nirt: controlling interfacial activity of nanoparticles: robust routes to nanoparticle- based...
Post on 18-Dec-2015
221 Views
Preview:
TRANSCRIPT
NIRT: Controlling Interfacial Activity of Nanoparticles: Robust Routes to Nanoparticle-NIRT: Controlling Interfacial Activity of Nanoparticles: Robust Routes to Nanoparticle-based Capsules, Membranes, and Electronic Materials (CBET 0609107)based Capsules, Membranes, and Electronic Materials (CBET 0609107)
Todd Emrick and Thomas P Russell, Polymer Science & Engineering Department, University of Massachusetts AmherstTodd Emrick and Thomas P Russell, Polymer Science & Engineering Department, University of Massachusetts AmherstAnthony Dinsmore and Narayanan Menon, Physics Department, University of Massachusetts AmherstAnthony Dinsmore and Narayanan Menon, Physics Department, University of Massachusetts Amherst
Benny D. Freeman, Chemical Engineering Department, University of Texas at Austin Benny D. Freeman, Chemical Engineering Department, University of Texas at Austin
Objectives: Harness the interfacial activity of nanoparticles, and the reactivity of functionalized ligands,for the preparation of robust, self-assembled structures , devices, and membranes
Materials for nano-composite films
Responsive Nanocomposites: using ligands to direct nanoparticles to polymer domains and interfacial boundaries
Thermalannealing
Idealized schematic of responsive nanocomposite
Effect on mechanical properties??
50 nm100 nm
25% OH terminated:NPs segregate to PS-PVP interface
50% OH terminated:NPs distributed within PVP domain
OH
OH HO
Lamellar morphology (solvent annealed films) with avg. 2.4 nm Au NPs
avg. 4.5 nm diameter Au NPs
Nanoparticle ripening + entropic penalty =
reorganization
170 deg C
Diblock copolymer host: polystyrene-poly(4-vinylpyridine)
Self-assembled nanorods and bionanorods using fluid interfaces
Hydrophilic segment Hydrophobic segment
* S
O
O
O O S O O *
100-X
O
O
SO
OO-Y+
S+Y-O
O
OX
Hydrophilic segment Hydrophobic segment
* S
O
O
O O S O O *
100-X
O
O
SO
OO-Y+
S+Y-O
O
OX
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
5
10
15
20
25
30
0 5 10 15 20 25 30
Wat
er P
erm
eab
ility
(L
.um
/(m
2.h
.bar
))
pH
t (days)
BPS-35N BPS-32K
BPS-32K/0.5%Au
94
95
96
97
98
99
100
5
10
15
20
25
30
0 5 10 15 20 25 30
Sa
lt R
eje
cti
on
(%
)
pH
t (days)
BPS-35N
BPS-32KBPS-32K/0.5%Au
PFDPFD
Low Concentration
PFDPFD
PFD
High Concentration
PFD
PFDPFD
High Concentration
PFDPFD
Washing
H2Ointerior
Oilphase
NanoparticleAssembly
20µm
Fluorescence confocal imagesof quantum dots on water droplets in a continuous oil phase
TOPO-covered CdSe quantum dots
122
/
/
/
/
/
/
/
/
2
/2
WO
WP
WO
OP
WO
WP
WO
OPWO R
z
R
zRzE
RzEWO
OPWP
/
//at min
z/R
E(z)/kT
Oil
Water
Emin
Pieranski, P. Phys. Rev. Lett 45, 569 (1980)
WP /
OP /
WO /
Interfacial assembly of nanoparticles: droplets and sheets
TCB
Water
20 m80 m
Droplet resizingthrough track-etch
membranes Confocal images
reduction in droplet size from
200 m to 10 m and less
Lin, Y., Skaff, H., Emrick, T., Dinsmore, A. D. & Russell, T. P., Science 299, 226-229.
2////
2
min/ lEngery Wel lInterfacia OPWPWOWO
OP
REEE
Interfacial energy well:
The structure and orientation of nanorods at the liquid-liquid interface can be manipulated by varying nanorod concentration in the bulk. At low TMV concentration, the rods orient parallel to the interface, which maximizes interfacial stabilizaiton. At high TMV concentrations, the rods orient normal to the interface, both mediating the interfacial interactions and neutralizing inter-rod electrostatic repulsion.
For charged nanorods like TMV, repulsive forces dominate the oil-water interfaces, which is strongly affected by the ionic strength, but not the pH, of the bulk solution in the range of pH = 6~8. Removal of the buffer solution leads to cleavage of the TMV nanorods at the oil/water interface.
25 µm
400 nm0.2 mg/ml
25 µm
400 nm0.2 mg/ml
B
0.8 mg/ml
B
0.8 mg/ml
5 µm
400 nm
B
0.8 mg/ml
B
0.8 mg/ml
5 µm
400 nm
B
0.8 mg/ml
B
0.8 mg/ml
5 µm
400 nm
Low concentration High concentration
/ / / / /2 sin 2 ( )o w p w p oE RL RL
Where / /
/
cos p w p o
o w
L>>R
2/ / / / /( ) ( )2p w o w p o p w p oE R Rh
Oil
Oil
Oil
Oil
Oil
Oil
1. Concentration2. pH value3. Ionic strength4. In-plane compression
Conditions
Au nanoparticles: EG4-058ACitrate-stabilized gold nanoparticles in water
~20 nm in diameter~1 mg/ml in water
Di-sulfonated poly(arylene ether sulfone) (BPS):BPS-XY series, X = mol% of disulfonated monomer (0<X<100), Y = “H” (free acid form) , “N” (sodium salt form), or “K” (potassium salt form).
Acid/base tolerance: steady water permeability and salt rejection over a wide range of pH
1. Measured in cross-flow cells. Feed solution: 2000 ppm NaCl, pressure = 27.2 atm (400 psig), flow rate = 1 gpm, temperature = 25oC.
2. BPS-32K/0.5%Au: BPS-32K with 0.5 wt% of Au nanoparticles (EG4-058A)
Binding energy of nanoparticles at oil-water interface
0 25 50 75 1000
20
40
60
80
salt conc. (M)
R=2.5 nmR=5 nm
0.8
1.2
1.6
0.00 0.01 0.02 0.03
R=10 nm
R2 (nm2)
E(k
BT
)
Salt concentration 0.007 mol/L0.017 mol/L0.027 mol/Llinear fit
E/R
2(k
BT
/nm
2 )
0 25 50 75 1000
20
40
60
80
salt conc. (M)
R=2.5 nmR=5 nm
0.8
1.2
1.6
0.00 0.01 0.02 0.03
0.8
1.2
1.6
0.8
1.2
1.6
0.00 0.01 0.02 0.030.00 0.01 0.02 0.03
R=10 nm
R2 (nm2)
E(k
BT
)
Salt concentration 0.007 mol/L0.017 mol/L0.027 mol/Llinear fit
E/R
2(k
BT
/nm
2 )
Nanoparticle binding energy (E) is measured from the change of interfacial tension as particles adsorb on a droplet. This data is for citrate-stabilized gold nanoparticles assembling on a droplet of octafluoropentylacrylate. We find E ~ R2 (R is the nanoparticle radius), as predicted from a continuum-scale model [Pieranski, PRL 45, 569 (1980)]. We also find that E can be increased by adding salt or by using ethylene glycol polymer ligands. These data provide the first measurements of E for nanoparticles at oil-water interfaces, and guide the design and fabrication of new materials via interfacial assembly.
top related