Nano technology John Summerscales University of Plymouth School of Marine Science and Engineering University of Plymouth

Orders of magnitude x 10-x 10+x 3 milli- (m) kilo- (k)* 6 micro- (μ) mega- (M) 9 nano- (n) giga- (G) 12 pico- (p) tera- (T) 15 femto- (f) peta- (P) 18 atto- (a) exa- (E) * note that capital K is used, in computing, to represent 210 or 1024, while k is 1000.

Sub-metre scales 0.0532 nm = radius of 1s electron orbital 0.139 nm = C-C bond length in benzene 0.517 nm = lattice constant of diamond atto- femto- pico- nano- micro- milli- metre

Nanostructures surface structures with feature sizes from nanometres to micrometres white light optics limited to ~1μm use electron-beam or x-ray lithography and chemical etching/deposition image = calcium fluoride analog of a photoresist from http://mrsec.wisc.edu/seedproj1/see1high.html

Carbon Elemental carbon may be or one of two crystalline forms: amorphous or one of two crystalline forms: diamond (cubic crystal sp3 structure) graphite (contiguous sp2 sheets) graphene (single atom thickness layers of graphite) or at nanoscale can combine to form spheres (buckminsterfullerenes or “bucky balls”) and/or nanotubes

Graphene single atom thickness layers of graphite thinnest material known one of the strongest materials known conducts electricity as efficiently as copper conducts heat better than all other materials almost completely transparent so dense that even the helium atom cannot pass through http://www.graphene.manchester.ac.uk/

Graphene * in-plane bond length = 0.142 nm (vs 0.133 for C=C bond) Property Units Magnitude Comment Source Thickness nm 0.33* [1] Areal density μg/m2 770 ~1g / football field [2] Tensile modulus GPa 500 Tensile strength 1000 ~333x virgin CF Transparency % absorption 2.3 * in-plane bond length = 0.142 nm (vs 0.133 for C=C bond) http://www.graphene.manchester.ac.uk/story/properties/ http://www.graphenea.com/pages/graphene-properties

Penta-graphene announced Feb. 2015 stable to 1000K (727ºC) semiconductor auxetic image from http://www.pnas.org/content/suppl/2015/01/27/1416591112.DCSupplemental/pnas.1416591112.sapp.pdf

Nanotubes Carbon-60 bucky-balls (1985) graphitic sheets seamlessly wrapped to form cylinders (Sumio Iijima, 1991) few nano-meters in diameter, yet (presently) up to a milli-meter long Image from http://www.rdg.ac.uk/~scsharip/tubes.htm

Nanotubes SWNT = single-wall nano-tube MWNT = multi-wall nano-tube benzene rings may be zigzag: aligned with tube axis armchair: normal to tube axis chiral: angled to tube axis Image from http://www.omnexus.com/documents/shared/etrainings/541/pic1.jpg via http://www.specialchem4polymers.com/resources/etraining/register.aspx?id=541&lr=jec MWNT = multi-wall nano-tube concentric graphene cylinders

Nanotube production arc discharge through high purity graphite electrodes in low pressure helium (He) laser vapourisation of a graphite target sealed in argon (Ar) at 1200°C. electrolysis of graphite electrodes immersed in molten lithium chloride under an Ar. CVD of hydrocarbons in the presence of metals catalysts. concentrating solar energy onto carbon-metal target in an inert atmosphere.

Nanotube purification oxidation at 700°C (<5% yield) filtering colloidal suspensions ultrasonically assisted microfiltration microwave heating together with acid treatments to remove residual metals.

Nanotube properties SWNT (Yu et al) MWNT (Demczyk et al) E = 320-1470 (mean = 1002) GPa σ´ = 13-52 (mean = 30) GPa MWNT (Demczyk et al) σ´ = 800-900 GPa σ´ = 150 GPa

2D group IV element monolayers Central column of periodic table (covalent bonding atoms) graphene (2D carbon) silicene (2D silicon) unstable germanene (2D germanium) rare stanene (2D tin) plumbene (2D lead) not attempted ?

Curran®: carrot fibres CelluComp (Scotland) nano-fibres extracted from vegetables carrot nano-fibres claimed to have: modulus of 130 GPa strengths up to 5 GPa failure strains of over 5% potential for turnips, swede and parsnips first product is "Just Cast" fly-fishing rod.

Exfoliated clays layered inorganic compounds which can be delaminated most common smectite clay used for nanocomposites is montmorillonite plate structure with a thickness of one nanometre or less and an aspect ratio of 1000:1 (hence a plate edge of ~ 1 μm)

Exfoliated clays Relatively low levels of clay loading are claimed to: improve modulus improve flexural strength increase heat distortion temperature improve gas barrier properties without compromising impact and clarity

nano-technology fabrication .. and .. probes chemical vapour deposition electron beam or UV lithography pulsed laser deposition atomic force microscope scanning tunnelling microscope superconducting quantum interference device (SQUID)

Atomic force microscope measures force and deflection at nanoscale image from http://en.wikipedia.org/wiki/Atomic_force_microscope

Scanning tunnelling microscope scans an electrical probe over a surface to detect a weak electric current flowing between the tip and the surface image from http://nobelprize.org/educational_games/physics/microscopes/scanning/index.html

Superconducting QUantum Interference Device (SQUID) measures extremely weak magnetic signals e.g. subtle changes in the electromagnetic energy field of the human body.

MEMS: micro electro mechanical systems Microelectronics and micromachining on a silicon substrate MEMS electrically-driven motors smaller than the diameter of a human hair Image from http://www.memsnet.org/mems/what-is.html

Controlled crystal growth Brigid Heywood Crystal Science Group at Keele controlling nucleation and growth of inorganic materials to make crystalline materials protein templates

Acknowledgements Various websites from which images have been extracted

To contact me: Dr John Summerscales ACMC/SMSE, Reynolds Room 008 University of Plymouth Devon PL4 8AA 01752.23.2650 01752.23.2638 jsummerscales@plymouth.ac.uk http://www.plym.ac.uk/staff/jsummerscales