Inorganic / Organic Nanocomposite Research
Peter Kofinas
Associate Professor
Department of Chemical Engineering
University of Maryland
College Park, MD 20742-2111
Research Programs

Chemical Engineering
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Sheryl Ehrman: Monodisperse Nanoparticle Processing
Tracey Holoman: Nanoparticle Interactions with Cells
Peter Kofinas: Block Copolymer Nanocomposites, Bioactive Hydrogels
Srinivasan Raghavan: Polyelectrolytes, Complex Fluids Rheology
Materials and Nuclear Engineering
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Robert Briber: Neutron Scattering, Polymer Physics
Luz Martinez-Miranda: Liquid Crystals, Magnetic Nanoparticles
Otto Wilson: Biomimetic Materials
Synthesis of Monodisperse Metal Nanoparticle Standard Materials
Sheryl H. Ehrman, Dept. of Chemical Engineering
Funding: National Institute of Standards and Technology
• Objective: Synthesize size monodisperse metal
nanoparticles for use as standard materials for
validating light scattering models. Results are used for
improving detection of contaminant particles on
surfaces.
• Approach: Use of a novel co-solvent spray pyrolysis
process to produce reduced metal nanoparticles, starting
from inexpensive metal salt precursors. Size selection
is accomplished via electrical mobility classification.
• Accomplishments:
Synthesis and deposition of monodisperse
(geometric standard deviation =1.03) copper
particles for use in light scattering studies.
Extension of this approach to other materials.
• Impact: Improved ability to detect surface
contaminants will lead to increased yield in many
manufacturing processes.
h
Porous Materials from Nanoparticle Agglomerates
Sheryl H. Ehrman and John N. Kidder
Dept. of Chemical Engineering, Dept. of Materials and Nuclear Engineering
Funding: University of Maryland’s Small Smart Systems Center
metal organic precursors in
• Objective: Develop a particle formation-CVD
process to produce porous films from nanoparticles.
• Approach: Use vertical furnace reactor and cold
deposition stage to synthesize and deposit
nanoparticles.
• Accomplishments:
Rapid growth of porous alumina films
Extension to multicomponent platinum/
alumina catalytic films
•Impact: Process is scalable. Substrate is kept at
low temperatures enabling deposition onto polymeric
membranes and other materials with low thermal
stability.
TEM images of
alumina aggregates
three zone
furnace
thermocouple
substrate
sampling stage
to filter,
cold trap, and
exhaust
cooling
water in
cooling
water out
Interactions Between Nanoparticles and Microbial Cells
Sheryl H. Ehrman and Tracey R. Pulliam Holoman, Dept. of Chemical Engineering
Luz Martinez-Miranda, Dept of Materials and Nuclear Engineering
Funding: ONR 0104127677
• Objective: Study fundamental interactions
E.coli
Growth Curves of E. coli with Nanomyte (nanoscale fumed
silica)
1.4
1.2
1
Absorbance (A )
between nanoparticles and cells.
• Approach: Culture E.coli bacteria in the presence
of silica and iron oxide nanoparticles to determine
effect of presence of nanoparticles on growth and cell
health.
•Accomplishments
•Initial results suggest nanoparticles are not
toxic to cells.
• Work continues towards functionalizing
magnetic nanoparticles to bind to specific cell
types and induce magnetoporation.
•Impact
Knowledge of nanoparticle/cell interactions
important for development of new technologies
for sensing biomolecules, and for new in-vivo
diagnostic and treatment capabilities.
nanoparticles
0.8
0.1g
0.6
0.2g
0.3g
0.4
control
0.2
0
0
-0.2
50
100
150
200
250
Time (min)
300
350
400
450
Study of liquid crystals and related nanometer materials
L. J. Martínez-Miranda, University of Maryland; NSF ECS-95-30933
Objective: To study defect structures in the nanometer, micrometer level,
by using Grazing Incidence X-ray diffraction.
Applications: A detailed study of the effect of the substrate surface in Flat
Panel Display Devices
Approach: Use GIXS to study the defect structure in detail. Compare to
different models.
Accomplishments: One of the first groups to study the structures as a
function of thickness, depth (incidence angle) and temperature of the films.



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31.4
32
31.2
layer thickness (Å)
in-plane spacing (Å)
b
31.5
31
30.5
30
11.6 µm
31
14.7 µm
30.8
30.6
3.5 µm
30.4
30.2
17 µm
30
29.5
0
5
10
film thickness (µm)
15
20
0
0.1
0.2
0.3
0.4
in c. an g le (d eg )
0.5
0.6
Alignment of Magnetic Biomimetic NanoParticles (O. Wilson,
Jr, L. J. Martínez-Miranda (U of Maryland) – UMCP GRB
Objective: To see how the particles
align in different surfaces
ISOTROPIC
1
SELFASSEMBLY OF
CLUSTERS
HOMEOTROPIC
2
HOMOGENEOUS
They undergo a phase transition as
illustrated to the right, similar to what
liquid crystals undergo in grated
surfaces. We find that in grated surfaces
the particles form a striped domain
Structure, as shown on top.
T,arb units~n
Applications: To look into the information
they can provide on bone reconstruction
STRIPED
DOMAIN
3
5
4
TIME
Sugar Binding Polymeric Molecular Imprints
Peter Kofinas
• Objective: Development of novel biomaterials using aqueous
synthesis techniques for molecular imprinting
 Ionic imprinting against glucose
 Ionic imprinting possibilities of other sugars
• Impact: Treatment and management of type II diabetes
mellitus and obesity
• Applications: Pharmaceutical, Food Additive, Isomer
Separations, Chemosensors, Catalysis
•Insoluble
•Selective Binding
•Hydrophilic
• Approach:
 Ionic imprint association during polymer
crosslinking and subsequent removal
 Creation of sugar-specific binding sites
 Measurement of sugar transport and binding
selectivity
• Accomplishments:
 Glucose imprinted polymers exhibit significant
specificity for glucose over fructose
 Crosslinker and template quantity affect specificity
and binding capacity
Polymer Hydrogels
Imprinted Against Glucose
•Mechanical Stability
• Glucose

Fructose
Characterization of Arborescent Graft Polymers
Robert M. Briber, Materials & Nuclear Engineering, U. of Maryland
Mario Gauthier, University of Waterloo
AFM micrograph of a film of 3rd generation
AGP molecules synthesized from 30k Mw PS
branches.
see: S. Choi, R.M. Briber, B.J. Bauer, D.-W. Liu, M.
Gauthier Macromolecules, 33(17), 6495-6501(2000)
Scaling of Rg with molecular weight of the form
Rg~M with =0.25. This indicates that
arborescent graft polymers become more dense
with increasing size (molecular weight). This
behavior must be self-limiting when the red line
intersects the line defining the hard sphere limit.
Polymer Chain Conformation in Ultrathin Films
R.M. Briber, Materials and Nuclear Engineering, U of Maryland
S.K. Kumar, Penn State U.
Experimental Sample Geometry
• Rg in thickness direction is constrained by film
dimensions.
• Rg in plane of film remains constant with
decreasing film thickness.
Results:
• Rg in plane of film is constant!
see: R.L. Jones, S.K. Kumar, D.L. Ho, R.M.
Briber, T.P. Russell, Nature, 400, 146(1999)
Characterization of Arborescent Graft Polymers
Robert M. Briber, Materials & Nuclear Engineering, U. of Maryland
Mario Gauthier, University of Waterloo
• Objective: Characterize the behavior of arborescent
graft polymers in solutions and in blends with linear
polymers
• Arborescent graft polymers are new molecules
with an unusual chain architecture. The goal is
to use small angle neutron scattering to measure
the size and shape in solutions and blends.
• The characterization of the size, shape and
density profile of arborescent graft polymers will
provide insight useful for tailoring them to meet
end use requirements as unimolecular micelles,
drug delivery vehicles and flow modifiers.
• Approach:
• Use small angle neutron scattering to measure
Rg and (r) in solutions and blends.
• Deuterated solvents and linear polymers are
used to provide neutron contrast.
Block Copolymers:Functional Nanostructure Templates
Peter Kofinas, Chemical Engineering


Microphase separation due to
block incompatibility or
crystallization
Templates for synthesis of metal
and metal oxide nanoparticles
A-Block
B-Block
Chemical Link
0 - 21 %
21 - 34 %
34 - 38 % 38 - 50 %
Increasing Volume Fraction of Minority component
A-Block
B-Block
Chemical Link
C-Block
Ring Opening Metathesis Polymerization (ROMP)
Peter Kofinas NSF CTS-981601
PCy3
PCy3
Cl
Cl
Ru
+
n
Ru
CHPh
Benzene
Cl
Cl
)n CHPh
(
PCy3
PCy3
PCy3
Cl
Ru
t-Bu
m
N
Cl
)mChPh
)n (
(
PCy3
Co
N
N
N
R
(
t-Bu
)mChPh
)n (
N
N
t-Bu
Synthesis of [Norbornene]400[Norbornene-dicarboxylic acid]50
Co
t-Bu
t-Bu
Co
t-Bu
Synthesis of [Norbornene]n[Norbornene-cobalt-amido]m
Magnetic Nanoparticles Within Block Copolymers
Peter Kofinas NSF CTS-981601
Co3O4
CoFe2O4
15nm
8
4
6
4
Moment (emu/g)
Moment(emu/g)
3
2
0
-2
-4
-6
-8
-7500
2
300 K
77K
5K
1
0
0. 6
-1
0. 3
-2
0
-3
-5000
-2500
0
Field (Oe)
2500
5000
7500
-0. 3
-0. 6
-4
-3
-50 -40 -30 -20 -10
0
10
20
Applied field (kOe)
30
-1. 5
40
50
0
1. 5
3
Magnetic Nanoparticle Formation
Peter Kofinas NSF CTS-981601
Cobalt Oxide
CoFe2O4 nanoparticles
Cobalt Oxide nanoparticles
SANS and Neutron Reflectivity
Peter Kofinas, Dept of Chemical Engineering
Robert Briber, Dept of Materials & Nuclear Engineering
Funding: NSF MRSEC DMR-008008
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Magnetic neutron scattering to separate and compare
 ordering of nanoparticles
 microphase separated block copolymer morphology
Obtain information about state of magnetic spin in sample
Follow microstructure development with temperature
Long range order in thin films
Polymeric Nanoscale Solid State Batteries
Peter Kofinas ONR N00140010039
O
O
O
n
n
t-Bu
NCH2
O
m
CH2N t-Bu
O
O
Co
TMS
O
O
• Objective: Synthesize a nanoscale all solid-state polymer battery
• Approach: Use a triblock copolymer where the three blocks
are the anode, electrolyte and cathode of the battery
• Accomplishments:
Synthesis and characterization of monomers.
Polymerization of lithium block as the anode.
• Impact: All-Solid State Battery advantages:
A Block B Block
No leackage of toxic liquid electrolyte
Production of thin films processed as
Coatings
Li x  Li1-x Mn 2 O 4
Sheets
TMS
A
B
C Block
E cell  3.60 V
E cell  E cathode  E anode
Solid
Cathode
Anode
(Oxidation)Electrolyte(Reduction)
C
Piezoelectric ZnO Nanoclusters Within Block Copolymers
Agis Iliadis, Dept of Electrical and Computer Engineering
Peter Kofinas, Dept of Chemical Engineering
Funding: NSF EECS-9980794
• Wet chemical
•
•
synthesis
Room
temperature
process
Cast thin or
thick films
Order of
100 nm
High Resolution XPS of Doped Block Copolymers
5
4.8
4.6
4.4
4.2
4
3.8
3.6
3.4
3.2
3
ZnCl2
1023.1
NSF ECS-9980794
c/s (x 10^4)
Agis Iliadis, Peter Kofinas
Literature Experimental
(eV)
(eV)
ZnCl2 1023.3
1023.1
ZnO
1021.7
1021.4
3.6
3.4
3.2
3
1021.4
c/s (x 10^4)
ZnO
Self-Assembled
Nanoparticles
2.8
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
Binding Energy (eV)
• With NH4OH
• Strong bases (NaOH, KOH) will not work
Microstructure Characterization

Gel Permeation Chromatography
 Molecular weight distribution

Transmission Electron Microscopy
 size, size distribution and crystalline quality of nanoclusters
 interface between block copolymer and metal oxide

Small-Angle and Wide-Angle X-ray Diffraction
 nanocluster long period spacing, size and orientation texture

Small-Angle Neutron Scattering, Neutron Reflectivity
 nanoparticle vs polymer matrix ordering
 conformation in thin films
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
Vibrating Sample and Squid Magnetometry
 Temperature and magnetic field dependence of magnetic
properties
X-Ray Photoelectron Spectroscopy
 Composition of Metal or Metal Oxide Nanoparticles
Long -Range Order in
Self-Assembled Block Copolymers
Perpendicular
Transverse
CD

FD
Sample
Orientation

Application of
 shear
 electric field
 magnetic field
causes orientation of
microdomains.
Microstructure Orientation
Texture:
 Parallel
Perpendicular
Transverse