# Ghostbuster Slime

### Science Concept

Polyvinyl alcohol mixed with borate forms a slimy gel.

### Materials

• 8 mL 4 %borate solution (4 g. / 100 mL)
• 50 mL polyvinyl solution (4 g. / 100 mL)
• Fluorescein indicator
• 250 mL beaker
• Stirring rod
• Microwave

### Solutions

• To make borate solution, dissolve 4 g. of borate in 100 mL of distilled water. Mix the solution until completely dissolved.
• To make polyvinyl solution, dissolve 4 g. of polyvinyl solution in 100 mL of distilled water. **Put the water in the beaker first, then add the polyvinyl, mixing the solution while you are pouring. This will disperse the solid easier into the liquid creating the solution quicker.

Note: Using the microwave heat both solutions to help the borate and polyvinyl chemicals dissolve in the water. Heat in 20-second intervals, stirring in between each interval. Make sure you do not let the solutions boil at any time. Make sure they are both completely dissolved, otherwise the solution will not form.

### Directions

• Place 50 mL of polyvinyl alcohol solution into a beaker and add approximately 8 drops of fluorscein indicator.
• Place 8 mL of borate solution into the polyvinyl alcohol solution and stir together.
• Stir until all materials are combined.

### Introduction

How many of you have seen the movie, Ghostbusters? I love that movie and one of my favorite parts is when Slimer came out and slimed everyone. Today I am going to try and make some of that same slime that was in the movie.

### Explanation

Polyvinyl alcohol (PVA) is a polymer. It is a chain of the monomers (vinyl alcohol, represented below as "A") that is linked together. The polymer can be represented as chains of A-A-A-A-A. Many units of vinyl alcohol make the polymer polyvinyl alcohol. When the polymer solution is mixed with the borate solution, (B), it will create a large complex structure because the borate causes the polyvinyl alcohol chains to cross-link. Borate contains the element boron.

A-A-A-A-A-A-A-A-A-A-A-A

B B B B B B B B B B B B

A-A-A-A-A-A-A-A-A-A-A-A

Poly(vinyl alcohol) is an addition polymer with an average molecular weight of about 100,000 daltons.  Borax reacts with water to form a B4O72+/HB4O7- buffer solution with a pH of about 9.  The borate ions form hydrogen bonds to the -OH groups on the PVA backbone that weakly cross-link this polymer. Cross-links either weaker or stronger than this would produce materials with very different properties.

### Safety

• When dealing with the slime wear rubber gloves to stay clean and safe.
• Wear safety goggles at all time during this experiment.
• Be careful stirring so no solution splashes up into your face or on you body.

### Waste Disposal

• This solution is safe to throw away. Since it is more solid than a liquid do not throw it down the sink. This might cause unnecessary problems in the drain. The slime doesn't have to be thrown away right away, it can be kept for a while in a plastic bag.

### Reference

• Borgford, C, and sommerlin, L, Chemical Activities, American Chemical Society, 1988, p. 87