To begin, place all required glassware in an oven at 140 degrees Celsius for at least one hour prior to use. For the impregnation of silica with PEI 800, first calculate the mass fraction of the amine required. Then take the desired amount of MCM-41 silica in a glass Petri dish and cover it with punctured aluminum foil.
After placing the covered dish in a vacuum oven, apply the vacuum. Then set the oven to a temperature of 110 degrees Celsius and leave it for a minimum of two hours to ensure complete drying of the silica. To prepare for the synthesis, using a clean, dry laboratory spatula, transfer the desired amount of PEI into the reaction vessel.
After capping the vessel, transfer it to a chemical fume hood and place it over a stir plate while clamping it securely. Once set, remove the lid of the reaction vessel and place a clean, dry stir bar into it. Using a pipette, transfer the desired amount of anhydrous methanol to the vessel from a graduated cylinder.
Stir the reaction mixture for 15 minutes to ensure the PEI is dissolved and dispersed in the solvent homogeneously. Next, using a clean, dry laboratory spatula, transfer the desired amount of silica that was dried in the oven onto weighing paper and add it to the PEI solution in the reaction vessel inside the fume hood. If needed, add additional methanol to rinse any residual silica from the vessel wall into the PEI solution.
Place the vessel in a heating block at 40 to 50 degrees Celsius to load the amine into the porous silica. Let the solution undergo stirring for about one hour while ensuring the stir bar is evenly mixing the solution. After that, remove the reaction vessel from the heat source and while still stirring, allow it to cool to room temperature.
When fully cooled, stop the stirring to remove the stir bar. Connect the vessel containing the sample to the vacuum on a Schlenk line. Let the reaction vessel remain on the Schlenk line until all solvent is visibly removed, then transfer the sample to a different storage container of choice, such as a glass Petri dish.
After placing the sample in a vacuum oven, turn on the vacuum. Allow the sample to dry under the vacuum at 70 degrees Celsius for at least 18 hours. Store the resultant white powdery material in a moisture-free, air-free environment until needed for further use.
