Diffuse Reflectance Infrared Spectroscopic Identification of Dispersant/Particle Bonding Mechanisms in Functional Inks

The overall goal of this procedure is to identify the dispersant molecules absorbed on dispersed particles within colloidal dispersions. This is accomplished by first centrifusion, the colloidal solution to separate the particles from dispersant. Next, the isolated particles are washed with solvents, recovered with centrifugation and oven dried.

The dried sediment is then mixed within a potassium bromide matrix and ground into a fine powder. Finally, the mixture is loaded into a sample holder and measured using diffuse reflectance infrared four. Your transform spectroscopy ultimately diffuse reflectance infrared four.

Your transformed spectroscopy is used to identify chemi orb and esor dispersant molecules. The main advantage of this technique over other methods like attenuated total reflectance infrared, is that in this technique, interferences from the solvent are minimized. Thus, this technique can help answer key questions in the field of collarette and surface science, including how are functional particles stabilized in colloidal dispersion.

In this video, I'll demonstrate the procedure associated with infrared spectroscopy, sample preparation and measurement To isolate surface functionalized particles from a colloidal dispersion. Begin by pipetting enough ink into a fresh conical tube such that the total mass of the particles is at least two grams. Place the tube into a swinging bucket, benchtop centrifuge, and spin down the functionalized particles for 30 to 90 minutes.

At room temperature for proper particle sedimentation, the spin speed should be optimized such that a clear, transparent supernatant is achieved within 90 minutes. Next, decamp the supernatant into a fresh tube and save an aliquot for further analysis. As for the pellet fraction, place the uncapped tube upside down on a paper towel and allow any remaining supernatant droplets to slide down the tube and be wicked away by the towel.

Rinse the upper layer of the hard packed pellet by adding two milliliters of fresh solvent containing the same composition used in the original ink formulation. Immediately decant the supernatant and repeat the wash three more times. Do not vortex the tube at any point during these wash steps.

After the final rinse, place the uncapped tube upside down for five minutes and remove any remaining solvent by wicking. Then transfer the functionalized particles from the tube onto a clean, dry watch glass with a metal spatula. If desired, clean excess particles from the spatula tip with a lint-free, non-abrasive cotton swab or the tip of another spatula.

Place the watch glass into a 50 degree Celsius oven and allow the solvent to slowly evaporate from the particles For approximately 24 hours. The sediments can be kept in the oven or other clean dry location for as long as three weeks before further processing. For assay the surface functionalized ink particles with diffuse reflectance infrared spectroscopy, A variety of FTIR spectrometers outfitted.

With a diffuse reflectance sampling apparatus can be used for the task for most ink particles. A standard deuterated L alanine doped triglycine sulfate detector will provide enough sensitivity for the assay. Turn on the infrared lamp source and let the lamp warm up for a minimum of one hour to increase the signal to noise ratio in IR spectroscopy.

Perform the chamber purge and let the lamp equilibrate for at least one day prior to measurements. This step needs to be done before alignment. To begin the setup process, place the diffuse reflectant sampling accessory into the spectrometer sampling compartment and align the sampling accessory itself following the manufacturer's instructions.

After sealing the sampling compartment, equilibrate moisture and carbon dioxide content in the chamber by feeding in a steady stream of dry nitrogen or carbon dioxide, free dry air at a per rate as suggested by the manufacturer of your instrument. Monitor the decrease in water and carbon dioxide Background IR in real time. At one or two minute intervals, record the time at which the two background IR peaks have both reached satisfactory levels.

The prerequisite for a successful sample preparation run is the availability of the following accessories, a small 35 millimeter agate mortar and pestle, small metal spatula, a razor blade and two diffuse reflectants infrared sample cups. To start manually clean each and every accessory with acetone. Place all accessories in an oven set at 50 degrees Celsius and let the items dry for 10 minutes.

After the dry bake, allow the items to slowly cool to room temperature on the lab bench while the accessories are cooling. Take the previously dried ink particles out of the 50 degree Celsius oven. Place a sheet of weighing paper on a micro balance.

Carefully measure out 25 milligrams of the ink particles and leave the particles on the micro balance for the time being. When the sample preparation accessories have cooled. Pour 0.5 grams of infrared spectroscopy potassium bromide powder into the agate mortar.

Since potassium bromide is hydroscopic, it is best to use commercially available premeasured potassium bromide packs to minimize the chance of excess water. Vapor adsorption during the Wang process, grind the potassium bromide with the mortar and pestle until the powder becomes uniform in appearance. Next, carefully fill one of the infrared sampling cups with the ground potassium bromide powder almost to the top.

Lightly press the top surface of the powder with the blunt end of the pestle and carefully top off the sampling cup. With more powder. Using a razor blade carefully level the surface layer of the powder such that it is flush against the rim of the sample cup, the completed pure potassium bromide sample cup will be designated as the reference sample.

To prepare the experimental sample cup, open a new pack of 0.5 grams of potassium bromide and pour it into the mortar overlay. This bed of potassium bromide with the previously weighed 25 milligrams of ink particles, grind the mixture with a mortar and pestle until both powders become uniform and appearance. Now, carefully transfer the ink particle potassium bromide mixture into a fresh infrared sampling cup.

Press the top surface of the powder with the blunt end of the pestle and carefully top off the sampling cup with more powder. Finally, level all excess powder with a razor blade. The reference and experimental samples are now ready for infrared spectroscopy.Measurements.

Begin by placing both the reference and experimental sample cups into the holder and then place the holder into the sampling compartment. Position the holder such that the reference cup containing the pure potassium bromide crystals is aligned with the infrared illumination path. Quickly close the infrared sampling compartment and re equilibrate the compartment by purging dry nitrogen or air for the time predetermined to be necessary to equilibrate water and carbon dioxide levels.

Usually at least five minutes to reduce the water and carbon dioxide Background peaks. Minimize the air exposure time during the sample loading process. After the chamber purge, illuminate the pure potassium bromide reference sample with the infrared radiation and measure the spectra within the frequencies of interest.

The number of scans should be optimized to maximize the signal to noise ratio while minimizing measurement. Time upon reference spectra collection, open the infrared sample compartment and reposition the holder such that the experimental sample cup will be aligned with the infrared illumination path. Finally, re equilibrate the sampling compartment, allowing dry nitrogen or air purge time necessary to reach equilibration and commence infrared spectra collection on the experimental sample using diffused reflectance infrared spectroscopy.

The data suggests that in a dispersion of nickel two oxide two, butanol and oleic acid, oleic acid association on the surface of nickel, two oxide particles may be mediated through the carbonyl group and the hydroxyl group of the fatty acid From the infrared spectroscopy data, one can speculate some possibilities in which carboxylic acid groups could interact with a metal oxide surface surface in diffuse reflectance infrared spectroscopy, minor deviations in sample preparation and equipment set up protocol such as the infrared lamp, warmup time prior to measurement can dramatically reduce the signal to noise, baseline quality and repeatability of the spectroscopic measurements. Following this procedure, additional experiments can be performed with attenuated total reflectance infrared spectroscopy in order to answer additional questions such as is the presence of adsorbates or the mechanisms of absorption changed by the presence of the solvent. Thank you for watching and good luck with your experiments.