Three Ways to Polyamides: The Impact of Polymerization Mechanism on Polymer Properties

Polymer chemistry lab experiments present a unique opportunity to allow students to experience the consequences of reaction mechanisms on the properties of the resulting product. In this organic chemistry experiment, students prepared a polyamide by three different reaction mechanisms that represent step-growth and chain-growth methods of polymerization: melt polycondensation of an amine and a carboxylic acid, interfacial polymerization of an amine and an acid chloride, and ring-opening polymerization of a lactam. Characterizing the polymers by both FTIR spectroscopy and differential scanning calorimetry requires students to consider how the choice of mechanism affects conversion of monomer to polymer, the resulting crystallinity of that polymer, and the challenges that must be overcome when setting up and executing the polymerization procedure.