Lecture 3 Properties of Nanomaterial- Surface to Volume Ratio.ppt

Well explained ppt

1. Lecture 2
LearningOutcomes:
1.Surfacetovolumeratioanditseffect
2.Surfacestatesanditsadvantages

2. What Is Nano ?
Nanotechnology:Amoregeneralizeddescriptionofnanotechnologywassubsequentlyestablishedby
theNationalNanotechnologyInitiative,whichdefinesnanotechnologyasthemanipulationofmatter
withatleastonedimensionsizedfrom1to100nanometers.
IUPAC Definition:a nanoparticle is a particle of any shape with dimensions in the range of 10
−9
to
10
−7
m.7
Introduction to nanotechnology

3. Introduction to nanotechnology
3
History of Nanotechnology
Asfarbackasthefourthcentury,nanoparticles
wereusedbyartisansforgeneratingaglittering
effectonthesurfaceofpots.Onetheleftisa
famousartifactcalledtheLycurgusCupresides
intheBritishMuseuminLondon.Whatmakes
thiscupuniqueisthatitscolorchangesfrom
green(whenilluminatedfromtheoutside)tored(whenilluminatedfrom
within)duetonanoparticlesofgoldandsilverintheglass.Modern
scientificevaluationofcolloidalnanoparticlesdidnotbeginuntil
MichaelFaraday'sworkofthe1850s.Heprovidedthefirstdescription,
inscientificterms,oftheopticalpropertiesofnanometer-scalemetalsin
hisclassic1857paper.In1959,RichardFeynmanfirstintroducedthe
conceptofnanotechnologyinhistalk“There'sPlentyofRoomatthe
Bottom,”inwhichhedescribedthepossibilityofsynthesisviadirect
manipulationofatoms.Theterm"nano-technology"wasthenfirstused
byNorioTaniguchiin1974.Withtheinventionofelectronmicroscopes,
analysesonsmallmattersbecomemucheasier.Thusresearchon
nanotechnologyflourishesquickly.Todate,nanotechnologyhasbecome
aninterdisciplinarybridgeduetouniquepropertiesofnanomaterials,
widelyappliedtopharmacy,therapeutics,electromagneticsandcatalysis.

4. 4
Three (of several) Senses of Small
•Sizeand surface area effects
1 nm –100 nm Fundamental materials
properties remainthe same but size,
shape and surface area alter some
behaviors work function, solubility,
chemical potential, contaminate sorption
•Critical Size and Characteristic
Length Scale Interesting or unusual
properties because the size of the
system approaches some critical
length(includes quantum effects). Many
characteristicsof material may have
normal or nearly normalbehavior
•New(Non-extensive) Properties
Systems not large enough to have
extensive properties. Particles become
effectively polymorphs of “bulk” materials
and statistical homogeneity may not be
valid.
n = 1
n = 3
n = 2
n = 4
n = 5
Energy /
(h
2
/8ml
2
)
25
16
1
4
9
0
size d
V= correlation length
d = range of
intermolecular forces
•Kelvin equation for solubility
•Gibbs-Thompson relation for
chemical potential
What do we we mean by small particle and why does their chemistry change?

5. LENGTH SCALES

6. DIFFERENCE BETWEEN BULK AND NANOMATERIALS
BULK carbon as graphite
Nano carbon as graphene

8. AN EXAMPLE TO START WITH

9. THE FIRST DIFFERENCE
–SURFACE TO VOLUME

10. WHAT IT DOES ?
•Thelargesurfaceareatovolumeratioofnanoparticlesopensmany
possibilitiesforcreatingnewmaterialsandfacilitatingchemicalprocesses.
Inconventionalmaterials,mostoftheatomsarenotatasurface;theyform
thebulkofthematerial.
•Innanomaterials,thisbulkdoesnotexist.Indeed,nanotechnologyis
oftenconcernedwithsinglelayersofatomsonsurfaces.Materialswith
thispropertyareunique.Forexample,theycanserveasverypotent
catalystsorbeappliedinthinfilmstoserveasthermalbarriersorto
improvewearresistanceofmaterials.

13. An example of nano and bulk coating on surface