To crosslink the films prepared last week, to prepare more glutaraldehyde fixant, and to synthesize the quaternary ammonium salt
Crosslinking Glutaraldehyde Films
- Allow the PVOH film containing glutaraldehyde to dry completely.
- Prepare a solution of 100 mL H2O, 2 mL concentrated H2SO4, and 20 g Na2SO4 in a 150 mL beaker. (solution is referred to as glutaraldehyde fixant)
- Place stir bar in beaker and a Buchner funnel top (cap) over the stir bar
- Heat solution to 70°C (temperature on hotplate should be about 160)
- Place film in solution for one hour.
- Prepare 100 mL of a 1% HCl solution in a 150 mL beaker. Place a stir bar and an inverted buchner funnel into beaker.
- Heat HCl solution to 70°C
- Remove film from glutaraldehyde fixant and rinse with distilled water.
- Place film into HCl solution for 30 minutes.
- Prepare 0.2 M sodium bicarbonate solution. (1.68 g in 100 mL)
- After 30 minutes, remove the film from the HCl solution and place into the sodium bicarbonate solution (at room temperature) for about 15 minutes.
- Use tweezers to remove the film from the sodium bicarbonate solution.
- Rinse film with deionized water.
- The films were then allowed to dry until Thursday, when they will be tested with DSC.
Glutaraldehyde Fixant Preparation
Glutaraldehyde fixant is prepared by making a solution of 100 mL H2O, 2 mL concentrated H2SO4, and 20 g Na2SO4 in a 150 mL beaker. We prepared this solution on a 1000 mL scale.
Quaternary Ammonium Salt Preparation
- Quaternary ammonium salt was prepared by reacting triethylamine with 4-Chloro-1-butanol.
- Reaction was calculated to produce 1 g product with a 2X excess of the 4-Chloro-1-butanol.
- 10 mL of acetonitrile was placed in a round bottom flask.
- 1.14 mL of 4-Chloro-1-butanol and 0.78 mL triethylamine, respectively, were added to the round bottom flask.
- The round bottom flask was placed on a reflux condenser under nitrogen.
- The reaction was allowed to reflux for 3 days (until Thursday afternoon)
No data was collected today.
- For future syntheses of the quaternary ammonium salt, a 1.1X excess of 4-Chloro-1-butanol will be added.
- The quaternary ammonium salt will be purified by adding it dropwise to a bath of ethyl acetate. The positive charge of the salt will cause it to precipitate out.
- On thursday, the purity of the quaternary ammonium salt will be assessed using NMR.
- After crosslinking, the 1% and 0.1% isopropyl films fell apart, while all other films remained intact. One possible cause/problem with the current film preparation technique is that because the water in the films has to evaporate over the course of 3 days, it is likely that the isopropyl alcohol added evaporated during this time period. On thursday, we will try to remake these films using phenol, instead of isopropanol, because it is less likely to evaporate.
- For future crosslinking, glutaraldehyde fixant will not be used, because a higher molecular weight PVA is being used. Glutaraldehyde fixant is only required when lower weight PVA is being used, because the presence of the sodium sulfate keeps the PVA from going into solution, but the higher molecular weight PVA is significantly less soluble, so the sodium sulfate is not needed. For crosslinking, only an HCl solution will be used.