CHEM 343 Lecture Notes - Anionic Addition Polymerization, Cationic Polymerization, Radical Polymerization

• School: CSU
• Department: Chemistry
• Course: CHEM 343
• Professor: Yian Shi

Document Summary

A polymer is a large molecule made by linking together repeating units of small molecules called monomers. The process of linking them up is called polymerization. Synthetic polymers can be divided into two major classes, depending on their method of preparation. Chain-growth polymers (or addition polymers) are made by the addition of monomers to the end of a growing chain. Step-growth polymers (or condensation polymers) are made by combining two molecules while, in most cases, removing a small molecule (generally water or an alcohol). The reacting molecules have reactive functional groups at both ends. Chain-growth polymerization proceeds by one of three possible mechanisms: radical polymerization, cationic polymerization, or anionic polymerization. Each mechanism has three distinct phases: initiation step that starts the polymerization, propagation steps that allow the chain to grow, termination steps that stop the growth of the chain. Head-to-tail addition is preferred, because the propagating site preferentially attacks the less sterically hindered carbon of the alkene.