Inorganic / Organic Nanocomposite Research

Peter Kofinas

Associate Professor

Department of Chemical Engineering

University of Maryland

College Park, MD 20742-2111

Research Programs

Chemical Engineering 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 Robert Briber: Neutron Scattering, Polymer Physics Luz Martinez-Miranda: Liquid Crystals, Magnetic Nanoparticles Otto Wilson: Biomimetic Materials

Synthesis of Monodisperse Metal Nanoparticle Standard MaterialsSheryl 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 AgglomeratesSheryl H. Ehrman and John N. Kidder

Dept. of Chemical Engineering, Dept. of Materials and Nuclear EngineeringFunding: University of Maryland’s Small Smart Systems Center

• 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 filmsExtension 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.

thermocouple

three zonefurnace

cooling water in

cooling water out

sampling stagesubstrate

to filter,cold trap, andexhaust

metal organic precursors in

TEM images of alumina aggregates

Interactions Between Nanoparticles and Microbial CellsSheryl H. Ehrman and Tracey R. Pulliam Holoman, Dept. of Chemical

EngineeringLuz Martinez-Miranda, Dept of Materials and Nuclear Engineering

Funding: ONR 0104127677

• Objective: Study fundamental interactions 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.

•ImpactKnowledge of nanoparticle/cell interactions important for development of new technologies for sensing biomolecules, and for new in-vivo diagnostic and treatment capabilities.

Growth Curves of E. coli with Nanomyte (nanoscale fumed silica)

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 50 100 150 200 250 300 350 400 450

Time (min)

Ab

sorb

an

ce (

A )

0.1g

0.2g

0.3g

control

E.coli

nanoparticles

Study of liquid crystals and related nanometer materialsL. 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.

29.5

30

30.5

31

31.5

32

0 5 10 15 20

in-p

lane

spa

cing

(Å

)

film thickness (µm)

b

30

30.2

30.4

30.6

30.8

31

31.2

31.4

0 0.1 0.2 0.3 0.4 0.5 0.6

laye

r th

ickn

ess

(Å)

inc. angle (deg)

17 µm

3.5 µm

14.7 µm

11.6 µm

Alignment of Magnetic Biomimetic NanoParticles (O. Wilson, Jr, L. J. Martínez-Miranda (U of Maryland) – UMCP GRB

They undergo a phase transition as illustrated to the right, similar to what liquid crystals undergo in gratedsurfaces. We find that in grated surfacesthe particles form a striped domain Structure, as shown on top.

Objective: To see how the particles align in different surfaces

Applications: To look into the informationthey can provide on bone reconstruction

T,a

rb u

nits

~

n

ISOTROPIC SELF-ASSEMBLY OF CLUSTERS

HOMEO-TROPIC H

OM

OG

EN

EO

US

STRIPEDDOMAIN

TIME

T,a

rb u

nits

~

n

ISOTROPIC SELF-ASSEMBLY OF CLUSTERS

HOMEO-TROPIC H

OM

OG

EN

EO

US

STRIPEDDOMAIN

TIME

12 3 5

4

Sugar Binding Polymeric Molecular ImprintsPeter 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

• 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

• Glucose

Fructose

•Insoluble

•Selective Binding

•Hydrophilic

•Mechanical Stability

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.

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.see: S. Choi, R.M. Briber, B.J. Bauer, D.-W. Liu, M.

Gauthier Macromolecules, 33(17), 6495-6501(2000)

Polymer Chain Conformation in Ultrathin FilmsR.M. Briber, Materials and Nuclear Engineering, U of Maryland

S.K. Kumar, Penn State U.

Experimental Sample Geometry

Results:• Rg in plane of film is constant!

• Rg in thickness direction is constrained by film dimensions.

• Rg in plane of film remains constant with decreasing film thickness.

see: R.L. Jones, S.K. Kumar, D.L. Ho, R.M. Briber, T.P. Russell, Nature, 400, 146(1999)

Characterization of Arborescent Graft PolymersRobert 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 TemplatesPeter Kofinas, Chemical Engineering

Microphase separation due to block incompatibility or crystallization

Templates for synthesis of metal and metal oxide nanoparticles

B-BlockA-Block

Chemical Link

C-Block

B-BlockA-Block

Chemical Link

0 - 21 % 21 - 34 % 34 - 38 % 38 - 50 %

Increasing Volume Fraction of Minority component

Ring Opening Metathesis Polymerization (ROMP) Peter Kofinas NSF CTS-981601

Ru

Cl

Cl

PCy3

PCy3

( CHPh)n

Ru

Cl

Cl

PCy3

PCy3

t-Bu

+ CHPhRu

Cl

Cl

PCy3

PCy3

n Benzene

N

N

Co

t-Bu

t-Bu

m

( )n

N N

Cot-Bu t-Bu

( )m

ChPh

( )n

N N

Co t-Bu

( )m

ChPhR

Synthesis of [Norbornene]400[Norbornene-dicarboxylic acid]50 Synthesis of [Norbornene]n[Norbornene-cobalt-amido]m

-4

-3

-2

-1

0

1

2

3

4

-50 -40 -30 -20 -10 0 10 20 30 40 50

Applied field (kOe)

Mo

me

nt

(em

u/g

)

300 K77K5K

-0.6

-0.3

0

0.3

0.6

-3 -1.5 0 1.5 3

Magnetic Nanoparticles Within Block CopolymersPeter Kofinas NSF CTS-981601

CoFe2O4

Co3O4

-8

-6

-4

-2

0

2

4

6

8

-7500 -5000 -2500 0 2500 5000 7500

Field (Oe)

Mo

me

nt(

em

u/g

)

15nm

Magnetic Nanoparticle Formation Peter Kofinas NSF CTS-981601

Cobalt Oxide

CoFe2O4 nanoparticles Cobalt Oxide nanoparticles

SANS and Neutron ReflectivityPeter Kofinas, Dept of Chemical Engineering

Robert Briber, Dept of Materials & Nuclear EngineeringFunding: NSF MRSEC DMR-008008

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 BatteriesPeter Kofinas ONR N00140010039

• 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:No leackage of toxic liquid electrolyteProduction of thin films processed as

CoatingsSheets

Anode CathodeSolid

A Block B Block C Block

Electrolyte(Oxidation) (Reduction)

anodecathodecell

cell

42x-1x

EEE

V60.3E

OMnLiLi

AB

C

TMSO

O

O

O

TMS

OO

OO

n

CH2N t-But-Bu CH2N

Co

n m

Piezoelectric ZnO Nanoclusters Within Block CopolymersAgis Iliadis, Dept of Electrical and Computer Engineering

Peter Kofinas, Dept of Chemical EngineeringFunding: 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 Agis Iliadis, Peter Kofinas NSF ECS-9980794

Literature (eV)

Experimental(eV)

ZnCl2 1023.3 1023.1ZnO 1021.7 1021.4

ZnO

2.8

3

3.2

3.4

3.6

10

18

10

19

10

20

10

21

10

22

10

23

10

24

10

25

10

26

10

27

10

28

10

29

10

30

Binding Energy (eV)

c/s

(x 1

0^

4)

ZnCl2

33.23.43.63.844.24.44.64.85

c/s

(x 1

0^

4)

1023.1

1021.4

Self-Assembled Nanoparticles

• 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

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

SampleSampleOrientatioOrientationn

FDCD

Application of shear electric field magnetic field

causes orientation of microdomains. Microstructure Orientation

Texture: Parallel

PerpendicularTransverse