User:Eleni N. Kalivas/Notebook/CHEM-571/2015/02/06

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February 6, 2015

  • MG absorption/rehydration trial
  • PVA-Alg-Hectorite

Procedure

Procedure adapted from | Kuo-Ying Amanda Wu and Keith D. Wisecarver (1992)<br.> Modified from 1/28/2015

  1. Prepare an aqueous solution of 13% PVA and 0.02% sodium alginate at 60°C (Stir plate on 3rd setting: ~68°C)
    • 1 gram of PVA and 0.16 g of sodium alginate in 7 mL of water (12.5% PVA and ~0.02% alginate)
      • Add alginate while stirring PVA-water solution
    • ~0.1 g of nanocomposite should be added to this mixture where applicable
  2. Cool dissolved and mixed solution to 35°C
  3. Prepare 210 mL of saturated citric acid with 4% calcium chloride
    1. Add 8.4 grams (4%) of calcium chloride to 210 mL of water
    2. Add citric acid to saturation (32 g citric acid)
      • 14.7g/100mL > 30.87 g/210 for solubility comparable to boric acid
  4. Add the PVA-Alg-Nanocomposite mixture drop-wise (by syringe) to the gently stirring (stir plate 3) citric acid-calcium chloride solution using a Pasteur pipette
  5. Stir for 2 hrs to allow solidification
  6. Rinse with water to remove excess reactants

Measurements

  • PVA-Alg-Hectorite
    • PVA: 1.003 g
    • Alg: 0.161 g
    • Hectorite: 0.105 g
    • Citric acid: 12.751 g
    • CaCl2: 8.414 g
  • PVA-Alg-NaMT vial: 706 mg
  • PVA-Alg-NaMT upscale synthesis: 1470 mg

Notes

  • Rehydration attempt done on shaker, started at 12:28pm
    • Beads on bottom of vial separate into individuals beads as they rehydrate
  • Try lessening/removing citric acid
  • Observation: beads that hold up seem to sink to the bottom where as the ones that fall apart float

List of Characterization Techniques

  • UV-vis absorption (equilibrium measurements)
  • DSC: wet >before and after dehydration (structure & cross-linking)
  • pXRD dry (structure & cross-linking)
  • FTIR/solvent washing (bonds)
  • Microscopy: dry and wet (swelling, bead size)?