Lisäyspolymeerien

Lisäyspolymeerit, also known as addition polymers, are a class of polymers formed through an addition polymerization reaction. In this process, monomers add to one another in such a way that the polymer contains all the atoms of the monomer. This contrasts with condensation polymers, where a small molecule like water is eliminated during the polymerization process.

The key characteristic of addition polymerization is that the repeating unit of the polymer has the same atoms as the monomer. This typically occurs with monomers containing double or triple bonds. When these monomers react, the pi bond breaks, allowing for the formation of single bonds and the creation of a long polymer chain. Common examples of monomers that undergo addition polymerization include ethene, propene, and vinyl chloride.

Polymerization can be initiated by free radicals, cations, or anions. Free radical polymerization is a widely used method. Initiator molecules generate free radicals, which then attack the double bond of a monomer, creating a new radical. This radical then adds to another monomer, propagating the chain reaction. The process continues until the chain is terminated.

Addition polymers are ubiquitous in modern life. Polyethylene, formed from the polymerization of ethene, is one of the most common plastics, used in packaging, films, and containers. Polypropylene, derived from propene, finds applications in textiles, automotive parts, and containers. Polyvinyl chloride (PVC), from vinyl chloride, is used in pipes, window frames, and flooring. The properties of addition polymers can be varied by altering the monomer structure, chain length, and branching.