Students need diapers, scissors, plastic cups, freezer bags and water to observe the absorption properties of hydrogel. Cut open the inside of a diaper and remove the stuffing and plastic lining. Place the stuffing and lining in a clean freezer bag and inflate slightly by blowing air into the bag before sealing. Shake the bag to separate the powder from the lining. Open the bag and remove all contents except the powder. Measure the powder and extract the contents of another diaper if needed to collect a 1-Tbsp. sample. Dump the hydrogel powder into a plastic cup and add 1/2 cup of water. Wait 30 seconds and observe what happens to the hydrogel. It should expand as it absorbs the water and form a gooey solid.
Hydrogel is a promising source for containing groundwater contamination, which may prove valuable in areas affected by major disasters, such as hurricanes or nuclear plant meltdowns. Hydrogels may be able to prevent dangerous toxins that spread through soil following these disasters that threaten drinking water. Students should test this potential use by removing the bottoms of two clear plastic bottles and drill a small hole through the center of each bottle cap. Screw on the caps and invert the bottles into drinking glasses so the open ends face up. Fill the bottles with 1 cup of potting soil each and mix 1 Tbsp. of hydrogel powder into the first bottle. Prepare one packet of red powdered drink mix according to directions, but do not add sugar. Pour 1/4 cup of red solution in each soil sample and observe what trickles into the glass below. Continue adding 1/4 cup to each bottle once every five minutes until the solution is gone. Based on the results of the experiment, students should conclude how effective hydrogel would be at preventing groundwater contamination.
Cross-linked polyacrylamide copolymer gels are widely used in home gardens and forest areas where water conservation is a high priority. Students should test how effective the copolymer gel is at retaining water by gathering two potted samples of five different plants, identical in maturity. Leave one of each sample unaltered and mix 1 dry tsp. of crystals into the second plant's potting soil. Place all plants in a sunny place outdoors during summer months. Observe water retention among plants by touch and examining drip pans underneath each pot. Record how often each plant must be watered to establish a proportional ratio of water consumption.
Student investigators will determine whether hydrogels can be used as an effective drug delivery system in a simple at-home experiment. Students should brew tea on the stove in a large pot and leave overnight. Pour tea into a plastic cup and add 1 tbsp. of hydrogel crystals, which can be collected from a diaper. Allow to absorb overnight. The crystals should turn brown. Sieve the mixture and rinse gel crystals. Dissolve 1 tsp. of salt in 200mL of water and pour into a plastic cup. Add 200mL distilled water to 2 plastic cups and place all three plastic cups on a sheet of copy paper. Stir 1 tsp. of sugar into the second cup. Divide the hydrogel crystals into the three cups and leave for 10-15 minutes. Observe the results and record data. Propose whether hydrogels are effective drug carriers and in what methods they could be employed.