comploids hough 2012 3€¦ · coatings food industry printing biology (e.g. genotyping) |3...

| 1

Outline

Introduction11

44

22

Applications of “Soft” Colloids

Conductive Nanogels for Transparent Electrodes

Temperature Sensitive Microgels

Structured Surfactant Liquids for Cleansing

33

Applications of Attractive Colloids

Colloids and DNA

Silica in Tires

Asphaltenes in Crude Oil

HASE Polymers for Rheology Modification

Applications of Anistropic Colloids

Ellipsoidal Colloids for Inks and Paints

Carbon Nanotubes for New Materials

Silver Nanowires for Transparent Electrodes.





| 2

Ellipsoids pull interface up along sides, down at tipsQuadrupolar symmetry causes long-range attractionSurfactant decreases surface tension. Decreased surface tension

should minimize interfacial deformations, restore coffee ring effectA provisional patent has been filed by UPENN, not including Rhodia.

But we have first knowledge of the technology. Will be tested inpaints.

Evaporation of Elliptical Colloidal Suspensions

Important in many applications Coatings Food industry Printing Biology (e.g. genotyping)

| 3

Evaporation of Elliptical Colloidal Suspensions

YUNNKER P.J., STILL T., LOHR M.A. and YODH A.G., Nature, 476 (2011) 308

| 4

Outline

Introduction11

44

22





33


Colloids and DNA

Silica in Tires











| 5

HOUGH L.A., ISLAM M.F., JANMEY P.A. and YODH A.G., Physical Review Letters, 93 (2004) 168102

Carbon Nanotube Gels

Soft Glassy Rheology

Percolation Exponent common for bond that resist stretching but freely rotate

| 6

Flow Behavior of Carbon Nanotube Gels

| 7

M.B. Bryning, D.E. Milkie, M.F. Islam, L.A. Hough, J.M. Kikkawa, A.G. Yodh, “Carbon Nanotube Aerogels”Advanced Materials, 19 (5), 661, (2007).

New Materials based on Carbon Nanotube Gels

| 8

Outline

Introduction11

44

22





33


Colloids and DNA

Silica in Tires











| 9

Silver Nanowires for Transparent Electrodes

Transparent electrodes = critical components of optoelectronic devices such as displays and solar cells

Indium Tin Oxide (ITO) = most used transparent

conductive oxide Expensive

Limited resources (indium) Not flexible required property for touch

screen and flexible displays

Transparent conductive electrode

PEDOT:PSS High conductive polymer but not enough

Solution: Incorporate network of metal nanostructure in PEDOT:PSS

9 Q. Benito, July 21th 2011

W. Gaynor, G. F. Burkhard , M. D. McGehee , P.

Peumans , Adv. Mater. 2011, XX, 1–6

| 10

Background

Synthesis of Ag nanostructures and nanowires largely reported

Chemical reduction method: Electrochemical reduction Aqueous solution reduction Classic polyol method

Described by Fievet and al. in 1989 for the synthesis of metallic nanoparticles

Synthesis of nanowires : first time 1992 by C. Ducamp-Sanguesa, R. Herrera-Urbina and M. Figlarz from university of Picardie (Amiens, France)

The polyol method did not change dramatically since the first report

Enhanced by Y. Xia and al. from university of Washington (Seattle, USA) in 2002

Reports of silver

nanowires

0

50

100

150

200

250

300

350

4001997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

Num

ber

of

public

atio

ns

[sourc

e

: Web o

f sc

ience

]

Publications about silver nanowires

B. Blin, F. fievet, D. Beaupere, M. Filglarz,

Nouv. J. Chim., 1989, 13, 67.

C. Ducamp-Sanguesa, R. Herrera-Urbina, M.

Figlarz, Journal of solid state chemistry, 1992,

100, 272.

Y. Sun, Y. Yin, B. T. Mayers, T. Herricks, and

Y. Xia, Chem. Mater. 2002, 14, 4736.

| 11

Motivation

Incorporation of Ag Nanowires in PEDOT:PSS [1]

Ag most conductive metal Nanostructure keep the transparency Wires shape percolate at lower concentration than

spheres Nanowires are flexible

PEDOT:PSS/Ag NW has demonstrated its efficiency

Better conductivity than ITO (20 Ω.sq-1 vs. 42 Ω.sq-1) Comparable transparency as ITO on glass On plastic sheet keep conductivity when bent

In Rhodia

PEDOT:PSS/Ag NW (Commercial) on plastic sheet 13 Ω.sq-1

80% forward scattering transmission (not total transmission) at 550nm (ITO ~ 90% on glass)

~30 weight% AgNW load

Roughness of PEDOT:PSS/Ag NW layer is a problem

Rhodia needs to synthesize urhis own Ag NW


Sheet resistance vs radius of curvature for ITO and PEDOT:PSS/Ag NW on PET.

Sheet resistance of PEDOT:PSS/Ag NW

(Commercial) measured in Rhodia

W. Gaynor, G. F. Burkhard , M. D. McGehee , P. Peumans , Adv. Mater. 2011, XX, 1–6

| 12

COMPASSnanowires

Commercialnanowires

~2.0g .. ~$28.6 ~0.1g .. ~$100.0

Motivation for Synthesis

| 13

Polyol method

Ethylene Glycol (EG):

Solvent High dielectric constant: good solvent for

AgNO3 and PVP.Reducer

PolyVinylPyrrolidone (PVP) :

Stabilizer: adsorb on silver surface, prevent aggregation

Directing: adsorb preferentially on 100 plane of fccAg, growth in <111> direction


B. Blin, F. fievet, D. Beaupere, M. Filglarz, Nouv. J. Chim., 1989, 13, 67.

Y. Sun, B. Mayers, T. Herricks, Y. Xia, Nano Lett., 2003, 3, 7.

Y. Gao, P. Jiang, D. F. Liu, H. J. Yuan, X. Q. Yan, Z. P. Zhou, J. X. Wang, L.

Song, L. F. Liu, W. Y. Zhou, G. Wang, C. Y. Wang, S. S. Xie,, 2004, J. Phys.

Chem. B 108, 12877.PVP on Ag surface,

reproduced from [10]

Needs: - AgNO3 = source of silver

- EG

- PVP

(- Additives)

| 14

The decahedral multiple twinned nanoparticles (MTPs)

Decahedral particles with 5-fold symmetry and ten 111 facets at its surface

Formation is driven thermodynamically: MTP shape minimizes the surface energy

Spontaneously created

Nanowires grow from these seeds

Amount of MTPs maximizes the yield of nanowires

Twin defects make then the most reactive (compare to single twinned, single crystal)

Can easily be etch by O2/Cl-


TEM image of sample taken prior to the appearance of silver nanorods. The arrow mark a decahedral MTP of silver . Reproduced from ref [11]

Sheme of decahedral MTP Reproduced from ref [11]


[B. Wiley, Y, Sun, Y. Xia, 2007, Acc. Chem. Res., 40, 1067

| 15

Growth mechanism

Redution of Ag creation of nanoparticules (heterogeneous or homogeneous nucleation)

Expension of large seeds (Oswald repining) formation of decahedral MTPs

Crystallization of Ag on twin boundaries (highest energy site)PVP drive the anisotropic growth in <111> direction

5-fold symmetry of the MTPs conserved during growth Nanowires with a pentagonal cross section


Scheme of growth mechanism . Reproduced from ref [13]


B. Wiley, Y. Sun, B. Mayers, Y. Xia, Chem. Eur. J. 2005, 11, 454 – 463

SEM image of silver nanowires. Reproduced

from ref

| 1616 Q. Benito, July 21th 2011

Silver Nanowires Synthesis

Two step process

Seeds produced in-situ

Use of LiCl as Cl source

Reaction under N2 : reproducibility and no O2 etching

Synthesis temperature: 180°C

Synthesis time: 40 minutes

Pictures of the synthesis at the end

| 17

Silver Nanowires Synthesis: experimental protocol

Typical synthesis:

Heat at 180°C EG + PVP + LiCl under N2

First step: Seeds stepAdd AgNO3 : Ag+ + Cl- AgCl = precipitation

Second step: Add AgNO3 within 20 minutes = growth of wires

Stop at 40 minutes


N2

AgNO3:

N2

AgNO3within 20 minutes

| 18

Cleaning of Nanowires

In order to remove PVP, EG, particles, and disperse NW in other solvent

Centrifugation:

In water or EtOHLow speed too avoid aggregationLong duration timeAddition of surfactant to avoid aggregation

| 19

LiCl is necessary to formed nanowires

Synthesis without LiCl:

Intensity ratio(111)/(200) = 2.5 Silver ParticlesSynthesis with LiCl:

Intensity ratio(111)/(200) = 3.1 Silver NanowiresRatio of bulk silver is 2.5

5 15 25 35 45 55 65 75 85

2θ (degree)

(a) Synthesis without LiCl

(b) Synthesis with LiCl

Ag (111)

Ag (311)Ag (220)

Ag (200)

Ag (222)

b

a

XRD patterns products of synthesis with and without use of LiCl

20 µm

20 µm

Optical microscopy of silver Nanowiresusing 100x oil objective

Optical microscopy of silver Nanoparticles using 100x oil

objective

| 20

Reduction of AgCl

Amount of AgCl/Ag calculated with XRD peaks areas of AgCl (200) and Ag (100)After 7h there is still AgCl (much more than Ag)AgCl is almost not reduced during the synthesis ~ 50 minutes

0

20

40

60

80

100

0 1 2 3 4 5 6 7

Am

ou

nt

Time (Hours)

% AgCl% Ag

| 21

AgCl in wires?

Nanowires centrifugated 15 times no particles observed under

optical microscope

XRD pattern show small peak of

AgCl ~ 2%

AgCl acts as nuclei ?No traces of Cl in NW by EELS

analysis5 10 15 20 25 30 35 40 45 50 55

2θ (degree)

Ag (111)

Ag (200)

28 30 32

AgCl (111)

AgCl (200)

XRD pattern of short and fat nanowires

TEM microscopy of a silver nanowires

| 22

Conditions Make a Difference

Temperature: increase kinetic, increase length of wires reaction at 180°C

Tried at 190°C (EG boiling point = 197°C) lots of particles, shorter wires

Tried at 220°C in DEG: does not work

At low temperature, short wires application in inkjet printing.

Duration of seeds step: increase of length

Amount of the second addition of AgNO3: increase amount of particles

Duration of second addition of AgNO3: no effects (reaction finish earlier)Initial ratio AgNO3 /LiCl: no effects in a limit of (values)

| 23

Confirmed by TGA analysis

Amount of Ag in solution compare to the total amount of AgNO3 (analysis done with TGA)

After 40/45 minutes reaction done


0

10

20

30

40

50

60

70

80

90

100

25 30 35 40 45 50 55 60 65

Po

urc

en

tag

e o

f A

g r

ed

uce

d

Time (minutes)

| 24

Surface Plasmon Resonance

At surface of metals: oscillating mobile electrons Surface plasmons (SPs).

Incident light same wavelength than SPs,Resonance Phenomenon of electrons = Surface Plasmon Resonance (SPR). SPR induce energy absorption at the same

wavelength Absorption peak.

Maximum wavelength correspond to transverse plasmon resonance of the wires

When the diameter of the wires increased, this wavelength is red shifted

[ ] )1(Im2

αλ

π=absC

)2(2/

1/3

+

−=

mp

mpV

εε

εεα

Typical absorption spectra of silver nanoparticles embedded

on different matri.

Cabs = absorption cross

section

λ = light wavelenght

V = particle volume

εp = dielectric function

of the particle

εm = dielectric function

of the particle

Equations which drive SPR.

Plasmonic solar cells, K.R. Catchpole, A. Polman, OPTICS EXPRESS,

2008, 16, 26, 21794

| 25

Equations of resistivity and percolation

Resistivity goes with (1)

Individual resistance of nanowires goes with (2)

Percolation goes with equation (3)


)2(2

dd

LR

Α∝∝ ρρ

)3(1

AL

dc ∝∝φ

J. Chen, B, Wiley, Y. Xia, Langmuir, 2007, 23, 4120

M. B. Bryning, M. F. Islam, J. M. Kikkawa, A. G. Yodh, Adv. Mater.,

2005, 17, 1186

ϕc = critical volume

fraction of percolation

L = length

d = diameter

A = aspect ratioIn 2D

R = resistance

ρ = effective resistivity

L = length

d = diameter

A = aspect ratio

)1()1(0d

λρρ +∝

ρ = effective resistivity

ρ0 = resistivity of bulk

material

λ = characteristic length

scale = 15 nm in [3]

d = diameter

J. Chen, B, Wiley, Y. Xia, Langmuir, 2007, 23, 4120

20 µm

Optical microscope image of percolated silver nanowires, obtained

with 60x oil objective

| 26

Conductivity measurements of PEDOT:PSS/Ag NW

Process do not involved high pressuresMix Ag NW dispersion with PEDOT:PSS

Spin coat a film on plastic or glass sheetDry in ovenMeasure resistivity on a square area

l

d

ld

dl

c =

×

×

=

2

2

2

2

π

π

φ

5.10×=×=l

ddensitycc φρ

%5.35.100.15

05.0=×=

m

mc

µ

µρ

Area Semi dilute is the area of the wire divided by

the area of the disk

| 27

Conductivity VS weight fraction

Here 19 Ω/sq and 76% transmission

Achieved 13 Ω/sq resistivity & 80% transmission(forward transmission)

Close to ITO


70

75

80

85

90

95

100

0 5 10 15 20 25 30

Tra

nsm

itio

n %

Weigth percent of Ag NW in dry film

0

50

100

150

200

250

300

0 5 10 15 20 25 30 35

Sh

ee

t re

sist

an

ce (Ω

/sq

)

Weigth percent of Ag NW in dry film

| 28

PEDOT:PSS:Silver Nanowires mixture comparable to commercial

PEDOT:PSS:AgNW(1) (Commercial) 80% Transmission @550nm ~30 weight% AgNW(1) load

PEDOT:PSS:AgNW(1) (COMPASS) 82% Transmission @550nm Unknown weight% AgNW(1) load

(1) AgNW: Silver Nanowires

| 2929 Q. Benito, July 21th 2011

COMPASS vs Commercial Nanowires

Optical microscope images using 60x oil objective~40 µµµµm average length for Commercial nanowires.~20 µµµµm average length for COMPASS nanowires.COMPASS nanowires diameters are smaller, diameter characterization is on going.

COMPASSnanowires

Commercialnanowires

~2.0g .. ~$28.6

20 µµµµm

20 µµµµm

| 30

Conclusion

Developed method for Ag Nanowires synthesis

High yield

Reaction can be scale up

Length up to 19 µm

Key points to control the dimensions

Ag nanoparticles can be easily obtained (printing electronic)

Ag NW tested in conductive polymersResults close to ITO

Films smoothness still need to be investigated


| 31

Larry Hough Pascal HerveRyan MurphyChantal BadreAhmed Alsayed

JC CastaingQ BenitoD BendejacqJ CorteseA GautierA DoranT FuttererG LaurentP GillotJY DellannoyAS Baehrel

Remi DreyfusCesare Cejas

Arjun YodhDoug DurianShu Yang Dennis DischerCherie KaganAbdullah MahmudYuli WeiTim StillJi Hyuk Choi

Acknowledgements

N. Seeman, D. Pine, P. Chaikin, P. Yunker

comploids hough 2012 3€¦ · coatings food industry printing biology (e.g. genotyping) |3...

Documents