User:Samiye Yaman/Notebook/Lab 581/2013/02/20

Experimental Chemistry

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Objections Description Part 1 Prepare 3 sets of hydrogels with phosphate buffers A)0.51 g of PVOH (MW:89,000-98,000) with 4 ml of phosphate buffer was placed on to a heat block at 100C. B)0.25 g of PVOH (MW:89,000-98,000) with 3 ml of phosphate buffer was placed on to a heat block at 100C. C)0.14 g of PVOH (MW:89,000-98,000) with 3 ml of phosphate buffer was placed on to a heat block at 100C. Homoginize each of the hydrogels solutions with 35 ml of safflower oil. Right after pouring in to a beaker, flash freeze it with liquid nitrogen then place them into freezer. (3 freeze thaw cycle, 20 hours freeze 4 hours room temperature) Part 2 Prepare 3 sets of hydrogels with phosphate buffers A)0.52 g of PVOH (MW:89,000-98,000) with 4 ml of phosphate buffer was placed on to a heat block at 100C. B)0.25 g of PVOH (MW:89,000-98,000) with 3 ml of phosphate buffer was placed on to a heat block at 100C. C)0.13 g of PVOH (MW:89,000-98,000) with 3 ml of phosphate buffer was placed on to a heat block at 100C. Homoginize each of the hydrogels solutions with 50 ml of safflower oil. Pour them in to a petri dish to have a larger surface area then place them into freezer.(-20C) (3 freeze thaw cycle) Part 3 Prepare a set of hydrogel with phosphate buffer A)0.25 g POVH (MW:89,000-98,000) with 4 ml of phosphate buffer was blaced to a heat block at 100C. Homoginize each of the hydrogels solutions with 50 ml of mineral oil. Pour them in to a petri dish to have a larger surface area then place it into the freezer.(-20C) (3 freeze thaw cycle) Data Notes Safflower oil was used instead of mineral oil. Safflower oil has lower freezing point (approximately -17) than mineral oil (fp:-30C) The reason why we wanted to try safflower oil was it has freezing point lower than -20C. Mineral oil did not freeze completely at -20C. We used big petri dishes instead of beakers to increase the surface area and have a less dense medium as hydrogels sink at the bottom of the container. (to observe if larger surface area will make any difference) Liquid nitrogen was used to flash freeze the hydrogels before they sink at the bottom of the container.