Chemical Properties of Silly Putty

Silicon and Silicone

• The original Silly Putty was created from a mixture of boric acid and silicone oil. The substance was named after its primary ingredient of silicone. Silicone is composed of single silicon atoms chemically bonded to two oxygen atoms. The physical properties of silicone compounds are not the same as elemental silicon, the principle ingredient in ordinary sand and quartz. Silicone compounds are called siloxanes, or polysiloxanes by scientists. Silicones are a mixture or organic and inorganic polymers, or long chains of bonded molecules.

Dimethylsiloxane

• Silly Putty is composed of 65 percent dimethylsiloxane, a type of polyorganosiloxane polymer. This ingredient is known as a viscoelastic material and its flexible covalent bonds give Silly Putty its flowing, elastic qualities. Dimethylsiloxane has a polymer backbone of alternating inorganic silicon-oxygen bonds with attached organic side-chains. Cross-linked bonds with multiple polymer chains allow Silly Putty to slowly flow like a liquid over time, though it's a plastic solid material.

Polydimethylsiloxane and Boric Acid

• Polydimethylsiloxane, or PDMS, is the most common siloxane compound and makes up 4 percent of Silly Putty. Linear PDMS is synthesized from dichlorodimethylsiloxane by hydrolisis, which is a chemical reaction with water. PDMS is a clear, colorless liquid containing about 38 percent silicon. Boric acid is a natural compound composed of boron, oxygen and hydrogen. Silly Putty contains 4 percent boric acid. Boric acid acts as a catalyst to cross-link Silly Putty's polymer chains.

Other Ingredients

• Silly Putty's other chemical ingredients include 9 percent thixotrol, an additive derived from castor oil. It increases Silly Putty's viscosity and prevents it from drying out. Trace compounds of around 1 percent include: titanium dioxide, glycerine and dimethyl cyclosiloxane. Silly Putty contains pigment for its pink, green, yellow and blue regular colors, also available as glow-in-the-dark colors. Thermochromic dye gives Silly Putty the ability to change colors from a chemical reaction induced by body heat.