Nanomaterials and Biomimetics Research in Chemical Engineering

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Nov 14, 2013 (3 years and 8 months ago)

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Nanomaterialsand Biomimetics
Research in Chemical Engineering
Jan Genzer, Rich Spontak, OrlinD. Velev,
and Peter K. Kilpatrick
Department of Chemical Engineering
NC State University
Presented at:
NASA Langley Core Competency Director’s Visit
September 4, 2003
0510152025303540
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
∆x =
θ
睡ter
†
d敧e
ⵣ潳→
θ
water
)
Position on substrate (mm)
0%
5%
10%
15%
20%
25%
30%
40%
50%
OTS:p.o = 1:10
tDIff
= 5'
10
30
40
50
60
70
80
90
100
110

source ≡chlorosilane/paraffin oil mixture
Vapor flux controlled by chlorosilane/paraffin oil ratio
Objective:
Achieve spatial control in wettability
Chaudhury & Whitesides
[
Science
256, 1539 (1992)]
Tunable molecular
gradients
Adv. Mater. (2001)
Novel assembly techniques
Molecular & macromolecular templating
101520253035404550
400
500
600
700
800
900
1000
1100
Position on the substrate, x (mm)
Particles per
µ
m
2
3
4
5
6
7
8
9
10
Dry PAAm thickness
before Au dip (nm)
Au particles
3-16 nm
Particle deposition
Objective:
Utilize gradient substrates in templating
Tailored polymer synthesis
202530354045
0
5
10
15
20
25

Dry PMMA thickness (nm)

Position on the substrate (mm)
0100200300400
0
5
10
15
20
25

Polymerization time (min)
Dry PMMA thickness (nm)



1520253035404550
0
1
2
3
4
5
6
7
PMMA
PHEMA

Dry polymer thickness (nm)
Position on substrate (mm)
1520253035404550
0
5
10
15
20
25
30
PMMA
PHEMA
Dry polymer thickness (nm)
Position on substrate (mm)
Objective:
Use combi methods to synthesize novel polymer structures and motifs
Macromolecules, (2003)
Chem. Comm., (2003)
Partial topics:
•kinetic of ATRP;
•block tunable copolymers;
•tunable polymer/nanoparticle dispersions.
Material screening methods
Adsorption of Au nanoparticles (Φ≈16 nm) adsorbing onto
PDMAEMA brush at different temperatures on silica.
300400500600700800
0.00
0.05
0.10
0.15
0.20
0.25
0.30
Absorbance
Wavelength (nm)
35°C
40°C
49°C
55°C
62°C
68°C
PDMAEMA
*
*
O
O
N
n

*
*
O
O
OH
n

PHEMA
Adsorption of proteins onto PHEMA molec. weight gradient (only asingle sample is utilized!).
Fibrinogen
(conjugated w/
AlexaFluor-594,
deposited onto
PHEMA substrate,
and incubated @ 4
°C
for 72 hrs)
PHEMA mwt increase
Objective:
Use gradients in screening protein adsorption behavior
35°C 49°C 55°C 68°C
Research interests of
Richard J. Spontak
Departments of Chemical Engineering
and Materials Science & Engineering
1.Nanostructured polymers
Block copolymer systems, physical gels, nanoporous media
Multifunctional materials used in dampening, separations & optics
2.Mesoporous media
High-pressure CO2
as a benign, low-T route to nanoporous polymers
Lightweight materials for delivery, separations, low-k dielectrics
3.Polymer Nanocomposites
Impregnation and growth of metals and metal oxides in polymers
Robust materials for use in catalytic reactions and gas separations
4.Advanced Microscopy Methods
Quantitative transmission electron microtomography for use in
quantifying volumetric characteristics at nanoscale resolution.
Energy-filtered TEM for high-resolution elemental imaging.
Environmental AFM for low-T characterization of soft materials.
Nanostructured Polymers
Motivation
:
Design and characterize
novel nanostructured polymer systems
that afford unique opportunities for
property development.
Phys. Rev. Lett.84, 518 (2000)
Adv. Mater. 14, 1615 (2002)
Langmuir18, 8266 (2002)
Block
copolymer
nm
mm
Scale
Trabecular
bone
200 nm
Fe-containing block
copolymer nanotubes
500 nm
Electron tomography
High temperature-stable
block copolymer gel
Mesoporous Media
Motivation
:
Develop viable and controllable process routes to
ultrahigh-porosity materials that provide low-weight, high-strength
and possibly surface-functionalized opportunities.
10 µm
1 µm
Surface-mediated thin-film foaming
5 µm
Foaming of
PMMA at low
pressures &
temperatures
in liquid CO2
Mesoporous
Silica in 3-D
10 µm
PMMA/PVDF
Polymer43, 5511 (2002)
1 µm
Velev et al.
Nature, 389, 447 (1997).
“Inside-out" templating:Colloidal crystals replicated into
structured porous materials
Silica
Latex microspheres
“Inverse opals”:
•Robust and self-sustained
•Uniform porosity and mass transfer
properties
•Could be a full photonic bandgap
material
Colloidal crystals:
•Maximal packing density and
surface/volume ratio
•Maximal structural stability
•Interaction with light: diffraction,
interference, scattering
1 µm
Nature, 389, 447 (1997).
Nature, 401, 548 (1999).
J. Am. Chem. Soc., 122, 9554 (2000).
Adv. Mater., 13, 396 (2001).
“Inside-out" templating:
Structured metallic films via colloidal crystals
Gold monolayer
Gold bilayers
CVD alternative
SERS sensor substrates
Potential uses for nanocoatings
Decorative materials
Energy harvesting
Photonics and optical
IR filters and mirrors
Wave guides
Electronic
Catalytic
Uniform porous supports
Low dielectric materials
Conductive/ Semiconductive
porous materials
Use of structuredmetallic filmsvia colloidal crystals
in chemical microsensors
Sample in
Sample out to
peristaltic pump
Raman spectrometer
probe
170 µl flow
chamber
Clamp SERS-active
layer
0.5 mm
thick
Appl. Spectr.56, 1524 (2002).
•Cell holds 170 ml,
response in < 3 min
•Excellent performance
with chemical agents, LOD
for cyanide = 10 ppb
•Revealed kinetic and
spectroscopic effects of
both fundamental and
practical importance
Electrical:
Interface on-chip
circuits
"Photonic":
Optical devices
Biological:
Sensors
Liquid
Microstructures and Devices via Dielectrophoretic
Manipulation and Assembly
Science
Science
,
,
294
294
, 1082 (2001)
, 1082 (2001)
Langmuir
Langmuir
,
,
15
15
, 3693 (1999).
, 3693 (1999).
Appl
Appl
. Phys.
. Phys.
Lett
Lett
,
,
82
82
, 949 (2003)
, 949 (2003)
Switchable crystalsBiosensors
Microwires
Dielectrophoreticassembly of microwires from metallic
nanoparticles
40 –150 V AC
200 -3000 Hz
Grounded
Single wire grown through gap
Gold nanoparticles 15-25 nm diameter
Dynamics of microwire assembly
High magnification, 8X speed
Hermanson, Lumsdon, Kaler and Velev
Science, 294
, 1082 (2001).
Predicting wire assembly in the presence of conductive object
in the liquid
Finite element electrostatic calculations using conformal triangles mesh (TriComppackage)
Growing wires would spontaneously
complete the circuit through the object
Self-centering of the wire after
growth begins
Experimental image
"Outside-in" templating:
Advanced structured particles templated by surface tension
Velev, Lenhoff and Kaler, Science, 287, 2240 (2000).
Small droplets,
φ> 20%, β→0
Large droplets,
surfactant, β> 1
Regular and
magnetic latex
Latex and metal
nanoparticles
100 µm
Four droplets of various suspensions held on a
fluidic chip
Energized columns of electrodes
750 nLdroplets containing
←red fluorescent latex
←gold nanoparticles
←white sulfate latex
←magnetic latex