Polymerization

Polymerization: Different forms of polymerization exist, categorized based on reaction mechanisms and functional groups according to IUPAC. Alkenes form polymers through radical reactions. High tonnages of polymers like polyethylene and PVC are produced annually. Homopolymers consist of repeated monomer units, while copolymers consist of more than one monomer unit. Stepgrowth vs. Chaingrowth Polymerization: Stepgrowth and chaingrowth are main classes of polymerization mechanisms. Stepgrowth requires precise stoichiometry control. Chaingrowth yields high molecularweight polymers but applies to specific monomers. Stepgrowth involves pairs of reactants combining to form longer polymer molecules. Chaingrowth involves rapid chain propagation by adding monomers to a growing chain. Stepgrowth Polymerization: Stepgrowth polymers are formed by independent reaction steps between monomer units. Most stepgrowth polymers are condensation polymers. Stepgrowth polymers increase in molecular weight slowly at lower conversions. Examples include polyesters and solidstate polymerization for polyamides. Polyurethanes are stepgrowth polymers formed without the loss of water. Chaingrowth Polymerization: Chaingrowth involves adding monomers to a growing chain with an active center. Long chains are formed from the beginning of the reaction. Chaingrowth polymerization is used in manufacturing polymers like polyethylene and PVC. Other forms include cationic and anionic addition polymerization. Ziegler–Natta polymerization allows control of polymer branching. Photopolymerization: Photopolymerization reactions are initiated by visible or ultraviolet light. Photopolymerization can be chaingrowth or stepgrowth. Light absorption triggers addition or condensation reactions in stepgrowth photopolymerization. Photopolymerization is used in 3D printing processes. Multiphoton polymerization enables the fabrication of complex structures. Polymer Chemistry: Various references and studies in polymer chemistry from different sources and authors. Covers contemporary polymer chemistry, polymer science, technology, and specific studies on controlled radical polymerization and methods for polymer fabrication.