User:Moira M. Esson/Notebook/CHEM-581/2013/03/01

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  1. Conduct pressure tests on all hydrogels using an unmodified pipette.
  2. Run fluorescence on all samples collected from the pressure tests.
  3. Decant the safflower oil from the microsphere samples prepared on 2013/02/22.

Pressure tests using an unmodified pipette

  • All pressure tests were conducted following the general protocol described on 2013/02/20.
  • Pressure tests were conducted using an unmodified pipette in order to determine if the very slight amount of sheer pressure caused by an unmodified pipette would cause a detectable amount of dye diffusion.

Table 1. Information concerning the pressure testing involving hydrogels with an unmodified pipette.

Sample Order PVOH vs. Clay Ratio PVOH Type Clay Selection Amount of Hydrogel Used (g)
150:50130K110% CEC NaMT w/ DMHXLBR0.1006
250:50130K110% CEC NaMT w/ DMHXLBR0.1022
450:50146K110% CEC Laponite w/ DMHXLBR0.1066
590:10130K110% CEC Laponite w/ DMHXLBR0.1083
690:10130K110% CEC NaMT w/ DMHXLBR0.1003
750:50130K110% CEC Laponite w/ DMHXLBR0.1036
990:10130K110% CEC NaMT w/ DMHXLBR0.1011
1090:10146K110% CEC NaMT w/ DMHXLBR0.1020
1250:50130K50% CEC NaMT w/ Bu3HdP+0.1015
1350:50146K110% CEC NaMT w/ DMHXLBR0.0998
1490:10130K50% CEC NaMT w/ Bu3HdP+0.1026

 Figure 1. Fluorescence of hydrogel samples modified with Lamponite clay using an unmodified pipette for pressure testing

Image:Fluorescence of Rhodamine 6G collected from pressure test of hydrogels with Lamponite clay and using an unmodified pipette.png

 Figure 2. Fluorescence of hydrogel samples modified with NaMT clay using an unmodified pipette for pressure testing

Image:Fluorescence of Rhodamine 6G collected after pressure test of hydrogels with NaMT clay and unmodified pipette.png

 Figure 3. Fluorescence of all hydrogel samples using and unmodified pipette for pressure testing


  • The amount of dye, or concentration of dye, that was diffused from the hydrogels using an unmodified pipette was significantly lower than that of a bent pipette.
  • The general trends observed using a bent pipette were also observed with an unmodified pipette.(Unmodified clay had the highest absorbance values. On average, hydrogels with NaMT clays had a higher absorbance than the hydrogels prepared with lamponite clays. Similarly, the higher molecular weight PVA hydrogels exhibited higher absorbance values, indicating these hydrogels are better at exerting/responding to sheer pressure).
  • Similar to the bent pipette, the concentration of Rhodamine 6G in the samples is extremely low in comparison to the 0.25μM Rhodamine 6G control, with the highest absorbance value of 9.204 observed in the 50:50 ratio of PVA MW 130,000:NaMT in comparison to the highest absorbance value of 606.17999 in the Rhodamine 6G 0.25μM. Another procedure that will exert more sheer pressure will be determined. A new method for the preparation of hydrogels will be considered where a single layer of clay will be incorporated into the hydrogel rather than having clay distributed throughout the hydrogel.


  • After the three cycle freeze thaw method, the microsphere samples were removed from the freezer.
  • The microsphere samples were allowed to sit outside of the freezer for approximately 1 week. During this time two distinct layers formed, a layer of the aqueous microspheres formed the lower most layer and a top layer of organic safflower oil formed.
  • In order to obtain the microspheres the safflower oil needed to be removed from the vials.

General Protocol for decanting the microspheres:

  1. All microsphere samples were placed on a flat surface and allowed to settle for approximately 15 minutes.
  2. Without touching the vial or moving the vial containing the microspheres(so as not to disturb the fine particles), a glass pipette was used to carefully removed the safflower oil. The safflower oil was placed in an appropriate waste container.


  • Many of the prepared microspheres became a gel rather than retaining their sphereical shape due to the fact a higher ratio of PVA was present in the PVA safflower oil emulsion. In the future, very small amounts of PVA will be placed in the vials.
  • DSC will be run on both the microspheres and the gels.

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