Ring-opening polymerization

A ring-opening polymerization is a chain polymerization in which a cyclic monomer of a (usually) bond to a further unit of the same is converted into a linear polymer by bond cleavage and subsequent formation. Driving force receiving such reactions usually only by reducing the ring strain in the monomer molecule, since no new, more energetically favorable bonds are formed and the entropy loss can not be compensated by the condensed off a low molecular weight by-product.

Application

An example is the conversion of lactams in polyamides, such as in the discovered by Paul Schlack 1938 polymerizability of caprolactam (specifically, ε - aminocaprolactam ) by ring opening. The final polyamide 6 was known worldwide under the trade name of Perlon.

Another technically important process, the production of polyethylene from ethylene. This reaction is a classic living polymerization in which the resulting molecular weight is determined by the ratio of monomer to initiator.

In the ring-opening metathesis polymerization (see alkene metathesis ) is the driving force also look into the ring strain of the monomers used.