What is the Difference Between Silicone and Silica

The key difference between silicone and silica is that silicone is a polymeric material, whereas silica is silicon dioxide.

Silicone and silica are industrially important materials. Both these substances contain silicon atoms as a component. However, these two substances have different chemical and physical properties, which make them useful in different applications.

1. Overview and Key Difference
2. What is Silicone
3. What is Silica
4. Silicone vs Silica in Tabular Form
5. Summary – Silicone vs Silica

What is Silicone?

Silicone is a polymer consisting of siloxane. Therefore, it is also known as polysiloxane. Silicone typically occurs as a colorless oil or as a rubber-like substance. It is useful in sealants, adhesives, lubricants, medicine, cooking utensils, thermal insulation, etc. There are some common forms of silicone, such as silicone oil, silicone grease, silicone rubber, silicone resin, silicone caulk, etc.

Silicone and Silica - Side by Side Comparison

Figure 01: Silicone Caulk

Silicone contains an inorganic silicon-oxygen backbone chain. This chain consists of two organic groups attached to each silicon center. Generally, the organic groups are methyl groups. This material can exist as either cyclic structures or polymeric structures. We can vary the –Si-O- chain length, side groups, crosslinking, etc. We can also synthesize silicones with a wide variety of properties and compositions. The consistency of silicone can vary from liquid to gel to rubber to solid-hard plastic.

Properties of Silicone

We can list down the important properties of silicone as follows:

Low thermal conductivity
Low chemical reactivity
Low toxicity
Thermal stability
Repelling water
No sticking into many substrates
No support for microbial growth
Electrical insulations
High gas permeability
Resistance to oxygen, ozone, and UV light

What is Silica?

The term silica is the common name for silicon dioxide, and it is an oxide of silicon. We use this term to name the purest form of SiO2. It occurs in quartz and as components in living organisms. Its molar mass is 60.08 g/mol. It appears as a transparent solid. The melting point and boiling points are 1,713 °C and 2,950 °C, respectively.

Figure 02: Sample of Silicon Dioxide

Silicon dioxide molecules show a tetrahedral geometry, with four oxygen atoms surrounding a silicon atom. Moreover, silicon dioxide has many crystalline forms; we call them polymorphs. There are some amorphous forms as well. In addition, we can convert silicon dioxide into silicon via a reduction reaction with carbon.

There are many uses of silicon dioxide. We use it for the production of Portland cement, for sand casting, in hydraulic fracturing, as a precursor to producing glass, to make optical fibres for telecommunication, as a food additive, etc.

What is the Difference Between Silicone and Silica?

Silicone and silica are important inorganic materials. Generally, silicone is made mainly using naturally occurring silica stones. The key difference between silicone and silica is that silicone is a polymeric material, whereas silica is silicon dioxide. We can easily prepare silicone from the reaction between silicon, oxygen, carbon, and hydrogen. However, for the preparation of silica, we use silicon and oxygen.

There are many uses of silicone and silica. Silicone is useful in the manufacture of cake moulds, cooking utensils, electrical insulation, adhesives, etc. On the other hand, silica is important in the manufacture of glass, ceramics, optical fibers, desiccants, etc.

Summary – Silicone vs Silica

Silicone is a polymer consisting of siloxane. The term silica is the common name for silicon dioxide, and it is an oxide of silicon. The key difference between silicone and silica is that silicone is a polymeric material, whereas silica is silicon dioxide.

Reference:

1. “Silicone.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.
2. “Silicones: Uses, Benefits, and Chemical Safety Facts.” ChemicalSafetyFacts.org.

Image Courtesy:

1. “Caulking” By Achim Hering – Own work (CC BY 3.0) via Commons Wikimedia
2. “Sample of silicon dioxide” By LHcheM – Own work (CC BY-SA 3.0) via Commons Wikimedia