Polyacrylic acid, coloured scanning electron micrograph (SEM). This is a transparent synthetic polymer, or plastic. It is often used to replace glass in windows as it resists breakage better compared to conventional glass. The polymer is a repeating chain made from the acrylic acid monomer (C3H4O2) and is commonly known as acrylic. It is also uses in the production of disposable nappies due to its high absorbency per unit mass. Magnification: x3330 when printed 10 centimetres wide.