Nanostructured Organic Nanostructured Organic Polymer and Hybrid Materials : Polymer and Hybrid Materials :
From Ultrathin Films to NanoparticlesFrom Ultrathin Films to Nanoparticles
Rigoberto C. AdvinculaRigoberto C. Advincula
Department of ChemistryDepartment of Chemical Engineering
University of HoustonUniversity of HoustonHouston, TX 77204
E-mail: [email protected] www.nanostructure.uh.edu
www.chem.uh.edu
University of Houston
www.nsm.uh.edu, www.chem.uh.edu, www.egr.uh.edu
Nanotechnology, Biotechnology, Materials Research, Molecular Design, Polymers, Superconductivity
Advincula Research Groupwww.nanostructure.uh.edu
Ph.D. Students: Derek Patton, Tim Fulghum, Suxiang Deng, Prasad Taranekar, Yu Shin Park, Jin Young Park, ChengyuHuang, Ted Limpoco, Guoqian Jiang, Imee Martinez, Rebecca Tsai. Chaitanya DandaPast; Chuanjun Xia, Mi-kyoung Park, Xiaowu Fan,Jason LocklinUndergraduates: Mansour Abdulbaki, Jamie Chen, Gabriel Clyde, Past: Risheng Xu, Rusty Rogers, Pemieson DiepPost-Docs and Research Staff: Dr. Akira Baba, Dr. Miko MillanPast: Dr. Seiji Inaoka, Dr. Ji Ho Youk, Dr. Shuangxi Wang, Dr. Qing-Ye Zhou, Dr. Kenji Onishi, Dr. Miko MillanVisiting: Paralee, Hiyoshi, Kawamura,Xinheng Past: Dr.Shinbo, Others: REU, Undergraduates, SEED, Foreign
•• Outline:Outline:• Introduction• Projects• Recent Studies
and Results• Conclusions
AcknowledgmentAcknowledgment
Advincula Research Group
Collaborations:- Zhenan Bao (Stanford)- Wolfgang Knoll (MPI-P)- Futao Kaneko ( Niigata University)- Hiroaki Usui (TUAT)- Jimmy Mays (UT/ORNL)- Norio Tsubokawa (Niigata University)
Funding: - NSF-CAREER- Welch Foundation - NSF Collaborative Research in Chemistry- NSF Chemical Sensors Program- Lintec Corp.- Dow Corning Corp.- Agilent Technologies
Introduction
Nanotechnology
- self-assembly- quantum effects- molecular building
blocks- surface science
Nanostructured Materials
Molecular and Macromolecular Design and Engineering at the nanoscale
-Design, synthesis, characterization-application
Organic and PolymerMaterials
- Surfactants, polymers, dendrimers, molecular organic crystals, films,
micelles, nanoparticles-Functional materials (optical,
electrical, spectroscopic)-Isotropic and “soft”
Inorganic Materials- crystals, quantum dots,films,
nanotubes, nanoparticles- Functional materials (optical,
electrical, spectroscopic)-Anisotropic or long
range order and “hard”
Hybrid materials/Nanocomposites
- Interfacial Phenomena
- Ultrathin Films
- Crystal Eng. - Solid state- High Vacuum
-FundamentalScience
-Technology
Inorganic• Nanoparticles : quantum dots,
nanocrystals, shape anisotropic nanoparticles
• Glasses and Ceramic particles• Ultrathin Films: solid state, high
vacuum, STM, doping, vacuum deposited.
• Superlattice structures: multilayer films, supramolecular structures, patterning
Nanostructured Materials : Inorganic/Metals
Nanostructured Materials : Carbon
Carbon• Carbon-Based
Nanomaterials nanotubes (SWNT and MWNT), fullerenes, polyacene structures
• Electrical and magnetic effects• Nanomechanical properties
Nanostructured Materials: Organic
Organic• Organic Polymers : homopolymers,
block-copolymers, polyelectrolytes
• Dendrimers and hyperbranched molecules – functional macromolecules with controlled shape and dimension
• Small Molecules: organic crystals, dyes, oligomers, amphiphiles
• Supramolecular Assemblies: mesophases, supramolecular structures
• Ultrathin Films: Langmuir-Blodgett films, Self-assembled Monolayers (SAM), Layer-by-layer, epitaxy
Outline of Projects
• Project 1. Electrodeposition and Patterning of Conjugated Polymers Using The Precursor Polymer Approach.
• Project 2. Nanostructured Ultrathin Films of Oligothiophenes and Dyes.
• Project 3. Living Anionic Surface Initiated Polymerization (LASIP) on Nanoparticles
• Project 4. Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte Complexes
• Project 5. Functional Dendrimers as Organic Nanoparticles
• Project 6. Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena
• Conclusions
Project 1
Electrodeposition and Patterning of Conjugated Polymers Using the Precursor Polymer Approach.
NSF-CAREER: DMR 99-82010
Agilent Technologies
Introduction … Conjugated Polymers
• Electro-optically active• Non-linear Optical Materials• Electrically-conducting Polymers• Luminescent Polymers• Lasing Polymers
• Electro-optically active• Non-linear Optical Materials• Electrically-conducting Polymers• Luminescent Polymers• Lasing Polymers
• intractable and insoluble• defects and impurities• mobility and band-gap conditions• processability• patterning
• intractable and insoluble• defects and impurities• mobility and band-gap conditions• processability• patterning
Introduction … Display Devices
Organic Light Emitting Diode (OLED) devices
Organic Light Emitting Diode (OLED) devices
IP (eV)
ITO (-4.8)
Ca (-2.7)
Thickness (ca. 100nm)
e-
h+
e-
e-
Bias V
hν
LUMOs
HOMOs
- Asymmetric structure (diode)
- Electrons are injected in LUMOs
- Holes are injected in HOMOs
- Charge hopping leads to recombination:
e- + h+ --> hν
- Maximum estimated external efficiency < 5%
Print the image with a conducting (PEDOT) and insulating (N) polymers. Coat with continuous layer of EL polymer.
a
acathode (continuous)
EL polymer (continuous)
ITO
PEDOT
Print the image with emitting (EL) and insulating (N) polymers.
cathode (continuous)
plastic substrateITO
PEDOT
plastic substrate
N-polymer R-G-B EL polymers
N-polymer
Print the image with dyes which difuse inside a wide-band emitting polymer film.
cathode (continuous)
plastic substrateITO
PEDOT
N-polymer R-G-B dyeswide-bandEL polymer
Challenges in PLED Patterning
Full color active matrix display CDT-Seiko Epson 1999
Efficiency Green ~20 lm/W @ 100 cd/m2 (2.6V) (>5% external efficiency)
Excellent red, and good blue
Half-life approximated at room temperature: red ~30,000 hr, green>10,000, blue~2,000 h.
Colors Excellent saturation, very close to standard PAL limits.
A- Shadow Masking.
B- Filters
C- Printing (inkjet)
D- Microlithography
E- Electropatterning
F- Self-Assembly
G- Nano-patterning ??
Patterning
Patterning by Electrodeposition
Cyclic
voltammeterReference electrode (Ag/Ag+)
Working electrode (ITO, Pt)
Counter-electrode (Pt)
n M M-(M)n-M
-2(n-1)e-
-2(n-1)H+
Monomers
S S
SS
S
SS
S
H
H
-e
-2H+
n
- Thin Films, R. Advincula, C. Xia, S. Inaoka, D. Roitman “Ultrathin Films of Conjugated Polymers on Conducting Surfaces” M. Soriaga, Editor.
Possibilities for site- directednanopatterning?
Problems with film morphology using traditional monomers
• ill-defined mechanism of film growth• chemical defects• rapid precipitation from solution
• ill-defined mechanism of film growth• chemical defects• rapid precipitation from solution
J. Phys. Chem. B, Vol. 103, No. 40, p.8456, 1999
Precursor Polymers: Electropolymerization approaches to Functional Ultrathin Films and Patterning of Conjugated Polymers
Electrochemistry
Electrochemistry
Electropolymerizable units
Conjugated Polymer systemConjugated Polymer system
Conjugated backboneConjugated backbone
Scheme I
Scheme II
- Baba, A.; Onishi, K.; Knoll, W.; Advincula, R.* J. Phys. Chem. B. 2004, 108, 18949-18955.- Xia, C.; Advincula, R.*; Baba, A.; Knoll, W.* Chem. Mater. 2004, 16, 2852-2856.- Deng, S.; Advincula, R.* Chem. Mater. 2002, 14, 4073-4080.- Taranekar, P.; Fan, X.; Advincula, R.* Langmuir 2002, 18, 7943-7952.
Intermolecular Intramolecular
Polyfluorenes
RR
n
Project 1a.Project 1a. Surface Grafting of Polyfluorenes onto SAM Modified Surface Grafting of Polyfluorenes onto SAM Modified Conducting Substrates by ElectrochemistryConducting Substrates by Electrochemistry
- Blue emitter- PLED Devices- Color-tuning via copolymerization- Synthesis by Suzuki or Yamamoto Coupling- Aggregation behavior as films- Polarized Emission in oriented films
Chuanjun Xia and R. C. Advincula;, Chemistry of Materials 2001, 13(5); p. 1682-1691.
Electropolymerization from Films or Solutions
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
Electropolymerization of P73 from solution
0.44V
10μA
Potential (V vs Ag/Ag+(0.01M))
350 400 450 500 550 600 650
0.0
0.2
0.4
0.6
0.8
1.0
P82 in THF solution
P82 spin-coated film
P82 electropolymerized
spin-coated film
P82 electropolymerized
from solution
INT
(nor
mal
ized
)
Wavelength(nm)
Photoluminescence of P82
Electropolymerization
SAM modified ITOSAM modified ITO
P73 spin-coated film after
electropolymerizationP73 spin-coated film after
electropolymerization
-0.2 0.0 0.2 0.4 0.6 0.8 1.0
0.58V
0.53V
0.78V
Eletrochemistry of the first 5 cycles
of the carbazole monolayer in ACN
0.5μA
Potential (V vs Ag/Ag+(0.01M))
Siloxane polymers• low surface tension• high gas permeability • thermal stability• water repellence
• high dielectric constant
SiO
R
R n
S
R
n• Important conducting polymer• Color tunable light-emitting polymer• Superconducting at low temperature• High mobilities • Non-linear optical polymer
Polythiophene
S
R
Oxidative polymerization by FeCl3
Grignard Coupling
Stille coupling
Electropolymerzation
S
R
BrBrMg
S
R
BrBu3Sn
S
R
n
Project 1 b.Project 1 b. Polysiloxane Modified Polythiophene Precursors
Xia, C.; Fan, X.; Park, M-K.; Advincula, R. “Ultrathin Film Electrodeposition of Polythiophene Conjugated Networks through a Polymer Precursor Route”, Langmuir 2001 17(25), 7893-7898.
Polysiloxane modified polythiophene - crosslinking
S
Br(CH2)9Br
Mg, NidpppCl2 S
(H2C)9Si
O HSi
OSin Si
OSi
OSin
CH2)11
S
SiO
SiO
SinCH2)11
S
Electrochemistry
or FeCl3
m
H2PtCl6
S
I
II
S S
SS
S
SS
S
H
H
-e
-2H+
n
250 300 350 400 450 500 550 600
0.0
0.2
0.4
0.6
0.8
1.0
INT
(nor
mal
ized
)
Wavelength(nm)
-0 .5 0 .0 0 .5 1 .0 1 .5
5 0 0 μ A
P o ten tia l (V vs A g /A g +(0 .01M ))-0 .5 0 .0 0 .5 1 .0 1 .5
2 0 0 μA
P o te n tia l(V vs A g /A g + (0 .0 1 M in A C N ))
-0 .5 0 .0 0 .5 1 .0 1 .5
2 0 0 μA
P o te n tia l(V vs A g /A g + (0 .0 1 M in A C N ))
(a)
(b) (c)
Xia, C.; Fan, X.; Park, M-K.; Advincula, R. Langmuir 2001 17(25), 7893-7898.
Nanostructured electrodeposited layer-by-layer films observed by Surface Plasmon Spectroscopy (SPS)
30 40 50 60
0.0
0.2
0.4
0.6
0.8
1.0
Bare gold Film after 3 cycles
Ref
lect
ivity
Incident Angle [deg]0 2 4 6 8 10 12
0
10
20
30
40
50
60
70
80
thic
knes
s (n
m)
Cycles
θ
prism
glass substrategold layer
organic thin film
HeNe Laser633 nm
photodiodedetector
computer interface
lock-in amplifier
chopper
Knoll, W. Annu. Rev. Phys. Chem. 1998, 49, 569-638.
- Attenuated total reflection (ATR) setup in a Kretschmann configuration, optics is away from the sample and subphase
- Evanescent wave optical technique- Quantitative treatment by the Fresnel theory- PSP excitation observed in reflectivity-angular
scan
Morphology Control from Copolymerization of Monomers and Precursor polymers
AFM image of the Indium-tin oxide (ITO) substrate
Deposited from a solution containing 0.09M thiophene and 0.01M precursor polymer.
0.08M thiophene and 0.02M precursor polymer.
0.07M thiophene and 0.03M precursor polymer.
Morphology dependent on Monomer/Precursor polymer ratio.
Combined SPS-Electrochemical Set-up
- Combined SPS and Electrochemical Cell Set-up- Calculated reflectivity
- Au(50nm)/electrolyte(ε = ε’ + iε” = 1.75 + i0) interface
- Au (50nm)/deposited film (10nm, ε = 2.25 + i0)/electrolyte.
- Kinetic information on the layer formation - monitoring the reflected intensity at a fixed angle, θobs
- Calculated reflectivity change at a fixed angle θobs - function of thickness of deposited film on the Au substrate.
Cyclic redox Stability of Cross-linked Films
• Potential Ramp, SPS and SPFELS kinetic curves during electro-deposition of different ratios of monomers and precursor polymers in the methylene chloride containing 0.1 M TBAH up to 5 cycles.
• Reversibility of cycle different with composition
• Changes in internal morphology with doping and dedoping – also composition dependent
Synthesis of Polysiloxane modified polypyrroles
BrNK N
H
Si
CH3
O
H2PtCl6
Si O
CH3
Si O
N N
CH3
Si
N
CH3
O Si
N
CH3
O
Electropolymerization
n
n
m
n
Si
N
CH3
O Si
N
CH3
O n
NH NH
NH
NH
NHHH - 2H+
NH
NH
NH
NH
NH
. . . . . .
+Electrode Surface
+ + + + + + ++300 400 500 600 700 800 900 1000 1100
0.1
0.2
0.3
0.4
0.5
0.6
Abso
rban
ce
Wavelength(nm)
Py100%Py50%Py25%Py10%Py05%PP100%
Taranekar, P.; Fan, X.; Advincula, R.* Langmuir 2002, 18, 7943-7952.
PrecursorPolypyrrole
PrecursorPolypyrrole
SAM modified ITOSAM modified ITO
Project 1c. Polypyrrole Precursors: “Nanodots” on Polypyrrole fiProject 1c. Polypyrrole Precursors: “Nanodots” on Polypyrrole filmslms
Electropolymerization ofPrecursor Polypyrrole
Electropolymerization ofPrecursor Polypyrrole
Nano-dots on Polypyrrole FilmNano-dots on Polypyrrole Film
• Designed synthesis • Morphology studies.• Electrochemistry• Spectroscopy • size of dots dependent on monomer: precursor polymer ratio.
OCH3SI O
CH3SI
CH3SI
N N N
OCH3SI O
CH3SI
CH3SI
N N N
Electropolymerization
nn
m
Synthesis of Poly (6-pyrrol-1-yl-hexyl methacrylates)
Electropolymerization
CH2Cl2/ TBAHN
(CH2)6
OH
CH3
C
O
CH2O
(CH2)6
N
Cl
O OO
(CH2)6
N
CH3
C
O
CH2O
(CH2)6
N
CH3
C
O
CH2O
(CH2)6
N
CH3
C
O
CH2O
(CH2)6
N
THF/ AIBN
1 2 3
CH2CCH3
+Electropolymerization
CH2Cl2/ TBAHNH
NH
NHa b
OO
N
n CH2CCH3
OO
N
n p: mole% of pyrrole in the solution p=1% Py 1% p=5% Py 5% p=10%Py 10% p=20% Py 20% p=50% Py 50% p=80% Py 80%
Non-conjugated Precursor Polymer
Conjugated Polymer
300 350 400 450 500 550 600 650
b)
a)
Py 5% Py 10% Py 20% Py 50% Py 80%
Abso
rban
ce
Wavelength (nm)
Intermolecular Intramolecular
- Deng, S.; Advincula, R.* Chem. Mater. 2002, 14, 4073-4080.
PrecursorPolypyrrole
PrecursorPolypyrrole
ElectropolymerizationElectropolymerization
Project 1d. PMMAProject 1d. PMMA--Polypyrrole Precursor Ultrathin FilmsPolypyrrole Precursor Ultrathin Films
Comparison of Morphology ofPolypyrrole and Precursor
Comparison of Morphology ofPolypyrrole and Precursor
Higher optical qualityHigher optical quality
• Optical studies• Electro-optical studies • Applications
-1.0 -0.5 0.0 0.5 1.0 1.5
0.0001
0.0000
-0.0001
-0.0002
-0.0003
Conjugated Polymer 1-2 1 2 3 4~33 34 35
I [A]
E[V] (vs. Ag/AgCl)
NO
O
NO
O
NO
O
NO
O
NO
O
NO
O
NO
O
NO
O
NO
O
HH
NO
O
NO
O
NO
O
NO
O
NO
O
NO
O
- 2H+
. . . . . .
+Electrode Surface
+ + + + + + ++
+Electrode Surface
+ + + + + + ++
dedopeddedopeddopeddoped
Project 1e. Polyvinylcarbazole (PVK) to polycarbazole
n
N
Film formation and cross-linking was found above 0.8 V by CV.
Two peaks of 0.6 - 1.2 V and above 1.2 V.
Potentiostatic or CV method
DC conductivity: Dielectric properties
PVKPVK
N
N
N
N
ClO4
ClO4ClO4
ClO4
-2 H+
N
N
m
inter-molecular- highly cross-linked
-10
-5
0
5
10
15
0 0.5 1 1.5
Voltage E/(V vs.Ag/AgCl)
Cur
rent
I [m
A]
1 510
20
15Low cross-link
PVK and Polyfluorenes: Work-Function Tunable PLED Devices
Si
N
Si
N
N
Si
N
N NN
NN
N N
Si Si
N
SiGlass
PVK / CzPFO
Al
ITO
X
PFO
PLED Performance changes withDoping of PVK Films: hole-transport
Baba, A.; Onishi, K.; Knoll, W.; Advincula, R. J. Phys. Chem. B 2004, 108, 18949-18955
Micro-contact Printing of SAMs
ODT
Gold
Stamp
Schematic representation of microcontact printing
PDMS Stamp
ODTsolution
Ink
ODT
Driedunder niotrogen
Micropatterned ODT SAM
ODT SAM
Patterning strategies: Micro-contact Printed Electrodeposition
0 100 200 300 400 500
4.0x10-5
6.0x10-5
8.0x10-5
1.0x10-4
1.2x10-4
1.4x10-4
1.6x10-4
1.8x10-4
2.0x10-4
2.2x10-4
0.75V 0.77V 0.79V
Cur
rent
(A/c
m2 )
Time (s)
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
-0.0004
-0.0002
0.0000
0.0002
0.0004
0.0006
on SAM
Cur
rent
(A/c
m2 )
Potential (V vs Ag/Ag+)
-0.0004
-0.0002
0.0000
0.0002
0.0004
0.0006
on Bare gold
Cur
rent
(A/c
m2 )
Micro-contact printing of SAM monolayer
-selective deposition of precursor polymer both by potentiostatic and CV methods
Micro-contact printing of SAM monolayer
-selective deposition of precursor polymer both by potentiostatic and CV methods
N
N
N
0.4 0.4
0.2
- Xia, C.; Advincula, R.*; Baba, A.; Knoll, W.* Chem. Mater. 2004, 16, 2852-2856.
Electrochemical Nanolithography of PVK? Yes• Electropolymerization and crosslinking of PVK• Substrate patterning independent of template• Robust patterns with height profile
Valiyaveetil, S.; Advincula, R.; Subbiah Advanced Materials 2005 in press.
NCHCH2
NCH CH2
HH
HH
n
+
n
+
NCHCH2
NCH CH2
HHHH
n
+
n
+
NCHCH2
NCH CH2
HH
n
n
-2H+
Further oxidationpolymerizationcross-linking
- 2eN
CHCH2 n
(c)
2
H2C CH
Nn
(b)
3,6ReactivityAu
PVK
Water meniscus
AFM tip
(a)
Au
PVK
AFM tip
(a)H2C CH
Nn
(b)
3,6Reactivity
Control of Nanopatterning Features
0.5μ
m/s
1 μm
/s
1.5μ
m/s
2 μm
/s
2.5μ
m/s
3 μm
/s
0.5μ
m/s
1 μm
/s
1.5μ
m/s
2 μm
/s
2.5μ
m/s
3 μm
/s
The nanopatterning of PVK film by writing lines with varying speed at constant voltage of -7v.
The polymer nanopatterns of line drawn at varying voltage of -3v to -10v at constant tip speed of 1 µm/s. Varying feature size ranging from 35 nm to 250 nm was observed.
Applied bias Vs Pattern Height
01234567
4 6 8 10 12
Applied Bias (-V)
Patt
ern
Hei
ght (
nm) PVK
Carbazole
Applied Bias Vs Pattern Width
0100200300400500600
4 6 8 10 12
Applied Bias (-V)
Patt
ern
wid
th (n
m)
PVK
Carbazole
(a) (b)AFM tip speed Vs Line Width
050
100150200250300
0 2 4 6 8 10 12
AFM tip speed (μm/s)
Line
Wid
th (n
m)
carbazolePVK
(c)
Applied bias Vs Pattern Height
01234567
4 6 8 10 12
Applied Bias (-V)
Patt
ern
Hei
ght (
nm) PVK
Carbazole
Applied Bias Vs Pattern Width
0100200300400500600
4 6 8 10 12
Applied Bias (-V)
Patt
ern
wid
th (n
m)
PVK
Carbazole
(a) (b)AFM tip speed Vs Line Width
050
100150200250300
0 2 4 6 8 10 12
AFM tip speed (μm/s)
Line
Wid
th (n
m)
carbazolePVK
(c)
Geometric Patterns based on Voltage Bias and Speed
(d)(d)(b)(b) (d)(d)(b)(b)(b)
(c)(c)
1 μm/s
-5V -5V-7V
-9V5 μm/s
10 μm/s20 μm/s
84nm
(a)
-9V
μm/s20 μm/s
-9V
μm/s20 μm/s
Valiyaveetil, S.; Advincula, R.; Subbiah JACS 2005 submitted.
SPM Monitoring of PatternedSPM Monitoring of Patterned--Electrodeposition of PolypyrroleElectrodeposition of Polypyrrole
θ0
He-Ne Laser (632.8 nm)
Polarizer
Lenses
CCD cameraElectrochemicalinstrumentation
Electrochemical cell
Microcontact Printed SAM (ODT) Polypyrrole
Au
Electropolymerization
45 50 55 60
0
1
Incident angle /deg
Ref
lect
ivity
Au Au/Polymerθ c
θobs
Reflectivity(at observation angle)
High (Au/Polymer)
Low (Au)
CCD screen
Experimental set-up for Electrochemical-surface plasmon microscopy (EC-SPM)
Experimental set-up for Electrochemical-surface plasmon microscopy (EC-SPM)
EC-SPMEC-SPM
Baba, A.; Advincula, R.; Knoll, W. " Evaluation of Electropolymerization Process of Pyrrole on Micropatterned Self-Assembled Monolayers" Polym Mat. Sci.Eng. Prep.(Am.Chem.Soc.,Div. PMSE), 2002 86, 48.
Microcontact-printing of Octadecylthiol on Au
ODT
Gold
Stamp
Schematic representation of microcontact printing
PDMS Stamp
ODTsolution
Ink
ODT
Driedunder niotrogen
Micropatterned ODT SAM
ODT SAM
0.86 V 50 60
0.4
0.6
0.8
Incident angle /deg
Ref
lect
ivity
Au Au/ODT
μCP Printing of ODT on Au, probed by SPS, SPM, and AFM: Resolution and patterning limits
μCP Printing of ODT on Au, probed by SPS, SPM, and AFM: Resolution and patterning limits
Electropolymerization process of pyrrole on Micropatterned Self-assembled Monolayers: EC-SPM
50 60 70
0.2
0.4
0.6
0.8
Incident angle /degree
Ref
lect
ivity
Au/MCP ODT
after 1 cycle
Exp.Calc.
ODT
Polypyrrole film
ODT
PDMS stamp
Gold
Stamp
Electropolymerization on MCP SAM
Change in reflectivity with polymer growth on pattern vs. Time- Different potential
Change in reflectivity with polymer growth on pattern vs. Time- Different potential
Polym Mat. Sci.Eng. Prep.(Am.Chem.Soc.,Div. PMSE), 2002 86, 48.
anodic
cathodic
EC-SPM: Different Angles and potentials
D=14nm
50 60 70
0.2
0.4
0.6
0.8
Incident angle /degree
Ref
lect
ivity
Au/MCP ODT
after 1 cycle
Exp.Calc.
60.0 °
61.0 ° 62.0 °
59.0°
80μm
0
100
Inte
nsity
[a.u
.]
0
100In
tens
ity [a
.u.]
0 100 2000
100
distance/μm
Inte
nsity
[a.u
.] 0.4 V
0 100 200distance/μm
OCP
0.0 V
0.9 V
0.4 V
0.0 V
-reflectivity changes with angle-Sensitivity to thickness and dielectric constant - reflectivity changes with potential
-reflectivity changes with angle-Sensitivity to thickness and dielectric constant - reflectivity changes with potential
Outline of Projects
• Project 1. Electrodeposition and Patterning of Conjugated Polymers Using The Precursor Polymer Approach.
• Project 2. Nanostructured Ultrathin Films of Oligothiophenes and Dyes.
• Project 3. Living Anionic Surface Initiated Polymerization (LASIP) on Nanoparticles
• Project 4. Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte Complexes
• Project 5. Functional Dendrimers as Organic Nanoparticles
• Project 6. Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena
• Conclusions
Project 2
Nanostructured Ultrathin Films of Oligothiophenes and Functional Dyes.
NSF-CAREER: DMR 99-82010
Field Effect Transistor (FET) Devices
SiliconSubstrateGate
molecularlyassembledoligothiophenesemiconductor
source drain
source drain
BOTTOM CONTACT
TOP CONTACT
SiO2
- Semiconductor layer supports a channel of holes (p-type) or electrons (n-type) between the source and drain electrodes.
- Density of charge carriers in the channel is modulated by voltage applied through the gate electrode.
- The most important criteria for a FET semi-conductor are: high charge carrier mobility, high current modulation (on/off current ratio), stability, and processability.
Application … FET Devices
Bao, Z.; Lovinger, A.. Chem. Mater. 1999, 11, 2607-2612
Ultrathin Films: nanometers to μm
spin-coating
self-assembled monolayer (SAM) Langmuir-Blodgett-Kuhn (LBK)
vacuum depositionand OMBEalternate polyelectrolyte
deposition (APD)
-
- - -
------
----- ++
+
+++
++
----
----
+ ++++̀ +
++
++++
+
+++
++
--
--+ ++++̀ +
++
++
+
+++
++
---
------
-----
• Thickness of a few nm to μm• Solution, interface, vacuum methods• Substrate support or free-solution
entities (micelles, lipids)• Multilayer films• Superlattice structures• Epitaxy
• Thickness of a few nm to μm• Solution, interface, vacuum methods• Substrate support or free-solution
entities (micelles, lipids)• Multilayer films• Superlattice structures• Epitaxy
Nanostructured Layer-by-layer Self-assembly
• Electrostatic (coulombic forces)• Interfacial phenomena and colloids• Solution properties: concentration,pH
salts,temperature• Surface sensitive techniques
-
- - -
------
----- ++
+
+++
++
----
----
+ ++++`
++
+
++
++
+
+++
++
--
--+ ++++`
++
+
++
+
+++
++
---
------
-----
Colloid particles
Polyelectrolytes coated-particlesHollow sphere shells
polyelectrolyte polyelectrolyte
Layer-by-Layer in the Advincula Research Groupwww.nanostructure.uh.edu
Nanostructured Layer-by-layer Organic and Polymer Materials
- Photoalignment films with dyes
- PLED and FET devices
- Biofunctional Films for Microarrays and Sensors
- ph-Sensitive Ion-Permselective Membranes
- Functional Colloidal Particles
• Advincula, R. et.al. J. Am. Chem. Soc. 2004, 126, 13723-13731.• Advincula, R. et.al. Chem. Mater. 2004, 16, 5063-5070.• Advincula, R. et.al. Langmuir 2003, 19, 8550-8554.• Advincula, R. et.al. Langmuir 2003, 19, 654-665.• Advincula, R. et.al. Langmuir 2003, 19, 916-923.• Advincula, R. et.al. Chem. Mater. 2003, 15, 1404-1412.• Advincula, R. et.al. Colloids Surf. A 2002, 198-200, 917-922.• Advincula, R. et.al. Langmuir 2002, 18, 4532-4535.• Advincula, R. et.al. Langmuir 2002, 18, 4648-4652.• Advincula, R. et.al. Chem. Mater. 2002, 14, 2184-2191.
Project 2a. Cross-Linked, Luminescent Spherical Colloidal and Hollow-Shell Particles
BrBr
N NBr- Br-
BuLi, dibromohexaneTHF, -78C
TMEDA
DMF/MeOH(1:1), 50Cn
Ionene 1
CH2
(CH2)5 (CH2)5
H2C N (CH2)2 N
Br- Br-
n
(a) PI
CH2 CH
SO3-Na+
m
(b) PSS
500 nm
1 μm
0 1 2 3 4 5 6 7 8 9 10-60
-40
-20
0
20
40
ζ-Po
tent
ial (
mV
)
Number of Layers
0 1 2 3 4 5 6
0
5
10
15
20
25
30
35
Laye
r Thi
ckne
ss [n
m]
Number of Layers
300 350 400 450 500 5500.0
0.2
0.4
0.6
0.8
1.0
Before Cross-linking of Fluorene After Cross-linking of Fluorene
Inte
nsity
[nor
mal
ized
]
Wavelength [nm]
n
CH3CNFeCl3
Park, M-K.; Xia, C.; Schütz, P.; Caruso, F. Advincula, R.“Cross-Linked, Luminescent Spherical Colloidal and Hollow-Shell Particles” Langmuir, 2001, 17 (24),7670 -7674.
Project 2b. Nanostructured Films of Oligothiophenes using the Layer-by-layer Approach
SBr SBr S
S
1. Mg, Ether
2.1. LDA
2. Br BrS
S Br
SS
SnBu3Bu3Sn+
SS
SS
SSBr
Br
Stille Coupling
SS
SS
SSN
N
Trimethylamine/THF
SS Br NBS/DMF
SS Br
Br
0 100 200 300 400-100
0
100
200
300
400
500
600
700
800
900
10-5M in H2O 10% THF 20% THF 90% THF 92% THF 94% THF 96% THF
Inte
nsity
Wavelength(nm)Xia, C.; Locklin, J.; Youk, J.; Fulghum, T.; Advincula, R. “Distinct Aggregation and Fluorescence Properties of a Water-Soluble Oligothiophene (6TN) Bolaform Amphiphile, Langmuir 2001; 18(3); 955-957. .
- water soluble- bolaform amphiphile- Distinct aggregation- fluorescence and absorption
SYNTHESIS
Spectroscopic, Ellipsometric, and SPS Characterization
300 400 500 6000.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
1st Layer 2nd Layer 3rd Layer 4th Layer 5th Layer 6th Layer 7th Layer 8th Layer 9th Layer 10th Layer
Inte
nsity
Wavelength (nm)
0 2 4 6 8 10 12 14 16 18 20
0
50
100
150
200
250
Pure H2O 30% THF
Thic
knes
s in
Å
Number of Layers
30 35 40 45 50 55 60
0.0
0.2
0.4
0.6
0.8
1.0
Ref
lect
ivity
Incidence Angle (θ)
Average Layer ThicknessPure H2O+6T+= 13.01 ÅPSS = 9.25 Å
30% THF+6T+= 6.88 ÅPSS= 4.30 Å
R. Advincula, J. Locklin, J. Youk, C. Xia, M.K. Park, X. Fan “Nanostructured Ultrathin Films of Water-soluble Sexithiophene Bolaform Amphiphiles Prepared Using Layer-by-Layer Self-Assembly”-Langmuir 2001; 18(3); 877-883.
AFM and XPS Characterization
1400 1200 1000 800 600 400 200 0
0
1000
2000
3000
4000
5000
6000
Na 1s
C KLL
O KLL
C 1s
Na KLL
O1s
Inte
nsity
(cou
nts
per s
econ
d)
Binding Energy (eV)
S
S
S
S
S
S
N+
N+
o
40o
36.5 A
Average aggregate size from AFM = 31.7 Å
Calculated tilt angle of aggregate from substrate = 58º
Tilt angle of 6T component = 18-22º
Langmuir 2001; 18(3); 877-883.
Fan, X.; Locklin, J.; Youk, J. H.; Blanton, W.; Xia, C.; Advincula, R.; “Nanostructured Sexithiophene/Clay Hybrid Mutilayers: A Comparative Structural and Morphological Characterization”, Chem. Mater. 2002; 14(5); 2184-2191.
0 -20 -40 -60 -80 -100
0
-1
-2
-3
-4
-5
-6
0 V
-20 V
-40 V
-60 V
-80 V
-100 V
Dra
in C
urre
nt (μ
A)
Drain-Source Voltage (VDS)
Transistor Activity: p- and n- channel
6TN (in 0.03 M NaCl) was solution cast onto polyelectrolyte covered Si wafer and solvent was evaporated under precise conditions
0 20 40 60 80 100-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
100 V
80 V
60 V
40 V
20 V
0 V
Dra
in C
urre
nt (μ
A)
Drain-Source Voltage (VDS)
Mobility: 0.008 cm2/V.sOn/Off ratio: 10
VDS from 0 to -100 V in 5 V incrementsVG from 0 to -100 V in 20 V increments
Mobility: 0.006 cm2/V.sOn/Off ratio: 9
VDS from 0 to 100 V in 5 V incrementsVG from 0 to 100 V in 20 V increments
Vg
VdId
Source Drain
Layer-by-layer Phthalocyanine Ambipolar FETs
Project 2c.Project 2c. Nanoparticle formation from Poleylectrolyte Nanoparticle formation from Poleylectrolyte Complexes of Complexes of SexithiophenesSexithiophenes
HAuCl4
Fast
Slow
PSS+ATTComplex
Wavelength (nm)
250 350 450 550 650
Abs
orba
nce
0
1
2
3
0.19/10.38/10.95/11.91/13.82/15.73/1TT+PSSSolution
250 350 450 550 6500.0
0.1
0.2
0.3
0.4
0.50.19/10.38/10.95/1
TT/HAuCl4
• Suggestion of Mayer and Mark (Eur. Polym. J., 1998, 34, 103)
1. Polymer containing sulfur would have the high affinity to gold surfaces
2. Polymer possessing reducing groups could be very suitable
• PSS increased the solubility of terthiophene amphiphile
S S
S
N+
CH - CH2m
Na+SO3-
CH - CH2m
SO3-
S SS
N+PolyelectrolyteComplex (PEC)
Poly(sodium styrenesulfonate) (PSS)
Amidatedterthiophene
(ATT)
+
Youk, J, H.; Locklin, J.; Xia, C.; Park, M.K. and Advincula, R.”Langmuir 2001 17(15); 4681-4683.
Coupling of Terthiophenes to form Sexithiophenes simultaneous with nanoparticle formation
-
--
-
-
-
--
-
- -
CH - CH2
CH - CH2
N+
(CH 2)6
S
S
CH - CH2
N+
(CH 2)6
S
S
S S
S
S
S
N+
(CH 2)6
l m
n
+.
SO 3- SO 3
-
SO 3-
• Sexithiophene bolaform amphiphile formation
• Mechanism (electrochemical or oxidative) needs to be determined
• Stabilization of gold particles is very important
• Characterization of complexes is very important
• New materials combining metallic, semi-conductor and organic materials: interesting electrical and optical properties.
Wavelength (nm)
250 300 350 400 450 500 550 600 650
Abs
orba
nce
0.0
0.5
1.0
1.5
PSS + ATT + HAuCl4PSS+ ATT + FeCl3PSS + AST
AST
SS
SN
SS
SS
SS
NN
SS
SN +
TEM Characterization
0.38/1 0.95/1 5.73/1
300 nm
- As the terthiophene concentration increases, the size of nanoparticles increases
- Nanoparticle partially stabilized: inhomogeneous growth and aggregation
- Increase in size, loss of spectroscopic properties associated with nanoparticle
Youk, J, H.; Locklin, J.; Xia, C.; Park, M.K. and Advincula, R.” Preparation of Gold Nanoparticles from a Polyelectrolyte Complex Solution ofTerthiophene Amphiphiles” Langmuir 2001 17(15); 4681-4683.
LBL Films as Nanoreactor Hosts for Nanoparticle Synthesis
Preparation of Gold Nanoparticles with PSS: Preparation of Gold Nanoparticles with PSS: WaterWater--soluble Terthiophene Complexsoluble Terthiophene Complex
(Youk et al. Langmuir 2001, 17, 4681.)(Youk et al. Langmuir 2001, 17, 4681.)
• REDOX reaction occurs between the terthiophenemoeity and the Au precursor with formation of AuNanoparticles and sexithiophene• Au nanoparticle partially stabilized by the PE complexresulting in irregular growth and aggregation
Gold Nanoparticle Formation in LBL Multilayer Films
• Red-shift in absorbance of the 3T moiety from 368 to 396 nm attributed to coupling of the terthiophene units to form sexithiophene with simultaneous formation of Au nanoparticles (surface plasmon peak = 580 nm)
• Position of the Au SP band and presence of broad absorption tail around 700 nm indicate aggregation and/or particles that deviate from a spherical geometry
Before After
J. Phys. Chem. B 1999, 103, 7441.Adv. Mater. 1998, 10, 133.
TEM Imaging
TEM image of a 3 bilayer PVP3T/PAA film containing Au nanoparticles after ~ 50 hrs at
60 ˚C/95% humidity. Scale bar = 200 nm.
TEM image depicting dendritic nanostructures formed with the PVP3T/PAA thin film.
Outline of Projects
• Project 1. Electrodeposition and Patterning of Conjugated Polymers Using The Precursor Polymer Approach.
• Project 2. Nanostructured Ultrathin Films of Oligothiophenes and Dyes.
• Project 3. Living Anionic Surface Initiated Polymerization (LASIP) on Nanoparticles
• Project 4. Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte Complexes
• Project 5. Functional Dendrimers as Organic Nanoparticles
• Project 6. Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena
• Conclusions
Project 3
Living Anionic Surface Initiated Polymerization (LASIP) on Surfaces and Nanoparticles:
Preparation of Nanocomposites
Army (ARO): DAAD19-99-1-0106
Grafting Methods for Polymer Brushes
Why Surface Initiated Polymerization (SIP)?- High brush density: ave. distance b/w grafting points < radius of gyration (Rg).- Functionalized surfaces, controlled surface energies, controlled surface chemistry- different methods of initiation: free-radical, ATRP, cationic, anionic,etc.- Model polymerization studies in confined environments- Novel and advanced materials, colloidal particle stabilizers, polymeric surfactants,
nanotechnology
“grafting to” surface bound monomer “grafting from” or SIP
Project 3a.Project 3a. Living Anionic Surface Initiated Polymerization on Living Anionic Surface Initiated Polymerization on Surfaces: Nanostructured SurfacesSurfaces: Nanostructured Surfaces
Grafting to Grafting From
OH
CH2
Cl-SiMe2-(CH2)11
-HCl
O
CH2
SiMe2-(CH2)11
sec-BuLi
O
Bu
SiMe2-(CH2)11 Li
O
Bu
SiMe2-(CH2)11
Li
toluene
growing polymer chain
toluene
toluene
• Polymer Brushes• Why Surface Initiated
Polymerization (SIP)?• Living Anionic SIP
Zhou, Q.; Nakamura, Y.; Inaoka, S.; Park, M.; Wang, Y.; Mays, J.; Advincula, R. in Polymer Nanocomposites, ACS Symposium Series 804, Edited by. Krishnamoorti, R. and Vaia, R.Oxford University Press, North Carolina, 2002.
SIP of Block Copolymers at Si and Au surfaces/substratesSIP of Block Copolymers at Si and Au surfaces/substrates
CH2
HS-(CH2)11OCH2
-S -(CH2)11O
sec-BuLi
Bu
-S-(CH2)11O Li
Bu
-S-(CH2)11O
toluene
Li
Au
toluene
Bu
-S-(CH2)11O
Li
Terminationstep
n
mn
PS
PIThickness = 6 nm ±2 nmΔm = 4.3 × 10-5 g/cm2
Grafting from
35 40 45 50 550.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
gold DPE PI-b-PSR
efle
ctiv
ity
Incident Angle [deg]
4000 3500 3000 2500 2000 1500 1000 500
0.000
0.001
0.002
0.003
C C stretch
C C ring stretch
methylene C-H aromatic C-H
Abs
orba
nce
Wavenumber [cm-1]
Advincula, R. et. al. Polymer Brushes by Living Anionic Surface initiated polymerization (LASIP) on surfaces, Langmuir, ASAP article.
Zhou, Q.; Wang, S.; Fan, X.; Pispas, S.; Sakellariou, G.; Hadjichristides, N.; Mays, J.; Advincula, R. Polymer Preprints (Am. Chem. Soc.), 2001, 42, 59.
Project 3b.Project 3b. Nanocomposite Materials Prepared by Surface Initiated Nanocomposite Materials Prepared by Surface Initiated Anionic Polymerization from NanoparticlesAnionic Polymerization from Nanoparticles
OH
CH2
Cl-SiMe2-(CH2)11
-HCl
O
CH2
SiMe2-(CH2)11
sec-BuLi
O
Bu
SiMe2-(CH2)11 Li
O
Bu
SiMe2-(CH2)11
Li
toluene
growing polymer chain
toluene
toluene
12-20 nm diameter
ClSi(CH3)2(CH2)8-DPE
Tolune O
OO
DPE
Si
SiSi
Si
+excess DPE
O
OO
DPE
Si
SiSi
Si
Stirring 3 days
centrifuge
redissolving
centrifuge
Si-gel- grafting from Si-nanoparticle surface by silane coupling
- Immobilization of the DPE derivative on silica surface
• Polymer Brushes- physisorption “grafting to”,
chemisorption “grafting from”• Why Surface Initiated
Polymerization (SIP)?- Novel, advance materials, colloidal
particle stabilizer, polymeric surfactants
- Model studies in confined environments
• Living Anionic SIP- Polymer conformation control, Higher
brush density- Block and graft copolymers
Zhou, Q.; Wang, S.; Fan, X.; Advincula, R.; Mays, J.; “Living Anionic Surface-Initiated Polymerization (LASIP) of a Polymer on Silica Nanoparticles”, Langmuir 2002; 18(8); 3324-3331.
LASIP on Si Nanoparticle Results
20 25
M=1.3x105
Free polymer
polymer cleaved
from si-gel
Ve, mL
0 100 200 300 400 500 600 700 800 9000.5
0.6
0.7
0.8
0.9
1.0
Initiator bound si-gel
Polymer bound si-gelWei
ght l
oss
(mg)
Temperature (0C)
- Broader Polydispersity on grafted polymer
-Living anionic polymerization mechanism demonstrated
- TGA results suggests stable grafted polymers
LASIP on Clay nanoparticles also reportedFan, X.; Zhou, Q.; Xia, C.; Cristofoli, W.; Mays, J.; Advincula, R.; “Living Anionic Surface-Initiated Polymerization (LASIP) of Styrene from Clay Nanoparticles Using Surface Bound 1,1-Diphenylethylene (DPE) Initiators”,Langmuir 2002; 18(11); 4511-4518.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
12 14 16 18 20 22 24
Monomer content (g styrene/g Si-nanoparticle)
Poly
mer
con
tent
(g
pol
ystr
yene
/g S
i-nan
opar
ticl e
A B CCollection Flask
Vacuum
Clay ParticleStirrer
Filter
Break Seal
Breaker
Other SIP Projects of the Advincula Research Group.
- Advincula, R. et.al. J. Phys. Chem. B. 2004, 108, 11672-11679. - Advincula, R. et.al. Macro. Rapid Comm. 2004, 25, 498-503.- Advincula, R. et.al. Langmuir 2003, 19, 916-923.- Advincula, R. et.al. Langmuir 2003, 19, 4381-4389.- Advincula, R. et.al. Colloids Surf. A 2003, 219, 75-86.- Advincula, R. et.al. Langmuir 2002, 18, 8672-8684.- Advincula, R. et.al. Langmuir 2002, 18, 3324-3331.- Advincula, R. et.al. Langmuir 2002, 18, 4511-4518.- Advincula, R. et.al. Chem. Mater. 2001, 13, 2465-2467.
Outline of Projects
• Project 1. Electrodeposition and Patterning of Conjugated Polymers Using The Precursor Polymer Approach.
• Project 2. Nanostructured Ultrathin Films of Oligothiophenes and Dyes.
• Project 3. Living Anionic Surface Initiated Polymerization (LASIP) on Nanoparticles
• Project 4. Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte Complexes
• Project 5. Functional Dendrimers as Organic Nanoparticles
• Project 6. Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena
• Conclusions
Project 4
Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte
Complexes
NASA (Microgavity): MSFC-NAG8-1678
Project 4a. Nanoparticles Using Star Block Copolymer and Polyelectrolyte Complex with Terthiophene Amphiphile
1. Silver: catalysis, photographic processes
2. CdS: optoelectronics,photoluminescence
3. Gold: optoelectronics, electronics, biosensors
4. Silica: insulator, catalyst support, membrane, filling material
5. Palladium: catalysis6. TiO2: photoelectrochemistry7. Metal oxide: Mg, Ca, Mn, Fe, Co, Ni,
Cu8. Polymer: conducting composite,
drug delivery
Nanoparticles and nanostructured Films; Fendler, J. H., Ed.; Wiley-VCH; Weinheim, 1998.
Iblock copolymers
(Stable and well-defined nanoreactor)
Iblock copolymers
(Stable and well-defined nanoreactor)
Nanoparticles with1. Size and shape uniformity2. Stability
1. Unique properties2. Ordered deposition3. Selective decoration
Nanoparticles with1. Size and shape uniformity2. Stability
1. Unique properties2. Ordered deposition3. Selective decoration
The Concept of Block Copolymers as Nanoreactors
Cationicpolyelectrolytes
Amphiphilicblock copolymers
(PS-b-P2VP)Dendrimers(PAMAM)
Self-assembledmonolayers
(n-Alkanethiols)
• “Stable Nanoreactor” for the control of size and shape of nanoparticles
• Strategies for the gold nanoparticle preparation
Nanoparticles as colloidal systems of a solid-state material -dimensions in between molecules and a bulk solid-state material.
Strategies for the synthesis of nanoparticles: surfactant or polymeric amphiphiles (block copolymers) micelles as a “nanoreactor” for nanoparticle synthesis.
Mechanism - Metal ions trapped inside the particles exposed to precipitating or reducing agents to start nanoparticle growth: the number of metal ions initially trapped inside the particle determine growth.
Key step: Control over the diffusion of reagents into the micelle.
Design: The possibility of attaching coordinating ligands to the polymer in order to stabilize both precursors and nanoparticles within.
Synthesis of Nanoparticles in General
a cb
Schematic representation of the concurrent process during reduction reaction inside block copolymer micelles.
a) Reduction is initiated by the entry of the reducing agent into the core of the micelles loaded by precursor salt.
b) Destabilized micelles exchange block copolymer and may coagulate.
C) “Empty” micelles are formed besides block copolymer stabilized gold particles.
H: reduction agent; O: precursor salt; crystal.
Wavelength (nm)
400 450 500 550 600 650 700
Abs
orba
nce
0.0
0.1
0.2
0.3
0.4
0.5
P4VP (NaBH4)PAMAM Dendrimer (UV)PS-b-P2VP (Hydrazine)
__200 nm
Star block copolymer
(PS-b-P2VP)N:Au=10:1
Reduction of Au in Star Copolymers
N
n m
PS P2VP
1. Synthesis of PS-b-P2VP
2. Synthesis of Star Block Copolymer
PS-b-P2VP + Coupling Agent(EGDMA)
(Ethylene glycol dimethacrylate)H2C=C(CH3)CO-OCH2CH2O-COC(CH3)=CH2
N + HAuCl4NH+ AuCl4
-4HAuCl4 + 3N2H4 --> 4Au + 3N2 + 16 HCl
1. Polyionic block 2. Reduction with Hydrazine
Polyionic star block copolymer Reduction, Nucleation and Growth
Youk, J, H.; Yang, J.; Locklin, J.; Park, M.K.; Mays, J.; Advincula, R.” Controlled Preparation of Gold Nanoparticles using Well-defined Star Block Copolymers” ACS-Polymer Preprints, 2001 42, 2, 358.
- Synthesis by anionic polymerization, complete characterization necessary
-Stability in solution compared to micelles
- Control of diffusion of salts and reducing agent in organic solvents
Youk, J. H.; Park, M.-K.; Locklin, J.; Advincula, R.; Yang, J.; Mays, J.; “Preparation of Aggregation Stable Gold Nanoparticles Using Star-Block Copolymers”, Langmuir 2002; 18(7); 2455-2458.
TEM Characterization of Nanoparticles formed from Star Copolymers
Wavelength (nm)
400 450 500 550 600 650 700
Abs
orba
nce
0.0
0.5
1.0
1.5
2.0
2.5
N:Au=10:1N:Au=10:3N:Au=10:5
__150 nm
• Controlled size of nanoparticles by controlling ratio of salt and reducing agents
• Very stable compared to micelles even after 1 month
• Control of diffusion of salts and reducing agent in organic solvents
• Good polydispersity
• Very stable!
Langmuir 2002; 18(7); 2455-2458.
Outline of Projects
• Project 1. Electrodeposition and Patterning of Conjugated Polymers Using The Precursor Polymer Approach.
• Project 2. Nanostructured Ultrathin Films of Oligothiophenes and Dyes.
• Project 3. Living Anionic Surface Initiated Polymerization (LASIP) on Nanoparticles
• Project 4. Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte Complexes
• Project 5. Functional Dendrimers as Organic Nanoparticles
• Project 6. Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena
• Conclusions
Project 5
Nanostructured Ultrathin Films and Functional Dendrimers
ACS-PRF: 35036-G7
Project 5a.Project 5a. Photoalignment and Synthesis of Photoalignment and Synthesis of AllAll--Azobenzene Azobenzene Functionalized DendrimersFunctionalized Dendrimers
ElectricField
PolarizationDirection
90 0
- Dendrimers as optical Nanoparticles - Anisotropic changes by photoisomerization on globular shape of dendrimer- changes in the refractive index, dielectric constants
N NC
C
C
C
OO
OO
O O
OO
CC
NN
OO
OO
C
C
O
O
NN
OEt
EtO
CC
OO
N
OEt
EtO
N
C
C
NN
O
OO
O C
C
NN
O
OO
O
C
C
O
ONN
EtO
EtO
C
C
O
O
N OEt
EtO
N
C
CN N
O
O O
O
C
C
O
ON N
OEt
EtO
C
C
O
O
N
OEt
OEt
N
C
CN N
O
OO
O
CC
N N
OO
OO
CC OO
NN
OEtEtO
C
C
O
ON
OEt
EtON
CC
NN
OO
OO
C
C
O
O
NN
EtO
OEt
CC
OO
N
EtO
OEt
N
C
C
NN
O
OO
OC
C
NN
O
O O
O
C
C
O
ON N
OEt
OEt
C
C
O
O
NEtO
OEt
N
C
CNN
O
OO
O
C
C
O
ONN
EtO
OEt
C
C
O
O
N
OEt
EtO
N
C
CNN
O
OO
O
CC
NN
OO
OO
CCO
O
NN
EtOOEt
C
C
O
ON
EtO
OEtN
SynthesisMatrix studiesPhotoisomerization
Organic Letters. S. Wang, R. Advincula, “Design and Synthesis of Photo-responsive Poly(benzyl ester) Dendrimers with All-azobenzene repeating units”- ASAP
Synthesis of Azobenzene-functionalized PAMAM Dendrimers
C6H13 NH2
OH
1) NaNO2/HCl0-5 oC
2)
C6H13 NN OH +
BrCH2COOCH2CH3
K2CO3acetone
refluxC6H13 N
N OCH2COOCH2CH3
1) NaOH/ethanlo-waterreflux C6H13 N
N OCH2COOH +
F F
OH
FF
F
DCC/DMAP
CH2CL2
C6H13 NN OCH2COO
FF
F F
F +
n NH2DMF
C6H13NNO
n NH
O
2) HCl (aq)
PAMAM Dendrimer
O(CH2)6NMe3BrNNOOC
F F
FF
F +
Reactive Dye - A
Alternative, Reactive Dye - B
Wang, S.; Park, M..; Advincula, R. Synthesis strategies and photoalignment of azobenzene functionalized dendrimers: Nanostructured ultrathin films and application Strategies, PMSE Preprints, 84, 236, 2001.
PAMAMPAMAM--PP--32A32A
Photoisomerization and Photoalignment Studies on LB-Monolayer
• Studies on Perimeter-Functionalized Dendrimers
• Monolayer prepared by LB Deposition on quartz
300 350 400 450 500 5500.00
0.02
0.04
0.06
0.08
0.10
0.12
Cis
Trans
Abso
rban
ce
Wavelength [nm]
- Deposition at 50 mN/m (high S.P.), molecular area of 620 Å2
- UV-vis spectra under UV light irradiation. - As trans-to-cis photoisomerization proceeds, π−π* band peak about 338 nm decreases, and n-π* absorption band at 440 nm increases.
PAMAMPAMAM--PP--32A32A
350 400 450 5000.00
0.02
0.04
0.06
0.08
0.10
Before Irradiation A⊥ A//
Abso
rban
ce
Wavelength [nm]
Photoalignment
Polarized UV light (>340 nm). A high dichroism - at various irradiation times (up to A(90)/A(0) = 1.45)
E-form, major component -visible light for the n-π* transition.
Photoisomerization
Wang, S.; Park, M..; Advincula, R. PMSE Preprints, 84, 236, 2001.
Bulk Photoisomerization and Photoalignment of PAMAM Dendrimers
300 350 400 450 500 5500.0
0.2
0.4
0.6
0.8
λ m ax = 349nm10-7 M PAMAM-azo in THF Irradiated at 350 nm
Before 5 sec 15 sec 30 sec 60 sec 120 sec 180 sec
Abs
orba
nce
wavelength [nm ]
300 350 400 450 500 5500.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14λmax = 342 nm
PAMAM-azoPhotoisomerization with 350 nm
Before 5 min 15 min 30 min 1 hr
Abs
orba
nce
Wavelength [nm]
Z
X
μtr
Yα
ϕ
e
300 350 400 450 500 5500.00
0.02
0.04
0.06
0.08
0.10
PAMAM-azo 100 % before
2 min 0o
2 min 90o
5 min 0o
5 min 90o
30 min 0o
30 min 90o Ab
sorb
ance
Wavelength [nm]
Advincula, R.*; Patton, D.; Park, M.-K.; Wang, S. “Evanescent Waveguide and Photochemical Characterization of Azobenzene Functionalized Dendrimer Ultrathin Films” Langmuir 2002, 18, 1688-1694.
Attenuated Total Reflection Spectroscopy:Waveguide Experiments
Air n1
Film n2
Substrate n3
Substrate n3
Air n1
Film n2m=0 m=1 m=2
β0 + β1 + mπ = kzd
β0, β1 = phase shiftsm = mode orderkz = wave vector
d = thickness
• Guided optical waves – waveguide modes (reflectivity as a function of angle θc)
• Kretschman configuration• Total internal reflection where n1<n2 and n3> n2 for
waveguide layer (n2 and thickness, d), n3, substrate, n1, air.
y : the direction of polarized lightnx, nz are calculated by TM-mode (p-wave)ny is calculated by TE-mode (s-wave)
Langmuir 2002, 18, 1688-1694.
Evanescent Waveguide Results
30 40 50 60 70
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95 p -po l
50 % P A M A M -A zo + P S be fo re a fte r 4 h r
Ref
lect
ivity
In c ident A ng le [deg ]
3 0 4 0 5 0 6 0 7 00 .6 5
0 .7 0
0 .7 5
0 .8 0
0 .8 5
0 .9 0
0 .9 5s -p o l
5 0 % P A M A M -A z o + P S b e fo re a fte r 4 h r
Ref
lect
ivity
In c id e n t A n g le [d e g ]
3 0 4 0 5 0 60 7 00 .0
0 .2
0 .4
0 .6
0 .8
1 .0 p -p o l
5 % P A M A M -A zo + P S b e fo re a fte r 4 h rs
Ref
lect
ivity
In c id e n t A n g le [d e g ]
3 0 4 0 5 0 6 0 7 0
0 .3
0 .4
0 .5
0 .6
0 .7
0 .8
0 .9
1 .0 s -p o l
5 % P A M A M -A z o + P S b e fo re a fte r 4 h rs
Ref
lect
ivity
In c id e n t A n g le [d e g ]
50% PAMAM-azoPolarization Irradiation
Timenx ny nz nx - ny Thickness
TM (p-wave) 0 hr 1.5047 1.5000 0
2596 nm4 hrs 1.5040 1.4900
TE (s-wave) 0 hr 1.5047 0.0033
4 hrs 1.5007
50 % PAMAM-azo + PS
The ny (same direction with polarization) is decreasing as the irradiation time increases. The nxdoes not change much, but nz (perpendicular to polarization) is decreasing. This result supports the photoalignment result (decreasing of A90).
Little birefringence (nx – ny) observed which is also consistent with photoalignment results.
R. Advincula, D. Patton, M.K. Park, S. Wang “Evanescent Waveguide and Photochemical Characterization of Azobenzene Functionalized Dendrimer Ultrathin Films ”-Langmuir 2002 18(5),1688-1694.
Total Dendrimer SynthesisTotal Dendrimer Synthesis
Two main approaches: Two main approaches: ConvergentConvergent and and DivergentDivergent
Jean M. J. Fréchet* Jean M. J. Fréchet* Chem. Rev.Chem. Rev. 2001,2001, 101,101, 38193819
Project 5b.Project 5b. Total Convergent Synthesis of an Total Convergent Synthesis of an AllAll--azoazo--benzene benzene dendrimerdendrimer
Target dendrimer molecule -The dendrimer is constructed by photo-sensitive azobenzene groups- The azobenzene groups are linked through benzyl ester bonds.
N NC
C
C
C
OO
OO
O O
OO
CC
NN
OO
OO
C
C
O
O
NN
OEt
EtO
CC
OO
N
OEt
EtO
N
C
C
NN
O
OO
O C
C
NN
O
OO
O
C
C
O
ONN
EtO
EtO
C
C
O
O
N OEt
EtO
N
C
CN N
O
O O
O
C
C
O
ON N
OEt
EtO
C
C
O
O
N
OEt
OEt
N
C
CN N
O
OO
O
CC
N N
OO
OO
CCO
NN
OEtEtO
C
C
O
ON
OEt
EtON
CC
NN
OO
OO
C
C
O
O
NN
EtO
OEt
CC
OO
N
EtO
OEt
N
C
C
NN
O
OO
OC
C
NN
O
O O
O
C
C
O
ON N
OEt
OEt
C
C
O
O
NEtO
OEt
N
C
CNN
O
OO
O
C
C
O
ONN
EtO
OEt
C
C
O
O
N
OEt
EtO
N
C
CNN
O
OO
O
CC
NN
OO
OO
CCO
O
NN
EtOOEt
C
C
O
ON
EtO
OEtN
NN CH2OH
EtOOC
EtOOC
NN CH2OH
HOOC
HOOC
NN
COOH
COOHHOOC
HOOC
G-1-OH
AB2-OH
AB4
• Target Molecule: generational control of azobenzene groups• Intelligent molecule: molecular shape and size could be changed upon irradiation
by UV light• Controlled azobenzene group density, a “macrodye”- quantifiable absorbing species• Controlled aggregates or “particulate chromophores” a nanoparticle• Globular shape change and translational movement within the matrix
(environment)
Synthesis: best route!
• Due to synthesis difficulties … design a new AB2 monomer for generation growth
TBDPSOH2C NN
COOH
COOH
-AB2 monomer : two activated carboxylic groups for generation growth and one hydroxymethyl group protected by tert-butyldiphenylsilane chloride (TBDPSCl)
-The protected group TBDPSCl - easy to remove and Stable towards acidic reaction conditions (acetic acid)
AB2
HOH2C NO2 TBDPSOH2C NO2
TBDPSOH2C NO
COOH
COOH
H2N
TBDPSClimidazoleDMF
1) Zn, 33-36 oC, N2
2-metoxyethanol
2) FeCl3, 0 ~5 oC ethanol, N2
acetic acidrt
~0 oC
96%
82%
TBDPSOH2C NN
COOH
COOH
91%
• do nitroso coupling-condensation with aniline
• Higher yields and reproducible towards convergent approach
• Generation growth:Esterification with benzyl alcohol (DCC/DMAP) and deprotect, repeat …
Example: Synthesis of G-4-OH
C
C NNO
OO
O
CC
OO
NN
OEt
EtO
C
C
O
ON
OEt
OEt
NC
CN N
O
OO
O
CC
NN
O OOO
CC
OO
NN
OEt
EtOCC
OO
N
OEt
EtON
CC
NN
O OOO
C
CO
O
NN
OEt
EtOC
C
OO
N
OEt
EtO
N
C
C
NN
O
OO
OC
C
NN
O
OO
O
C
C
O
ONN
EtO
EtO
C
CO
O
N OEt
EtO
N
CC
NN
OH
OOO
G-4-OH
G-3-OH + AB2DCC/DPTS G-4-OSPDBT HF-pyridine
Overall yield 64%The Dendron G-4-OH was easily obtained by coupling G-3-OH with AB2 monomer, using the same coupling reaction condition, in presence of DCC/DPTS, followed by de-protection with HF-pyridine in overall 64% yield.
MALDI-TOF-MS: [M + K] 4723.1 (calcd. for C257H216 N30O60, 4684.5).
All- azobenzene Dendrimer Shape Anisotropic “Organic Nanoparticle”
G-3-OH
NN
HOOC
HOOCCOOH
COOH
+ DCC/DPTS
38%
G-3-4AB4
The first example of photo-responsive all-azobenzene dendrimers bearing up to 29 azobenzene groups for 4 generations were prepared by a convergent approach…
MALDI-TOF-MS: [M+K] 9179.3 (calcd. for C500H418N58O120, 9158.2).
NN
EtO OO
NN
O
O
O
O
OEt
N N
EtOO
O
OEt
NN
EtO
O
O
N
O
OO
O
OEt
NN
EtO
O
O
EtO
NO
N
O
O
O
N
O
N
O
O
ON
O
O
O
O
NN
OEt
O
O
NN
O
OO
O
OEt
NN
OEt
O
O
OEt
NNEtO
O
O
NO
OO
O
OEt NN
EtO
O
OOEt
N
O
NO
O
ON
NN
OEtOO
NN
O
O
O
O
EtO
NN
OEtO
O
EtO
NN
OEt
O
O
N
O
OO
O
OEt
NN
OEt
O
O
OEt
NO
N
O
O
O
N
NN
EtO
O
ON NO
O O
O
EtO
NN
OEt
O
O
EtO
N NOEt
O
O
NO
OO
O
EtON
N
OEt
OOEtO
N
O
N O
O
O
N
Wang, S. and Advincula, R. “Design and Synthesis of Photoresponsive Poly(benzyl ester) Dendrimers with all-Azobenzene Repeating Units, Organic Letters; 2001, 3(24), 3831-3834.
ππ--Conjugated DendrimersConjugated Dendrimers
Luping Yu* Luping Yu* JACSJACS 1997,1997, 119,119, 90799079Klaus Müllen* Klaus Müllen* Chem. Rev.Chem. Rev. 1999,1999, 99,99, 17471747Jeffrey S. Moore* Jeffrey S. Moore* Acc. Chem. Res.Acc. Chem. Res. 1997,1997, 30,30, 402402
Conjugated dendrimers with rigid structures, such as phenylacetylene, phenylene vinylene, and polyphenylene dendrimers have also been developed in recent years.
Project 5 c.Project 5 c. Synthesis and Deposition of Thiophene Synthesis and Deposition of Thiophene DendrimersDendrimers
S
BuLi/C6H13Br
S C6H13
(1)
NBS/DMF
S C6H13Br
(2)
(1) Mg
NidpppCl2
S
Br
Br
SC6H13
S SC6H13
(3) 3T
BuLi/Bu3SnCl SC6H13
S SC6H13
Bu3Sn
(4)
S
Br
Br
Pd(PPh3)4
S
S
C6H13
S
SC6H13
S
S C6H13
S
C6H13
(5) 7T
S
S
C6H13
S
SC6H13
S
S C6H13
S
C6H13
Bu3Sn
(6)
S
S
C6H13
S
S
C6H13
S SC6H13
S S
S
SS
C6H13
S
C6H13
S
C6H13
S C6H13
S C6H13
(7) 15T
Xia, C.; Fan, X.; Locklin, J.; Advincula, R. C.; “A First Synthesis of Thiophene Dendrimers”, Organic Letters 2002; 4(12); 2067-2070.
BuLi/CuClBuLi/CuCl2 2 Coupling to Thiophene DendrimersCoupling to Thiophene Dendrimers
BuLi/CuCl2S
C6H13
S SC6H13
SC6H13
SSC6H13
(8) 6T
BuLi/CuCl2S
S
C6H13
S
S C6H13
S
SC6H13
S
C6H13
S
S
C6H13
S
SC6H13
S
SC6H13
S
C6H13
(9) 14T-1
SC6H13
S SC6H13
(3) 3T
S
S
C6H13
S
SC6H13
S
S C6H13
S
C6H13
(5) 7T
Synthesis of Thiophene DendrimersSynthesis of Thiophene Dendrimers
S
Br
Br S
Br
BrS
Br
BrLDA/CuCl2
(11)
(4), Pd(PPh3)4
(6), Pd(PPh3)4 DMF S
S
C6H13
S
SC6H13
SS C6H13
S
C6H13
S
S
C6H13
S
SC6H13
SSC6H13
S
C6H13
(12) 14T-2
S
SC6H13 S
S
C6H13
S
S
C6H13
SS
S
S
SC6H13
SC6H13 S
C6H13
SC6H13
S
C6H13
S
S
C6H13
S
S
C6H13
S
S
C6H13
S S S
S
SC6H13
S
C6H13
S
C6H13
SC6H13
S C6H13
(13) 30T
11H NMR of the DendrimersH NMR of the Dendrimers
6T
7T
15T
14T-1
14T-2
30T1H-NMR spectra of 6T, 7T, 15T, 14T-1, 14T-2, and 30T in THF-d8 at 290K. For 6T, 14T-1, 14T-2, and 30T, the interior protons on the thiophene ring show singlets downfield; and the exterior protons show doublets upfield. For 7T and 15T, two doublets were found for the two protons at the focal thiophene, one at the most down field, and the other hidden in the singlets.
MALDIMALDI--TOFTOF--MS CharacterizationMS Characterization
1000 2000 3000 40000
5000100001500020000250003000035000400004500050000
30T
Cou
nts
Mass
05000
1000015000200002500030000
14T-2
Cou
nts
05000
1000015000200002500030000
14T-1
Cou
nts
1 8 1 0 1 8 1 5 1 8 2 0 1 8 2 5 1 8 3 0 1 8 3 5 1 8 4 0
3 7 9 0 3 7 9 5 3 8 0 0 3 8 0 5 3 8 1 0 3 8 1 5 3 8 2 0 3 8 2 5 3 8 3 0
1 8 1 0 1 8 1 5 1 8 2 0 1 8 2 5 1 8 3 0 1 8 3 5 1 8 4 0
The MALDI-TOF analysis verified monodispersed masses for 14T-1, 14T-2, 15T, and 30T giving: 1824.0, 1823.6, 1905.3, and 3809.5, respectively. These are consistent with the calculated values: 1823.6, 1823.6, 1905.6, and 3809.2.
Size Exclusion ChromatographySize Exclusion Chromatography
44 46 48 50 52 54Elution Volume
30T14T-114T-2
15T 7T
1.0053202.63809.53809.230T
1.0041791.11905.31905.615T
1.0011903.61823.61823.614T-2
1.0041955.11824.01823.614T-1
1.007989.7___913.57T
DPIMnMALDIMass
UVUV--vis and Photoluminescencevis and Photoluminescence
250 300 350 400 450 500 550 600
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
3T
3T 6T
6T
PL
Inte
nsity
(Nor
mal
ized
)
Abso
rban
ce (N
orm
aliz
ed)
Wavelength (nm)250 300 350 400 450 500 550 600 650
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
7T
14T-1
7T
14T-1
14T-2
14T-2
PL
inte
nsity
(nor
mal
ized
)
Abso
rban
ce (N
orm
aliz
ed)
Wavelength (nm)
250 300 350 400 450 500 550 600 650
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
30T
15T
30T
15T
PL
Inte
nsity
(Nor
mal
ized
)
Abso
rban
ce (N
orm
aliz
ed)
Wavelength (nm)
Broad absorption spectraand finite photoluminescence
Size and configuration dependence
Summary of Optical and Electrochemical PropertiesSummary of Optical and Electrochemical Properties
2.542.5054349730T
___2.6252947315T
2.672.7354945414T-2
2.572.4853450114T-1
___2.825004407T
___2.714764586T
___3.334493723T
Eg (eV) from CV
Eg (eV)PL (nm)Absorption Onset (nm)
-2.5 -2.0 0.0 0.5 1.0 1.5
14T-1
Fc+/Fc
Potential (V)
14T-2
0.5μA/ m m 2
30T
Xia, C.; Advincula, R.*; Locklin, J.; Giess, A.; Nonidez, W. “Characterization, Supramolecular Assembly, and Nanostructures of Thiophene Dendrimers” J. Am. Chem. Soc. 2004, 126, 8735-8743.
Nanoparticle Aggregates on Mica: 14 TNanoparticle Aggregates on Mica: 14 T--11
14T-1, drop casted from 1.1μM solution in THF after slow evaporation
Globular aggregates formedwith different sizes
500nm
Nanoparticle Aggregates on Mica: 30TNanoparticle Aggregates on Mica: 30T
150nm
30T, drop casted from 0.58μM solution in THF after slow evaporation
Small aggregates or individual molecules
Nanoparticle SelfNanoparticle Self--Assembly of 30T on Graphite (HOPG)Assembly of 30T on Graphite (HOPG)
100nm
30T, drop casted from 0.58μM solution in THF after slow evaporation
Epitaixal registry on graphite, Conformation?Molecular modeling needed
Self-assembled structure of TG2-12 on HOPG. STM topographic image. The unit cell dimensions are a=(6.4±0.1)nm, b=(5.4±0.1)nm, α=(78±2)°Tunneling conditions for the STM image: Ut=0.1V, set point current=1nA.
SelfSelf--Assembly of Assembly of 14T14T--11 on HOPGon HOPG
14T-1 on HOPG, films prepared from (a) 0.11μM solution; (b) 1.1μM solution. The solvent was allowed to evaporate very slowly.
Self-assembled structure of 14T on HOPG. STM topographic image. The unit cell dimensions are a=(6.4±0.1)nm, b=(5.4±0.1)nm, α=(78±2)°Tunneling conditions for the STM image: Ut=0.1V, set point current=1nA.
Epitaxial Packing of Epitaxial Packing of 14T14T on HOPGon HOPG
S
S
S
S
S
S
S
S
S
S
S
S
S
S
Xia, C.; Advincula, R.*; Locklin, J.; Giess, A.; Nonidez, W. “Characterization, Supramolecular Assembly, and Nanostructures of Thiophene Dendrimers” J. Am. Chem. Soc. 2004, 126, 8735-8743.
Outline of Projects
• Project 1. Electrodeposition and Patterning of Conjugated Polymers Using The Precursor Polymer Approach.
• Project 2. Nanostructured Ultrathin Films of Oligothiophenes and Dyes.
• Project 3. Living Anionic Surface Initiated Polymerization (LASIP) on Nanoparticles
• Project 4. Nanoparticle Synthesis Using Block Copolymer Micelles, Star Copolymers and Polyelectrolyte Complexes
• Project 5. Functional Dendrimers as Organic Nanoparticles
• Project 6. Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena
• Conclusions
Project 6
Hybrid Nanoparticle-Dendron Materials: Energy Transfer Phenomena
Welch Foundation
CdSe Nanoparticles
www.qdot.com
- Spatial confinement of electronic excitation to physical dimensions of the nanocrystals (particle in a box)
-Strong absorbers (ε = 36,000 -700,000) depending on size
- High surface/volume ratio nanoparticles
Fluorescence efficiency and stability is strongly affected by capping agent
Ligands for Semiconducting Nanocrystals
Some Typical Organic Ligands• Phosphine/Phosphine Oxide, e.g.
trioctylphosphine/trioctyl phosphine oxide
• Alkylamine, e.g. octadecylamine• Dendrimers, e.g. poly(amidoamine)• Electroactive surfactants, e.g.
oligothiophenes, perylene based stabilizers
The nature of the capping agent can have a profound effect on the photophysics of the nanoparticles
– Organic and inorganic capping agents have been employed– Organic ligands offer improved solubility in common organic
solvents
Some Typical Inorganic Shells• Higher band gap materials, e.g. ZnSe• Using this approach, fluorescence
quantum yield has been increased by more than 50%
CdSe
ZnSeCore-shell Structure
Gold Nanoparticles
• Potential applications in optoelectronics, electronics, catalyst, biosensors, etc.
Surface Functionalization of Au NPs Surface Functionalization of Au NPs
OrganicOrganic--inorganic Hybrid Nanostructures: inorganic Hybrid Nanostructures: Advantages and ApplicationsAdvantages and Applications
• From the strong interaction between metal nanoparticles and conjugated polymers, unique photophysical and electrochemical properties are expected to arise leading to a wide range of potential applications in electronic and optoelectric devices
Electroluminescence EnhancementWith Polyfluorene/Au NP nanocomposites
Chem. Mater. 2004, 16, 688.
Recognition and Detection of Biomolecules
JACS 2002, 124, 9606.
Project 6a. Dendron Stabilized Quantum Dot Nanoparticles
Wang et al. JACS 2002, 124, 2293Guo et al. JACS 2003, 125, 3901
Advantages of dendron capping:•Increased thermal, chemical, and photochemical stability•More reliable workup (processing) procedures
Linear- TOPO capped Hyperbranched- Dendron capped
Synthesis and Spectroscopic Properties of Branched P7T
S S C6H13
SBr C6H13
Mg/Ether2,3-dibromothiopheneNi(dpp)Cl2
BuLi, THF, -78oCbromohexane NBS/DMF
S
S
S
C6H13
C6H13 3TS
S
SBu3Sn
C6H13
C6H13
BuLi, THF, -78oCBu3SnCl
S
S S
S
S
S
SP O
HO
OH
C6H13
C6H13
C6H13
C6H13
P7T7T
S
S S
S
S
S
S
C6H13
C6H13
C6H13
C6H13
2,3-dibromothiophenePd(PPh3)4, DMF
BuLi, THF, -78oCdiethylchlorophosphate
BrSiMe3, CH3OH
300 400 500 600 700
Pho
tolu
min
esce
nce
[a.u
.]
Abs
orba
nce
Wavelength, nm
QY = 25 %ε = 23,301Eg = 2.66 eV
Broad Absorbance SpectrumEmission λmax = 521 nm
P7T Ligand Exchange
300 400 500 600 700
0.0
0.2
0.4
0.6
0.8
1.0A
bsor
banc
e
Wavelength, nm
-Deconvolution: ~30 dendrons per nanocrystal- FT-IR can use to follow changes on the P=O stretching region. Peak at 796 cm-1 impt.- Photoluminescence of nanocrystal and dendron are quenched: electron transfer between
ligand and nanoparticle- Synthesis of TOPO-caped CdSe using Peng et. al. procedure J. Am. Chem. Soc. 2001, 123, 183.
CHCl3
Inert Atmosphere
300 400 500 600 700
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Abso
rban
ce
Wavelength, nm
Nanocrystal before P7T/CdSe complex
Photovoltaic Cells: Hybrid Materials
-Nanocrystals are good electron acceptors
- Nanocrystal visible band gap, both conjugated polymer and nanocrystal contribute to absorption
PREVIOUS:Major factor with CdSe photovoltaic cells is the aggregation (phase separation) of CdSe nanocrystals within conjugated polymer matrix.
Huynh, W. et al. Science 2002, 295, 2425
Hybrid Material: Current-Voltage Response of Film
0.0 0.3 0.6
-0.002
-0.001
0.000
Pin= 0.1 mW/cm2
Dark
Cur
rent
(mA
/cm
2 )
Voltage (V)
Voc = 0.62 VIsc = 1.56 x 10-6 A/cm2
FF = 0.3Pin = 0.1 mW/cm2
Power Conversion Efficiency, ηe = 0.29 %
Glass
CdSe capped with thiophene dendronsAl
ITO
Chem. Mater. 2004, 16, 5187-5193
CdSe PS
S
S
S
S
S
S
C6H13
C6H13
C6H13
C6H13
OO
OP
SS
S
S
S
S
S
C6H13
C6H13
C6H13
C6H13
OO
O
P
S
SS
S
S
S
S
C6H13
C6H13C6H13
C6H13
OO O
P
S
SS
S
S
S
S
C6H13
C6H13 C6H13
C6H13
O OO
Energy Transfer in Gold Nanoparticles Capped with α−Functionalized Thiophene Dendrons
Previous Project: Functionalization of PAMAM Dendrimer
S
S S
NHCH2
= tertiary amine
=
=
= unreacted NH2
SC6H13
SSC6H13
POCl3
SC6H13
SSC6H13
CHO G4NH2S
C6H13
SSC6H13
CN G4
H
3T6C
DMF
3T6C-CHO
SC6H13
SSC6H13
CH2 NH G4
+
G4(3T6C)
NaBH3CN
Deng, S.; Advincula, R. C. et.al. J. Am. Chem. Soc. 2005, 127, 1744
1 2
3
4
5
6
7
89
101112
13
14
15
16
17
18
1920
21
Metal Nanoparticle in Dendrimer
Ligand DesignLigand Design
S
C6H13
SS C6H13
O
HN
HS
10
10
S
C6H13
SS C6H13
O
HN
HS
HSC23T6C HSC113T6C
S
O
HN
HS
C6H13
S
S
C6H13
S
S
C6H13
S
SC6H13
HSC27T6CS
C6H13
S
S
C6H13
S
S
C6H13
S
SC6H13
O
HN
HS
HSC117T6C
Ligand Synthesis: 3T and 7TLigand Synthesis: 3T and 7T
SC6H13
SSC6H13
O
OH
SC6H13
SSC6H13
1) n-BuLi
2) CO23) H3O+
NHO
O
O
EDC
SC6H13
S SC6H13
O
ON
O
O
S
C6H13
SS C6H13
O
HN
HSNH2
HS HSC23T6C
S
C6H13
SS C6H13
O
HN
HS10
HSC113T6C
NH2
HS
10
AC6H1
3
S
S
C6H13
S
S
C6H13
S
SC6H
13
SC6H13
S
S
C6H13
S
S
C6H13
S
SC6H13
OH
O
SC6H13
S
S
C6H13
S
S
C6H13
S
SC6H13
O
O
N
O
O
1) n-BuLi
2) CO23) H3O+
NHO
O
O
EDC
SC6H13
S
S
C6H13
S
S
C6H13
S
SC6H13
O
O
N
O
O
NH2HS
S
O
HN
HS
C6H13
S
S
C6H13
S
S
C6H13
S
SC6H13
HSC27T6C
10
SC6H13
S
S
C6H13
S
S
C6H13
S
SC6H13
O
HN
HS
HSC117T6C
NH2HS10
3T and 7T3T and 7TChain Length VariationChain Length Variation
Au NPs Synthesis and hybridizationAu NPs Synthesis and hybridization
Au
SO
HNS
C6H13
S
SC6H13
S
SC6H13
SS C6H13
S
OHN
S
C6H13
S
SC6H13
S
SC6H13
S
S
C6H13
S
OHN
S
C6H13
SS C6H13
S
S
C6H13
S
S
C6H13
S
O
NH
S
C6H13
S
S
C6H13
SS C6H13S
SC6H13
S
O
HN
S
C6H13
S
S
C6H13
SSC6H13 S
SC6H13
S
ONH
S
C6H13
S
S
C6H13
S
S
C6H13
S
S
C6H13
S
O NH
S
C6H13
SSC6H13
S
S
C6H13
S
S
C6H13
S O
NH
S
C6H13
S
SC6H13
S
SC6H13
SSC6H13
2) TBAB
1) AuCl3, DDAB
S
OHN
SH
C6H13
S
S
C6H13
S
S
C6H13
S
S
C6H13
S
S S
O
NH
HS
6.66, m6.85, d
2.76, m7.44, s
6.97, d
6.06, br
2.67, t
1.64, m
1.30, m
0.88, t
3.41, q
1.5
6.66, m
2.76, m
1.64, m
1.64, m1.64, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
0.88, t
1.30, m
S
S S
O
NH
S
6.66, m6.85, d
2.76, m7.44, s
6.97, d
6.06, br
2.67, t
1.64, m
1.30, m
0.88,t
3.41, q
6.66, m
2.76, m
1.64, m
1.64, m1.64, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
1.30, m
0.88, t
1.30, m
Au
NMR and IR ComparisonNMR and IR Comparison
4000 3500 3000 2500 2000 1500 1000
Abso
rban
ce (a
.u.)
Wavenumber (cm-1)
HSC23T6C Au-SC
23T6C
3500 3000 2500 2000 1500 1000
Ab
sorb
ance
(a.u
.)
Wavenumber (cm-1)
HSC11
3T6C Au-SC113T6C
UVUV--vis Spectra: Effects of Different Chain Lengths for 3Tvis Spectra: Effects of Different Chain Lengths for 3T
300 400 500 600 700
349
349
527
350
524
A
bsor
banc
e (a
.u.)
Wavelength (nm)
HSC23T6C HSC23T6C and Au-SC23T6C Au-SC23T6C
300 360 420 480 540 600 660 720 780
342
520
344
513
346
Abs
orba
nce
(a.u
.)
Wavelength (nm)
HSC113T6C HSC113T6C and Au-SC113T6C Au-SC113T6C
300 400 500 600 700
535
531
311
Abs
orba
nce
(a.u
.)
Wavelength (nm)
HSC27T6C HSC27T6C & Au-SC27T6C Au-SC27T6C
300 400 500 600
519
555
A
bsor
banc
e (a
.u.)
Wavelength (nm)
HSC117T6C HSC117T6C & Au-SC117T6C Au-SC117T6C
UVUV--vis Spectra: Effects of Different Chain Lengths for 7Tvis Spectra: Effects of Different Chain Lengths for 7T
MPCs vs. Optically Matched Mixtures
300 400 500 600 700
345 nm
523 nm
Abs
orba
nce
(a.u
.)
Wavelength (nm)
Au-SC23T6C Au NPs & HSC23T6C
Au
S
C6H13
S
S
C6H13
OHN
S
S
C6H13
S
S
C6H13
ONH
S
SC6H13
SS C6H13
O
HN
S
SC6H13
SSC6H13
O
NH
S
S
C6H13
S
S
C6H13
OHN
S
S
C6H13
S
S
C6H13
ONH
S
SC6H13 S
S
C6H13
O
HN
S
S C6H13S
S
C6H13
O
NH
S
Au-SC23T6C
Au OH
O
OHO
OH
O
HO O
OHOOH
O
HOOHO
O
Au NPs
S
C6H13
SS C6H13
O
HN
HS
HSC23T6C
Energy Transfer StudiesEnergy Transfer Studies
400 450 500 550 600
454.5
456.5
Inte
nsity
(a.u
.)
Wavelength (nm)
Au NPs & HSC23T6C Au-SC23T6C
90% fluorescence quenched
400 450 500 550 600 650
453
454
Inte
nsity
(a.u
.)
Wavelength (nm)
Au NPs & HSC113T6C AuSC113T6C
70% fluorescence quenched
3T3T
7T7T
450 500 550 600 650 700 750
532.5
536
Inte
nsity
(a.u
.)
Wavelength (nm)
Au NPs & HSC27T6C Au-SC27T6C
85% fluorescence quenched
450 500 550 600 650 700 750
534.5
540
Inte
nsity
(a.u
.)
Wavelength (nm)
Au NPs & HSC117T6C Au-SC117T6C
60% fluorescence quenched
Conclusions
• Nanostructured Materials are important for improved properties and phenomena
• Nanotechnology owes both to organic and inorganic/metal materials and hybrids.
• Organic and Polymer Synthesis is essential to nanotechnology!• Nanoscale phenomena is observed in a variety of sizes, geometry,
and shapes: ultrathin films to nanoparticles
• An interdisciplinary approach is critical for future growth in this field.