What is the chemical nature of polyester? What are polycot and polywool?

Polyester (poly + ester) is actually made up of the repeating units of a chemical called an ester. Esters are the chemicals which give fruits their smell. Fabrics are sold by names like polycot, polywool, terry cot etc. as the name suggests, these are made by mixing two types of fibres, polycot is a mixture of polyester and cotton. Polywool is a mixture of polyester and wool.