Nanoparticle Characterization Nee

Composite Properties to Product S

The New Steel?Februar

y , 28 2011

Lee SilvermanDuPont Nanocomposite TechnologiesCentral Research and DevelopmentWilmington, Delaware
P titi i N t h l S

Nano 

(nanosc

more d

Nanostructured bulk materials(nanoscale internal structure)

Partitioning 

Nano

tec

hnology 

Space 

Levels of

more d

Levels of

Nanoscale 

Design

50 nm

Nan

Textured Surfaces: (Physically Patterned or Surface Films

3/10/2011

(Physically Patterned or

textured on the nanoscale)

Surface Films(Nanoscale in suthickness only)
Na o ate a s a e a ab g ec 

nomaterials are an Enabling Techn

CompositesDesired property combinations can be achieved with proper selection of materials and microstructure

• Manipulation of materials on very fine Manipulation of materials on very fine

scale is broadly useful across polymer platforms

• Resulting materials have more 

function and value in use 

Unique function and value in use

Structure/property relationships are fundamental to material development

Combinations

to material development

3/10/2011
Na osca e Sc e ce a d g ee g a 

noscale Science and Engineering a

Product Stewarship:Many nanostructures do NOT involve nanoparticles.But most if not all nano-specific SHE questions that are discussed relate to particles with nanoscale dimensions

• “There is an important distinction between applications that use nanosca

larger objects and chemicals or pharmaceuticals in which the nanometreis a discrete nanoparticle or nanotube .... Exposures to substances and nanoparticles are covered by existing understanding and regulation.... Tconsidered further in this report except in that they may be in the form of incorporated into materials in the nanometre size range incorporated into materials in the nanometre size range. ”

3/10/2011

Excerpted from Nanoscience and nanotechnologies: opportunities and uncertainties; Royal Society and 

Academy of Engineering, 2004 
Enviro e ta , ea t a d Sa ety, a 

nmental, Health and Safety, an

Stewardship Requires Data“All fiber types capable of depositing in the thorax are ntheir pathogenic potential...A complete characterization (i.e., dimensions, fiber numaerodynamic diameter) of the fiber aerosol and retained essenti l ” a .

• R. McClellan, et. al. – Regul Toxicol Pharmacol, 16 (1992) 321-64

“A robust structure/activity paradigm has emerged from fib t i l ) th t hi hli ht fib l th thi fibre toxicology) that highlights fibre length, thinness, a

biopersistence as major factors in determining the pathfibre.”

• K Donaldson Crit Rev Toxicol 39 (2009) 487 K. Donaldson, Crit. Rev. Toxicol. 39 (2009) 487-500

Therefore product stewardship requires extensive chara

3/10/2011

Therefore product stewardship requires extensive chara
Enviro e ta e e se nmental Defense –Duot a

Pont Nan

Framework“A framework to facilitate the responsible development, use and disposal of nano-scale materials.” Collaboration begun in October 2005 Objective: A systematic and disciplined process, develoObjective: A systematic and disciplined process, devel

broad collaboration 

• Identify, manage and reduce potential health, safety and environmental 

lifecycle of such nanomaterials”

• Model and tool for industry, public interest groups, academia and govern• Make available information, tools and methods developed

Framework was published on June 21, 2007

3/10/2011

www.nanoriskframework.com
A Mi f F ili d N El t A Mix o

f

Familiar an

d

New Elemen

t

s

Familiar risk management paradigm

• Development of informational profiles (base sets)• Information driven• Reasonable worse case assumptions• Appropriate bridging• Applying life cycle thinking

As of 2/1/2011

• Total visits to website – 20,365• Total Downloads – 9144 • Total Countries – 134 

3/10/2011 www.nanoriskframework.com
Enviro e ta e e se nmental Defense –Duot a

Pont Nan

Framework Iterate

Profile

Lifecycle(s)

Describe

Material 

&

Evaluate

Risks

Assess

Risk Mgmt

Decide,

Document

&

Lifecycle(s)

Properties

&

Application

Risks Risk Mgmt &

Act 

Exposure

Hazards

Assess, prioritize & generate data

3/10/2011

www.nanoriskframework.com
Environmental Defense –DuPont Nan

Iterate

o e ta e e se uot a

Framework

Typical Information 

Profile

Lifecycle(s)

Commercial NameTechnical Name

Particle SizeSize Distribution

yp

Describe

Material 

&

Evaluate

Risks

Assess

Risk Mgmt

Decide,

Document

&

Lifecycle(s)

Properties

Common FormChemical CompositionMolecular Structure

Surface-Area

Particle DensitySolubility &

Application

Risks Risk Mgmt &

Act 

Exposure

Hazards Crystal Structure

Physical FormBulk Density

DispersabilityAgglomeration SChemical Reactiv

Assess, prioritize & generate data

y

Surface ReactivitPorositySurface Charge

3/10/2011

www.nanoriskframework.com

Surface Charge
Na oco pos te es g u es nocomposite Design Rules: Particle Dimensionality Defines Prope

Properties/usesIsotropy, transparency, electronic, magnetic, photonic, model systems

spheres

electrical conductivity, themomechanical, network 

t t fill f fib

rods

structures, fillers for fibersBarrier, thermomechanical, flame retardancy, CTE in plane, very high interfacial area

plates

3/10/2011
Nanocomposite Systems Require Com

N ti l P l

a oco pos te Syste s equ e Co 

Particles, Polymers and Processes 

Nanoparticles Polymer

TiO SiO Di i & P l i 

Polyi

Fluoropolym

Therm

Dispersion &

Compatibilization

TiO2, SiO2, 

BaTiO3, AlN, diamonds, Qdots, polymers... Interfacial Chemistry

• Surfactants

Polya

Polye

CNT, Al2O3, 

SiC, TiO2

tubes....

• Surfactants• Coupling agents

Structures & Interphase

• Dendrimers• Multiblock polymers Polyo

Ionom

Othe

Clay, exfoliated graphite

• Multiblock polymers• Flexible links

Process Technology

• Polymer processing• Milling/grinding

3/10/2011

graphite.. • Milling/grinding Othe

• Particle 

formation/modification
Processes Developed to Create Excellent DProcesses Developed to Create Excellent D

in Multiple Polymers

3/10/2011
Diffus o a e s e spect at 

ion Barrier vs. Filler Aspect Rat

(Nielsen Model)

Tortuous Path Model

0.81.0

y

Aspect ra

0.6

e Permeability

0.20.4

Relative

0.0

0 2 4 6 8 10 12 

V l F ti Ribb

1000

Aspect ratio = t/w

w

t

3/10/2011 After L.E. Nielsen, 

Journal of Macromolecular Science, Part A, 1 (1967) 929 

Volume Fraction Ribbons
Pe co at o es o d to spect at 

rcolation Threshold to Aspect Rati

(Garboczi Model)

Pc ≡ 

for 

3/10/2011 E.J. Garboczi, et. al., 

Physical Review E, 52 (1995) 
G ap e e/ o ysty e e ect ca Co 

raphene/Polystyrene Electrical Con

Fits Garboczi Model 

3/10/2011 S. Stankovich, et. al., 

Nature 442 (2006) 282-286
The a Co duct ty s spect at 

rmal Conductivity vs. Aspect Rati

(Gao Model)

252015

K

e/Km

10

Volume Kp/Km = 

Contac

50

10-3 10-2 10-1 100 101 102 103

3/10/2011 L. Gao, et. al.,

Chemical Physics Letters, 434 (2007) Pages 297-

10 10 10 10 10 10 10

Aspect Ratio
Elast c odu us to e spect at o ic Modulus to Filler Aspect Ratio(Halpin-Tsai)

MatrMatr

45

E

0

Aspect Ratio = 100 40

45

E

0

Aspect Ratio = 100 40

34

Modulus Ec/E

34

Modulus Ec/E

2

Relative M

1

0% 2% 4% 6% 8% 

Layered Silicate Concentration (wt %)

3/10/2011 After J.C. Halpin, et. al.,

Polymer Engineering and Science, 16 (1976) 

Layered Layered Silicate Silicate Concentration Concentration (wt %)
T h i f M i N ti Tec

h

niques 

for 

Measuring 

Nanoparti

c

Method Dry/Solvent Dispersed Com

Plates Spheres Rods Plates Sph

Surface Area (BET)Static Light Scattering Static Light Scattering

(SLS)Dynamic light scatterin

g( ) DLS

Scanning Electron Microscopy (SEM)Transmission Electron Transmission Electron

Microscopy (TEM)Scanning Probe Microscopy (SPM)

3/10/2011

Small Angle X-ray Scattering (SAXS)
T h i f M i N ti Tec

h

niques 

for 

Measuring 

Nanoparti

c

Method Composite

Plate Sphere Rod Distribution Multi- modal 

Surface Area (BET)Static Light Scattering Static Light Scattering

(SLS)Dynamic light scattering (DLS)

Scanning Electron Micr. (SEM)Transmission Electron Micr (TEM) Micr. (TEM)Scanning Probe Micr. (SPM)Small An

gle X-ra

y

3/10/2011

Scattering (SAXS)
El t Mi b A bi Elec

tron Microscopy can 

be 

A

mbiguo

3/10/2011

5 v% clay in PMMA
I di id l Cl Sh t ARE I l Indi

vidual Clay Shee

ts ARE Irregular

Height images (AFM) 

Laponite Montmorillonite

3/10/2011 Images courtesy of Greg B
A Th Mi t t Diff tAre These Micros

truc

tures Different

Silica in polystyrene (10%) Silica 

3/10/2011
N d t M th S (Di Nee

d

to 

Measure the 

Spaces (Dispe

1.61.8

2 02.5

Silica in polystyrene (10%) Silica 

0 60.8

1

1.21.4

S(q)

1.01.52.0

S(q)

50 v%40 v%30 v%20 v%10 v%

3/10/2011 0

0.20.4

0.6

0.00 0.01 0.02 0.03 0.04 0.05 

q (1/A)

0.00.5

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10

q (1/A)

H

Effective h

Hard sphere model

SAXS Data
Na opa t c e C a acte at o equ 

noparticle Characterization Requir

Product Stewardship, Property UnderNanoRisk Framework is rigorous and data driven asses

• Materials and application descriptions• Lifecycle profiles• Risk evaluation and Management• Decide, document and act• Review and adapt

Nanoparticle characterization is a fundamental part of thstewardship processProtecting people and environment is our highest priori

3/10/2011 www.nanoriskframework.com
Na opa t c e C a acte at o s equ 

noparticle Characterization is Requ

Understanding Property DevelopmenParticle size, shape, distribution responsible for propertCharacterization of platy and rod-like particles onerous 

• Best done in highly oriented systems and low particle concentrations• This is rarely p the case in nanocomposites

Characterization almost impossible in nanocomposites

• Size distributions (especially multimodal)• Faceted particles Faceted particles• Highly irregular particles (especially re-entrant shapes)• High loadings

Dispersion very important also Dispersion very important also

• But is the subject of another (lengthy) discussion

3/10/2011