Polycarbonates

In 1957 three different companies developed procedures for production of polycarbonates. The chain repeat unit of a typical policarbonate is:

The synthesis of this polycarbonate requires phosgene and bisphenol-A as starting chemicals.
Thermoplastic polycarbonates retain their properties unchanged between –100 and +140°C. They possess high surface hardness, insulating properties and weather resistance. They also have excellent optical properties such as transparency and high refractive index.