OBJECTIVES
ACCIDENTALLY PLACED THIS ENTRY ON THE FEBRUARY 4th; HOWEVER, THIS ENTRY SHOULD BE UNDER FEBRUARY 6th. THANK YOU.
- 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.
- Dissolve ~ 1.0g total of PVOH 146K and clay additive selected (laponite) in 5mL hot deionized H2O
- Acidify the solution using 0.25mL 0.5M H2SO4
- Dissolve ~ 0.6g cellulose acetate butyrate (CAB) in 25mL 1,2-dichloroethane within a round bottom flask
- Pour the acidified PVOH 146K solution into the 25mL 1,2-dichloroethane solution within the clean round bottom flask
- Stir 1,2-dichloroethane, CAB, and PVOH 146K solution for 30 minutes
- After 30 minutes of stirring, add 0.75mL glutaraldehyde to the solution
- After the addition of glutaraldehyde, allow the reaction to carry out for 3 additional hours at 55°C
- Filter the produced microspheres from the solution using a a sintered glass filter and a vacuum
- Wash the collected microspheres using ~ 2-3mL of the following solvents in the following order:
* 1,2-dichloroethane
* acetone
* hot water
* cold water
* methanol
- Scrape off all of the collected microspheres into a small glass vial. Leave the lid off of the small glass vial.
- Freeze microspheres in liquid nitrogen for ~ 2 minutes
- 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
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'
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PVOH 146K added(g) |
0.9001
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Laponite clay added (g) |
0.1004
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Cellulose Acetate Butyrate added (g) |
0.6066
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Glutaraldehyde added (mL) |
0.75
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H2SO4 added (mL) |
0.25
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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
- Filter a clay solution selected using the vacuum filtration system setup
- Attach all parts of the apparatus to the vacuum filtrator system
- Place a piece of Whatman #42 filter paper in the Buchner Funnel
- Turn on the vacuum filtrator system
- Check the suction rate to ensure that enough pressure is applied
- Pour an exchanged clay solution into the Buchner funnel
- Allow vacuum filtration to continue until the clay is completely dry
- Discard the aqueous filtrate solution and place it in a labeled waste container
- Collect the soil filtrate on the filter paper and scrape it into a small labeled metal pan
- Place metal pan with the soil filtrate in the oven to dry for ~ 2-3 days
- Wash all glassware and equipment first with H2O and then with acetone for later use
Notes
ACCIDENTALLY PLACED THIS ENTRY ON THE FEBRUARY 4th; HOWEVER, THIS ENTRY SHOULD BE UNDER FEBRUARY 6th. THANK YOU.
- 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.
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