ACS-PRF Summer School on Nanoparticles 2004
Polyelectrolytes and Nanoparticles:
Synthesis and Mediation
Rigoberto C. Advincula
Department of Chemistry
University of Houston
Houston, TX 77204
E-mail: radvincula@uh.edu
www.chem.uh.edu
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Nanoscience or Nanotechnology ?
-
self-assembly
quantum effects
molecular building blocks
surface science
Self-assembly or directed
assembly
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Nanostructured Materials
Molecular and Macromolecular
Design and Engineering at the nanoscale
-Design, synthesis, characterization
-application
- Interfacial
Phenomena
- Ultrathin Films
Organic and Polymer
Materials
- Surfactants, polymers, dendrimers,
molecular organic crystals, films,
micelles, nanoparticles
-Functional materials (optical,
electrical, spectroscopic)
-Isotropic and “soft”
R.C. Advincula/ University of Houston
- Crystal Eng.
- Solid state
- High Vacuum
-Fundamental
Science
-Technology
Inorganic Materials
- crystals, quantum dots,films,
nanotubes, nanoparticles
- Functional materials (optical,
electrical, spectroscopic)
-Anisotropic or long
range order and “hard”
Hybrid materials/
Nanocomposites
ACS-PRF Summer School on Nanoparticles 2004
Convergence of Materials in Interfacial and
Colloidal Phenomena
500 nm
100nm
R.C. Advincula/ University of Houston
•
Quantum dot nanoparticles
•
Colloidal particles
•
Organic nanoparticles
•
Polyelectrolytes, surfactants
•
Hybrid organic-inorganic
•
nanocomposites
ACS-PRF Summer School on Nanoparticles 2004
Innovative Surface Sensitive Analytical Techniques
CCD camera
Electrochemical
instrumentation
Lenses
He-Ne Laser (632.8 nm)
θ0
Polarizer
Au
Electrochemical cell
Electropolymerization
Microcontact Printed SAM (ODT)
•
Scanning probe microscopy
•
Time-resolved and frequency resolved
spectroscopy
•
Evanescent wave techniques
•
Light scattering methods
•
Surface sensitive acoustic methods
R.C. Advincula/ University of Houston
Polypyrrole
ACS-PRF Summer School on Nanoparticles 2004
Patterning Methods and Devices
PDMS Stamp
Ink
ODT
solution
Dried
under niotrogen
ODT
ODT
Stamp
drain
source
ODT SAM Gold
BOTTOM CONTACT
molecularly
assembled
oligothiophene
semiconductor
Micropatterned ODT SAM
Schematic representation of microcontact printing
•
Lithographic and nonlithographic methods
•
Photolithography and soft-lithography
•
Semiconductor devices
•
Display and nonlinear optical devices
R.C. Advincula/ University of Houston
Gate
Silicon
Substrate
SiO2
TOP CONTACT
source
drain
ACS-PRF Summer School on Nanoparticles 2004
Nanoparticles
1.
2.
3.
4.
5.
6.
7.
8.
Silver: catalysis, photographic
processes
CdS: optoelectronics,
photoluminescence
Gold: optoelectronics, electronics,
biosensors
Silica: insulator, catalyst support,
membrane, filling material
Palladium: catalysis
TiO2: photoelectrochemistry
Metal oxide: Mg, Ca, Mn, Fe, Co, Ni,
Cu: magnetic properties
Polymer: conducting composite,
drug delivery
II
Synthesis
Synthesis
(Stable
and
(Stable andwell-defined
well-defined
nanoreactor)
nanoreactor)
R.C. Advincula/ University of Houston
Nanoparticles with
Nanoparticles with
1. Size and shape uniformity
1. Size and shape uniformity
2. Stability
2. Stability
1. Unique properties
1. Unique properties
2. Ordered deposition
2. Ordered deposition
3.3.Selective
Selectivedecoration
decoration
ACS-PRF Summer School on Nanoparticles 2004
Synthesis of Nanoparticles: the Concept of Nanoreactors
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.
•
Strategies for the gold nanoparticle preparation
Cationic
polyelectrolytes
Amphiphilic
block copolymers
(PS-b-P2VP)
Dendrimers
(PAMAM)
Self-assembled
monolayers
(n-Alkanethiols)
• “Stable Nanoreactor” for the control of size and shape of nanoparticles
Nanoparticles and nanostructured Films;
R.C. Advincula/ University of Houston
Fendler, J. H., Ed.; Wiley-VCH; Weinheim,
1998.
ACS-PRF Summer School on Nanoparticles 2004
Synthesis of Nanoparticles in General
a
c
b
Schematic representation of the
concurrent process during reduction
reaction inside block copolymer
micelles.
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.
R.C. Advincula/ University of Houston
0.5
P4VP (NaBH4)
PAMAM Dendrimer (UV)
PS-b-P2VP (Hydrazine)
0.4
Absorbance
a) Reduction is initiated by the entry of
the reducing agent into the core of the
micelles loaded by precursor salt.
Star block
copolymer
(PS-b-P2VP)
N:Au=10:1
0.3
0.2
0.1
0.0
400
450
500
550
600
650
700
Wavelength (nm)
__200 nm
ACS-PRF Summer School on Nanoparticles 2004
Mechanism:
•
Reduction:
HAuCl4
•
•
•
•
Cl
reduction
-
Cl
-
Au
Cl
Cl
-
Reducing agent
(Organic or inorganic reducing agent, UV irradiation, electrochemistry, etc)
The relative rate of Nucleation and Growth of Nanoparticles
- Manage the particle size
γ
Nucleation
RC ∝
Ln(C/C o)
Where Rc is radius of initial particle, γ is interfacial tension, and C/Co is the
degree of supersaturation.
Growth
- Ostwald-ripening process: One particle per domain
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
PS-b-P2VP Micelles Containing Gold nanoparticles:
Aggregation
M. Moller et al., Macromolecules, 2000, 33, 4791.
PS(300)-b-P[2VP Au0.5(300)]
(a) Directly after deduction (b) 30 min after reduction
R.C. Advincula/ University of Houston
A dried film
C=0.01mg/ml solution
ACS-PRF Summer School on Nanoparticles 2004
Organic Ultrathin Film Multilayer Assemblies
Langmuir-Blodgett
(LB) Film
Si O Si
O
O
Si O Si
O
O
Organic
and Polymeric
Ultrathin
Multilayer films
Chemisorption
R.C. Advincula/ University of Houston
Layer-by-Layer
(LbL) Film
•
How different is this from spincoating?
•
Nanostructured multilayer
architecture
•
control molecular orientation and
organization on the nanoscale
•
precisely tunes the macroscopic
properties of the organic and
polymer thin films
•
Applications in microelectronics,
electro-optics, sensors, and
biotechnology
•
To be explored? Organic and
polymer multilayers by vapor
deposition and thermal
evaporation methods
ACS-PRF Summer School on Nanoparticles 2004
Nanostructured Layer-by-layer Self-assembly
from Solution
Deposition Process
Equilibrium of Deposition
•
•
•
•
Electrostatic (coulombic forces)
Interfacial phenomena
Solution properties:
concentration,pH
salts,temperature
Surface sensitive techniques
R.C. Advincula/ University of Houston
++++++-
-
+++++++ -
-+`+ ++
-+ +
-+ +
-+ +
-+
+++++
++---
-+`+ ++
-++ ++
-+
-+ +
-
ACS-PRF Summer School on Nanoparticles 2004
Structure – Fuzzy Nanoassemblies?
1.0
0.6
0.4
substrate
Relative Composition
(A/Bd)n
0.8
0.2
- Neutron reflectometry
Bragg peaks appear (NR-3 ~6)
((A/B)m(A/Bd))n, m = 1, 2, 3
0.0
1
2
3
4 5 6 7 8
Layer Number
9 10
- Interpenetration
- Stratification
R.C. Advincula/ University of Houston
Decher, G. Science 1997, 277, 1232.
ACS-PRF Summer School on Nanoparticles 2004
A Variety of Materials for the LbL Technique
Polyelectrolytes
Typical polyelectrolytes
n
n
Bio-organic materials
N Cl
Poly(diallyldimethylammonium chloride) (PDADMAC)
SO3Na
Poly(styrene sulfonated) (PSS)
n
CH2
Poly(allyamine hydrochloride) (PAH)
CH2CH2NH2
H
co
n
proteins, virus, lipids, albumin, DNA, polypeptides,
enzymes, avidin, bacteriorhodopsin
Polysaccharides; chitosan, dextan sulfate,
cellulose sulfate
Inorganic materials
NH3 Cl
N
conjugated polymer; poly(phenylene vinylene)
precursor, poly(p-phenylene), polyaniline,
sulfonated polyaniline, polythiophenes
dendrimers, liquid crystalline polyelectrolytes,
diazo-resins, azo-polymers
N
n
Poly(ethyleneimine) (PEI)
C
n
O
OH
Poly(acrylic acid) (PAA)
Charged nanoobjects; Silica, metal oxides,
semiconductor nanoparticles (CdS, TiO2, CdSe,
CdTe), metal colloids (Au, Pt), charged latex
spheres, microcrystallites, metallo-supramolecular
complexes
clay platelets; Montmorillonte, hectorite, saponite
a-zirconium phosphate, graphite oxide, MoS2
Small organic materials
bolaamphiphiles, phthalocyanine, Azobenzene
dyes, cyanine dyes
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
New Applications and Devices from LBL films
http://www.chem.fsu.edu/multilayers/multilayerpatents.htm
Ultrathin Film Electrochromic Devices
Anti-reflective Coatings
Electrochemical Photovoltaic Devices
Corrosion Resistance Films
Modification of PLED and OLED Devices
Nanoporous and Ion-permselective Membranes
Field Effect Transistor Devices
Solid-State Polyelectrolyte materials
Electro-resistive and Piezoelectric Thin Films
Nonlinear Optical Thin Film Materials
Chemical and Gas-sensor Devices
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
POLYELECTROLYTES and NANOPARTICLES
• Mediate synthesis of nanoparticles: precursor approach
• Adsorption of nanoparticles to polyelectrolytes and vice
versa: fundamental studies in adsorption kinetics,
flocculation, electrical double layer, etc.
• Active and passive media: separation of nanoparticles,
synthesis of nanoparticles, interaction of nanoparticles
(stabilization)
• Preparation of thin films containing nanoparticles: flat
substrates and colloidal particles with nanoparticles
• Coating of Colloidal Particles with Polyelectrolyetes and
Nanoparticles: subject of a future review
• Tethering of polyelectrolytes to nanoparticles: DNA and
proteins.
• Nanocomposite preparation
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Nanoparticles and colloidal stability
R.C. Advincula/ University of Houston
•
Particles in colloid (A) uncharged
particles are free to collide and
agglomerate and (B) charged
particles repel each other
•
Steric stabilization of particles by
(A) entropic effects and (B)
osmotic effects
•
Droplet of a colloid suspension
dried slowly, the particles
aggregate at the rim of the
droplet because of attractive
capillary forces.
ACS-PRF Summer School on Nanoparticles 2004
Interfacial Behavior of Polyelectrolyte Nanoparticle Systems
•
•
•
•
•
•
The stability of a colloidal system is primarily determined by the electrostatic and
van der Waals interaction present in the system.
The co-adsorption of nanoparticles to polyelectrolytes causes extensive swelling of
polyelectrolyte surface layers
Surface force measurements: The electrostatic repulsive forces are reinforced by
the presence of particles while attractive binding forces are decreased
(separation)
Nanoparticle adsorption is slow due to complex formation, retarded diffusion, and
barrier effects.
Ionic strength, concentration, and adsorption history dependent.
Importance in flocculation and multilayer thin films.
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Polyelectrolyte Nanoparticle Composites: LBL assembly
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Topic 1: Collective and Individual Plasmon Resonance in
Nanoparticle LBL films by Spin-assisted assembly
•
•
•
•
•
•
•
R.C. Advincula/ University of Houston
•
Nanoscale films with Au nanoparticles (NPs) and
polyelectrolyte LBL were prepared by spinassembly.
Plasmon resonance peaks from isolated NPs and
interparticle interactions were analyzed from the
UV-vis spectra.
Collective plasmon resonance observed on films
with sufficient density: intralayer coupling (620
nm), and interlayer, interparticle resonance
observed at 800 nm
Environment of NP’s in polyelectrolyte critical for
sensing.
Au/PAH-PSS structure deposited on PEI surface
Topographic AFM image and height histogram
UV-vis of solutions for small and large nanoparticle
Tsukruk et. al. Langmuir 2004, 20, 882
ACS-PRF Summer School on Nanoparticles 2004
Interlayer and intralyer interaction in Au nanoparticles
•
•
•
•
R.C. Advincula/ University of Houston
UV-visible extinction
spectrum of the Au (PAHPSS) film with 22% Au NP
surface density with three
major absorption bands
UV-vis absorption with
different NP densities.
Variation of plasmon
resonance peak positions
and their intensity ratio
Tsukruk et. al. Langmuir 2004, 20, 882
ACS-PRF Summer School on Nanoparticles 2004
Topic 2: Enhanced Luminescence of Quantum Dots on Gold
colloids in Polyelectrolyte LbL Media
•
•
•
•
•
•
Enhancement of PL of the CdSe core-shell QD on gold colloids as
a function of distance between metal and QD. LBL polyelectrolyte
was uses as spacer layer with distance dependent enhancement
and quenching.
PL intensity versus the number of polyelectrolyte layers between
the QD and the gold colloids. Excitation at 550 nm.
SPR enhancement of the PL
Absorption spectra of Au colloidal film on glass.
Differential AFM image of AU colloidal film on glass.
Artemyev et. al. Nanoletters 20002, 12, 1449
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Topic 3: DC Transport in Nanocrystal assemblies
•
•
•
•
Follow the film conductivity:function of the number of layers
Linear increase in conductance with increasing layers
Probe both in-layer and cross-layer charge transport
Conductor to insulator transition
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Effect of the linker on the conductivity of the assemblies
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Topic 4: Electrostatically assembled Fluorescent Thin Films of
Rare-earth doped Lanthanum Phosphate Nanoparticles
•
•
•
•
•
R.C. Advincula/ University of Houston
LbL films of rare earth (QDs) base on (Ce, Tb, Eu, Dy, etc.) on
flat substrates and PS microspheres.
PL spectra of PS sphere coated with one layer of a mixture of
Ce/Tb doped and Ce/Dy doped nanoparticles. 273 nm
excitation.
Plot of PL intensity vs. composition of the mixture of green and
yellow NP.
TEM image of the LaPO4 NPs (green) dried from an aqueous
solution illustrating high monodispersity. The close packing is
due to the high concentration of NP.
Caruso et. al. Chem. of Mater. 2002, 14, 4509
ACS-PRF Summer School on Nanoparticles 2004
Topic 5: Ultrathin Cross-linked Nanoparticle Membranes
•
•
•
•
•
•
R.C. Advincula/ University of Houston
Chemical cross-linking of the ligands attached to
the nanoparticles as an effective route to
“freeze” interfaces. Vinylbenzene ligand and
AIBN initiator from solution
Nm thick membranes prevent convection but
allow diffusion of small molecules across the
interface- liquid/liquid interface.
Fluorescence confocal microscopy on a
nanoparticle assembly where an air bubble was
introduced by a micropipet showing (a)
preferential segregation of the CdSe at the
interface at oil/water and water/oil.
Nanoparticle sheets (free standing)
Organic dye (red solution) becoming entrapped
and then diffusing across a membrane of crosslinked nanoparticles.
Emrick et. al. JACS 2003, 125, 12690
ACS-PRF Summer School on Nanoparticles 2004
Topic 6: Grafted Block Copolymer Brushes: Synthesis of
Nanoparticles
•
•
•
R.C. Advincula/ University of Houston
Polyelectrolyte brushes of PS and PAA tethered
to a Si/SiOx surface using the grafting from
strategy. Silver or Pd ions were complexed.
NPs were formed after addition of reducing
agent and high temperature treatment.
Analyzed by AFM, FT-IR and XPS.
Boyes et. al. Macromolecules 2003, 36, 9539
ACS-PRF Summer School on Nanoparticles 2004
Topic 7: Complexation Approach to Hybrid Nanocomposite
Materials
•
•
•
•
R.C. Advincula/ University of Houston
In-situ synthesis of nanoparticle on the
surface of microspheres by employing ion
exchange of counterions in the electrical
double layer of latex beads
The use of a three layer hybrid core shell
particle as structural units of the
nanocomposite material.
TEM micrographs of PMMA-PMASS beads
covered with CdS and Ag NP’s obtained
under different magnification. (A) periodic
array, (B) fragment (C) high resolution image
of CdS particle.
Kumacheva, J. Am. Chem. Soc. 2002, 124, 14512
ACS-PRF Summer School on Nanoparticles 2004
Topic 8: Catalysis: Selective Hydrogenation by Pd Nanoparticles
Embedded in Polyelectrolyte Multilayers
•
•
•
R.C. Advincula/ University of Houston
Catalytic properties of nanoparticles
embedded in polyelectrolyte films. High
surface area by limiting aggregation of
NPs (stabilization) and also impart
catalytic selectivity (decreases
unwanted isomerization) by restricting
access to active sites.
TEM image of 3.5 bilayers in copper
grid
Bruening et. al. JACS 2004, 126, 2658
ACS-PRF Summer School on Nanoparticles 2004
Topic 9: Nanorainbows: Graded Semiconductor Films from
Quantum Dots
•
•
•
•
•
•
R.C. Advincula/ University of Houston
LBL deposition of 1-D graded
semiconducting films. Possibilities for
photodetectors, bipolar transistors,
waveguides, etc.
CdTe dispersion of different sizes allow
for the preparation of graded films.
AFM image of the PDDA/CdTe films
with polymer and NPs as last layers
PL spectra of different sizes
Cross-sectional confocal microscopy
image of the graded LBL film of CdTe
NPs made of 10 bilayers of green,
yellow, orange, and red NPs. 220 nm
thickness.
Kotov et. al. JACS 2001, 123, 7738
ACS-PRF Summer School on Nanoparticles 2004
Topic 10: Lateral Patterning of CdTe Nanocrystal Films by the
Electric Field Directed LBL Assembly Method
•
•
•
•
•
R.C. Advincula/ University of Houston
Electric field directed LBL assembly
(AFDLA) was used to patter 2 different
types of CdTe nanocrystals on ITO.
Pixel array of CdTe with different colors
for EL device.
Use of bias voltage to control amount
of deposition of NP and polyelectrolyte
(PDDA): monitored by QCM
Large contrast was observed.
PL spectra of different sizes
Gao et. al. Langmuir 2002, 18, 4098
ACS-PRF Summer School on Nanoparticles 2004
Patterning and EL Device Behavior
•
•
•
•
•
R.C. Advincula/ University of Houston
PL and EL spectra of PDDA/CdTe with
different sizes. EL spectra at 5V bias.
Lateral structures of the CdTe (green)
and CdTe (red).
Large contrast was observed.
PL spectra of different sizes
Gao et. al. Langmuir 2002, 18, 4098
ACS-PRF Summer School on Nanoparticles 2004
ADVINCULA GROUP
• Project 1. Synthesis of Nanoparticles using Star Block copolymers
• Project 2. REDOX Formation of Au Nanoparticles in LBL Films
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
The Concept of Block Copolymers as Nanoreactors
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.
•
Strategies for the gold nanoparticle preparation
Cationic
polyelectrolytes
Amphiphilic
block copolymers
(PS-b-P2VP)
Dendrimers
(PAMAM)
• “Stable Nanoreactor” for the control of size and shape of nanoparticles
R.C. Advincula/ University of Houston
Self-assembled
monolayers
(n-Alkanethiols)
ACS-PRF Summer School on Nanoparticles 2004
Synthesis of Nanoparticles in General
a
c
b
Schematic representation of the
concurrent process during reduction
reaction inside block copolymer
micelles.
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.
R.C. Advincula/ University of Houston
0.5
P4VP (NaBH4)
PAMAM Dendrimer (UV)
PS-b-P2VP (Hydrazine)
0.4
Absorbance
a) Reduction is initiated by the entry of
the reducing agent into the core of the
micelles loaded by precursor salt.
Star block
copolymer
(PS-b-P2VP)
N:Au=10:1
0.3
0.2
0.1
0.0
400
450
500
550
600
650
700
Wavelength (nm)
__200 nm
ACS-PRF Summer School on Nanoparticles 2004
Project 1: Reduction of Au in Star Copolymers
1. Synthesis of PS-b-P2VP
- Synthesis by anionic polymerization,
complete characterization necessary
-Stability in solution compared to
micelles
m
n
N
PS
- Control of diffusion of salts and
reducing agent in organic solvents
P2VP
2. Synthesis of Star Block Copolymer
PS-b-P2VP + Coupling Agent
(EGDMA)
(Ethylene glycol dimethacrylate)
H2C=C(CH3)CO-OCH2CH2O-COC(CH3)=CH2
1. Polyionic block
N
+ HAuCl4
2. Reduction with Hydrazine
NH + AuC l4
-
4HAuCl4 + 3N2H4 --> 4Au + 3N2 +
16 HCl
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.
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.
R.C. Advincula/ University of Houston
Polyionic star block copolymer
Reduction, Nucleation and Growth
ACS-PRF Summer School on Nanoparticles 2004
Characterization of Star Block Copolymer: GPC
PS
Polymer
Mn
Mw
PDI
PS
25,100
35,300
1.25
PS-b-P2VP
PS-b-P2VP
33.800
41.200
1.22
Star Block
Copolymer
106,200
155,100
1.46
Star block copolymer
20
Star block copolymer: After fractionation with THF
PS: 65.1 wt%, P2VP:34.9wt%
R.C. Advincula/ University of Houston
25
30
Retention time (min)
35
ACS-PRF Summer School on Nanoparticles 2004
UV-vis spectroscopy
2.5
2.0
Absorbance
• Absorption band at 525 nm for all
Au:N = 1:10
Au:N = 3:10
Au:N = 5:10
samples: Surface plasmon
resonance of Au nanocrystals)
1.5
•
Increase of absorbance intensity
with increasing the size of gold
nanoparticles
1.0
0.5
0.0
400
450
500
550
600
650
700
Wavelength (nm)
R.C. Advincula/ University of Houston
Langmuir. R. Advincula, M.K. Park, J.Youk; J. Locklin, J. Yang;
J. Mays “The Preparation of Aggregation Stable Gold
Nanoparticles using Star Block Copolymers”- ASAP article-web
ACS-PRF Summer School on Nanoparticles 2004
TEM
N:Au=10:1
Avg. Size: d=4.1 nm
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
TEM
N:Au=10:3
Avg. Size: d=5.5 nm
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
TEM
N:Au=10:5
Avg. Size: d=6.7 nm
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
UV-vis Spectroscopy (After several Months)
•
Peak position shifted from 525 nm
to 530 nm for N:Au=10:3 and 10:5
after 1 month
2.5
N:Au=10:1
N:Au=10:3
N:Au=10:5
Absorbance
2.0
•
Shift to longer wavelength
:Increase of the average size of gold
nanoparticles
1.5
• Increase of absorbance intensity for
N:Au=10:3 and 10:5 with time due to
the additional reduction process
1.0
0.5
0.0
400
450
500
550
600
Wavelength (nm)
R.C. Advincula/ University of Houston
650
700
ACS-PRF Summer School on Nanoparticles 2004
TEM (After several months)
N:Au=10:1
Avg. Size: d=4.1 nm
R.C. Advincula/ University of Houston
N:Au=10:3
Avg. Size: d=6.0 nm
N:Au=10:5
Avg. Size: d=8.0 nm
ACS-PRF Summer School on Nanoparticles 2004
Project 2a. Nanoparticle formation from Poleylectrolyte
Complexes of Sexithiophenes
3
0.5
0.19/1
0.38/1
0.95/1
0.4
HAuCl4
Slow
0.3
0.2
2
Absorbance
0.1
Fast
0.0
250
350
450
550
TT/HAuCl4
0.19/1
0.38/1
0.95/1
1.91/1
3.82/1
5.73/1
TT+PSS
Solution
1
PSS+ATT
Complex
650
0
250
350
450
550
650
Wavelength (nm)
CH - CH2
Poly(sodium styrene
sulfonate) (PSS)
m
S
+
N+
S
S
Amidated
terthiophene
(ATT)
SO3 Na+
CH - CH2
S
S
S
N+
-
SO3
m
Polyelectrolyte
Complex (PEC)
•
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
Youk, J, H.; Locklin, J.; Xia, C.; Park, M.K. and Advincula, R.”Langmuir 2001 17(15); 4681-4683.
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Coupling of Terthiophenes to form Sexithiophenes simultaneous
with nanoparticle formation
CH - CH 2
SO 3
N
l
CH - CH 2
-
SO 3
- -
-
N+
+
(CH 2 )6
(CH 2 )6
+
.
S
•
m
S
S
S
S
S
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.
S
S
- --
S
N+
SO 3
-
CH - CH 2
N
S
-
PSS + ATT + HAuCl4
PSS+ ATT + FeCl3
PSS + AST
AST
1.0
n
S
S
+
S
S
1.5
Absorbance
(CH 2 ) 6
0.5
S
N
0.0
250
300
350
400
450
500
Wavelength (nm)
N
S
S
S
S
R.C. Advincula/ University of Houston
S
S
N
550
600
650
ACS-PRF Summer School on Nanoparticles 2004
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 of
Terthiophene Amphiphiles” Langmuir 2001 17(15); 4681-4683.
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Project 2b. LBL Films as Nanoreactor Hosts for Nanoparticle
Synthesis
• REDOX reaction occurs between
the terthiophene
moeity and the Au precursor with
formation of Au
Nanoparticles and sexithiophene
• Au nanoparticle partially stabilized
by the PE complex
resulting in irregular growth and
aggregation
Preparation of Gold Nanoparticles with PSS:
Water-soluble Terthiophene Complex
(Youk et al. Langmuir 2001, 17, 4681.)
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Growth of PVP-3T and PAA films
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Gold Nanoparticle Formation in LBL Multilayer Films
Before
•
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
R.C. Advincula/ University of Houston
After
J. Phys. Chem. B 1999, 103, 7441.
Adv. Mater. 1998, 10, 133.
ACS-PRF Summer School on Nanoparticles 2004
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.
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Conclusions
• Nanoparticle (NP) synthesis and colloidal dispersions are essential
nanomaterials: high surface area and qunatum size effects ( PL and
plasmons)
• Polyelectrolytes can be used to mediate synthesis of NPs from
precursors or as media for film assembly of nanoparticles
• Interaction of NPs and nanoparticles follows classical colloidal
phenomena
• Advantages in stability and processing
• Synthesis and assembly of nanoparticles in films and colloids: active
and passive role of polyelectrolytes
• Film preparation results in a variety of functions and phenomena
observed: sensor, devices, optical materials, etc.
R.C. Advincula/ University of Houston
ACS-PRF Summer School on Nanoparticles 2004
Acknowledgment
Students: Chuanjun Xia, Mi-kyoung Park, Xiaowu Fan, Jason Locklin, Derek Patton, Tim Fulghum, Suxiang Deng,
Prasad Taranekar, Post-Docs: Dr. Seiji Inaoka, Dr. Ji Ho Youk, Dr. Shuangxi Wang, Dr. Qing-Ye Zhou, Dr. Ken Onishi,
Dr. Akira Baba, Dr. Mitchell Millan.
Collaborations: Wolfgang Knoll (MPI-P), Futao Kaneko ( Niigata University), Hiroaki Usui (TUAT)
Zhenan Bao
(Stanford
University), Jimmy Mays (UT/ORNL)
R.C. Advincula/
University
of Houston