Pva polymer slime

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228

76

PVA polymer slime

A solution of polyvinyl alcohol (PVA) can be made into a slime by adding borax solution, 

which creates crosslinks between polymer chains. In this activity, some interesting 

properties of the slime are investigated. Students are guaranteed to enjoy the activities 

involved.

This experiment is easy to set up – providing the chemicals are available, and should take no 

more than about 30 mins. It can be done by students in groups of two or three.

Apparatus and chemicals

Eye protection

Each working group requires:

Beaker (100 cm

3

)

Measuring cylinder (50 cm

3

)

Disposable plastic cup 

Metal spatula 

Petri dish (or watch glass) 

Water-based felt-tipped pen 

Spirit-based felt-tipped pen 

Disposable plastic gloves

Polyvinyl alcohol, (-[CH

2

CH(OH)]

n

-), 4% (or 8%) aqueous solution, 40 cm

3

 (see note 1)

Borax, hydrated sodium tetraborate (Na

2

B

4

O

7

.10H

2

O), 4% (or 8%) aqueous solution, (Low 

hazard), 10 cm

3

 (see note 1)

Food colour or fluorescein (Low hazard) (optional)

Hydrochloric acid, about 0.5 mol dm

-3

, (Low hazard at this concentration), 20 cm

3

 (optional) 

(see note 2) 

Sodium hydroxide, about 0.5 mol dm

-3

 (Corrosive), 20 cm

3

 (optional) (see note 2)

Technical notes

Borax, hydrated sodium tetraborate (Na

2

B

4

O

7

.10H

2

O) (Low hazard) Refer to CLEAPSS® Hazcard 14

Fluorescein (Low hazard) Refer CLEAPSS® Hazcard 32 and Recipe card 35

Hydrochloric acid (Low hazard at concentration used) Refer to CLEAPSS® Hazcard 47A and 

Recipe card 31 

Sodium hydroxide (Corrosive) Refer to CLEAPSS® Hazcard 91 and Recipe card 65

Slime. Refer to CLEAPSS® Recipe card 59

1    Polyvinyl alcohol (PVA) can be high MW (about 120 000) or low MW (about 15 000). If 

high MW PVA is used, prepare a 4% solution by placing 960 cm

3

 of water into a tall 1 dm

3

 

beaker. Measure out 40 g of high MW PVA and add this slowly to the beaker of water, 

with stirring. If low MW PVA is used, prepare an 8% solution by placing 920 cm

3

 of water 

into a tall 1 dm

3

 beaker. Measure out 80 g of low MW PVA and add this slowly to the 

beaker of water, with stirring.

 

 In each case, heat the mixture gently, stirring occasionally, until the solution clears. Avoid 

boiling the solution. After cooling, this solution can be poured into suitable smaller 

containers, which can then be sealed and stored indefinitely.

 

 If a 4% aqueous solution of PVA is used a 4% aqueous solution of borax will be required. If 

an 8% aqueous solution of PVA is used an 8% aqueous solution of borax will be required.

•   

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229

2    The hydrochloric acid and aqueous sodium hydroxide are best supplied in small glass 

bottles fitted with teat pipettes.

disposable cup

spatula

borax

solution

polyvinyl alcohol

solution

Procedure

HEALTH & SAFETY: Wear eye protection, and protective gloves if handling the slime.

a   Place 40 cm

3

 of the polyvinyl alcohol solution in the plastic cup.

b   If supplied, add one drop of food colour or fluorescein dye to the solution. Stir well.

c    Measure out 10 cm

3

 of borax solution into the beaker and add this to the polyvinyl 

alcohol solution, stirring vigorously until gelling is complete. This gel is sometimes 

known as a ‘slime’.

d    Wearing disposable gloves, remove the slime from the cup and knead it thoroughly to 

mix the contents completely. Roll the slime around in your hand, gently squeezing the 

material to remove air bubbles at the same time. Alternatively, place the slime in a plastic 

bag and mix and squeeze the mixture from outside the bag.

Tests

e   Test the properties of your slime in the following ways.

 

 1   Pull the slime apart slowly. What happens?

2   Pull the slime apart sharply and quickly. What happens?

3   Roll the slime into a ball and drop it on to the bench. What happens?

4   Place a small bit of slime on the bench and hit it hard with your hand. What happens?

5    Write your name on a piece of paper with a water-based felt-tipped pen. Place the 

slime on top, press firmly, and then lift up the slime. What has happened to the 

writing and to the slime? Try the same again, this time using a spirit-based pen. Does 

this show the same effect?

 

Tests 6–8 below are optional.

 

6    Place a very small piece of slime in a Petri dish. Add the dilute hydrochloric acid 

dropwise, stirring well after each drop. When you notice a change record the number 

of drops added and your observations.

 

7    Now add dilute sodium hydroxide solution to the same sample used above in 6, 

stirring after each drop. When you notice a change record the number of drops 

added and your observations.

 

8   Can tests 6 and 7 be repeated time and time again to give the same results?

 ••

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230

Teaching notes

Tell students to keep the slime away from clothes as it can produce permanent stains. 

The slime can be stored in an air-tight container, such as a plastic bag with a twist-tie. It is 

advisable to dip the slime in some water before storing, to keep it from drying out. Slime 

gets dirty from handling and may become mouldy after several days. When this happens 

you should throw it away. Do not put it down the sink because it clogs the drain.

Slime-type materials are available under a variety of different brand names, and can be 

found in many toy stores. Slime is sometimes described as a reversible cross-linking gel. 

The cross-linking between the polymer chains of polyvinyl alcohol occurs by adding borax, 

Na

2

B

4

O

7

.10H

2

O (sodium tetraborate).

PVA glue contains the polymer polyvinyl alcohol (also called polyethenol) and has the structure:

H

C

OH

H

2

C

H

2

C

H

C

OH

H

C

OH

Borax forms the borate ion when in solution. This ion has the structure:

H

O

H

H

O

B

O

H

O

_

The borate ion can make weak bonds with the OH groups in the polymer chains so it can 

link the chains together as shown below. This is called cross-linking.

H

O

H

H

O

B

O

H

O

H

C

O

H

2

C

H

2

C

H

C

O

H

C

O

H

H

H

H

H

H

CH

O

H

2

C

H

2

C

CH

O

CH

O

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231

Slime is a non-Newtonian fluid that is dilatant – ie under stress, the material dilates or 

expands. Other well known stress-thickening materials are quicksand, wet sand on the 

beach, some printer’s inks, starch solutions and ‘Silly Putty’. Dilatant materials tend to have 

some unusual properties.

●

   Under low stress, such as slowly pulling on the material, it will flow and stretch. If careful, 

you can form a thin film.

●

   Pull sharply (high stress) and the material breaks.

●

   Pour the material from its container then tip the container upwards slightly, the gel self 

siphons.

●

   Put a small amount of the material on a table top and hit it with your hand, there is no 

splashing or splattering.

●

   Throw a small piece onto a hard surface; it will bounce slightly.

Adding acid to the slime breaks the crosslinking producing a liquid with lower viscosity. 

Adding alkali reverses the process and the slime should be regenerated.

Various types of slime have been manufactured. In this investigation you use the polymer 

polyvinyl alcohol, which is reasonably cheap and is readily available from suppliers because 

it is widely used as a thickener, stabiliser and binder in cosmetics, paper cloth, films, cements 

and mortars. In ethanol solution polyvinyl alcohol solution dries to leave a thin plastic film 

that is useful in packaging materials, especially as it is biodegradable.

Reference

This experiment has been reproduced from Practical Chemistry: 

http://www.practicalchemistry.org/experiments/intermediate/polymers/pva-polymer-

slime,153,EX.html

Useful resource

This website has a short video of preparing slime.

http://matse1.mse.uiuc.edu/polymers/e.html

This website gives a background on slime

www.madehow.com/Volume-6/Slime.html

This website contains more links

www.msm.cam.ac.uk/SeeK/slime.htm

(Websites accessed December 2009)

Health & Safety checked, February 2008 

Updated 29 Oct 2008