Introduction to Large Scale Bead Synthesis
- After testing bead protocol III one more time, I have observed that the emulsions in the reaction mixture is present. However, the cross-linking is weak or glutaraldehyde has lost its potency.
- I devised a new protocol by increasing the time to cross-link and having a second addition of glutaraldehyde as seen on the picture.
Large Scale Synthesis
- Create a solution of 2.5 g PVA, 0.275 g NaMT, and 30 mL 10% HCl.
- Place this solution on a hot plate and heat/stir until everything has dissolved.
- Add 10 mL of this solution to a 50 mL solution of ethyl acetate stirring at 240 rpm in a dropwise manner.
- Add 1 mL of glutaraldehyde and stir at 260 rpm for 3 minutes.
- After 3 minutes, add 1 mL of glutaraldehyde and stir at 300 rpm for 2 minutes.
- After 7 minutes, add 7 mL of sodium bicarbonate and stir for 30 seconds.
- Remove the solution, put it into 2 50 mL Falcon tubes.
- Centrifuge the solutions for 1 minute at 3000 rpm.
- Pipette all of the liquid out of the tubes and replace with deionized water.
Scanning the Beads
- Courtesy of Tami Tinsley, during Thanksgiving break, she took some of the samples and analyzed them as follows:
- To discover the morphology and elemental characteristics of the PVA+clay beads a Scanning Electron Microscope (SEM) and Engery Dispersive Spectrometry (EDS) were used.
- The beads were first analyzed using an Olympus SZX7 steromicroscope with a Highlight 3100 attachment, to determine the geranal size, shape, and color of the beads. This step is important because the SEM cannot determine color differences.
- Image 1, Olympus SZX7
- Image 2, the general overview taken on the steromicroscope are pictured.
- Next a stub was set up with the three different types of beads present, white, clear and a mixture. An image of the stub was taken with the knotch faces down so that the orientation of the beads could be determined in the SEM.
- Image 3, the stub set up with clear, white, and mixed beads.
- The beads were analyzed on a Jeol JSM-661OLV Scanning Electrom Microscope with low vacuum.
- Image 4, stub and holder before inserted into SEM
Overall the mixed and the white beads have a much smoother surface than that of the clear beads. It was my theory that the clear beads did not have as much clay in them as the white and the mixed. EDS was completed on the three types of beads to confirm that theory.
- The EDS results confirmed that the clear beads had half the amount of sodium than the white and mixed beads.