Lee - Organic Materials Chemistry - Spring Review 2013

Integrity  Service  Excellence
DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution
Organic Materials
Chemistry
Charles Lee
Program Officer
AFOSR/RTD
Air Force Research Laboratory
Date: 7 Mar 2013

2DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution
2013 AFOSR SPRING REVIEW
NAME: Charles Lee
BRIEF DESCRIPTION OF PORTFOLIO:
To exploit the uniqueness of organic/polymeric materials
technologies for enabling future capabilities currently unavailable by
discovering and improving their unique properties and processing
characteristics
LIST SUB-AREAS IN PORTFOLIO:
Photonic Polymers/Organics
Electronic Polymers/Organics
Novel Properties Polymers/Organics
NanoTechnology

Organic Materials Chemistry
Research Objective and Challenges
To exploit the uniqueness of organic/polymeric materials technologies
for enabling future capabilities currently unavailable by discovering
and improving their unique properties and processing characteristics
Challenges:
- Discover New Properties
- Control Properties
- Balance Secondary Properties
Approach:
–Molecular Engineering
–Processing Control
–Structure Property Relationship
• Program Focused on developing New and Controlled Properties
• Not applications specific, but often use applications to guide the
properties focuses
0
0.5
1
1.5
2
2.5
3
3.5
0 200 400 600 800 1000
Tensile Modulus (GPa)
CompressiveStrength(GPa)
Pitch Based Carbon Fibers PAN Based Carbon Fibers

4
Self Assembled Micelle vs Covalently Bonded
Micelle for Nanoparticle Synthesis
Zhiqun Lin, Georgia Tech
Fe2O3
Small Molecule Block Co-Polymer Star-Like Molecule
Diameter (nm) 16±1.49 10.8±2.98 10.1±0.5
Grams/L 2.94 1.81 36.2
# Particles/L 2.6×1017 6.6×1017 1.3×1019
Crown Core
Star-Like Micelle
Small Molecule Block
CoPolymer
Star-Like
Molecule
Au – Diameter (nm) 9±0.44 13±2 10.1±0.3
Grams/L 5.11 0.56 20.2
# Particles/L 6.9×1017 2.5×1016 2.0×1018
Pt - Diameter (nm) 73±5.74 6.0±0.98 6.2±0.2
Grams/L 4.86 0.86 26.3
# Particles/L 1.1×1015 3.6×1017 1.1×1019
Fe2O3–Diameter (nm) 16±1.49 10.8±2.98 10.1±0.5
Grams/L 2.94 1.81 36.2
# Particles/L 2.6×1017 6.552×1017 1.3×1019
Cd-Se-Diameter (nm) 8.5±0.65 ----- 9.9±0.3
Grams/L 0.98 ----- 22.8
# Particles/L 5.2×1017
----- 7.5×1018
PbTiO3-Diameter (nm) ----- 50±4.9 9.7±0.4
Grams/L ----- 2.12 31.2
# Particles/L ----- 4.1×1015 7.5×1018

5DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution 5
NPs Synthesis by Novel Amphiphilic
Star-Like Block Copolymers as
Template

Core/Shell Nanoparticles –
with Large Lattice Mismatch
DFe3O4 = 6.1±0.3 nm (core)
DPbTiO3 = 3.1±0.3 nm (shell)
Core/shell nanostructures are
conventionally obtained by dissimilar
materials epitaxy, which requires
moderate lattice mismatches (<2%)
between the two different materials in
order to obtain high-quality core/shell
heterostructures, which would
otherwise be difficult to obtain.
Fe3O4/PbTiO3
 Despite more than 40% lattice mismatch between Fe3O4 and PbTiO3, Fe3O4/PbTiO3
core/shell nanoparticles can be readily crafted by this approach!!!

Hollow Nanoparticles
– Au Nanoparticles
Hollow noble metal
nanoparticles are the subject of
intense research for use in
bioimaging, photothermal
therapy, drug delivery, etc.
The thickness of Au
= 3.2±0.3nm
The diameter of hollow core
= 5.6±0.4nm
Janus Nano-Particles

Phototropic liquid crystals
Tim White, Tim Bunning, AFRL/RX
“Phototropism”: A term used to describe light induced phase changes in liquid crystals.
An example of light induced order-disorder:
365 nm
Azo-NLC
Nematic
Azo-NLC
Isotropic
“Negative” phototropism – S (order parameter) decreases with light

In this case of “positive” phototropism, illumination increases the compatibility of
the napthopyran as the molecular shape becomes planar and quasi-rod like
aligning favorably with the liquid crystalline phases.
365 or 405 nm
Dark
“Closed form” “Open form”
Light Induced Disorder-Order in
Napthopyran (AMI15)/LC Mixtures
• New class of photochromic molecules that increase order upon
light exposure employed for disorder-order transitions.
• Demonstration of full gamut of Light Induced Phase Transitions

AMI15/8CB Mixture
Shows Additional Transition
“Positive” phototropism – S (order parameter) increases with light
32.0 °C 32.0 °C
Nematic Smectic A
32.0 °C
Nematic
AMI15/8CB shows Photoinduced
• Isotropic to Nematic Transition
• Nematic to Smectic A Transition8CB
40.3 °C 40.3 °C
Isotropic Nematic
40.3 °C
Isotropic
Before light With light (365 nm) After light
T. Kosa, L. Sukhomlinova, L. Su, B. Taheri, T.J. White, and T.J. Bunning,” Light Induced Liquid Crystallinity",
Nature, 2012, 485, 347-349.

Different Phase Change
with Chiral Dopant
400 500 600 700 800 900
0
20
40
60
80
100
Transmission(%)
Wavelength (nm)
After irradiation – sample becomes both absorptive and reflective
~ 6 wt% R1011
Before irradiation – sample completely transmissive in VIS and NIR
R1011 – a chiral dopant from Merck
5CB
Before light With light (365 nm) After light
Data collected at AFRL/RX
Data collected at AFRL/RX
AMI15/5CB/R1011 Mixture shows Photoinduced:
• Isotropic to Cholesteric Phase Transition

400 500 600 700 800
0.00
0.25
0.50
0.75
1.00
NormalizedTransmission
Wavelength (nm)
No dichroism evident in isotropic state
400 500 600 700 800
0.00
0.25
0.50
Absorbance(a.u.) Wavelength (nm)
E//N
EN
Dichroism in nematic phase
The mixture changes color and becomes polarized at the same time
(Plain Glasses become Polarized Sunglasses)
Naphthopyran Phototropic Mixtures
Unprecedented “Photo-dichroism”
For the Isotropic to Nematic Transition in
AMI15/5CB Mixtures,
Dramatic light induced changes in dichroic ratio
from ~0 to 0.722

COE Georgia Tech/AFRL
Joint Project
• To craft novel organic-inorganic nanocomposites composed of
Superparamagnetic Iron Oxide Nanoparticles (SPION) intimately and
permanently connected with nematic liquid crystals (LCs) and chiral
azo molecules with high helical twisting power (HTP) for many
potential applications.
potential for application in communication devices, molecular devices, light-controllable
devices, optical display system, optical data recording, photo-optical triggers, polarizers,
and reflectors, and electromagnetic sensors, etc.
With light (365 nm) After light
365 or 405 nm
Dark
“Closed form” “Open form”
Kosa and White et. al, Nature, 2012, (485), 347–349.
Color switching
Light –induced liquid crystallinity

One-Dimensional Palladium Wires
Tobias Ritter (YIP), Harvard U
Background on 1-D Metal Chains:
• Solid-state mixed-valence 1-D chains with Metal–Metal bonds
• Aqueous mixed-valence oligomers
Mixed-valence (d7-d8) oligomers: Pt blues,
Ir blues, Rh oligomers.
[Rh2(bridge)4]2
6
[Rh2(TMB)4]
2+
H2SO4
H2O
[Rh2(TMB)4Rh2(bridge)4Rh2(bridge)4]8
[Rh2(TMB)4Rh2(bridge)4Rh2(bridge)4]2
16
12 Rh Atom Chain -- longest 1-D metal chain
previously characterized
Chem. Ber. 1908, 41, 312.
Science 1982, 218, 1075.
Coord. Chem. Rev. 1999, 182, 263.
Angew. Chem. Int. Ed. 2001, 40, 4084.
J. Am. Chem. Soc. 1981, 203, 2220.
N N
C C
"bridge":
N N
C C
"TMB":
Angew. Chem. Int. Ed. 1969, 8, 35.
Angew. Chem. Int. Ed. 1996, 35, 2772.
J. Organomet. Chem. 2000, 596, 130.
Inorg. Chem. Commun. 2001, 4, 19.
-There are a few reports of infinite 1-D
chains in the solid state with metal–metal
bonds.
-Not solution stable; Solid-state syntheses
• take several days or weeks
• low yield (usually 50% or less)
• small scale (< 100 mg)

N
N
Pd O
O
Pd O
O Me
Me
n
nF
N
N
Pd
O
O
Pd
O
O Me
Me
N
N
Pd
O
O
Pd
O
OMe
Me
XeF2 (1 eq.)
CH2Cl2, –50 °C
97%
1.00 g
1.04 g
New Chemistry – Solution
Processible Palladium Wires
From Dimers to Wires:
• Infinite Pd chains in solid state revealed by X-ray crystallography
• Rapid, High-Yielding, Gram-Scale, Solution-Phase Synthesis
PhICl2
CH2Cl2
-30 °C
Pd-Pd Bond
Formation
N
N
Pd
O
O
Pd
O
O
Me
Cl
Cl
Me
N
N
Pd O
O
Pd O
O Me
Me
Oxidation of dipalladium(III) complexes with coordinating
anions (Cl–) leads to Pd dimers with covalent bond
between the metal atoms.
The polymerization occurs in solution in less than 5 minutes, giving pure material on
large scale

• Lengths up to 750 nm
(>1,300 Pd atoms)
observed in solution
• The longest solution-
stable metal–metal bonded
chain previously reported
with assigned length
contains 12 metal atoms‡.
• Choice of counter-Anion
controls chain length
• Enabled efficient device
fabrication, not possible
with previous 1-D wires
Nature Chem. 2011, 3, 949–953.
‡J. Am. Chem. Soc. 1981, 203, 2220–2225.
Solution Stable 1-Dimensional
Palladium Wire
1-D metal wires are predicted to display room
temperature superconductivity
n
n FN
N
Pd
O
O
Pd
O
O
Me
Me
III
III
Semiconductor350 nm length
(>600 Pd
atoms)
750 nm length
(>1,300 Pd
atoms)

Thin-Film Conductivity:
• Solution processing capabilities allow for thin-film coating
• Four-point probe device used to measure conductivity of 1-D wire polymers film
n
n FN
N
Pd
O
O
Pd
O
O
Me
Me
III
III
Semiconductor
Nature Chem. 2011, 3, 949–953.
Devices were fabricated
using thin films of the 1-D
wire polymers, which
could be deposited from
dichloromethane solutions
either by drop casting or
spin coating.
Four Point Probe Measurement

Tuning of Electronic Properties
5
6
7
8
9
10
0.0037 0.0039 0.0041 0.0043
ln(Conductance)
1/T (1/K)
n
n FN
N
Pd
O
O
Pd
O
O
Me
Me
III
III
Semiconductor
bandgap = 1 eV
Nature Chem. 2011, 3, 949–953
Shorter chains with
more coordinating
fluoride anions display
higher bandgap
Longer chains with less
coordinating BF4
anions display lower
bandgap
bandgap = 0.7 eV
8
9
10
11
12
0.0035 0.00375 0.004 0.00425 0.0045
ln(Conductance)
1/T (1/K)
Tuning Flexibility: • Side Group Solubility
• Counter Ion
• Pd Oxidation State
5
6
7
8
9
10
0.0037 0.0039 0.0041 0.0043
ln(Conductance)
1/T (1/K)
n
n FN
N
Pd
O
O
Pd
O
O
Me
Me
III
III
Semiconductor
bandgap = 1 eV
0.5n
0.5n FN
N
Pd
O
O
Pd
O
OMe
Me
2.5
2.5
Metallic Conductor
Above 200 K
Films based on Pd(III)
wires display
semiconductivity, with
adjustable bandgap.
Films based on
Pd(2.5)display the
first example of a
transition to a
metallic state
observed at ambient
pressure for a
polymer based on 1-D
metal wires.
Solution-stable 1-D metal wires with tunable conductive properties may have an
impact on areas such as:
• Next-Generation Solar Cells
• Molecular Sensors
• Molecular Wires for Nanoscale Circuits

Power Generation with Body Heat
Choongho Yu & Jaime Grunlan, Texas A&M
First demonstration of electricity generation from polymeric materials
Flexible TE polymers
Connected to
a multimeter
Cut by
scissors
Voltage –Time response
Voltage
Time

20DISTRIBUTION STATEMENT A – Unclassified, Unlimited DistributionT(K)
0 5 10 15 20 25
Voltage(mV)
0
1
2
3
4
5
6
7
1 junction
2 junctions
3 junctions
T(K)
0 5 10 15 20 25
Power(nW)
0
5
10
15
20
25
1 junction
2 junctions
3 junctions
Air-stable fabric thermoelectric modules made of
n & p-type composites
Voltage output vs Temperature
(1) Flexible composite (2) Module fabrication
N-type P-type
(3) Multiple junctions in series
1.4 mm
Power output vs Temperature
Voltage and
power are being
increased by:
(a) stacking more
layers;
(b) connecting
more modules
Carbon
nanotubes
+ Paper
(cellulose
fibers)
Carbon
nanotubes +
Poly-
ethyleneimeine
(PEI) +
NaBH4 treatment

Improving Power Factor by Tuning P-type
composites with multiple CNT stabilizers
 Double-walled carbon nanotubes (DWNT) are
stabilized with two different molecules in poly(vinyl
acetate) latex:
 PEDOT:PSS (conductive)
 TCPP (semi-conductive)
50
60
70
80
90
100
0
30,000
60,000
90,000
120,000
150,000
0 10 20 30 40 50
SeebeckCoefficient(μV/K)
ElectricalConductivity(S/m)
DWNT Concentration (wt%)
Electrical Conductivity
Seebeck Coefficient
0
250
500
750
1,000
1,250
1,500
0 10 20 30 40 50
PowerFactor(μW/(m·K2))
DWNT Concentration (wt%)
Highest PF ever
reported for fully
organic composite
at ~500
μW(m·K2)!
Electrical conductivity increases with DWNT
concentration; while the Seebeck coefficient remains
relatively insensitive.
The power factor (S2σ) increases with DWNT concentration and
is within an order of magnitude of traditional inorganics (maroon
shaded region).

Different Module Design Concept
David Carroll, Wake Forest U.
Using Different CNT Compositions and
TE Module Concept
The garment has recently been shown on
CNN International, CNBC, and the
Discovery Channel.

• Laser Refraction
• Optical Signal Processing
• Wave Front Correction
• 3D Holographic Display
• Image Correlation
Photorefractive Polymers
Multi-TD’s Interests

Two Beam Coupling Optical Correlation
Jed Khoury AFRL/RY (11RY01COR)
Cross Correlation in Signals with Cluttered Background
and Poor Discrimination are Issues in Target Recognition
Applications
Breakthrough in Correlation Filter
Success due to Two Efforts
1. The holographic, dynamic range
compression developed by
AFRL/RY (Jed Khoury)
2. Organic photorefractive material
that was developed by University
of Arizona/Nitto Denko
Both efforts funded by AFOSR
George AsimellisCharles WoodsJed Khoury Bahareh Haji-saeed

Computer Simulation Comparing Two-Beam
Coupling Correlation vs SOA Correlation Algorithms
Yaroslavsky
Matched filter Phase-only filter
Two Beam Coupling
Compression filterInput
Using input that has a lot of background
noise, Two Beam Coupling Correlation is:
• 1.5X better than Yaroslavsky Optimal filter
• 10X better than Phase-only filter
• superior to Matched filter (failed to
recognize target)
No correlation filter in the last 50 years, since the first correlation invented by
Vander Lugt (1963), have been designed that can improve simultaneously the
discrimination, the signal-to-noise ratio, and the peak-to-noise ratio.
But the scheme will require very large beam ratio, that will require a
photorefractive material that has very high diffraction efficiency.
L L
Input
PR CCD

BULK PHOTOREFRACTIVE CORRELATION VS
THIN FILM PR POLYMER CORRELATION
Jed Khoury, AFRL/RY
Arcs instead of full rings due asymmetric
dephasing
Thick arc line due broad impulse response
Only first order correlation peaks
Bulk
photorefractive
Thin film photorefractive
polymer
Many orders
Sharp narrow symmetric
Asymmetric
Thick
one
order
broad
Input Image
Full rings, nearly symmetric due to
Negligible dephasing factor in thin film polymer
Narrow rings lines due narrow impulse
response with thin photorefractive polymer
Very narrow and sharp correlation peak due
Narrow impulse response
Numerous correlation orders due very small
dephasing
A Thick BSO Crystal
Point source
(δ-function input)
A Thin Nitto Denko Organic Material
Thick diffracted beam
(Broad impulse response )
Point source
(δ-function input)
Thin diffracted beam
(Narrow impulse response )
Dephasing Factor is small in thin film holographic materials.

Two Beam Coupling Experiment
with PR Polymer Thin Film(1)
Input Data

Two Beam Coupling Experiment
with PR Polymer Thin Film (2)
Input Data

Applied to Synthetic
Aperture Radar Data
CCCCC
CCCCCCCCCC
CCCCCCCCCC
C
Reference
template
Target
Low
resolution
images
synthesized
from
the MSTAR
data base
Dynamic range compression increases
The first correlation filter that can improve simultaneously the
• SNR (100X)
• PNR,
• Discrimination (3 orders of Magnitude)
Correlation filter that outperforms optimal digital correlation filters
Material Chemistry Makes It Possible!!!

Portfolio Trends
Decreasing Emphases:
-Organic Solar Cells
-Organic Transistors
Increasing Emphases:
-Self Assembly in Solid State
-Radical, Spin and Excited State Controlled
Properties

Flexible Photodetector
Summary
• Program Focused on developing New and Controlled Properties
• Not applications specific, but often use applications to guide
the properties focuses
• Scientific Challenges
- Discover New Properties
- Control Properties
- Balance Secondary Properties
• General Approaches
- Molecular Design
- Processing Control
- Establish Structure Properties Relationship

Lee - Organic Materials Chemistry - Spring Review 2013

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Lee - Organic Materials Chemistry - Spring Review 2013