From foam beverage cups to the DNA and proteins that form your body, polymers are everywhere. Polymers are chains of chemical subunits, called monomers. Polymers can be made by addition, forming a single long chain, or condensation, forming complex branching structures. Naming polymers starts with the prefix "poly" and then follows guidelines set up by the International Union of Pure and Applied Chemistry.
Naming the Monomer
Most polymers are organic compounds, meaning they are made up of carbon-containing monomers. As with polymers, guidelines are in place for naming organic compounds. Naming a monomer starts by counting the number of carbon atoms; for example, a one-carbon compound has the base "meth," while a two-carbon compound has the base "eth." After that, add-on syllables indicate single or double carbon bonds, functional groups such as alcohols or keytones, and the number of functional groups. Numbers in the name, called locants, indicate the carbon atom where the group is attached.
Basic Polymer Naming
To name an addition polymer with only one monomer, you insert the name of the monomer in parentheses after the "poly" prefix: for example, "poly(methyl methacrylate)." If the name could indicate several different compounds, the class of polymer can be used to clarify, such as "polyether." If the monomer is one word with no locants, the parentheses can be eliminated, as in "polystyrene." As the structure of the polymer gets more complex, more naming rules are involved.
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Copolymers are polymers made up of more than one monomer. Along with condensation polymers and polymer assemblies, copolymers are named using italic qualifiers. A qualifiers, such as "ran" to denote a copolymer with a random distribution of monomers, can be used as a prefix in naming the copolymer or as a connective between the names of the component monomers. The more complex the structure and makeup of the polymer, the more complicated the name: for example, "cyclo-polystyrene-graft-polyethylene."
Rather than using the monomer to name the polymer, you can name some polymers based on their structure. In this case the polymer is named based on a constitutional repeating unit, a structural subunit, rather than the monomer that formed the polymer. To find the constitutional repeating unit, you break the polymer structure into the smallest possible repeating units; there may be more than one. The preferred constitutional repeating unit is the one that has the locant with the lowest number. For example, 1-bromoethane-1,2-diyl has a locant of one, which makes it preferable to 2-bromoethane-1,2-diyl.