SYNTHESIS OF WELL-DEFINED POLYMERS BY CONTROLLED RADICAL POLYMERIZATION

Controlled radical polymerizations can be achieved by using either uni molecular or bimolecular exchange between growing radicals and dormant chains. Dormant chains can be represented as either covalent species or organometallic compounds. Systems based on alkoxyamines, organochro mium, organoaluminum compounds, and alkyl iodides are discussed in det ail. In many systems, straight semilogarithmic plots indicate a consta nt number of growing radicals. A linear increase of molecular weights with conversion indicates a constant number of chains capable of growt h but being predominantly in the dormant state. Some of these systems can be used in the synthesis of block copolymers and for end-functiana lization.