User:Elizabeth Schott/Notebook/Nanoparticles/2015/05/29

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May 29 2015: Poly (vinyl alcohol) Crosslinked Hydrogel Membranes

  • The purpose of this experiment was to find the most efficient way to dissolve poly (vinyl alcohol) into water as a preliminary step in order to form hydrogel membranes

Procedure

1) Using a 600 mL beaker filled with water, a hot plate, 3 ring stands, 3 clamps, and a thermometer, a hot water bath was set up prior to the experiment to the temperature of 90 degrees.

2) Using a plastic weigh boat and scale, 2 grams of 31-50 g/mol poly (vinyl alcohol) was weighed and transferred to a plastic vile. This was repeated twice to make a total of 3 identical viles and label 1-3.Using a graduated cylinder, 20 mL of deionized water was then added to each of the viles. Vile 1 was left to sit at room temperature. Vile 2 was moved to the hot water bath, and a stopwatch was set to record end time of dissolution. Vile 3 was placed in a sonicater, and a stopwatch was set to record end time of dissolution. At 5 minute intervals, the tubes were shaken. After the poly (vinyl alcohol) had fully dissolved in the water in each of the viles, they were removed, time was recorded, and were transferred to a freezer for the first freeze-thaw cycle.

3) Using a plastic weigh boat and scale, 2 grams of 89-98 g/mol poly (vinyl alcohol) was weighed and transferred to a plastic vile. This was repeated twice to make a total of 3 identical viles and label 1-3. Using a graduated cylinder, 20 mL of deionized water was then added to each of the viles. Vile 1 was left to sit at room temperature. Vile 2 was moved to the hot water bath, and a stopwatch was set to record end time of dissolution. Vile 3 was placed in a sonicater, and a stopwatch was set to record end time of dissolution. At 5 minute intervals, the tubes were shaken. After the poly (vinyl alcohol) had fully dissolved in the water in each of the viles, they were removed, time was recorded, and were transferred to a freezer for the first freeze-thaw cycle.

4) Using a plastic weigh boat and scale, 2 grams of 89-98 g/mol poly (vinyl alcohol) was weighed and transferred to a plastic vile. This was repeated but with .2 grams of Chitosan. Using a graduated cylinder, 20 mL of deionized water was then added to the vile. The vile was moved to the hot water bath, and a stopwatch was set to record end time of dissolution. At 2 minute intervals, the tube was shaken. After solvent of poly (vinyl alcohol) and Chitosan had fully dissolved in the water, the vile was removed, time was recorded, and was transferred to a freezer for the first freeze-thaw cycle.

5) Using a plastic weigh boat and scale, 2 grams of 89-98 g/mol poly (vinyl alcohol) was weighed and transferred to a plastic vile. This was repeated but with .2 grams of Alginic acid. Using a graduated cylinder, 20 mL of deionized water was then added to the vile. The vile was moved to the hot water bath, and a stopwatch was set to record end time of dissolution. At 2 minute intervals, the tube was shaken. After solvent of poly (vinyl alcohol) and Alginic acid had fully dissolved in the water, the vile was removed, time was recorded, and was transferred to a freezer for the first freeze-thaw cycle.

6) Using a plastic weigh boat and scale, 2 grams of 89-98 g/mol poly (vinyl alcohol) was weighed and transferred to a plastic vile. This was repeated but with .2 grams of Cloisite Na+. Using a graduated cylinder, 20 mL of deionized water was then added to the vile. The vile was moved to the hot water bath, and a stopwatch was set to record end time of dissolution. At 2 minute intervals, the tube was shaken. After solvent of poly (vinyl alcohol) and Cloisite Na+ had fully dissolved in the water, the vile was removed, time was recorded, and was transferred to a freezer for the first freeze-thaw cycle.

7) After approximately 4 hours, the viles left at room temperature were transferred to the hot water bath and timed until the solvent had dissolved. Time was recorded, and the vile were transferred to the freezer for the first freeze-thaw cycle.


Results

Normgel.png EXTRAGEL.png

The tables show the times at which the solute fully dissolved in the solvent.

Discussion

The use of poly (vinyl alcohol) hydrogel membranes is typically associated with studies towards use for wound dressing and care. Because these hydrogels have a high content of water, it helps to maintain a moist environment around wounds that has shown to increase re-epitheliazation rates. Our goal is to see if these hydrogels can also be used to absorb gold nanoparticles. To make these gels, the freeze-thaw technique is used, which is why we put all viles in the freezer to be taken out the following Monday. In our experiment, two important conclusions were drawn. The first being that the 89-98 g/mol poly (vinyl alcohol) took less time to dissolve (in all heating techniques) than the 31-50 g/mol poly (vinyl alcohol). The second being that the viles that were placed in the hot water bath took less time to dissolve than those in the sonicater and those left at room temperature. This procedure was modeled after a study at King Saud University.

EMS