Cellulose Nanocrystal Cellulose Nanocrystal Characterization by AFMCharacterization by AFM

RoyaRoya LahijiLahiji Post Doc @NINTPost Doc @NINTX. X. XuXu Mechanical EngMechanical EngRyan WagnerRyan Wagner Mechanical EngMechanical Eng

Arvind RamanArvind Raman Prof. Mechanical EngProf. Mechanical EngRon ReifenbergerRon Reifenberger Prof. PhysicsProf. Physics

Robert MoonRobert Moon Forest Products LabForest Products LabPurduePurdue-- Materials EngMaterials EngBirck Nanotechnology CenterBirck Nanotechnology Center

2009 2009 IntnIntn’’ll Conf. on Nanotechnology for the Forest Products Industry, Conf. on Nanotechnology for the Forest Products Industry, June 24June 24--26, 2009, Edmonton, Alberta, Canada26, 2009, Edmonton, Alberta, Canada

OutlineOutline

MotivationMotivationAtomic Force Microscopy (AFM)Atomic Force Microscopy (AFM)ResultsResultsSummarySummary

Crystalline

Disordered

Aci

d H

ydro

lysi

s

Cellulose Nanocrystals (CNCs)Cellulose Nanocrystals (CNCs)

Wood cellulose nanocrystals, Wood cellulose nanocrystals, LiaLia StanciuStanciu

Cellulose NanocrystalsCellulose Nanocrystals

BeckBeck--CandanedoCandanedo et al., et al., BiomacromoleculesBiomacromolecules, 2005, 6, 1048, 2005, 6, 1048

CNC Source Length Cross-Section Algal >1000nm 10-20nm

Bacterial 100 to >1000nm 5-10nm by 30-50nm

Cotton 200-350nm 5nm

Tunicate 100 to >1000nm 10-20nm

Wood 100-300nm 3-5nm

CottonCotton TunicateTunicate WoodWood

400nm

Cellulose NanocrystalsCellulose NanocrystalsPropertiesProperties

Cellulose NanocrystalsCellulose NanocrystalsPropertiesProperties

Encouraging Reinforcement Material

CNC Functional UnitCNC Functional Unit““uniformuniform”” building block building block High Aspect ratioHigh Aspect ratio““GoodGood”” Mechanical propertiesMechanical properties““ReactiveReactive”” surfacesurface

Ideal Ideal GREENGREEN NanoparticleNanoparticle

Function

AvailabilityAvailabilitySustainabilitySustainabilityBiodegradableBiodegradableNonNon--petroleum Basedpetroleum BasedRenewableRenewableCarbon NeutralCarbon NeutralCarbon SequesteringCarbon SequesteringLow Health RiskLow Health Risk

EnvironmentEnvironmentAnimalAnimal

Green

Source: Ikkala, 2004.

CNC CompositesCNC Composites

Composite PropertiesComposite PropertiesThermal StabilityThermal StabilityElastic ModulusElastic ModulusElongationElongationTensile StrengthTensile Strength

CNCCNC--Matrix InterfaceMatrix InterfacePercolation ThresholdPercolation Threshold

L. Oksman, Wood fiber 2007 conference

T. Zimmermann, Wood fiber 2007 conference

Not Reaching Full PotentialCNCs

No CNCs

Percolation ThresholdPercolation Threshold

( )m

f

f

fE

VEVcE −+

= 11 ( ) mfffc EVEVE −+= 1

E

Volume Fraction Fiber

E1

E2

Capadona et al., Science, 2008.

0 1

Transverse Load Transfer

Motivation: CNC CharacterizationMotivation: CNC Characterization

Not much known about CNCsNot much known about CNCsCharacterize Characterize ““building blockbuilding block””

Surface ChemistrySurface ChemistryMechanical PropertiesMechanical PropertiesWater Interaction Water Interaction UniformityUniformityCNC MorphologyCNC Morphology

Insight for Composite Processing & PropertiesInsight for Composite Processing & PropertiesLoad Transfer across Transverse SurfacesLoad Transfer across Transverse Surfaces

CNCCNC--Matrix InterfaceMatrix InterfaceCNCCNC--CNC InterfaceCNC Interface

Necessary for Predictive ModelingNecessary for Predictive Modeling

Modulus of ElasticityModulus of ElasticityBased on Idealized Cellulose Based on Idealized Cellulose IIββ SimulationsSimulations

No Transverse Elasticity

Developing Characterization ProtocolsDeveloping Characterization ProtocolsWhere we are atWhere we are at…….. ……where we need to be!where we need to be!

Approach: Approach: AFM TechniquesAFM TechniquesContinuum ModelingContinuum ModelingMolecular Dynamic ModelingMolecular Dynamic Modeling

Stone AgeF 1

ObjectivesObjectivesDevelop CNC Measurement CapabilitiesDevelop CNC Measurement CapabilitiesAssess Uniformity of CNCsAssess Uniformity of CNCs

Surface ChemistrySurface ChemistryMechanical PropertiesMechanical Properties

InIn--situ with Changes in Relative Humiditysitu with Changes in Relative Humidity

Scanning Probe Microscopy (SPM)Scanning Probe Microscopy (SPM)TipTip--Surface Interactions: Surface Interactions:

Physical contactPhysical contact Electrostatic forceElectrostatic forceLateral forceLateral force CapacitanceCapacitancevan van derder Walls interactionsWalls interactions ThermalThermalMagnetic forceMagnetic force

Ernst-Moritz-Arndt-University, Greifswald

Xintek

Tips Radius Tips Radius ~10nm (typical)~10nm (typical)~2nm (ultra sharp) ~2nm (ultra sharp)

a) contact b) non-contact, small amplitude

c) intermittent contact, large amplitude

d) jumping

a) contact b) non-contact, small amplitude

c) intermittent contact, large amplitude

d) jumping

Imaging Modes Imaging Modes Contact Contact Vibrating (non & intermittent contact)Vibrating (non & intermittent contact)JumpJumpImaging under Gas or LiquidImaging under Gas or LiquidTip Chemical FunctionalizationTip Chemical Functionalization

Atomic Force Microscopy (AFM)Atomic Force Microscopy (AFM)

TopographyTopographyStiffnessStiffnessPullPull--off forceoff force

AFMAFM--PurduePurdueNanotech AFMNanotech AFM

Si tips, 10nm tip radiusSi tips, 10nm tip radiusStiffness 0.65 N/m Stiffness 0.65 N/m (manufacturer)(manufacturer)

measure each tipmeasure each tip0.90.9--2.5N/m2.5N/m

Resonance Frequency: ~40KHzResonance Frequency: ~40KHzAtmosphere ControlAtmosphere Control

30% & 0.1% RH30% & 0.1% RH

Sharp AFM tips Sharp AFM tips (<10nm)(<10nm)Consistent tip shapeConsistent tip shapeDurableDurableLess expensiveLess expensiveImage & Property MeasurementImage & Property Measurement

AFM TipsAFM TipsSharp Sharp (<10nm)(<10nm)

Good

Ultra Sharp Ultra Sharp (<2nm)(<2nm)Inconsistent tip shapeInconsistent tip shapeFragileFragileExpensiveExpensive

Bad

10 nm

CNC: ~4CNC: ~4--10nm10nm

Mica

ArtifactsArtifactsChanging contact curvatureChanging contact curvatureEdge effectsEdge effectsAFM Tip dilationAFM Tip dilationAFM Tip bluntingAFM Tip bluntingAFM TipAFM Tip--toto--Tip changesTip changesMeniscus FormationMeniscus Formation

Idealized TipIdealized Tip--CNC Contact Geometry CNC Contact Geometry

AFM Tip

AFM: ForceAFM: Force--DisplacementDisplacement

A

BC

DE

A

B

C

D E

F

G

H

F

G

H ApproachWithdraw

AFM: ForceAFM: Force--DisplacementDisplacement

IIII -- PullPull--off Force off Force TipTip--Surface InteractionSurface InteractionAdhesionAdhesionCNCCNC--surface Chemistry?surface Chemistry?

II --Slope Slope CantileverCantilever--CNC stiffnessCNC stiffnessElastic ResponseElastic ResponseCNCCNC--Modulus?Modulus?

II

II

ApproachWithdraw

Force DisplacementForce Displacement

90nm

Topography

Data CollectedData CollectedTopography, PullTopography, Pull--off, Stiffnessoff, Stiffness128 x 128 points128 x 128 pointsResolution based on mapping areaResolution based on mapping area

Maps Maps TopographyTopographyStiffnessStiffnessPullPull--off Forceoff Force

~2wt% CNC suspension 400nm

Deposit ~10 μl of solution on to freshly cleaved mica sheet

DI wash

Sample PreparationSample Preparation

TopographyTopography

Observations Observations Variable heightVariable height

RH influence?RH influence?not likelynot likelyScanScan--toto--scan ~1nm scan ~1nm not not ““exactlyexactly”” same tracesame trace

0.1% RH0.1% RH

012345678

0 20 40 60 80 100 120 140 160 180 200

Distance (nm)

Hei

ght (

nm) 0.1% RH

012345678

0 20 40 60 80 100 120 140 160 180 200

Distance (nm)

Hei

ght (

nm)

30% RH

0.1% RH

40nm

0.1% RH

×

40nm

0.1% RH

40nm

0.1% RH

×

30% RH30% RH

40nm

30% RH

×

40nm

30% RH

40nm

30% RH

×

×mica CNC

StiffnessStiffness

1.4

1.5

1.6

1.7

1.8

1.9

2.0

0 20 40 60 80 100 120 140 160 180 200

Distance (nm)

Effe

ctiv

e St

iffne

ss (N

/m)

30% RH

0.1% RH

mica CNC

43nm

0.1% RH

43nm

30% RH

× ×

××

1.4

1.5

1.6

1.7

1.8

1.9

2.0

0 20 40 60 80 100 120 140 160 180 200

Distance (nm)

Effe

ctiv

e St

iffne

ss (N

/m)

30% RH

0.1% RH

30% RH

0.1% RH

mica CNC

43nm

0.1% RH

43nm

30% RH

× ×

43nm

0.1% RH

43nm

30% RH

× ×

××

Observations Observations Uniform along lengthUniform along lengthEdge effectsEdge effectsNo CNC height effectsNo CNC height effects

RH RH StiffnessStiffnessMica & CNCMica & CNCMeniscus InfluenceMeniscus Influence

30% RH30% RH 0.1% RH0.1% RH

Force Displacement Force Displacement MOEMOEFo

rce

Distance

Cantilever B

ending

d

Nano Crystal

Approach

Tip Contact

Stiffness PlotsStiffness PlotsRemove Cantilever ContRemove Cantilever Contd several locations d several locations

d ~ Indentation Depth

Mechanical Properties: Wood CNCsMechanical Properties: Wood CNCs

“AFM TIP”

Cellulose

RH=0.1% RH=0.1%

Transverse Modulus Transverse Modulus E=18E=18--50 50 GPaGPa, , Mean: 35 Mean: 35 GPaGPaMedian: 39.5 Median: 39.5 GPaGPa Reasonable, but how accurate?

Forc

e (n

N)

Forc

e (n

N)

Forc

e (n

N)

Forc

e (n

N)

Forc

e (n

N)

Indentation (nm) Indentation (nm)

Indentation (nm) Indentation (nm) Indentation (nm)

Modulus of ElasticityModulus of ElasticityBased on Idealized Cellulose Based on Idealized Cellulose IIββ SimulationsSimulations

Within Range

Mechanical Properties: Tunicate CNCsMechanical Properties: Tunicate CNCs

“AFM TIP”

Cellulose

Hertz ModelHertz Model Continuum ModelContinuum Model Molecular DynamicMolecular Dynamic

Extracting Elasticity:Extracting Elasticity:

Idealized Crystals:Idealized Crystals:

2/3CdF =

Mechanical Properties: Tunicate CNCsMechanical Properties: Tunicate CNCs

806040200

1.41.31.21.1

1

Z[nm]

Nor

mal

forc

e[V

]30 nm

mica

CNC

-0.5 0 0.5 1 1.50

10

20

30

40

50

d (nm)

F (n

N)

Force Indentation Curve

fd cnck*a*(x+b)1.52/3)( bdakL +

0 0.2 0.4 0.6 0.8 10

1

2

3

4R2 Values of Fits

coun

t

R2

Transverse Modulus Transverse Modulus 30 Points along line 30 Points along line HertzHertzMean: 13 Mean: 13 GPaGPa ±± 9 9 GPaGPa (3 STD)(3 STD)

Mechanical Properties: Tunicate CNCsMechanical Properties: Tunicate CNCs

Mechanical Properties: Tunicate CNCsMechanical Properties: Tunicate CNCs

Transverse Modulus Transverse Modulus 100 Points along line 100 Points along line HertzHertzMean: 3 Mean: 3 GPaGPa ±± 5 5 GPaGPa (3 STD)(3 STD)

51nm 706050403020100

10

8

6

4

2

0

X[nm]Z[

nm]

Analysis of Transverse FZ curves

0 0.005 0.01 0.015 0.02 0.0250

0.05

0.1

0.15

0.2

0.25

Doffset (V)

F (V

)

Force Indentation Curve Comparison of Mica vs. Mica FZ curve

9080706050403020100

2

1.5

1

0.5

0

X[nm]Z[

nm]

51nm 302520151050

0.8

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

Z[nm]

Nor

mal

forc

e[V

]-0.01 0 0.01 0.02 0.030

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Doffset (V)

F (V

)

Force Indentation Curve

9080706050403020100

1.4

1.2

1

0.8

0.6

0.4

0.2

0

X[nm]

Z[nm

]

302520151050

0.8

0.75

0.7

0.65

0.6

0.55

0.5

Z[nm]

Nor

mal

forc

e[V

]

51nm

0 0.01 0.02 0.03 0.040

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Doffset (V)

F (V

)

Force Indentation Curve

9080706050403020100

1.5

1

0.5

0

X[nm]Z[

nm]

51nm 302520151050

0.8

0.75

0.7

0.65

0.6

0.55

0.5

Z[nm]

Nor

mal

forc

e[V

]0 0.5 1 1.5 2

0

5

10

15

20

D (nm)

F (n

N)

Force Indentation Curve

fd cncC*k*a*(x+b)1.5

0 0.2 0.4 0.6 0.8 10

1

2

3

4

5

6R2 Values of Fits

coun

t

R2

51nm 80706050403020100

2.5

2

1.5

1

0.5

0

X[nm]Z[

nm]

302520151050

0.75

0.7

0.65

0.6

0.55

0.5

0.45

Z[nm]

Nor

mal

forc

e[V

]0 0.5 1 1.5

0

5

10

15

D (nm)

F (n

N)

Force Indentation Curve

fd cncC*k*a*(x+b)1.5

0 0.2 0.4 0.6 0.8 10

1

2

3

4

5

6R2 Values of Fits

coun

t

R2

51nm 80706050403020100

1.4

1.2

1

0.8

0.6

0.4

0.2

0

X[nm]

Z[nm

]

302520151050

0.75

0.7

0.65

0.6

0.55

0.5

0.45

Z[nm]

Nor

mal

forc

e[V

]0 0.5 1 1.5

0

5

10

15

D (nm)

F (n

N)

Force Indentation Curve

fd cncC*k*a*(x+b)1.5

0 0.2 0.4 0.6 0.8 10

0.5

1

1.5

2

2.5

3R2 Values of Fits

coun

t

R2

51nm 80706050403020100

1.2

1

0.8

0.6

0.4

0.2

0

X[nm]Z[

nm]

302520151050

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

Z[nm]

Nor

mal

forc

e[V

]0 0.5 1 1.5

-5

0

5

10

15

D (nm)

F (n

N)

Force Indentation Curve

fd cncC*k*a*(x+b)1.5

0 0.2 0.4 0.6 0.8 10

1

2

3

4R2 Values of Fits

coun

t

R2

51nm 706050403020100

10

8

6

4

2

0

X[nm]

Z[Å

]

302520151050

0.75

0.7

0.65

0.6

0.55

0.5

0.45

0.4

Z[nm]

Nor

mal

forc

e[V

]0 0.2 0.4 0.6 0.8 1

-5

0

5

10

15

D (nm)

F (n

N)

Force Indentation Curve

fd cncC*k*a*(x+b)1.5

0 0.2 0.4 0.6 0.8 10

1

2

3

4

5R2 Values of Fits

coun

t

R2

Summary Summary Key ObservationsKey Observations

Variable CNC Height ProfileVariable CNC Height ProfileUniform StiffnessUniform StiffnessInfluence of RH on measurementsInfluence of RH on measurements

Elastic Modulus EstimatesElastic Modulus EstimatesComplimentary Experimental & Modeling Complimentary Experimental & Modeling QualitativeQualitative

Wood: 18Wood: 18--50GPa (FEM)50GPa (FEM)Tunicate: 0Tunicate: 0--22 22 GPaGPa (Hertz)(Hertz)

Artifacts need to be accounted forArtifacts need to be accounted for……

AcknowledgementsAcknowledgements

Forest Product Laboratory:Jim Beecher, Chris Hunt, Rick Reiner, Allan Rudie, Ron Sabo

Funding: Cooperative Agreement with Purdue Funding: Cooperative Agreement with Purdue

Funding: Seed Grant Funding: Seed Grant

Thank YouThank You

Questions ?