The chemical formula for one unit of methyl methacrylate is C5H8O2, or five carbon atoms, eight hydrogen atoms and two oxygen atoms. Many individual units of methyl methacrylate join together in a polymer to make acrylic plastic.
Plastics and Polymers
A polymer is a very large molecule of indefinite size in which many individual identical units of elements called monomers are joined together. Sometimes all of the monomers are the same kind, while at other times two or three different kinds combine in the overall polymer. All plastics are polymers, including acrylic plastic.
Chemists and chemical engineers call what we know of as acrylic plastic poly methyl methacrylate or PMMA. In popular usage, acrylic glass is a more common term than acrylic plastic. Some common brand names are Plexiglas, Lucite and Perspex.
Acrylic plastic works well as a substitute for glass when you need something strong, lightweight and transparent but also shatter-resistant. Large public aquariums often use acrylic instead of glass to make their exhibit tanks and underwater tunnels.