Radical polymerization

Radical polymerization is a chain-growth process in which reactive radicals add monomer units to growing polymer chains. It proceeds through initiation, propagation, and termination, and is widely used to make carbon-chain polymers.

Radical initiation: The step that creates reactive radicals capable of adding monomer and starting polymer chains. Initiation supplies the first chain-carrying radicals, often by decomposing an initiator.
Free radical: An atom or molecule with an unpaired electron, often making it highly reactive. Radical polymerization depends on radicals that add to monomer and carry chain growth.
Emulsion polymerization: A polymerization process in which monomers react in an aqueous emulsion stabilized by surfactants. Radical emulsion polymerization efficiently produces latex particles and waterborne polymer products.
Cationic polymerization: A chain-growth polymerization in which positively charged chain ends add monomers. It uses carbocation chain ends rather than radical chain ends.
Autoacceleration: A rise in polymerization rate caused when increasing viscosity slows termination more than propagation. As conversion thickens the mixture, radical chains terminate less often and the rate can surge.
Chain propagation: The repeated addition of monomer units to a reactive chain end. Propagation is the growth step repeated throughout a radical polymerization.
Vinyl monomer: A molecule containing a carbon–carbon double bond that can undergo addition polymerization. Its double bond provides the site attacked during chain propagation.
Suspension polymerization: A process that polymerizes monomer droplets dispersed in a continuous liquid phase. Radical initiators inside droplets make discrete polymer beads, as in polystyrene production.
Anionic polymerization: A chain-growth polymerization in which negatively charged chain ends add monomers. Its ionic active centers behave differently from radicals and can support living chains.
Molecular weight distribution: The spread of polymer-chain molecular weights within a sample. Random initiation, propagation, and termination create a distribution of chain lengths.

Linked from 26 pages