A large, high-molecular-weight molecule formed by the combination of many smaller monomers in a process known as polymerization. It is the formation of polymers from the constituent parts of substances in printing ink vehicles that is responsible for the drying and hardening of many types of ink films. (See Vehicle.)
The chemical formulae of polymers are typically of the form (X'a'Y'b'...)'n', where X and Y indicate the component elements having the atomic quantities indicated by the numerals a and b. The formula enclosed in parentheses is the monomer or oligomer, and the n indicates that an unspecified and variable number of the monomers comprise the chain. For example, polyethylene is a polymer of ethylene, and has the chemical formula (C2H4)'n', where each monomer (an ethylene molecule) contains two atoms of carbon bonded to four atoms of hydrogen, the n indicating that many of these molecules are strung together.