Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

The overall goal of this zirconium phosphate synthesis by three methods and its exfoliation is to obtain various aspect ratio nano platelets which can serve as a model discotic liquid crystal system. This method can help answer key questions in the synthesis of different sizes of zirconium phosphate in the exfoliation techniques field. Such is how to control the aspect ratio of the zirconium phosphate by various synthesis methods, and importantly how to obtain nearly mono dispersed zirconium phosphate nano platelets.

The minute one day of the technique that we demonstrated is that where they will obtain zirconium phosphate nano plates off sizes ranging from 200 nanometers to 2, 000 nanometers with good control and for proper disposary. This method provide insight into liquid crystal model materials it can also be applied for other systems such as pickling emulsifiers. To synthesize alpha zirconium phosphate using the hydrothermal method dissolve six grams of zirconochloride octahydrate in 3.75 mL of deionized water in a beaker.

Add 48 mL of 15 molar phosphoric acid into a teflon lined pressure vessel followed by 8.25 mL of water. Then add the zirconochloride solution drop wise to the phosphoric acid solution under vigorous stirring. Place the vessel into a hydrothermal autoclave composed of a stainless steel shell, pressure plate, and lid and then tighten it well.

Place the hydrothermal autoclave into a convection oven at 200 degrees Celsius for 24 hours. After the reaction, allow the hydrothermal autoclave to cool down eight hours to room temperature under ambient cooling. Transfer the supernatant liquid portion in the reactor to a waste disposal container since it contains unreacted phosphoric acid which is corrosive.

Collect alpha zirconium phosphate nano platelets in two centrifuge tubes. Add 40 mL of water to each centrifuge tube and vortex for one minute. After centrifuging the tubes at 2, 500 x g for five minutes, remove the top liquid in the tubes.

Repeat this step three times to ensure that all of the acid is washed away. Dry the zirconium phosphate water sticky mixture in an oven at 65 degrees Celsius for eight hours and then grind it using a mortar and pestle. To synthesize alpha zirconium phosphate using the reflux method, mix six grams of zirconochloride octahydrate with 60 mL of 12 molar phosphoric acid in a 150 mL round bottom flask.

Reflux the prepared mixture in an oil bath at 94 degrees Celsius for 24 hours. Wash the product with deionized water three times as done for hydrothermal synthesis and then dry the zirconium phosphate water sticky mixture in the oven at 65 degrees Celsius for eight hours. Grind the dried bulky sample into powder using a mortar and pestle and stock for later use.

To synthesize alpha zirconium phosphate using the microwave assisted method add one gram of zirconochloride octahydrate into 10 mL of 12 molar phosphoric acid solution and stir the resulting mixture well in a 20 mL scintillation vial. Pour 5 mL of the resulting mixture into a 10 mL glass vessel specified for a microwave reactor. Set the reaction temperature to 150 degrees Celsius, set the pressure limit to 300 psi and allow the reaction to happen for one hour.

After the reaction, let the glass vessel cool down for about 15 minutes and then follow the same procedure as before for acid washing and drying of alpha zirconium phosphate crystals. Disperse one gram of alpha zirconium phosphate into 7.8 mL of deionized water in a 45 mL centrifuge tube. Add 2.2 mL of TBAOH then vortex for at least 40 seconds.

Notice that the molar ratio of zirconium to TBAOH is kept at 1:1. Sonicate the resulting concentrated suspension for one to two hours. Leave the sonicated suspension for two to three days to allow full intercalation of tetrabutyl ammonium cations and complete exfoliation of crystals.

Optionally, concentrated suspension can be diluted with water to obtain better exfoliation. In this case, add 20 mL of water to 10 mL of exfoliated suspension. Centrifuge the exfoliated samples at high rotation speed for half an hour to remove the bottom sediment and the top liquid.

Collect the middle part in another container. Add another five mL of water and centrifuge again for half an hour. After letting the suspension settle over night remove the top liquid and stock the remaining suspension for liquid crystal study.

The suspension can be diluted at different ratios to see isotropic, nomadic and other possible phases. Scanning electron microscopy, or SCM, images of pristine alpha zirconium phosphate prepared via the hydrothermal method, the reflux method, and the microwave assisted method are shown. Shown here are transmission electron microscopy images of the microwave assisted growth of zirconium phosphate crystals at 150 degrees Celsius.

The phosphate nano platelet is shown at 10 minutes and at 60 minutes. In this image the left bottle contains unexfoliated zirconium phosphate suspended in water and the right bottle has exfloliated zirconium phosphate nano platelets. Different dilutions of stock suspension are shown to exhibit liquid crystal and isotropic nomadic co-existent phase except for the last two vials which are fully nomadic.

The image is a snapshot of the suspensions placed between crossed polarizers. Once mastered this technique can be done in one hour to synthesize layered zirconium phoshate nano platelets in the four days to obtain liquid crystals if it is performed properly. While working out this procedure, one should make sure that the precursors are mixed well.

Following this procedure other studies like nano plates stabilize pickling motion can be also performed in other through answer additional questions such as two dimensional materials in pickling emulsifications. After its development this technique for the researchers in the field of software and condense matter to explore liquid crystals of inorganic and aquatic systems. After watching this video you should have the understanding how to synthesize nearly mono dispersed zirconium phosphate nano platelets.

And then use them for different applications in the fundamental studies on liquid crystals. Don't forget working with phosphoric acid can be extremely hydrous so when you are doing experiments don't forget the personal protective equipment and also you need to deal with the wasted acid properly.