User:Moira M. Esson/Notebook/CHEM-581/2013/04/12

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Objectives

  1. Finish PVA/clay film preparation.
  2. Finish preparing DSC samples.
  3. Run DSC.
  4. Run X-ray on prepared microspheres with a 50:50 ratio of PVA/clay.
  5. Add deionized H2O to all prepared hydrogels in preparation for DSC.
  6. View prepared microspheres under microscope.


DSC

  • The general protocol for DSC was used
  • Specific DSC parameters and protocols set to analyze PVA/clay samples were:
   # Equilibrate sample at ~ -40°C
   # Ramp sample temperature up from 20-240°C
   # Ramp sample temperature down from 20-(-40°C)
   # Repeat segment #2 again


Table 1. DSC sample preparation

Sample Name Sample Mass (mg) Pan / Lid Mass (mg)
90:10 PVOH 146K 50% CEC NaMT3.1049.78
90:10 PVOH 146K NaMT3.0149.99


Film Preparation

  • The general protocol for film preparation described on 2012/08/29 was followed. The necessary amount of clay was added in the correct ratio. All films were prepared on a 0.5g scale. The films were placed in a freezer at -20°C immediately after pouring. These films will undergo the cyclic freeze-thaw procedure used for hydrogel preparation.


Table 2. Film Preparation

PVOH vs. Clay Ratio Clay Selection PVOH 130K Mass (g) Actual Clay Mass (g) H2O Added (mL)
50:50NaMT0.262600.247708.0
90:10NaMT0.401000.121408.0
50:50Laponite0.247500.245808.0
90:10Laponite0.405800.109108.0
90:10110% CEC Laponite w/ DMHXLBR0.250800.248508.0
50:50110% CEC Laponite w/ DMHXLBR0.398200.108408.0


X-Ray Analysis

General Protocol:

  1. Use a Kimwipe and acetone to thoroughly clean the low background sample holder
  2. Insert Sample into the low background holder. Note: Must make sure that the sample is completely flat and that the particle sample size is very small. If the sample is too large, use a mortar and pestle to completely grind the sample
  3. Turn on the chiller
  4. Turn on Miniflex II. This is the white button on the machine
  5. Turn on X-ray. The machine will be on when the red lights on the button labeled x-ray light up
  6. Using a Geiger counter, test the radiation from the machine
  7. Set sample in sample holder and record sample holder number
  8. Close the door to the x-ray
  9. Open software on computer
  • 50:50 PVA 130K:110%LP was run on the x-ray. The data will be collected during the next session.

Hydrogel DSC preparation

  • 3mL of deionized H2O was added to each of the hydrogel samples. H2O was added in order to soften the hydrogels to allow DSC sample preparation. H2O was also added in order to remove any excess Rhodamine 6G still present.
  • The hydrogels will soak in deionized H2O until the next session. The water will be changed each day in order to remove the most Rhodamine 6G.

Microscope

  • In order to determine if true microspheres had been prepared, it was necessary to view the prepared microspheres under a microscope.
  • To obtain true microspheres, the prepared samples were sonicated with a high power-probe sonicator.


General Protocol:

  1. Remove microsphere samples from vial. Place microsphere samples in a clean, 50mL falcon tube.
  2. Add 10mL deionized H2O to the tube.
  3. Sonicate the microspheres using the high power probe sonicator for 3 minutes.

Note: Use protective ear equiptment whenever opearting the high power sonicator

  1. Once the microspheres are completely mixed(the solution should be a milk white color), add a small amount of sample onto a glass slide using a Pasteur pipette.
  2. View microspheres starting on the lowest magnification setting.


  • Two microsphere samples were viewed under the microscope: PVA MW130,000 and 50:50 PVA 130,000:110% LP
  • When viewed, both samples contained microspheres.

Notes

  • A plain oil sample will need to be run on the x-ray as a reference. Because of the presence of safflower oil in the prepared microsphere samples, the oil peak will be determined using the control oil spectrum.




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