Composites Design and Manufacture (Plymouth University teaching support materials) Nanotechnology.

Lecture PowerPoint

Review papers

Subject Index

Nanotechnology is an enormous subject.  For a comprehensive introduction see, for example, [1-3].  This page specifically addresses nanoscale composite materials and related structures.  Al-Quraishi et al [4] have reviewed the experimental techniques developed for the mechanical testing of two-dimensional materials.

• Carbon allotropes and nanotubes
• Two-dimensional monolayers
• Vegetable fibres
• Bacterial cellulose
• Exfoliated clays
• Fluid bicontinuous gels
• Porous liquids
• Nanocemology
• Micro Electro Mechanical Systems
• Nanotechnology probes

References

1. GA Ozin and A Arsenault, Nanochemistry, A Chemical Approach to Nanomaterials, Royal Society of Chemistry, Cambridge, 2005. ISBN 0-85404-664-x.  PU CSH Library.
2. SC Tjong, Nanocrystalline Materials, Their Synthesis-Structure-Property Relationships and Applications, Elsevier, 2006. ISBN 0-08-044697-3.
3. WK Liu, EG Karpov and HS Park, Nano Mechanics and Materials, Wiley, 2006. ISBN-13: 978-0-470-01851-4.
4. KK Al-Quraishi, Q He, W Kauppila, Min Wang and Y Yang, Mechanical testing of two-dimensional materials: a brief review, International Journal of Smart and Nano Materials, 2020, 11(3), 207-246.

Carbon allotropes and nanotubes

Elemental carbon can occur in an amorphous form or as either of two crystalline forms:

• diamond (cubic crystal structure with the neighbours of each atom symmetrically arranged at the corners of regular tetrahedron with a C-C bond length of 1.54Å), or
• graphite (parallel sheets of carbon atoms at the corners of contiguous regular hexagons with C-C bond length of 1.42Å within the sheet and 3.35Å between layers).

The carbon atom can also combine to form spheres and/or tubes at the nanoscale.  These structures include the Carbon 60 form known as buckminsterfullerene (named after the geodesic structures of Buckminster Fuller) discovered by Harry Kroto, Bob Curl and Rick Smalley in 1985 [1-3] which won them the Nobel Prize in Chemistry for 1996 [4].  James P Birk has presented a stereoscopic image of the C60 "bucky ball", while Jianyu Huang at Sandia National laboratories and Boris Yakobson at Rice University have used electron microscope video and computer simulations (YouTube Shrink Wrap buckyball video) show that buckyballs start life as distorted, unstable sheets of graphite which shed loosely connected threads and chains until all that remains is the perfectly spherical buckyball.

Iijima [5] discovered long, thin carbon nanotubes in 1991.  The topic was recently reviewed by Terrones [6].  The Iijima nanotubes were considered to be elongated fullerenes consisting of concentric graphene cylinders (multi-walled carbon nanotubes (MWNTs) with interlayer spacings slightly greater than that of graphite at 3.4Å.  Single-walled carbon nanotubes (SWNTs) have also been isolated.  The molecular configurations of SWNTs include "zigzag" (edges of the benzene rings running parallel to the tube axis), "armchair" (edges of the benzene rings running perpendicular to the tube axis) and "chiral" where the edges of the benzene ring follow a spiral path along the tube.

Terrones [6] suggests that optimal conditions for the arc discharge production of nanotubes involve passing a 80-100 amp DC current through high purity graphite electrodes (6-10 mm outer diameter at ~1-2 mm apart in a low pressure (500 torr) helium atmosphere.  A combination of carbon MWNTs and nested polyhedral graphite is deposited on the cathode at 1 mm/min while the anode is consumed.  Alternative production techniques [6] include:

• laser vapourisation of a graphite target sealed in an argon atmosphere inside a furnace at 1200°C.
• electrolysis of graphite electrodes immersed in molten lithium chloride under an argon atmosphere.
• chemical vapour deposition of hydrocarbons in the presence of metal catalysts.
• concentrating solar energy (flux equivalent to ~ 5 MW/m² producing a temperature of 2800K) onto a carbon-metal target in an inert atmosphere.

These production methods produce MWNTs and polyhedral particles from which they must be separated.  This might be achieved by oxidation at 700°C (<5% yield), filtering colloidal suspensions, ultrasonically assisted microfiltration or microwave heating together with acid treatments to remove residual metals.

Researchers at Cambridge University have produced live videos showing the nucleation and growth by chemical vapour deposition (CVD) of carbon nanofibres and nanotubes at minute particles of nickel catalyst.  The movies offer greater insight into the self-assembly of the microscopic structures.  The CVD process uses acetylene gas to deposit minute crystalline droplets referred to as "catalyst islands" (the nickel).  In nanofibre production, the catalyst was gradually squeezed upwards as carbon formed around it.  In single-walled nanotube production, the application of gas was reduced so that the carbon lifted off the catalyst to form a tubular structure.

Fan et al [12] have produced a new atomically thin material, biphenylene networks, by assembling carbon-containing molecules on an extremely smooth gold surface. The molecules first form chains of linked hexagons, then a further reaction connects the chains together to form a regular array of squares and octagons.  the biphenylene network exists in two chiral (mirror) forms.

Tibbets et al [13] have reviewed the fabrication and properties of vapour-grown carbon nanofiber/polymer composites.  Gibson et al [14] have reviewed the vibration of carbon nanotubes and their composites.  The paper considers modelling and simulation of vibrating nanotubes, studies of nanomechanical resonators and oscillators, characterisation of nanotube mechanical properties, augmentation of the dynamic structural properties of composites, nanotube-based sensors and actuators, use of ultrasound to disperse the tubes in liquids (sonication), Raman scattering and interactions with high frequencies.

An important consideration in generating high-quality nano-particle reinforced composites is obtaining a uniform distribution of reinforcement rather than agglomerated (clumped) particles. Dassios et al [15] have sought to achieve this by sonication.

Poland et al [16] considered the similarities between the needle-like shape of carbon nanotubes and asbestos. They exposed the mesothelial lining of the body cavity of mice, as a surrogate for the mesothelial lining of the chest cavity, to long multiwalled carbon nanotubes. Asbestos-like, length-dependent, pathogenic behaviour included inflammation and the formation of lesions known as granulomas. On the basis of their results, they suggest there is a "need for further research and great caution before introducing such products into the market if long-term harm is to be avoided".

References for carbon allotropes and nanotubes

1. HW Kroto, JR Heath, SC O'Brien, RF Curl and RE Smalley, C60: Buckminsterfullerene, Nature, 1985, 318(6042), 162-163.
2. HW Kroto, Space, Stars, C60 and Soot, Science, 1988, 242(4882), 1139-1145.
3. HW Kroto, C60: Buckminsterfullerene, the Celestial Sphere that Fell to Earth, Angewandte Chemie, 1992, 31(2), 111-129.
4. The Nobel Prize in Chemistry 1996, 9 October 1996
5. S Iijima, Helical microtubules of graphitic carbon, Nature, 7 November 1991, 354(6348), 56-58.
6. M. Terrones, Carbon nanotubes: synthesis and properties, electronic devices and other emerging applications, International Materials Reviews, 2004, 49(6), 325-377.
7. MF Yu, BS Files, S Arepalli and RS Ruoff, Tensile loading of ropes of single wall carbon nanotubes and their mechanical properties, Physics Review Letters, 12 June 2000, 84(24), 5552-5555.
8. JP Lu, Elastic properties of carbon nanotubes and nanoropes, Physical Review Letters, 1997, 79(7), 1297-1300.
9. MMJ Treacy, TW Ebbesen and JM Gibson, Exceptionally high Young's modulus observed for individual carbon nanotubes, Nature, 20 June 1996, 381(6584), 678-680.
10. EW Wong, PE Sheehan and CM Lieber, Nanobeam mechanics: elasticity, strength, and toughness of nanorods and nanotubes, Science, 26 September 1997,  277(5334), 1971-1975.
11. BG Demczyk, YM Wang, J Cumings, M Hetman, W Han, A Zettl and RO Ritchie, Direct mechanical measurement of the tensile strength and elastic modulus of multiwalled carbon nanotubes, Materials Science and Engineering: A, 1 September 2002, 334(1–2), 173–178.
12. QT Fan, LH Yan, MW Tripp, O Krejči, S Dimosthenous, SR Kachel, MY Chen, AS Foster, U Koert, P Liljeroth and JM Gottfried, Biphenylene network: a nonbenzenoid carbon allotrope, Science, 2021, 372(6544), 852-856.
13. GG Tibbetts, ML Lake, KL Strong and BP Rice, A review of the fabrication and properties of vapor-grown carbon nanofiber/polymer composites, Composites Science and Technology, June 2007, 67(7-8), 1709-1718.
14. RF Gibson, EO Ayorinde and Y-F Wen, Vibrations of carbon nanotubes and their composites: a review, Composites Science and Technology, 2007, 67(1), 1-28.
15. KG Dassios, P Alafogianni, SK Antiohos, C Leptokaridis, N-M Barkoula and TE Matikas, Optimization of sonication parameters for homogeneous surfactant-assisted dispersion of multiwalled carbon nanotubes in aqueous solutions, The Journal of Physical Chemistry C, 2015, 119(13), 7506-7516.
16. CA Poland, R Duffin, I Kinloch, A Maynard, WAH Wallace, A Seaton, V Stone, S Brown, W MacNee and K Donaldson, Carbon nanotubes introduced into the abdominal cavity of mice show asbestos-like pathogenicity in a pilot study, Nature Nanotechnology, July 2008, 3(7), 423-428.

Other resources for carbon allotropes and nanotubes

• ISO/TS 80004-13:2017 on Vocabulary-Graphene and related two-dimensional (2D) materials
• NPL good practice guide (GPG) 145: Characterisation of the structure of graphene.
• P Brown and K Stevens, Nanofibres and nanotechnology in textiles, Woodhead Publishing/CRC Press, Cambridge/Boca Raton, 2007.  ISBN: 1-84569-105-9.
• PJF Harris, Carbon Nanotubes and Related Structures: New Materials for the Twenty-First Century, Cambridge University Press, 1999. ISBN 0-521-55446-2 (hb) or ISBN 0-521-00533-7 (paper).  Contents pages and Chapter 1.  PU CSH Library
• Ado Jorio, Gene Dresselhaus and Mildred S Dresselhaus (editors), Carbon Nanotubes - Advanced Topics in the Synthesis, Structure, Properties and Applications Series: Topics in Applied Physics , Vol. 111 , 2008. ISBN-13: 978-3-540-72864-1.
• AJ Pollard and CA Clifford, Characterising graphene for the real world, Materials World, January 2019, 27(1), 34-37 (URL needs member login!).
• animated images from Shigeo Maruyama
• Thomas A Adams II, Physical properties of carbon nanotubes , 26 April 2000.
• Peter Harris, A carbon nanotube page, http://www.personal.rdg.ac.uk/~scsharip/tubes.htm
• David Tomanek, The Nanotube Site, 14 August 2006.
• Carbon nanotubes (Wikipedia).
• The nanotechnology era is here. The possibilities are endless. Ahwahnee Inc, 2003-2006.
• Nanotube Modeler: generation of nano-geometries (JCrystalSoft), 2005-2006.
    NanotubeModeler software download (4.2 MB, Version 1.3.3, 07/17/2006)

Two-dimensional monolayers

• GROUP IV elements
• Graphene (2D carbon)  [1 and review papers]  Graphene-FlagShip video.
  Graphene is a two dimensional single layer of carbon atoms with sp² molecular orbitals (essentially a plane of contiguous benzene rings).  It is the thinnest known material and has high strength, the highest known thermal conductivity (~5 kW/m.K) of any material and electrical conductivity similar to copper with a carrier mobility of 10⁶ cm²/Vs.  The absence of crystalline defects means that graphene is almost completely transparent, yet a single layer absorbs 2.4% of visible light. The molecular structure is so dense that the helium atom cannot pass through it.  the relative quality and cost of graphene from different sources are given in Table 3.  Kemp [2] has presented a brief summary of the issues surrounding graphene.
Table 3:  Relative quality and costs of graphene from different production techniques

Process	Quality	Cost
Mechanical exfoliation	high	high
Chemical Vapour Deposition (CVD)	high	low
Molecular assembly for nanoelectronics	low	high
Liquid phase exfoliation	low	low
Epitaxial growth on silicon carbide (SiC)	medium	medium

The modulus and strength are often quoted with high values, but will of course be dependent on the thickness of the monolayer used in the calculation.  Given the statistical nature of electron orbitals, the monolayer thickness is a difficult concept!  The University of Manchester "tend to use the 3.14Å thickness for most calculations, which is the per-layer thickness extracted from graphite" [3]. Shi et al [4] predicted the equivalent Young's modulus and the thickness of graphene sheets (GS) using an analytical method linked with an atomic interaction based continuum model and a continuum elastic model in the cases of both stretching and bending.  The equivalent Young's modulus and the thickness of the GS used in continuum mechanical models were calculated and proposed to be 2.81 TPa and 1.27 Å respectively.

Penta-graphene has been proposed as a new allotrope of carbon by researchers in the USA, China and Japan [5].  theoretical calculations have suggested that the material is stable to 1000K (727°C), is a semiconductor and is auxetic (negative Poisson's ratio).  Koratkar [6] has discussed how different forms of graphene can be synthesized and then added to polymer composites as the main or hybrid nanofiller to influence the electrical and mechanical properties.

In addition to graphene, there are a number of other possible allotropes [7]:

• diamene: a single layer of diamond produced by pressing a (more stable) bilayer graphene film [8, 9].
• graphane: two-dimensional hydrogenated graphene with formula (CH)_n and sp³ bond configuration.
• graphone: a semihydrogenated derivative of graphene.
• graphyne: "long-hypothesised" atomic planar monolayers of carbon atoms with three forms:
  α (Fig 1B), β (Fig 1C) and γ (Fig 1D) combining sp (-C≡C-) linkages and sp² bond configurations.
  The γ-form is now claimed to have been created at University of Colorado Boulder [10].
• graphidyne: a variant of graphyne with two acetylenic linkages in each unit cell rather the single linkages in graphyne.
• novamene: combining hexagonal sp³ diamond insulator and ring sp² graphene conductor chemical structures [11].
  

  
  Figure 1: A: graphene, B: α-graphyne, C: β-graphyne, and D: γ-graphyne
  (Image loaded from https://www.dovepress.com/cr_data/article_fulltext/s40000/40324/img/fig2.jpg)

• Silicene (2D silicon)  [12-14]
  Indications are that conversion to the 3-D crystal is energetically preferred.  Akinwande at the University of Texas at Austin announced the creation of transistors from silicene in February 2015.
• Germanene (2D germanium)  [15]
• Stanene (2D tin)  [16]
  Theoretical physicists at the US Department of Energy and Stanford University have predicted that a single layer of tin atoms could conduct electricity with 100 percent efficiency at computer chip operating temperatures.
• Plumbene (2D lead)
  Guo et al [17] fabricated ultrathin lead films on silicon substrates with atomic-scale control of the thickness over a macroscopic area, albeit that films thinner than 12 atomic monolayers (AML) were rough and below 22AML only odd-layered films were stable.  Zhao et al [18] have predicted a novel class of 2D Quantum Spin Hall (QSH) insulators from X-decorated plumbene monolayers (PbX where X = H, F, Cl, Br or I) with extraordinarily giant bulk gaps from 1.03 eV to a potential record value of 1.34 eV.

• OTHER ELEMENTS and MOLECULES
• Borophene (2D boron) [19, 20]
  Mannix et al [18] heated boron using an electron beam evaporator to grow single-atom thick 2D boron sheets (borophene) on silver, obtaining the best results with the substrate at 550°C.  Theory predicts that electrically-conductive borophene (bulk boron is a semiconductor) could out-perform graphene in electronic applications.  However, the starting material is a neurotoxic gas, diborane, and the sheets are unstable when exposed to air.
• Boron nitride (BN) [21]
  Boron nitride is the combination of the Group II atom boron (B) and the Group V atom nitrogen (N), which sit either side of carbon in the Periodic Table.  The 2D material adopts a (graphene-like) hexagonal sheet structure with alternate boron and nitrogen atoms (hexagonal boron nitride: hBN).  Mechanochemical exfoliation to produce nanosheets can be achieved using a standard mill and urea (H₂N-C(O)-NH₂).  BN is a good electrical insulator so could be used as a reinforcing filler for electronics packaging.  It is also fluorescent, so may find applications in laser emitters, optoelectronic devices, drug delivery, bioimaging and non-destructive testing.
• Phosphene (2D phosphorous) [22, 23]
  Phsophorene is stable in deoxygenated (by bubbling inert gas through the liquid) water, so black phosphorous can be dispersed using amphiphilic surfactants and sonication.  Phosphorene is a semiconductor with a tuneable bandgap that also varies with thickness.
• Molybdenum disulphide (MoS₂)
• Rhenium disulphide (ReS₂)

References for two-dimensional monolayers

1. Manchester Graphene, Graphene is going to revolutionize the 21st Century, accessed 11:34 on Saturday 18 January 2014.
2. M Kemp, Graphene - a perspective, Materials World, October 2015, 23(10), 46-47.
3. C Soutis, Graphene webinar Q&A, private communication, 28 September 2020.
4. J-X Shi, T Natsuki, X-W Lei and Q-Q Ni, Equivalent Young's modulus and thickness of graphene sheets for the continuum mechanical models, Applied Physics Letters, 2014, 104(22), 223101.
5. S Zhang, J Zhou, Q Wang, X Chen, Y Kawazoe and P Jena, Penta-graphene: a new carbon allotrope, Proceedings of the National Academy of Sciences of the United States of America (PNAS), direct submission published online 02 February 2015. Supplementary material.
6. N Koratkar, Graphene in Composite Materials: synthesis, characterization and applications, DEStech Publications, Lancaster PA, 2013.  ISBN 978-1-60595-056-3.
7. Qing Peng, AK Dearden, J Crean, L Han, S Liu, X Wen and S De, New materials graphyne, graphdiyne, graphone, and graphane: review of properties, synthesis, and application in nanotechnology, Nanotechnology, Science and Applications, 10 April 2014, 7, 1-29.
8. Y Gao, T Cao, F Cellini, C Berger, WA de Heer, E Tosatti, E Riedo and A Bongiorno, Ultrahard carbon film from epitaxial two-layer graphene, Nature Nanotechnology, 2017.
9. Ellis Davies, Tough as diamond, Materials World, February 2018, 26(2), 18.
10. Y Hu, C Wu, Q Pan, Y Jin, R Lyu, V Martinez, S Huang, J Wu, LJ Wayment, NA Clark, MB Raschke, Y Zhao and W Zhang, Synthesis of γ-graphyne using dynamic covalent chemistry, Nature Synthesis, 2022.
11. LA Burchfield, M Al Fahim, RS Wittman, F Delodovici, N Manini, Novamene: a new class of carbon allotropes, Materials Science ~ Chemistry, 7 Feb 2017, 3(2), e00242.
12. A Acun, B Poelsema, HJW Zandvliet and R van Gastel1, The instability of silicene on Ag(111), Applied Physics Letters, 2013, 103, 263119.
13. Silicene – a one-atom-thick layer of silicon – is tipped to be graphene’s main contender. But recent research has shown that producing it may be far trickier than initially thought, Materials KTN, accessed 10:50 on Saturday 18 January 2014.
14. Wonder material silicene has suicidal tendencies; UT researches demonstrate that graphene 2.0 can barely be made, University of Twente, 08 January 2014, accessed 10:50 on Saturday 18 January 2014.
15. D Johnson, New germanium-based material could replace silicon for electronics, IEEE Spectrum, 11 April 2013.
16. Will 2-D tin be the next super material? Theorists predict new single-layer material could go beyond graphene, conducting electricity with 100% efficiency at room temperature, Stanford SLAC National Accelerator Laboratory, 21 November 2013.
17. Y Guo, Y-F Zhang, X-Y Bao, T-Z Han, Z Tang, L-X Zhang, W-G Zhu, EG Wang, Q Niu, ZQ Qiu, J-F Jia, Z-X Zhao and Q-K Xue, Superconductivity modulated by quantum size effects, Science, 10 December 2004, 306(5703), 1915-1917.
18. H Zhao, C-w Zhang, W-x Ji, R-w Zhang, S-s Li, S-s Yan, B-m Zhang, P Li and P-j Wang, Unexpected giant-gap Quantum Spin Hall insulator in chemically decorated plumbene monolayer, Scientific Reports, 02 February 2016, 6, 20152.
19. K Allen, Borophene's unlocked potential, Materials World, Apriil 2017, 25(4), 3.
20. AJ Mannix, X-F Zhou, B Kiraly, JD Wood, D Alducin, BD Myers, X Liu, BL Fisher, U Santiago, JR Guest, MJ Yacaman, A Ponce, AR Oganov, MC Hersam and NP Guisinger, Synthesis of borophenes: Anisotropic, two-dimensional boron polymorphs," Science, 18 December 2015, 350(6267), 1513-1516.
21. S Frost, Step aside for boron nitride, Materials World, February 2016, 24(2), 12-14.
22. S Frost, Bridging the band gap, Materials World, October 2015, 23(10), 18-19.
23. N Daniels, The tiny promise of phosphorene, Materials World, June 2016, 24(6), 21.

Vegetable fibres

David Hepworth and Eric Whale founded a company, CelluComp (Burntisland, Fife, Scotland), to utilise Curran^® nanofibres extracted from vegetables.  Their initial material choices were carrot and sugarbeet although turnips, swede (rutabagas) and parsnips we also expected to provide raw materials.  The fibres were claimed to have a modulus of 130 GPa, strengths up to 5 GPa and failure strains of over 5%.  The company's first product was the "Just Cast" fly-fishing rod.

Siqueira et al [3] have separated nanofibres from carrot juice and demonstrated their reinforcing efficiency in cellulose acetate butyrate (CAB) to be in the range 79-88%.

References for vegetable fibres

1. Donald Houston, Root of strength and innovation, 09 February 2007.
2. The future is orange for hi-tech material made from carrots, Guardian Unlimited, 09 February 2007.
3. G Siqueira, K Oksman, SK Tadokoro and AP Mathew, Re-dispersible carrot nanofibers with high mechanical properties and reinforcing capacity for use in composite materials, Composites Science and Technology, 8 February 2016, 123, 49-56.

Bacterial cellulose (BC)

• F Esa, SM Tasirin and NA Rahman, Overview of bacterial cellulose production and application, Agriculture and Agricultural Science Procedia, 2014, 2, 113–119.
• SMAS Keshk, Bacterial cellulose production and its industrial applications, Journal of Bioprocessing and Biotechniques, 2014, 4, 150.
• S-P Lin, IL Calvar, JM Catchmark, J-R Liu, A Demirci, K-C Cheng, Biosynthesis, production and applications of bacterial cellulose, Cellulose, October 2013, 20(5), 2191-2219.
• BV Mohite and SV Patil, A novel biomaterial: bacterial cellulose and its new era applications, Biotechnology and Applied Biochemistry, March/April 2014, 61(2), 101–110.
• K Qiu and AN Netravali, A review of fabrication and applications of bacterial cellulose based nanocomposites, Polymer Reviews, 2014, 54(4), 598-626.
• E Rykkelid, Growing bacterial cellulose (video)

Exfoliated clays

Many clays are layered inorganic compounds which can be delaminated (normally referred to as exfoliated in this context). These materials have potential as precursors for the development of various nanostructures.  The most common smectite clays used for nanocomposites are montmorillonite [1], saponite and hectorite.  The montmorillonite nanoclay [2] has a plate structure with a thickness of one nanometre or less (a few atoms) and an aspect ratio of 1000:1 (hence a plate edge of ~ 1 μm) [with potential implications for health and safety].  Relatively low levels of clay loading are claimed to improve modulus, flexural strength, heat distortion temperature, barrier properties etc without compromising impact and clarity [2].

Maniar [2] identifies the first patent in this area as Carter et al (1950) [3] and the second as assigned to Unitka Limited in 1976 [4] with the market debut of a montmorillonite/polyamide-6 nanocomposite in 1989.

References for exfoliated clays

1. JN Hay and SJ Shaw, Clay-Based Nanocomposites (AZoM)
2. KK Maniar, Polymeric nanocomposites: a review, Polymer-Plastics Technology and Engineering, 2004, 43(2), 427-443 [103 references].
3. W Carter Lawrence, G Hendriks John and DS Bolley, Elastomer reinforced with a modified clay, United States Patent 2 531 396, 1950.
4. Unitka, Japanese Patent 109 998 , 1976 (no further detail in [2]).

Fluid bicontinuous gels

Colloidal particles (nanoparticles) can have equal affinity for two fluids and hence adsorb irreversibly to the fluid-fluid interface. Stratford et al have presented computer simulations of a pair of solvents containing such particles where the new interface formed on demixing sequesters the colloidal particles.  Interfacial tension forces the particles into close contact and the interface coarsens then is curtailed.  The jammed colloidal layer appears to enter a glassy state with a multiply connected, solid-like film in three dimensions. The resulting gel contains inter-penetrating domains of each fluid.

References for fluid bicontinuous gels

1. Philippe Poulin, New gels for mixing immiscible liquids, Science, 30 September 2005, 309(5744), 2174 - 2175 (Plymouth shelfmark 500SCI - not available in UoP electronic resources).
2. K Stratford, R Adhikari, I Pagonabarraga, J-C Desplat and ME Cates, Colloidal jamming at interfaces: a route to fluid-bicontinuous gels, Science, 30 September 2005, 309(5744), 2198 - 2201 (Plymouth shelfmark 500SCI - not available in UoP electronic resources) Supporting Online Material  Movie S1  Movie S2  Movie S3.

Porous liquids

Giri et al [1] have reported free-flowing liquids with bulk properties determined by their permanent porosity.  These "porous liquids" have cage molecules that are highly soluble in solvents and have well-defined pore space which the solvent molecules are too large to penetrate.  Zhang et al [2] suggested that the liquid-like polymeric matrices may be used as separation media and the empty cavities as gas transport pathway allowing the porous liquid to function as a promising candidate for gas separation.  Zhang et al [3] have presented a minireview of recent advances in the design of porous ionic liquids, including the synthesis of ordered and disordered porous ionic liquid-based nanoparticles or membranes with or without templates, together with potential for room temperature porous ionic liquids.

References for porous liquids

1. N Giri, MG Del Pópolo, G Melaugh, RL Greenaway, K Rätzke, T Koschine, L Pison, MF Costa Gomes, AI Cooper and SL James, Liquids with permanent porosity, Nature, 12 November 2015, 527, 216–220.
2. J Zhang, S-H Chai, Z-A Qiao, SM Mahurin, J Chen, Y Fang, S Wan, K Nelson, P Zhang and S Dai, Porous Liquids: a promising class of media for gas separation, Angewandte Chemie International Edition, first published 17 November 2014.
3. S Zhang, K Dokkoa and M Watanabe, Porous ionic liquids: synthesis and application, Chemical Science, 2015, 6(7), 3684-3691.

Nanocemology

Nanocemology [1] is the science of ultra-fine, micro- and nano-scale mechanisms occurring in, and affecting the performance of microscopic constituent materials and the pore structure of cement and concrete.  The Nanocem Marie Curie Research Training Network [2] aims to develop ultra-high-strength concrete of low permeability, high tensile strength whose density will be sufficient to secure high abrasion and chemical resistance.

References for nanocemology

1. D Ball, Nanocemology - the key to the future, Concrete, February 2007, 41(1), 29-30.
2. Nanocem Marie Curie Research Training Network

Nanotechnology probes

URLs for Atomic Force Microscope (AFM)

• Atomic force microscopy (Wikipedia)
• Atomic force microscopy: measuring intermolecular interaction forces - general concept and defining characteristics of AFM. from David Baselt, The tip-sample interaction in atomic force microscopy and its implications for biological applications, PhD thesis, California Institute of Technology, 1993.
• Arunan Nadarajah, What is an Atomic Force Microscope?

URLs for Scanning tunnelling microscope (STM)

• Scanning tunneling microscope (Wikipedia)
• The Scanning Tunneling Microscope (NobelPrize.org)

URLs for Superconducting Quantum Interference Devices (SQUID)

• SQUID (Wikipedia)
• Superconducting Quantum Interference Device

URLs for nanotechnology

• AZojono - Journal of Nanotechnology Online
• Institute of Nanotechnology (IoN)
• Institute of Nanotechnology - Books

Further reading (most recent first)

1. Ignac Capek, Nanocomposite structures and dispersions, Elsevier, 2006. ISBN 0-444-52716-8.
2. EPS Tan and CT Lim, Mechanical characterization of nanofibers: a review, Composites Science and Technology, 2006, 66(9), 1102-1108. ISSN 0266-3538.
3. K-t Lau, C Gu and D Hui, A critical review on nanotube and nanotube/nanoclay related polymer composite materials, Composites Part B: Engineering, 2006, 37(6), 425-436.
4. ET Thostenson, C Li and T-W Chou, Nanocomposites in context, Composites Science and Technology, 2005, 65(3-4), 491-516.
5. R Murugan and S Ramakrishna, Development of nanocomposites for bone grafting, Composites Science and Technology, 2005, 65(15-16), 2385-2406.
6. Ludwik Leibler, Nanostructured plastics: Joys of self-assembling, Progress in Polymer Science, 2005, 30(8-9), 898-914.
7. C Wang, Z-X Guo, S Fu, W Wu and D Zhu, Polymers containing fullerene or carbon nanotube structures, Progress in Polymer Science, 2004, 29(11), 1079-1141.
8. Z-M Huang, Y-Z Zhang, M Kotaki and S Ramakrishna, A review on polymer nanofibers by electrospinning and their applications in nanocomposites, Composites Science and Technology, 2003, 63(15), 2223-2253.
9. SS Ray and M Okamoto, Polymer/layered silicate nanocomposites: a review from preparation to processing, Progress in Polymer Science, 2003, 28(11), 1539-1641.
10. T Liu, C Burger and B Chu, Nanofabrication in polymer matrices, Progress in Polymer Science, 2003, 28(1), 5-26.
11. K Ishizu, K Tsubaki, A Mori and S Uchida, Architecture of nanostructured polymers, Progress in Polymer Science, 2003, 28(1), 27-54.
12. ET Thostenson, Z Ren and T-W Chou, Advances in the science and technology of carbon nanotubes and their composites: a review, Composites Science and Technology, 2001, 61(13), 1899-1912.