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Silicone vs. organic polymers

Compared to carbon-based polymers, polydimethylsiloxane (PDMS) polymers:

• Have more open, more flexible molecular chains – are less rigid.
• Have the ability to form much longer chains without solidifying.
• Have stronger, more stable bonds and are more resistant to harsh environmental, processing, and operating conditions.
• Are more flexible and flowable at low temperatures, and do not break down under high temperatures.
• Are able to align their organic substituents more effectively at interfaces; can more easily “connect” with other materials and formulation ingredients.
• Flow more easily and are capable of forming thinner films.

Carbon and silicon – so close ... and yet, so different

Carbon	Silicon
C is organic (plant-based)	Si is inorganic (mineral-based)
C forms covalent bonds	Si forms hybrid ionic/covalent bonds
CO2 is a simple gas	SiO2 is a complex solid polymer
CCl4 is a reasonably stable fluid	SiCl4 is highly reactive to water and some organic substances

Some important differences between silicon and carbon

• The silicon atom is larger than the carbon atom. Its bonds are longer and more flexible with wider bond angles.
• Silicon is less electronegative than carbon (1.8 for silicon vs. 2.5 for carbon); it is able to give up more of its electrons to form strong, energetic bonds with other elements.
• Silicon only forms single bonds, not multiple bonds (single bonds are more stable and harder to break than double or triple bonds).

Learn more about the physical and chemical properties of silicones.