User:Moira M. Esson/Notebook/CHEM-581/2013/02/06

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  1. Prepare PVA(MW 130,000) microspheres through suspension cross-linking of a polymeric solution with glutaraldehyde.
  2. Remove prepared MW 130,000 PVA hydrogels from freezer and begin soaking in water.
  3. Finish preparing PVA(MW 130,000) hydrogels for freeze-thaw method.
  4. Filter prepared clay exchanges.
  5. Prepared DSC samples of all used clays.

PVA Microspheres

General Protocol:

  • Reaction should be carried out using a reflux condenser and a thermostatic water bath of 55°C.
  1. Dissolve 1g total of PVA and clay additive in 5mL hot,deionized water.
  2. Acidify the solution using 0.25mL 0.5M H2SO4.
  3. Dissolve 0.6g Cellulose acetate butyrate(CAB) in 25mL 1,2-dichloroethane.
  4. Pour the acidified PVA solution into the 25mL 1,2-dichloroethane solution. Place all in a clean round bottom(RB) flask.
  5. Stir the water/1,2-dichlorethane solution for 30 minutes.
  6. After 30 minutes stirring, add 0.75mL glutaraldehyde(GA) to the solution.
  7. After the addition of glutaraldehyde, allow the reaction to carry out for 3 additional hours at 55°C.
  8. Filter the produced microspheres from the solution using a a sintered glass filter and a vacuum.
  9. Wash the collected microspheres using the following solvents in the following order:
    1. 1,2-dichloroethane
    2. acetone
    3. hot water
    4. cold water
    5. methanol
  10. Dry the microspheres at 60°C overnight.
  • The following procedure was adapted from the article Poly(vinyl alcohol) microspheres with pH- and thermosensitive properties as temperature-controlled drug delivery [1]

1,2-dichlorethane safety:

  1. 1,2-dichloroethane is highly flammable. Care must be used at all times when dealing with 1,2-dichloroethane
  2. Avoid all 1,2-dichloroethane skin contact by wearing gloves and googles.
  3. Avoid any 1,2-dichlorethane contact with extreme heat, open flame, or electrical sparks.
  4. 1,2-dichloroethane should be kept in the flammable storage safety cabinet when not in use.
  5. When in use, 1,2-dichloroethane should be kept in the fume hood.

PVA Microsphere information:

Preparation of Microspheres using PVA MW 146,000-186,000 '
Amount of PVA added(g) 0.9001
Amount of Lamponite clay added(g) 0.1004
Amount of cellulose acetate butyrate added(g) 0.6066
Amount of GA added(mL) 0.75
Amount of H2SO4 added(mL) 0.25


  • The dispersion agent(hereout referred to as CAB), lamponite clay and PVA formed a sort of suspension in the water/organic solvent solution. It did not appear to fully dissolve. Used a spatula to scrape the side of the RB flask in order to try and break up the large chunks.
  • After addition to heat, the large chunks generally broke apart. Small spheres seemed to be forming after approximately an hour spinning.

Hydrogel Preparation

  • The general protocol described on January 30th was followed.

Clay Filtration