Grambling State University Layer by Layer Nanoarchitectures Assembled from Alumina (Al 2 O 3 ) and...
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Transcript of Grambling State University Layer by Layer Nanoarchitectures Assembled from Alumina (Al 2 O 3 ) and...
Grambling State University
Layer by Layer Nanoarchitectures Assembled
from Alumina (Al2O3) and Zirconia (ZrO2) Systems
Kristan R. Moore1, 2, Tabbetha A. Dobbins1, 2, and Vimal Kamenini2
1 Dept. of Physics, Senior, Grambling State University2 Institute for Micromanufacturing, Louisiana Tech
University
Grambling State University
Introduction Planar substrate ConclusionColloidal substrate
• There is a research lacking in creating triple phase boundaries.• In creating these boundaries, there is a need to stabilize and control
them.• Using the layer-by-layer (LbL) technique allows:
– these boundaries to be stabilized and controlled– the concentration and deposition time to be studied to ascertain their
affect on the degree of control• This project will show that the morphology of these boundaries can
be controlled using the layer-by-layer (LbL) technique.• The positive controls in this experiment were:
– a fixed concentration of 2 mg/mL, and– a fixed deposition time of 10 minutes
• The negative control in this experiment:– the isoelectric points are unknown
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Sketch of Potential curves
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
Working pHWorking pH
Working pH
μm-Al2O3 nm-Al2O3
nm-ZrO2
ζ (mV)
pH
pHpH
ζ (mV)
ζ (mV)
Introduction Planar substrate Colloidal substrate Conclusion
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Layer-by-Layer Approach• Is the deposition of uniform multilayer thin films from
polyelectrolyte solutions.• During LbL nanoassembly, the film growth that
occurs is the result of Coulombic interactions between polymneric cations and anions.
• This assembly of alternating layers of oppositely charged polymers, nanoparticles, or proteins, provides the opportunity for the formation of 5-500 nm thick films with monolayers of various substances growing in a preset sequence on any substrate—preferably silicon or gold—at a growth step of about 1 nm.
Introduction Planar substrate Colloidal substrate Conclusion
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• The polyelectrolytes used were:– PAH (polyallylamine hydrochloride)– PSS (polystyrene sulfonate)– PEI (polyethyleneimine)
• The powders used were:– μm-Al2O3
– nm-Al2O3
– nm-ZrO2
Introduction Planar substrate Colloidal substrate Conclusion
Grambling State University
• Example of LbL assembly on a planar substrate
PSS
PAH
Substrate
PAH
PSS
ZrO2
PEI
ZrO2
PEI
PSS
Al2O3
PSS
Al2O3
PSS
PEI
PSS
PEI
Substrate
Introduction Planar substrate Colloidal substrate Conclusion
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nm-ZrO2
μm-Al2O3 nm-Al2O3
Introduction Planar substrate Colloidal substrate Conclusion
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0
2000
4000
6000
8000
10000
12000
14000
16000
18000
0 5 10 15 20 25 30 35
Cha
nge
in F
requ
ency
(H
z)
Layer
(PEI/PSS)2 + (Al2O3/PEI/PSS)4 + (Al2O3/PSS)11
ConclusionColloidal substratePlanar substrateIntroduction
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0
5000
10000
15000
20000
25000
30000
35000
40000
0 5 10 15 20 25 30 35 40
Cha
nge
in F
requ
ency
(H
z)
Layer
(PEI/PSS)2 + (PEI/ZrO2/PSS)4 + (PEI/ZrO2)11
Introduction Planar substrate Colloidal substrate Conclusion
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Top (nm-Al2O3)
Middle (nm-ZrO2)
Bottom (nm-Al2O3)
ConclusionColloidal substratePlanar substrateIntroduction
(PEI/PSS)2 + (PEI/ZrO2/PSS)4 + (PEI/ZrO2)11 + (PEI/PSS)2 + (Al2O3/PSS)15 + (PEI/PSS)2 + (PEI/ZrO2)15 + (PEI/PSS)2 + (Al2O3/PSS)15
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• Example of LbL assembly on colloidal particles
Adsorption Centrifuge Deionized Water
Centrifuge Adsorption Centrifuge Deionized Water
Sep
arat
ion
Rin
se
Sep
arat
ion
Rin
se
Sep
arat
ion
PS
S
PE
I
1:Colloidal Suspension
2: Expose to PSS-2mg/mL(negative charge)
3: At 14,000
rpm for 5 min
4: Expose to D.I.
H2O
5: At 14,000
rpm for 5 min
6: Expose to PEI - 2mg/mL(positive charge)
7: At 14,000
rpm for 5 min
8: Expose to D.I. H2O
Introduction Planar substrate Colloidal substrate Conclusion
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Latex + (PEI/PSS)2 + (PEI/Silica)
Latex + (PEI/PSS)2 + (PEI/Silica) + (PEI/PSS)2 + (PEI/Silica)
Latex + (PEI/PSS)2 + (PEI/Silica) + (PEI/PSS)2 + (PEI/Silica)
ConclusionColloidal substratePlanar substrateIntroduction
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Introduction Planar substrate Colloidal substrate Conclusion
(Al2O3/PSS) + (PEI/PSS) + (PEI/ZrO2)
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ConclusionColloidal substratePlanar substrateIntroduction
(Al2O3/PSS) + (PEI/PSS) + (PEI/ZrO2)3
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• Planar substrate
– Layer by layer self-assembly determined that, not only were the multilayers successfully deposited, but the morphology can also be controlled.
– Future experiments include optimizing the working pH to provide maximum density in the Al2O3 and ZrO2 layers.
• Colloids– Layer by layer self-assembly determined that
colloidal particles can be assembled from coating m-size particles with nm-size particles.
– Future work will include determining how to better attach the nm-size particles to the m-size particles.
Introduction Planar substrate Colloidal substrate Conclusion