developing standard measurements to allow comparisons ... · pdf fileto allow comparisons...

" Developing Standard Measurements to allow comparisons acrossto allow comparisons across

experiments "

Department of ChemistryDepartment of ChemistryHoward FairbrotherHoward Fairbrother

NNI W k h p Na at ial a d th

Johns Hopkins UniversityJohns Hopkins University

NNI Workshop - Nanomaterials and the Environment & Instrumentation,

M t l a d A al ti al M th d Metrology, and Analytical Methods,

October 6 – 7, 2009.

What is the state of research What is the state of research ffin this area of research at in this area of research at

the current time?the current time?

All over the place!NANOTUBE -SUPPLIERS .COM

42 nanotube suppliers (Courtesy of Alex Starr)Manufacture Product Type Product Method Product Id %C(purity) Diameter (nm) Length (μm) Cost $/g

NanoLab Inc MWCNT CVD PD15L5-20 >95% 15 5 – 20 110Mercorp MWCNT CVD MRCMW >90% 35(±10) 30 60

Helix MWCNT CVD MWNT 95% 10 – 30 0.5 – 40 28Nanocs MWCNT CVD CNTM0001 High? 20 1 – 100 160Nanocyl MWCNT CVD NC3100 95% 9.5 1.5 53y

SES Research MWCNT CVD 900-1201 95% 10 – 30 5 – 15 70

Arkema MWCNT CVD Graphistrength C100 90% 10 – 15 0.1 – 10 ??Arkema MWCNT CVD Graphistrength U100 97% 10 – 15 0.1 – 10 ??Bayer MWCNT CVD baytubes C 150 P 95% 5 – 20 1 – 10 ??Bayer MWCNT CVD baytubes C 150 HP 99% 5 – 20 1 – 10 ??

Helix MWCNT CVD SD MWNT 95% <10 0 5 40 75Helix MWCNT CVD SD-MWNT 95% <10 0.5 – 40 75Helix MWCNT CVD SD-MWNT 95% 10 – 20 0.5 – 40 40Helix MWCNT CVD MWNT 95% 10 – 30 0.5 – 40 28Helix MWCNT CVD MWNT 95% 20 – 40 0.5 – 40 28Helix MWCNT CVD MWNT 95% 40 – 60 0.5 – 40 28Helix MWCNT CVD MWNT 95% 60 – 100 0.5 – 40 28

Carbon Solutions SWCNT Arc Ap-SWNT 40-60% 1 – 10 1 – 5 50NanoLab Inc SWCNT Arc D1L1-10J 40% 1 – 1.5 10 225

Carbon Solutions SWCNT Arc P2-SWNT 70-90% 4 – 5 0.5 – 1.5 400SweNT SWCNT CoMoCat 90% 1 1 500Unidym SWCNT HipCo

SES Research SWCNT CVD 900-1351 90% <2 1 – 5 250Nanocs SWCNT Arc CNTM0002 2 – 1 0 50 nm – Many 250

Helix SWCNT CVD HP-SWNT 90% 1.3 0.5-40 210Helix SWCNT CVD LC-SWNT 50-70% 1 2 - 1 5 0 5-3 83Helix SWCNT CVD LC SWNT 50 70% 1.2 1.5 0.5 3 83

Mercorp SWCNT Arc MRSW 12% 1.2 - 1.4 10-50 60Nanocyl SWCNT CCVD NC1100 70% 2 Many ??

Development of Reference Materials is Emerging - NIST

Au NPs CNTs

But… It is probably unrealistic and But… It is probably unrealistic and bl h llbl h llunreasonable to expect that all unreasonable to expect that all

research on EHS effects of research on EHS effects of research on EHS effects of research on EHS effects of nanomaterialsnanomaterials (engineered or (engineered or

h i ) i i l h i ) i i l otherwise) is going to use sole source otherwise) is going to use sole source reference materials (RMs), so…reference materials (RMs), so…reference materials (RMs), so…reference materials (RMs), so…

I would advocate a policy of minimum characterization minimum characterization

requirements for studies to be suitable for publication.

These requirements would b l d d hobviously depend on the nanomaterial under nanomaterial under

consideration.

Using CNTs as an example

Showing a SEM g

Image is not sufficient

Key Materials Properties (for CNTs)Structure - Length distribution (AFM, TEM)

Chemical Composition (EDS, Elemental p ( ,Analysis)

Purity (Raman for a:C and Elemental Analysis for y ( ymetal content)

For Colloidal Suspensions:

Particle Size (DLS)Particle Size (DLS)

Surface Properties (EM, Chemical Composition)

Verification that you are studying Verification that you are studying what you think you are studyingy y y g

Effect of Oxidation on MWCNTsOH O

HNO3

Reflux

Pristine - MWCNT

n 14

OHOReflux

Surface Oxideson

cent

ratio

n%

) 10

12

14

Oxy

gen

Co

(ato

mic

%

4

6

8

0 20 40 60 80

Surf

ace

0

2

[HNO3] % w/w

More Oxidized CNTs are more stable towards Aggregation

900

)

700

8004.3%7.6%9.5%

Dia

met

er (n

m)

400

500

600

0 200 400 600 800 1000100

200

300

Time (s)

0 200 400 600 800 1000

pH = 6

64 mM NaCl

7.5 mg CNT/L

Oxidized MWCNTs in Suspension

Individual nanotubes

TEM AFM

Effect of Surface Oxidation on SWCNTs

on 400

ncen

trat

io

300

350

atio

n C

onm

M N

aCl)

200

250

al C

oagu

l(m

100

150

200

0 2 4 6 8 10 12 14 16 18 20

Crit

ica

50

100

Atomic % Surface Oxygen

If you are going to make If you are going to make If you are going to make If you are going to make quantitative claims use quantitative claims use quantitative techniquesquantitative techniques

Characterization of Oxides on Characterization of Oxides on CNTsCNTs

0.030(C-O-C)

FTIR Spectroscopy

0 020

0.025 (C=C)(C-O-C)ss

(C-O-C)as

bsor

banc

e

0.015

0.020

(O-H)(C=O)

(C-H)b

Ab

0.005

0.010

100012501500175030003250350037500.000

Wavenumber (cm-1)

FTIR identifies oxygen functional groups but provides no quantification

Chemical Derivatization of Surface Oxides?

R t l ti l t ith ifi f ti l Reagent selectively reacts with specific functional groups Reagent contains a CF3 tag. Vapor phase chemical process Vapor phase chemical process

Label chemical quantified by XPS

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