User:Moira M. Esson/Notebook/CHEM-581/2013/01/30

Objectives

• Prepare all polyvinyl alcohol(MW 146,000-186,000) hydrogels with clay additives
• Run X-ray diffraction, DSC, and FTIR spectroscopy of all clay samples that were added to the PVOH hydrogels
• Preparation of dye stock solutions.

Preparation of Hydrogels

General Protocol:

1. Using a clean 10mL-20mL beaker, add the desired amount of polyvinyl alcohol. (If preparing a 90:10 ratio of polyvinyl alcohol to clay hydrogel, add ~0.9g PVOH. If preparing a 50:50 ratio of polyvinyl alcohol to clay, ~0.5g polyvinyl alcohol should be added. All hydrogels were prepared on a 1g scale.)
2. Add the desired amount of clay to the sample.
3. Add a magnetic stir bar to the beaker and 6mL of distilled to the reaction mixture.
4. Add 8wt% DMSO to the reaction mixture.
5. Heat the reaction mixture to 80°C. If the reaction mixture begins to boil, immediately reduce heat.
6. Allow the reaction mixture to stir at 80°C for at least 2 hours, or until complete dissolution of polyvinyl alcohol and equal distribution of clay throughout the reaction mixture.
7. Remove reaction mixture from heat and place in freezer(-20°C) for 24 hours. After 24 hours, remove from the freezer and allow to thaw for 24 hours.
8. Repeat this process three times.

The following procedure was adapted from PVA–clay nanocomposite hydrogels for wound dressing
Hydrogel information:

• Need to add table of info

Observations:

• Hydrogels containing sodium montmorillonite(NaMT) required the addition of 1mL distilled H₂O and required longer heating time. This should be noted when dye is added. A separate, slightly more concentrated stock solution of dye should be prepared for addition to any hydrogels with NaMT additive.
• After preparation of 6 hydrogels, realized that the inclusion of dye will be necessary before the freeze-thaw crosslinking method is performed. I.e. Dye should be added during heating process of PVOH-clay reaction mixture.

Calcualtions for dye preparation