Polymer Formation How polymer forms ? Polymer Formation Polymers are formed by two main ways called addition and condensation polymerization. In addition, polymerization, an initiator (or catalyst) reacts with a starting monomer. The result of this initiation reaction is a monomer attached to the initiator with an unsatisfied bond. The unsatisfied bond is free to react with another monomer, thus adding to the chain. The process repeats over and over again until two chains combine or another initiator binds to the end of the chain, both of which will terminate the chain. In condensation polymerization, a monomer with an exposed H (hydrogen) atom binds with a monomer with exposed OH (oxygen-hydrogen) atoms. During the reaction, water is released (compensated) as the H and OH combine to form H2O (water).