Bridgie Cawthon1, Marshall Tekell2, Sanat Kumar2
1) Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, 2) Department of Chemical Engineering,
Columbia University
FEI TALOS F200X
Introduction
Methods
Results Conclusion and Next Steps
Acknowledgements
1. Van Roosmalen, A. J., and J. C. MOL. “Cheminform Abstract: An Infrared Study of the Silica Gel Surface. 1. Dry Silica Gel.” Chemis cher Informationsdienst, vol. 10,
no. 13, 1979, https://doi.org/10.1002/chin.197913007.
2. Gun'ko, V.M., et al. “Mechanism and Kinetics of Hexamethyldisilazane Reaction with a Fumed Sili ca Surface.” Journal of Colloi d and Interface Science, vol. 228, no.
1, 2000, pp. 157–170., https://doi.org/10.1006/jcis.2000.6934.
3. Jhalaria, M., Jimenez, A. M., Mathur, R., Tekell, M. C., Huang, Y., Narayanan, S., Benicewicz, B. C., & Kumar, S. K. (2022). Long-term aging in miscible polymer
nanocomposites. Macr omolec ules,55(11), 4502–4515. https://doi.org/10.1021/acs.macromol.2c00332
4. Yoshitake, & Kato. (2007, March 6). PROCESS FOR PRODUCING HYDROPHOBC SILCA POWDER.
Reaction Mechanism
-LUDOX AS-30 (Commercial silica, SiO2) reacts with
HMDS to attach trimethylsilyl (TMS) groups to surface
-Reaction occurs at 70 oCfor 3 hours
-Surface chemical change alters solubility properties
Scattering, Microscopy, Spectroscopy, and Gravimetric
Analysis Used to Characterize Particles
-Dynamic Light Scattering (DLS)
-Small Angle X-Ray Scattering (SAXS) (Photo by Isabella Huang)
-Transmission Electron Microscopy (TEM)
-Fourier Transform Infrared Spectroscopy (FTIR)
-Thermogravimetric Analysis (TGA)
LUDOX AS-30 Particle Size Distribution Comparison
Solubility in Methyl Ethyl Ketone
SAXS form factor image
Characterization of Surface Chemistry Using ATR-FTIR
Soft material membrane research is at the front of much
sustainability research because of their abilities in
separating green house gases, desalination of water, and
other purposes. Membranes of this nature require special
polymer grafted nanoparticles for casting. Polymerization
initiated from the surface of nanoparticles requires
compatibility between nanoparticles and common organic
solvents like methyl ethyl ketone (MEK). The resulting “hairy”
nanoparticles can be used to create gas-separation
membranes with enhanced gas permeabilities and tunable
gas selectivities. However, high polydispersity hiders
selectivity. DLS: Intensity, volume, and number distribution
TEM image analysis of LUDOX AS-30
Above: The two images above left and middle show a comparison between MEK-ST and reacted
LUDOX solution in MEK. TGA analysis done on 300 μLof reacted LUDOX shows a final weight of
nanoparticle present of 28.04 mg, corresponding to a solution concentration of 93.5 mg/mL.
Nissan MEK-ST solution
Motivation: Particle shape and size distribution can be
improved using commercial silica colloids
Problem: Monodisperse silica is too hydrophilic to be used
in organic solvents
Modified LUDOX AS-30 in MEK TGA showing high solubility of Si-OH in MEK
ØA monodisperse particle size is observed (14-18 nm
diameter), and the polydispersity in particle size relative to
MEK-ST is significantly reduced.
ØLUDOX AS-30 is capable of undergoing changes is surface
chemistry, altering its hydrophobicity. This allows it to be a
suitable starting material for creating hydrophobic
monodisperse silica nanoparticles.
ØFurther improvement of the dispersion of the modified silica
is the next challenge of this problem. Additional milling and
drying techniques for the product will be tried to disrupt any
particle aggregation that may be happening.
ØOnce dispersion is optimized and controllable, the next step
is to attempt a matrix-free polymerization via a solution of
monomers. The polymer chains grafted to the surface would
then be cast into films and further analyzed.
References
Iam very grateful to have gotten the chance to work in
Dr.Kumar’s lab this summer under his PhD candidate Marshall.
Additional thanks to Dr. Avila of Chemistry for use of FTIR
instrument.
7000100 200 300 400 500 600
Temperature T(°C)
30.0
28.0
28.5
29.0
29.5
Weight (mg)
Ramp 20.00 °C/min to 120.00 °C
Isothermal 10.0 min
Ramp 30.00 °C/min to 700.00 °C
2022-06-17-1-LUDOX-rxn
Time: 33.97 min
Temperature: 677.07 °C
Weight: 28.042 mg
Weight Percent: 93.624 %
TA Instruments Trios V5.1.1.46572
3100300029002800
Frequency (cm-1)
0
0.002
0.004
0.006
0.008
0.01
0.012
3850375036503550
Absorbance
Frequency (cm-1)
Dried AS-30
Reacted AS-30
