6250_DS.pdf|title=Spaceloft 6250|publisher=Aspen Aerogels|accessdate=25 April 2014|url-status=dead|archiveurl=https://web.archive.org/web/20140427010028/http://www.aerogel.com/products/pdf/Spaceloft_6250_DS.pdf|archivedate=27 April 2014|df=dmy-all}}</ref> which are composites of aerogel with some kind of fibrous batting.<ref>{{cite web|url=http://www.aerogel.org/?p=1058|title=Strong and Flexible Aerogels|website=Aerogel.org|accessdate=17 July 2014|url-status=live|archiveurl=https://web.archive.org/web/20141011004216/http://www.aerogel.org/?p=1058|archivedate=11 October 2014|df=dmy-all}}</ref>', 101 => '', 102 => '== Applications ==', 103 => '[[File:Stardust_Dust_Collector_with_aerogel.jpg|right|thumb|The [[Stardust (spacecraft)|Stardust]] dust collector with aerogel blocks. (NASA)]]', 104 => '{{more citations needed section|date=May 2013}}Aerogels are used for a variety of applications:', 105 => '* In 2004 about US$25 million of aerogel insulation product were sold, which had risen to about US$500 million by 2013. This represents the most substantial economic impact of these materials today. The potential to replace conventional insulation with aerogel solutions in the building and construction sector as well as in industrial insulation is quite significant.<ref>{{cite journal|date=2012|title=Aerogel-based thermal superinsulation: an overview|journal=[[Journal of Sol-Gel Science and Technology]]|volume=63|issue=3|pages=315–339|doi=10.1007/s10971-012-2792-9|last1=Koebel|first1=Matthias|last2=Rigacci|first2=Arnaud|last3=Achard|first3=Patrick|url=http://doc.rero.ch/record/318248/files/10971_2012_Article_2792.pdf}}</ref>', 106 => '* In granular form to add [[Thermal insulation|insulation]] to [[Window#Skylight|skylights]]. [[Georgia Institute of Technology]]'s 2007 [[Solar Decathlon]] House project used an aerogel as an insulator in the semi-transparent roof.<ref>[https://web.archive.org/web/20080216122656/http://solar.gatech.edu/light_roof.php Solar Decathon 2007]. GATech.edu</ref>', 107 => '* A chemical [[Adsorption|adsorber]] for cleaning up spills.<ref>{{cite web|url=http://www.news.wisc.edu/22566|title='Greener' aerogel technology holds potential for oil and chemical clean-up|last=Spoon|first=Marianne English|date=25 February 2014|website=University of Wisconsin Madison News|accessdate=29 April 2015|url-status=live|archiveurl=https://web.archive.org/web/20150428193731/http://www.news.wisc.edu/22566|archivedate=28 April 2015|df=dmy-all}}</ref>', 108 => '* A [[catalyst]] or a catalyst carrier.', 109 => '* Silica aerogels can be used in imaging devices, optics, and light guides.<ref>{{Cite journal|last=Gurav|first=Jyoti|last2=Jung|first2=In-Keun|date=30 June 2010|title=Silica Aerogel: Synthesis and Applications|url=|journal=Journal of Nanomaterials|volume=2010|pages=1–11|doi=10.1155/2010/409310|pmid=|access-date=|doi-access=free}}</ref>', 110 => '* A material for filtration due to its high surface area and porosity, to be used for the removal of heavy metals.', 111 => '* [[Thickening agent]]s in some [[paint]]s and [[cosmetics]].', 112 => '* As components in energy absorbers.', 113 => '* Laser targets for the United States [[National Ignition Facility]].', 114 => '* A material used in impedance matchers for transducers, speakers and range finders.<ref>{{Cite journal|last=Hrubesh|first=Lawrence W.|date=1 April 1998|title=Aerogel applications|url=https://zenodo.org/record/1259629|journal=Journal of Non-Crystalline Solids|volume=225|issue=1|pages=335–342|doi=10.1016/S0022-3093(98)00135-5|bibcode=1998JNCS..225..335H}}</ref>', 115 => '* Commercial manufacture of aerogel 'blankets' began around the year 2000, combining silica aerogel and fibrous reinforcement that turns the brittle aerogel into a durable, flexible material. The mechanical and thermal properties of the product may be varied based upon the choice of reinforcing fibers, the aerogel matrix and [[Opacifier|opacification additives]] included in the composite.', 116 => '* [[NASA]] used an aerogel to trap [[space dust]] particles aboard the [[Stardust (spacecraft)|Stardust]] spacecraft. The particles vaporize on impact with solids and pass through gases, but can be trapped in aerogels. NASA also used aerogel for thermal insulation of the [[Mars Rover]].<ref>[http://marsrovers.jpl.nasa.gov/mission/sc_rover_temp_aerogel.html Preventing heat escape through insulation called "aerogel"] {{webarchive|url=https://web.archive.org/web/20071013103911/http://marsrovers.jpl.nasa.gov/mission/sc_rover_temp_aerogel.html |date=13 October 2007 }}, ''NASA CPL''</ref><ref>[http://www.aero.org/publications/crosslink/fall2006/backpage.html Down-to-Earth Uses for Space Materials] {{webarchive|url=https://web.archive.org/web/20070930011123/http://www.aero.org/publications/crosslink/fall2006/backpage.html |date=30 September 2007 }}, ''The Aerospace Corporation''</ref>', 117 => '* The [[US Navy]] is evaluating aerogel undergarments as passive thermal protection for divers.<ref>{{cite journal|last=Nuckols|first=M. L.|date=2005|title=Manned Evaluation of a Prototype Composite Cold Water Diving Garment Using Liquids and Superinsulation Aerogel Materials|url=http://archive.rubicon-foundation.org/3487|journal=United States Navy Experimental Diving Unit Technical Report|volume=NEDU-05-02|author2=Chao J. C.|author3=Swiergosz M. J.|accessdate=21 April 2008|url-status=dead|archiveurl=https://web.archive.org/web/20080820004306/http://archive.rubicon-foundation.org/3487|archivedate=20 August 2008|df=dmy-all}}</ref>', 118 => '* In [[particle physics]] as radiators in [[Cherenkov effect]] detectors, such as the ACC system of the Belle detector, used in the [[Belle Experiment]] at [[KEKB (accelerator)|KEKB]]. The suitability of aerogels is determined by their low [[index of refraction]], filling the gap between gases and liquids, and their transparency and solid state, making them easier to use than [[cryogenic]] liquids or compressed gases. Their low mass is also advantageous for space missions.', 119 => '* [[Resorcinol]]–[[formaldehyde]] aerogels (polymers chemically similar to [[phenol formaldehyde resin]]s) are used as precursors for manufacture of carbon aerogels, or when an organic insulator with large surface is desired. They come as high-density material, with surface area about 600&nbsp;m²/g.', 120 => '* Metal–aerogel [[nanocomposite]]s prepared by impregnating the hydrogel with solution containing ions of a [[transition metal]] and irradiating the result with [[gamma ray]]s, precipitates nanoparticles of the metal. Such composites can be used as [[catalyst]]s, sensors, [[electromagnetic shielding]], and in waste disposal. A prospective use of platinum-on-carbon catalysts is in [[fuel cell]]s.', 121 => '* As a drug delivery system owing to its [[biocompatibility]]. Due to its high surface area and porous structure, drugs can be adsorbed from supercritical {{chem|CO|2}}. The release rate of the drugs can be tailored by varying the properties of the aerogel.<ref>{{cite journal|date=2004|title=Feasibility study of hydrophilic and hydrophobic silica aerogels as drug delivery systems|journal=Journal of Non-Crystalline Solids|volume=350|pages=54–60|bibcode=2004JNCS..350...54S|doi=10.1016/j.jnoncrysol.2004.06.031|author=Smirnova I.|author2=Suttiruengwong S.|author3=Arlt W.}}</ref>', 122 => '* Carbon aerogels are used in the construction of small electrochemical double layer [[supercapacitor]]s. Due to the high surface area of the aerogel, these capacitors can be 1/2000th to 1/5000th the size of similarly rated electrolytic capacitors.<ref>{{cite web|url=http://powerelectronics.com/portable_power_management/batteries/power_aerogel_capacitors_support/|title=Aerogel Capacitors Support Pulse, Hold-Up, and Main Power Applications|date=1 February 2002|author=Juzkow, Marc|work=Power Electronic Technology|url-status=live|archiveurl=https://web.archive.org/web/20070515141549/http://powerelectronics.com/portable_power_management/batteries/power_aerogel_capacitors_support/|archivedate=15 May 2007|df=dmy-all}}</ref> Aerogel supercapacitors can have a very low [[Electrical impedance|impedance]] compared to normal supercapacitors and can absorb or produce very high peak currents. At present, such capacitors are [[Electrical polarity|polarity-sensitive]] and need to be wired in series to achieve a working voltage of greater than about 2.75&nbsp;[[Volt|V]].', 123 => '* [[Dunlop Sport]] uses aerogel in some of its racquets for tennis, squash and badminton.', 124 => '* In water purification, [[chalcogel]]s have shown promise in absorbing the heavy metal pollutants mercury, lead, and cadmium from water.<ref>Carmichael, Mary. [http://www.msnbc.msn.com/id/20123389/site/newsweek/ First Prize for Weird: A bizarre substance, like 'frozen smoke,' may clean up rivers, run cell phones and power spaceships.] {{webarchive |url=https://web.archive.org/web/20070817195536/http://www.msnbc.msn.com/id/20123389/site/newsweek/ |date=17 August 2007 }} Newsweek International, 13 August 2007. Retrieved on 2007-08-05.</ref>', 125 => '* Aerogel can introduce disorder into [[superfluid]] [[helium-3]].<ref>Halperin, W. P. and Sauls, J. A. [[arxiv:cond-mat/0408593v1|Helium-Three in Aerogel]]. Arxiv.org (26 August 2004). Retrieved on 7 November 2011.</ref>', 126 => '* In aircraft de-icing, a new proposal uses a [[carbon nanotube]] aerogel. A thin filament is spun on a winder to create a 10&nbsp;micron-thick film. The amount of material needed to cover the wings of a jumbo jet weighs {{convert|80|g}}. Aerogel heaters could be left on continuously at low power, to prevent ice from forming.<ref>{{cite news|url=https://www.economist.com/blogs/babbage/2013/07/de-icing-aeroplanes|title=De-icing aeroplanes: Sooty skies|date=26 July 2013|publisher=The Economist|accessdate=11 December 2013|url-status=live|archiveurl=https://web.archive.org/web/20131230212607/http://www.economist.com/blogs/babbage/2013/07/de-icing-aeroplanes|archivedate=30 December 2013|df=dmy-all}}</ref>', 127 => '* Thermal insulation transmission tunnel of the [[Chevrolet Corvette (C7)]].<ref>Katakis, Manoli. (11 July 2013) [http://gmauthority.com/blog/2013/07/what-does-nasa-have-to-do-with-the-2014-corvette-stingray/ NASA Aerogel Material Present In 2014 Corvette Stingray] {{webarchive|url=https://web.archive.org/web/20140222024500/http://gmauthority.com/blog/2013/07/what-does-nasa-have-to-do-with-the-2014-corvette-stingray/ |date=22 February 2014 }}. GM Authority. Retrieved on 2016-07-31.</ref>', 128 => '* [[CamelBak]] uses aerogel as insulation in a thermal sport bottle.<ref>[http://www.pinkbike.com/news/camelbak-podium-ice-insulated-bottle-review-2014.html Camelbak Podium Ice Insulated Bottle – Review] {{webarchive|url=https://web.archive.org/web/20141003153250/http://www.pinkbike.com/news/camelbak-podium-ice-insulated-bottle-review-2014.html |date=3 October 2014 }}. Pinkbike. Retrieved on 31 July 2016.</ref>', 129 => '* 45 North uses aerogel as palm insulation in its Sturmfist 5 cycling gloves.<ref>[http://45nrth.com/products/gloves/sturmfist-5 Unparalleled Cold Weather Performance] {{webarchive|url=https://web.archive.org/web/20160110032732/http://45nrth.com/products/gloves/sturmfist-5 |date=10 January 2016 }}. 45NRTH. Retrieved on 31 July 2016.</ref>', 130 => '', 131 => '== Production ==', 132 => '[[File:Aerogel_nasa.jpg|thumb|[[Peter Tsou]] with a sample of aerogel at [[Jet Propulsion Laboratory]], [[California Institute of Technology]].]]', 133 => 'Silica aerogels are typically synthesized by using a sol-gel process. The first step is the creation of a [[colloidal]] [[Suspension (chemistry)|suspension]] of solid particles known as a "sol". The precursors are a liquid [[alcohol]] such as ethanol which is mixed with a [[silicon alkoxide]], such as [[tetramethoxysilane]] (TMOS), [[tetraethoxysilane]] (TEOS), and polyethoxydisiloxane (PEDS) (earlier work used sodium silicates).<ref>{{Cite journal|last=Dorcheh|first=Soleimani|last2=Abbasi|first2=M.|date=2008|title=Silica Aerogel; Synthesis, Properties, and Characterization|url=|journal=Journal of Materials Processing Technology|volume=199|issue=1–3|pages=10–26|doi=10.1016/j.jmatprotec.2007.10.060|pmid=|access-date=}}</ref> The solution of silica is mixed with a catalyst and allowed to gel during a [[hydrolysis]] reaction which forms particles of silicon dioxide.<ref name="Making silica aerogels">{{cite web|url=http://eetd.lbl.gov/ECS/Aerogels/sa-making.html|title=Making silica aerogels|publisher=Lawrence Berkeley National Laboratory|url-status=dead|archiveurl=https://web.archive.org/web/20090514144121/http://eetd.lbl.gov/ecs/aerogels/sa-making.html|archivedate=14 May 2009|df=dmy-all|access-date=28 May 2009}}</ref> The oxide suspension begins to undergo [[condensation reaction]]s which result in the creation of metal oxide bridges (either [[Oxo ligand|M–O–M, "oxo" bridges]], or M–OH–M, "[[-ol|ol]]" bridges) linking the dispersed colloidal particles.<ref>{{cite journal|date=2002|title=Chemistry of Aerogels and their Applications|journal=[[Chemical Reviews]]|volume=102|issue=11|pages=4243–4265|doi=10.1021/cr0101306|pmid=12428989|last1=Pierre|first1=A. C.|last2=Pajonk|first2=G. M.}}</ref> These reactions generally have moderately slow reaction rates, and as a result either acidic or basic [[catalyst]]s are used to improve the processing speed. Basic catalysts tend to produce more transparent aerogels and minimize the shrinkage during the drying process and also strengthen it to prevent pore collapse during drying.<ref name="Making silica aerogels" />', 134 => '', 135 => 'Finally, during the drying process of the aerogel, the liquid surrounding the silica network is carefully removed and replaced with air, while keeping the aerogel intact. Gels where the liquid is allowed to evaporate at a natural rate are known as [[xerogel]]s. As the liquid evaporates, forces caused by [[surface tension]]s of the liquid-solid [[Interface (chemistry)|interfaces]] are enough to destroy the fragile gel network. As a result, xerogels cannot achieve the high porosities and instead peak at lower porosities and exhibit large amounts of shrinkage after drying.<ref>{{cite journal|date=1992|title=Aerogels|journal=[[Journal of the American Ceramic Society]]|volume=75|issue=8|pages=2027–2036|doi=10.1111/j.1151-2916.1992.tb04461.x|last1=Fricke|first1=Jochen|last2=Emmerling|first2=Andreas}}</ref> To avoid the collapse of fibers during slow solvent evaporation and reduce surface tensions of the liquid-solid interfaces, aerogels can be formed by [[Freeze-drying|lyophilization]] (freeze-drying). Depending on the concentration of the fibers and the temperature to freeze the material, the properties such as porosity of the final aerogel will be affected.<ref>{{Cite journal|last=Zhang|first=Xuexia|last2=Yu|first2=Yan|last3=Jiang|first3=Zehui|last4=Wang|first4=Hankun|date=2015-12-01|title=The effect of freezing speed and hydrogel concentration on the microstructure and compressive performance of bamboo-based cellulose aerogel|journal=Journal of Wood Science|language=en|volume=61|issue=6|pages=595–601|doi=10.1007/s10086-015-1514-7|issn=1611-4663}}</ref>', 136 => '', 137 => 'In 1931, to develop the first aerogels, Kistler used a process known as [[supercritical drying]] which avoids a direct phase change. By increasing the temperature and pressure he forced the liquid into a [[supercritical fluid]] state where by dropping the pressure he could instantly gasify and remove the liquid inside the aerogel, avoiding damage to the delicate three-dimensional network. While this can be done with [[ethanol]], the high temperatures and pressures lead to dangerous processing conditions. A safer, lower temperature and pressure method involves a solvent exchange. This is typically done by exchanging the initial aqueous pore liquid for a [[carbon dioxide|CO₂]]-miscible liquid such as ethanol or [[acetone]], then onto liquid carbon dioxide and then bringing the carbon dioxide above its [[Critical point (thermodynamics)|critical point]]. A variant on this process involves the direct injection of supercritical carbon dioxide into the pressure vessel containing the aerogel. The end result of either process exchanges the initial liquid from the gel with carbon dioxide, without allowing the gel structure to collapse or lose volume.<ref name="Making silica aerogels" />', 138 => '', 139 => '[[Resorcinol]]–[[formaldehyde]] aerogel (RF aerogel) is made in a way similar to production of silica aerogel. A carbon aerogel can then be made from this resorcinol–formaldehyde aerogel by [[pyrolysis]] in an [[inert gas]] atmosphere, leaving a matrix of [[carbon]]. It is commercially available as solid shapes, powders, or composite paper. Additives have been successful in enhancing certain properties of the aerogel for the use of specific applications. Aerogel [[Composite material|composites]] have been made using a variety of continuous and discontinuous [[reinforcement]]s. The high aspect ratio of fibers such as [[fiberglass]] have been used to reinforce aerogel composites with significantly improved mechanical properties.', 140 => '', 141 => '== Safety ==', 142 => 'Silica-based aerogels are not known to be [[carcinogenic]] or toxic. However, they are a mechanical [[Irritation|irritant]] to the eyes, skin, respiratory tract, and digestive system. They can also induce dryness of the skin, eyes, and mucous membranes. Therefore, it is recommended that protective gear including respiratory protection, gloves and eye goggles be worn whenever handling or processing bare aerogels, particularly when a dust or fine fragments may occur.<ref>[http://aerogel.com/products/pdf/Cryogel_5201_10201_MSDS.pdf Cryogel® 5201, 10201 Safety Data Sheet] {{webarchive|url=https://web.archive.org/web/20101223111216/http://www.aerogel.com/products/pdf/Cryogel_5201_10201_MSDS.pdf |date=23 December 2010 }}. Aspen Aerogels. 13 November 2007</ref>', 143 => '', 144 => '== See also ==', 145 => '* [[Carbon nanofoam]]', 146 => '* [[Nanogel]]', 147 => '* [[FOGBANK]]', 148 => '', 149 => '== References ==', 150 => '{{reflist}}', 151 => '; Further reading{{Refbegin}}', 152 => '* NASA's Stardust comet return mission on [http://stardust.jpl.nasa.gov/tech/aerogel.html AEROGEL.]', 153 => '* {{cite journal|date=1998|title=Aerogels – Airy Materials: Chemistry, Structure, and Properties|journal=[[Angewandte Chemie International Edition]]|volume=37|issue=1/2|pages=22–45|doi=10.1002/(SICI)1521-3773(19980202)37:1/2<22::AID-ANIE22>3.0.CO;2-I|author=N. Hüsing|author2=U. Schubert}}', 154 => '* {{cite journal|date=2002|title=Chemistry of aerogels and their applications|journal=[[Chemical Reviews]]|volume=102|issue=11|pages=4243–4266|doi=10.1021/cr0101306|pmid=12428989|author=Pierre A. C.|author2=Pajonk G. M.}}', 155 => '{{Refend}}', 156 => '', 157 => '== External links ==', 158 => '{{Commons category|Aerogel}}', 159 => '* [http://www.aerogel.org Open source aerogel]', 160 => '* [http://stardust.jpl.nasa.gov/photo/aerogel.html NASA photos of aerogel]', 161 => '* [http://lbl.gov/Science-Articles/Archive/aerogel-insulation.html LBL article covering the development of aerogels]', 162 => '', 163 => '{{emerging technologies|topics=yes|robotics=yes|manufacture=yes|materials=yes}}', 164 => '', 165 => '[[Category:Emerging technologies]]', 166 => '[[Category:Aerogels]]' ]