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.

**Step-growth vs. Chain-growth Polymerization:**

– Step-growth and chain-growth are main classes of polymerization mechanisms.
– Step-growth requires precise stoichiometry control.
– Chain-growth yields high molecular-weight polymers but applies to specific monomers.
– Step-growth involves pairs of reactants combining to form longer polymer molecules.
– Chain-growth involves rapid chain propagation by adding monomers to a growing chain.

**Step-growth Polymerization:**

– Step-growth polymers are formed by independent reaction steps between monomer units.
– Most step-growth polymers are condensation polymers.
– Step-growth polymers increase in molecular weight slowly at lower conversions.
– Examples include polyesters and solid-state polymerization for polyamides.
– Polyurethanes are step-growth polymers formed without the loss of water.

**Chain-growth Polymerization:**

– Chain-growth involves adding monomers to a growing chain with an active center.
– Long chains are formed from the beginning of the reaction.
– Chain-growth 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 chain-growth or step-growth.
– Light absorption triggers addition or condensation reactions in step-growth 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.https://en.wikipedia.org/wiki/Polymerization