User:Karlena L. Brown/Notebook/PVOH Research/2013/02/04

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  • Begin preparing polyvinyl alcohol microsperes for experimental analysis
  • Filter surfactant exchanged modified clays
  • Complete freeze and thaw crosslinked clay cycle #1

90:10 PVOH Clay Microsphere Preparations

*Reaction should be carried out using a reflux condenser and a thermostatic water bath of 55°C.

  1. Dissolve ~ 1.0g total of PVOH 146K and clay additive selected (laponite) in 5mL hot deionized H2O
  2. Acidify the solution using 0.25mL 0.5M H2SO4
  3. Dissolve ~ 0.6g cellulose acetate butyrate (CAB) in 25mL 1,2-dichloroethane within a round bottom flask
  4. Pour the acidified PVOH 146K solution into the 25mL 1,2-dichloroethane solution within the clean round bottom flask
  5. Stir 1,2-dichloroethane, CAB, and PVOH 146K solution for 30 minutes
  6. After 30 minutes of stirring, add 0.75mL glutaraldehyde 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 ~ 2-3mL of the following solvents in the following order:
       * 1,2-dichloroethane
       * acetone
       * hot water
       * cold water
       * methanol
  1. Scrape off all of the collected microspheres into a small glass vial. Leave the lid off of the small glass vial.
  2. Freeze microspheres in liquid nitrogen for ~ 2 minutes
  3. Place on [ask Dr. Hartings name of machine again] overnight to completely dry

* The following procedure was adapted from the article Poly(vinyl alcohol) microspheres with pH- and thermosensitive properties as temperature-controlled drug delivery [1]

Preparation of Laponite Microspheres using PVOH MW 146,000-186,000 '
PVOH 146K added(g) 0.9001
Laponite clay added (g) 0.1004
Cellulose Acetate Butyrate added (g) 0.6066
Glutaraldehyde added (mL) 0.75
H2SO4 added (mL) 0.25

Important 1,2 Dichloroethane and Glutaraldehyde Safety

  • Glutaldehyde is toxic colorless liquid (MW: 100.12 g / mole)
  • 1,2 Dichloroethane is a toxic colorless flammable liquid (MW: 98.96 g / mole)
  • Avoid all glutaldehyde and 1,2 dichloroethane skin contact by wearing gloves and googles
  • Glutaldehyde should be kept in the freezer when not in use
  • 1,2 Dichloroethane should be kept in a flammable cabinet when not in use
  • When in use, both glutaldehyde and 1,2 dichloroethane should be kept in the fume hood
  • 1,2 Dichloroethane should be capped at all times when not in use to inhibit inhalation and free floating volatile particles in the air
  • Keep the glutaldehyde vial in a beaker so that it does not spill
  • Keep anything and everything containing some form of 1,2 dichloroethane in the hood and allow all residue to evaporate off before washing
  • If spilled, wipe up glutaldehyde with paper towel while wearing gloves
  • If spilled, use a spill kit towel to soak up excess 1,2 dichloroethane. Allow some of the residual essence of 1,2 dichloroethane to evaporate; then use acetone to wipe over area contaminated with 1,2 dichloroethane.
  • Keep all spills of glutaldehyde and 1,2 dichloroethane contained in the fume hood
  • Wash hands after removing gloves that were in contact with glutaldehyde or 1,2 dichloroethane

Clay Exchanged Solutions & Vacuum Filtration Procedures

The clays being filtered are the clays that were prepared on 2/1/13

Setup of a vacuum filtration system:

  * Clean 250mL Erlenmeyer Filter Flask
  * Large Buchner Funnel
  * Whatman #42 Filter Paper
  * Long Secure Rubber Hose
  1. Filter a clay solution selected using the vacuum filtration system setup
  2. Attach all parts of the apparatus to the vacuum filtrator system
  3. Place a piece of Whatman #42 filter paper in the Buchner Funnel
  4. Turn on the vacuum filtrator system
  5. Check the suction rate to ensure that enough pressure is applied
  6. Pour an exchanged clay solution into the Buchner funnel
  7. Allow vacuum filtration to continue until the clay is completely dry
  8. Discard the aqueous filtrate solution and place it in a labeled waste container
  9. Collect the soil filtrate on the filter paper and scrape it into a small labeled metal pan
  10. Place metal pan with the soil filtrate in the oven to dry for ~ 2-3 days
  11. Wash all glassware and equipment first with H2O and then with acetone for later use



  • Clays previously prepared on 2/1/13 only exchanged for ~ 5 days rather than a week.
  • While attempting to filter the clays, due to vacuum filtration moving rather slowly during separation, clays only were filter for ~ 2.5 hours before actually being placed in the oven.
  • The temperature of the oven when the clays were placed in was ~ 90°C.
  • When removing clays from freeze and thaw process in cycle #1, many clays appeared to maintain ice crystals within their structure.
  • NaMT clays after freezing and thawing cycles appeared more rigid than laponite samples, but all in all PVOH 146K structure was maintained.
  • As freezing and thawing continued, PVOH 146K control sample became more crystalline and clear in appearance.
  • For all hydrogels that were removed with dye previous placed and attached within their contents, ~ 3mL of water was added to each beaker to analyze as well as quantify if and how much dye would leak out of each hydrogel.