Transcript Ionic Liquid Nanoparticles - Louisiana State University

NANOPARTICLES DERIVED FROM A
GROUP OF UNIFORM MATERIALS
BASED ON ORGANIC SALTS
Analytical Research Seminar
Aaron Tesfai
Warner Research Group
Department of Chemistry.
Louisiana State University. Baton Rouge,LA 70803
Outline
• Introduction to Ionic Liquids (ILs)
–Brief history
–Common cation/anion combinations
–Properties of ILs
–Group of Uniform Materials Based on Organic Salts
(GUMBOS)
• Synthesis and Characterization of Micro- and
NanoGUMBOS
–Surfactantless Melt-Emulsion-Quench
–Surfactant-Assisted-Melt-Emulsion-Quench
–Reverse Micelle
• Magnetic Particles from GUMBOS
–Synthesis and characterization of [Bm2Im][FeCl4] GUMBOS
particles
–Magnetic susceptibility of [Bm2Im][FeCl4] GUMBOS particles
Ionic Liquids (ILs)
•
Ionic liquids are defined as organic salts with melting points at
or below 100 °C
– Liquid at room temperature (room temperature ionic
liquids RTILs)
– Solid above room temperature (frozen ionic liquids)
•
The name ILs was first used by a Latvian-German chemist
Paul Walden
•
Walden discovered the first ionic liquid, ethyl ammonium
nitrate with a melting point of 12 °C in 1914
•
The term ILs used to distinguish these compounds from
inorganic salts that melt at high temperature
•
Low melting point - asymmetry between the ions prevent
formation of stable crystal lattice (“frustrated crystal packing”)
Welton T. Chem Rev 1999, 99, 2071-2083
Philippe Hapiot and Corinne Lagrost Chem. Rev. 2008, 108, 2238–2264
Del Po’polo, M. G.; Voth, G. A. J. Phys. Chem. B 2004, 108, 1744-1752
P. Walden, Bull. Acad. Imper. Sci. (St. Petersburg) 1800 (1914)
www.uni-tuebingen.de
Common Cations and Anions
Common cations:
R
R
R
R
R
N
N
N
N
P
CH3
R
R
1-alkyl pyridinium
R
R
1-alkyl-3-methyl-imidazolium Tetraalkyl-phosphonium
R
Tetraalkyl-ammonium
Common alkyl (R-) chains: R = Ethyl, Butyl, Hexyl, Octyl and Decyl
Common anions:
F3C
S
F
O
O
N
S
CF3
F
P
F
O
F
F
F
F
O
bis(trifluoromethylsulfonyl)imide
hexafluorophosphate
F
B
OF
F
tetrafluoroborate
-O
N+
O
nitrate
Properties of Ionic Liquids
•
Tunability
•
Thermal stability
•
Dissolve many organic and inorganic materials
•
Low volatility
•
Environmentally friendly
Group of Uniform Materials Based on Organic
Salts (GUMBOS)
1-butyl-2,3-dimethylimidazolium tetrachloroferrate
Cl
N
N
Cl
Fe
Cl
M.P. -2 °C
Cl
[Bm2Im] [FeCl4]
N
N
1,3,3-Trimethyl-2-[7-(1,3,3-trimethyl-1,3-dihydroindol-2-ylidene)-hepta-1,3,5-trienyl]-3H-indolium
bis(trifluoromethylsulfonyl)imide
[HMT] [NTF2]
F3C
S
O
M.P. > 120 °C
O
O
N
S
CF3
O
Tesfai et al. ACS Nano. 2009 accepted.
Bwambok et al. submitted to ACS Nano 2009.
Objectives
•
To investigate the use of GUMBOS that are solid above room temperature
for possible GUMBOS-based nano- and micro- particle synthesis
•
To characterize the nano- and microGUMBOS
• Scanning Electron Microscopy (SEM)
• Transmission Electron Microscopy (TEM)
• Differential Interference Contrast (DIC)
• Fluorescence Microscopy
• Atomic Force Microscopy
•
To dope the GUMBOS and investigate the possibility of using
nanoGUMBOS to entrap various materials such as drug molecules
Synthesis and Characterization of
Micro- and NanoGUMBOS
•Surfactantless Melt-Emulsion-Quench
•Surfactant-Assisted Melt-Emulsion-Quench
•Reverse Micelle
GUMBOS Used
F F
F P F
F F
N
N
[bm2Im][PF6]
[1-butyl-2,3-dimethylimidazolium] [hexafluorophosphate]
GUMBOS
Melting point
Miscibility with
H2O
[1-butyl-2,3-dimethylimidazolium]
[hexafluorophosphate]
42 °C
No
Surfactantless Synthesis of NanoGUMBOS
1. Add 25 mg of GUMBOS into 8 mL of DI water
2. Heat mixture at 70 °C
3. Homogenize solution for 10 min, Probe sonication for 10 min
4. Freeze mixture in an ice water bath
1
2
3
Tesfai et al. Nano Lett. 2008, 8, 897-901.
4
Characterization of NanoGUMBOS
SEM
TEM
Electron micrographs of [bm2Im][PF6] nanoGUMBOS synthesized using surfactantless
synthesis: (a) SEM image showing an average nanoparticle diameter of 90 ± 32 nm. (b) TEM
image with an average nanoparticle diameter measured as 88 ± 34 nm.
Tesfai et al. Nano Lett. 2008, 8, 897-901.
Surfactantless Synthesis: Nile Red Doped
NanoGUMBOS
A
(A) solid [Bm2Im][PF6]
B
(B) melted [Bm2Im][PF6]
Tesfai et al. Nano Lett. 2008, 8, 897-901.
C
(C) o/w emulsion
D
(D) [Bm2Im][PF6] nanoparticle crop
Surfactantless Synthesis : SEM and Optical Microscopy (DIC)
and (Fluorescence) of microGUMBOS
Solid [bm2Im][PF6] microGUMBOS with average diameters of ~ 3-μm imaged with (a)
SEM, (b) Optical microscopy (DIC), (c) Optical microscopy (fluorescence), (d) Overlay
of DIC and fluorescence.
Tesfai et al. Nano Lett. 2008, 8, 897-901.
Synthesis and Characterization of
Micro- and NanoGUMBOS
•Surfactantless-Melt-Emulsion-Quench
•Surfactant Assisted-Melt-Emulsion-Quench
•Reverse Micelle
Surfactant-Assisted Synthesis of NanoGUMBOS
1. Add 1% w/v Brij-35 in DI water
2. Add 25 mg of GUMBOS to mixture and placed in water bath set to 70 °C
3. Homogenize solution for 10 min, Probe Sonication for 10 min
4. Freeze mixture in an ice water bath
1
2
3
Tesfai et al. Nano Lett. 2008, 8, 897-901.
4
Surfactant-Assisted Synthesis: TEM of NanoGUMBOS
Representative TEM image of 45 ± 7 nm [bm2Im][PF6] nanoGUMBOS synthesized using surfactant-assisted
synthesis, employing Brij-35.
Tesfai et al. Nano Lett. 2008, 8, 897-901.
Synthesis and Characterization of
Micro- and NanoGUMBOS
•Surfactantless-Melt-Emulsion-Quench
•Surfactant Assisted-Melt-Emulsion-Quench
•Reverse Micelle
Surfactant Employed for Reverse Micelle Synthesis:
Aerosol-OT (AOT)
O
O
O
Na O3S
O
Sodium bis(2-ethyl-hexyl)sulfosuccinate (AOT)
• Double chain amphiphile
• Able to form reverse micelles
AOT Interface
• Able to solubilize water
• R value (wo): [water]/[surfactant]
Bound Water
Bulk Heptane Continuum
Inner Bulk Water
AOT Reverse Micelle
Basic Processes for Nanoparticle Formation within
AOT Reverse Micelles
A
0.1 M AOT
in 5 mL heptane
120 μL of 0.2-0.6 M
[Bm2Im][Cl]
in water
Tesfai et al. ACS Nano. 2009. accepted
B
0.1 M AOT
in 5 mL heptane
120 μL of 0.2-0.6 M
[Na][BF4]
in water
TEM Images of [Bm2Im][BF4] NanoGUMBOS
Reagent
Concentration
(M)
Particle Size
(nm)
Standard
Deviation (nm)
A: 0.2
14.7
± 2.2
B: 0.4
20.8
± 1.8
C: 0.5
34.3
± 4.8
D: 0.6
68.0
± 17
NaBF4
N
N
N
N
BF4
Cl
[Bm2Im][Cl]
[Bm2Im][BF4]
Tesfai et al. ACS Nano. 2009. accepted
Size Distributions of [Bm2Im][BF4] NanoGUMBOS
Synthesized in water-containing AOT reverse micelles at various reagent concentrations: [AOT] = 0.1 M;
molar reagent concentrations: 0.2, 0.4, 0.5, and 0.6 M.
Tesfai et al. ACS Nano. 2009 accepted.
Tapping Mode AFM Images of [Bm2Im][BF4]
NanoGUMBOS
220 nm
A
0.4 M [Bm2Im][BF4]
12 µm
2 µm
12 µm
0
200 nm
C
B
0
D
2 µm
(A) 60 × 60 μm2 topographical image and (B) simultaneously acquired phase image. (C) Zoom-in view 12 × 12 μm2
view and (D) corresponding phase channel.
Tesfai et al. ACS Nano. 2009 accepted.
Tesfai et al. submitted to ACS Nano. 2009.
Conclusions
•
NanoGUMBOS (SEM) were obtained with average diameters of 90 nm using
Surfactantless-Melt-Emulsion-Quench-Technique.
•
TEM was in good agreement with SEM yielding average diameters of 88 nm
(Surfactantless-Melt-Emulsion-Quench-Technique).
•
MicroGUMBOS (SEM) were obtained with average diameters of ~3 μm
(Surfactantless-Melt-Emulsion-Quench-Technique).
•
Doping the microGUMBOS suggests that they may be used to entrap various
materials including drugs.
•
The use of an emulsifying agent (Surfactant-Assisted-Melt-Emulsion-QuenchTechnique)yields nanoGUMBOS of ~45 nm in diameter.
• Smaller particle size
• Size control
•
A facile and reproducible method for synthesizing four distinct sizes of
nanoGUMBOS has been developed (Reverse Micelle Synthesis).
• NanoGUMBOS size was influenced by increasing reagent concentration
within each reverse micelle.
Magnetic Particles From GUMBOS
Applications of Magnetic Nanoparticles
Magnetothermal
Iron oxide magnetic nanoparticles injected Application of external magnetic field
In tumor
Drug Targeting
Superparamagnetic iron oxide nanoparticles are guided
towards the lungs in the presence of an external magnetic
field
Amirfazli, A. Nature Nanotech. 2007, 8, 467-468.
Objectives
•
To investigate the use of magnetic GUMBOS for possible GUMBOS-based
particle synthesis
•
To characterize the GUMBOS particles
• Transmission Electron Microscopy (TEM)
• Atomic Force Microscopy
Magnetic Particles from GUMBOS
•Synthesis and characterization of
[Bm2Im][FeCl4] GUMBOS particles
•Magnetic susceptibility of [Bm2Im][FeCl4]
GUMBOS particles
Basic Processes for Magnetic Particle Formation within
AOT Reverse Micelles.
A
0.1 M AOT
in 5 mL heptane
120 μL of 0.3 - 0.4 M
[Bm2Im][Cl]
in water
Tesfai et al. ACS Nano. 2009 accepted.
B
0.1 M AOT
in 5 mL heptane
120 μL of 0.3 - 0.4 M
[FeCl3].6H2O
in water
TEM Images of Magnetic GUMBOS Particles
Micrographs of magnetic [Bm2Im][FeCl4] GUMBOS particles obtained from TEM revealing mean particle sizes of (A) 98.0
± 17 nm and (B) 199.0 ± 26 nm.
FeCl3.6H2O
Reagent
Concentration
(M)
Particle Size (nm)
Standard Deviation
(nm)
A: 0.3
98
± 17
B: 0.4
199
± 26
N
N
N
N
FeCl4
Cl
[Bm2Im][Cl]
Tesfai et al. ACS Nano. 2009 accepted.
[Bm2Im][FeCl4]
Size Distributions of Magnetic GUMBOS Particles
[AOT] = 0.1 M; molar reagent concentrations: 0.3 and 0.4 M.
Tesfai et al. ACS Nano. 2009 accepted.
Tapping Mode AFM Images of [Bm2Im][FeCl4] GUMBOS
Particles
230 nm
A
B
0.3 M [Bm2Im][FeCl4]
3 µm
520 nm
C
3 µm
0
D
0.4 M [Bm2Im][FeCl4]
3 µm
0
3 µm
(A) Topographical image of magnetic nanoGUMBOS with a diameter near 100 nm and (B) the matching
phase image. (C) Topography of 200-nm GUMBOS Particles and (D) the corresponding phase frame.
Tesfai et al. ACS Nano. 2009 accepted.
Absorption Spectra of Bulk [Bm2Im][FeCl4]
[Bm2Im][FeCl4]
528
0.05
N
N
FeCl4
0.04
Absorbance
FeCl4
0.03
N
N
684
0.02
617
0.01
0
500
550
600
650
700
Wavelength (nm)
Tesfai et al. ACS Nano. 2009 accepted.
750
800
1Hayashi,
S. et al. Chem. Lett. 2004, 33, 1590-1591.
Magnetization (emu/g)
Magnetic Susceptibility of Bulk [Bm2Im][FeCl4]
Alongside [Bm2Im][FeCl4] NanoGUMBOS
nanoGUMBOS
0.2
bulk
0.0
-0.2
T = 15K
-10000 -5000
0
5000
10000
Applied magnetic field (Oe)
GUMBOS/nanoGUMBOS
Magnetic Response (emu/g)
[Bm2Im][FeCl4] GUMBOS
34.3 x 10-6
[Bm2Im][FeCl4] nanoGUMBOS
34.3 x
10-6
Tesfai et al. ACS Nano. 2009 accepted.
GUMBOS
Magnetic Response (emu/g)
[BmIm][FeCl4]
1
40.6x10-6
[HmIm][FeCl4]
1
39.6 x 10-6
[OmIm][FeCl4]
1
36.6 x 10-6
1Hayashi,
1590.
S.; Hamaguchi, H.-o. Chemistry Letters. 2004, 33,
Conclusions
•
Two distinct sizes of magnetic nanoGUMBOS were synthesized and
characterized
• Particle size was influenced by increasing reagent concentration in each
reverse micelle.
•
UV-Vis spectrum confirmed the well known characteristic peaks of FeCl4 for
the bulk magnetic GUMBOS.
•
Both the bulk and nanoGUMBOS demonstrated to be magnetic
Acknowledgements
• Prof. Isiah M. Warner
• Postdoctoral Research
Associates
• Warner Research Group
• Garno Research Group
• National Science Foundation
(NSF)
• National Institutes of Health
(NIH)
• Phillip W. West Endowment