11
Particle Characterization at the Nanoscale
Greg MeyersDow ChemicalDow Chemical
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
22
Outline
• Experience with an Interlaboratory Study for Nanoparticle (NP) Sizing
• New NP Sizing TechnologyNew NP Sizing Technology
M h i l P ti t th N l• Mechanical Properties at the Nanoscale
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
33
Interlaboratory Study• ASTM Sponsored ILS#166 in 2008
(basis for ASTM E 2490-09, published June 2009)
• Evaluation of Photon Correlation Spectroscopy (PCS) • with comparison by direct methods (AFM, TEM, SEM)y ( )• 26 participating laboratories
• NIST Au colloid reference materialsNIST Au colloid reference materials
RM 8011 – nominal 10 nm RM 8012 – nominal 30 nmRM 8013 – nominal 60 nm
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
44Our Results with Au NPs
12141618
M 8
011 TEMSEMAFMPCS
68
10RM
A A A A40
6 7 8 9 10 11 12 13 14 15 16 17 186 7 8 9 10 11 12 13 14 15 16 17 186 7 8 9 10 11 12 13 14 15 16 17 186 7 8 9 10 11 12 13 14 15 16 17 18Particle diameter (nm)
There are statistically significant
25
30
35
RM
801
2
There are statistically significant differences between all techniques
for the smallest particles
60
70
13
20
B B B B
TEM of 8013 AFM of 8011
30
40
50
60
RM
801
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
AFM
_C
DLS
_C
SEM
_C
TEM
_C All PairsTukey-Kramer0.05
55
Interlaboratory Study• ILS 166 average data is average ofeach laboratory’s mean
• Quite good agreement across many10
15
20
amet
er (n
m)
DowILS 166 ave.
RM 8011 (10 nm)
• Quite good agreement across manylabs, primarily due to clear instructionsfor sample prep, data acquisition, andreporting
0
5
PCS (90º) TEM SEM AFM
mea
n di NIST ROI
40
• Recognition that different techniquescan give statistically different values20
30
40
diam
eter
(nm
) RM 8012 (30 nm)
0
10
PCS (90º) TEM SEM AFM
mea
n d
80
From NIST RM8011 documentation...
40
60
diam
eter
(nm
) RM 8013 (60 nm)
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
0
20
PCS (90º) TEM SEM AFM
mea
n
66Current Challenges• Differences between techniques – this is acceptable
– Different interactions are measured– Different assumptions are made– Different models may be appliedDifferent models may be applied– Sampling statistics variable
• Real systems can be more complexM b lti d l l di i– May be multimodal, large dispersion
– May have primary, aggregated, or agglomerated populations– May be heterogeneous in structure/composition
• Quality of test methods used across laboratories are being addressed through interlaboratory studies
• Accurate sizing of particles that are non-spherical using indirect methods• Accurate sizing of particles that are non-spherical using indirect methods
• Relevant size, shape, surface area metrics for risk assessment
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
• Lack of standards for broader compositions, shapes, surface chemistries and physical properties
77Mass Selective Particle SizingSuspended Microchannel Resonator (commercialized as Archimedes*)
f
For each particle, relate buoyant mass to density, Spherical equivalentBuoyant mass
sizesizemassmass
mass, and size via:
* Affinity Biosensors
(density)
sizesize Affinity Biosensors
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
88NP Sizing Needs & Timing• Additional NIST particle standards mirroring
manufactured NPs (1-3 years)– SiO2 and CeO2 (slurry), TiO2 (cosmetic, paint), Ag (antimicrobial), ( y) ( p ) g ( )
CNT or graphene (fillers), dendrimer (drug delivery)
• Techniques or algorithms to deal with non-spherical h (1 3 )shapes (1-3 years)– Fund research into new analysis methods– Improved throughput for direct imaging/analysis (microscopy)
• More interlaboratory studies including both routine and developmental instrumentation for sizing, surface area (ongoing in standards bodies)(ongoing in standards bodies)– Need to advertise participation opportunities more widely– Surface area techniques should be evaluated near term– Consider inversion algorithms for indirect methods as part of
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
Consider inversion algorithms for indirect methods as part of interlaboratory studies
99NP Sizing Needs & Timing (con’t)• Heterogeneous NP particle development (3-5 years)
– Physically heterostructured NPs• Porous (closed/open cell), core/shell( p ),
– Chemically heterogeneous NPs• Hydrophobic/hydrophilic (surface functionalized particles)• Compositionally heterogeneous on the surface (Janus particles)
• Particles for physical property testing (5-10 years)– Sized NP series for mechanical, thermal, optical, magnetic
propertiesproperties
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
1010Nanoscale Mechanical PropertiesDow – Veeco NIST ATP Program 2004-2007
Quantitative Nanoindentation in the AFM
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
1111
Lateral ForcesBefore Force Volume After Force Volume
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
• solid 700nm PS latex particles dislodged from surfactant rings
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Lateral ForcesThe problem
120%
Deflection Error vs. Sample Modulus
80%
100%
ngle
err
or
k = 0.1 N/m
k = 1 N/m
20%
40%
60%
efle
ctio
n an
k 1 N/m
k = 10 N/m
k = 100 N/m
0%
20%
1.0E+06 1.0E+07 1.0E+08 1.0E+09 1.0E+10 1.0E+11 1.0E+12
Sample modulus [Pa]
D
k = 1000 N/m
X
p [ ]
Errors can be reduced using • passive levers with stiffer springs• active levers
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
active levers
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Lateral ForcesDeflection Lateral Compensation (DLC)*– works with any cantilever
Sample
X-piezoX=cDef
Use the cantilever deflection signal to control the AFM’s X-piezo and compensate for the lateral motion
Improved accuracy on homogeneousmaterial standards
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
compensate for the lateral motion material standards*L Huang, C Meyer and C Prater, Journal of Physics: Conference Series 61, 805–809 (2007)
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Regimes of Deformation
180nN
• Hollow Latex Used in Coatings• Understanding deformation of
nanostructured particles at the ElasticResponse of shell
8 0
particle level • Requires very stable AFM
platform2.0
3.04.0
5.0
6.07.08.0
Mod
ulus
(GPa
)
Type 1Type 2
Spherical tip(K = 32.9 N/m, apex R~60 nm)
550nNElastic-Plastic
0.0
1.0
0.00 0.10 0.20 0.30 0.40
t/R
3Response of shell
3
350nm t/R=0.2
1.1uN
‘Kink’ at point where shell buckles
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G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
1 um x 1um
1515In-situ TEM Deformation of CdS NP
YouTube video
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
1616Needs for NP Mechanics & Timing• Accessible methods for calibrating spring constant of high stiffness
probes (40-1000N/m) of arbitrary cross-section for AFM indentation into materials with E>10 GPa (1-3 years)
• Alternative tip geometries including flat punch for AFM indentation (1-3 years)
• Libraries of NPs of various sizes on rigid substrates (3-5 years)– Metal cluster deposition; centrifugal force deposition/separation by spin
coating
• Develop nanoscale test for NP adhesion in biological, ceramic, or polymeric material matrix (3-5 years)
• Models and simulation to support experimental deformation and fracture regimes for NPs (ongoing)
I l b di AFM b d i d i f NP
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
• Interlaboratory studies on AFM based indentation of NPs are needed (ongoing)
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Acknowledgements• NIST ATP
– NIST Program Award # 70NANB4H3055• Dow• Dow
– Steve Rozeveld, Cliff Todd, Stew Wood (sizing) – Hamed Lakrout, Valeriy Ginzburg, Bob McIntyre (ATP)
• Affinity Biosensors– Ken Babcock
• Hysitrony– Oden Warren, Mike Okerlund, Julia Nowak
• Veeco– Sergei Belikov1 Sergei Magonov2 Natalia Erina Lin Huang– Sergei Belikov , Sergei Magonov , Natalia Erina, Lin Huang,
Chanmin Su, Charles Meyer, Craig Prater3
1 current affiliation 3M Corporation2 current affiliation Agilent Technologies
G. F. Meyers NNI Workshop Nanomaterials and the Environment, Oct 6-7, 2009
current affiliation Agilent Technologies3 current affiliation Anasys Instruments