Step-Growth Polymers for High-Performance Materials

Recent developments in the application of Ni(0) and Pd(0) catalyzed carbon-carbon bond forming reactions to the preparation of well defined polymer structures by step polymerization reactions are discussed. Three types of coupling reactions using these catalysts are especially applicable to step polymerizations: (a) homocoupling reactions of organic electrophiles, (b) cross-coupling reactions of organic electrophiles with alkenes or alkynes, and (c) cross-coupling reactions of organic electrophiles with organometallic compounds. The organometallic compounds which have been most useful to polymer chemists include: organomagnesium, organozinc, organostannane, and organoboronic acids (and their esters). This survey of the scope of these reactions includes, for each type of reaction, a discussion of: the types of electrophiles and leaving groups, and their reactivity; reaction mechanism; catalysts; selectivities; and limitations.