Make Guar Gum Slime
Curiosity often overwhelms those who see an unrecognizable substance. “What is it?” they wonder, “What can it be?”
Capture your students’ attention with this “goopy” slime recipe.
• Polymers, polymerization
Slime is generally considered nonhazardous; however, it should not be ingested and should only be used in the manner intended. It is not recommended that students be allowed to take slime home. Slime will easily stain clothing, upholstery, and wood surfaces. With food coloring added, it will stain these surfaces and skin even more readily. Wear chemical splash goggles, chemical-resistant gloves, and a chemical-resistant apron. Please review current Material Safety Data Sheets for additional safety, handling, and disposal information.
1. Add 250 mL (or one cup) of distilled or deionized water to the small plastic cup. If desired, add a few drops of food coloring to the water and stir.
2. Slowly and with constant stirring, add 2 g of guar gum to the water. Note: If the guar gum is added too quickly, it will form large, undesirable clumps. Stir until dissolved. The mixture will thicken slightly within 1–2 minutes.
3. Add 10 mL (or one table spoon) of 4% sodium borate solution. Stir. The mixture should gel in 1–2 minutes.
Slime can be disposed of with regular household garbage unless otherwise is regulated by your local, state or federal government. review all federal, state and local regulations that may apply, before proceeding.
• Try using distilled or deionized water. The ions present in tap water may interfere with the polymerization reaction, causing the slime to turn watery after only an hour or two. Slime made with distilled or deionized water will retain its properties and consistency for several days.
• Store the slime in an airtight container or bag to prevent it from drying out.
Guar gum, a natural polymer with a molecular weight of about 220,000 g/mole, is made from the ground endosperms of Cyamopsis tetragonolobus, a legume cultivated in India as livestock feed. Guar gum has 5–8 times the thickening power of starch and is commonly used as a binding or thickening agent in foods and cosmetics.
Guar gum is a long-chain polyalcohol with 1,2-diol groupings capable of complexation with the borate ion, B(OH)4–. The structures given below are oversimplified, but may help to visualize the network complex as it extends in three dimensions.
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