Monotactic Polymers

Polymers with one stereoisomeric center per base unit are called monotactic. Examples of monotactic polymers are poly(ethylidene), - CH(CH3)-3h, with one central asymmetric atom per chain link, poly-(propylene), - H2—CH(CH3>, with one asymmetric central atom per two chain links, and poly(propylene oxide), - CH2—CH(CH3)—O, with one asymmetric central atom per three chain links. 

If all the bonds follow in the same sequence, i.e., ( + )( — )( + )( — )( + ) (-) or ( + ) (—) ( —) ( + ) (+) (—) (-) ( + ), then one speaks of holotactic polymers. Holotactic, monotactic polymers thus show only isotactic or syndiotactic diads, whereas real polymers always possess a number of configurational defects, i.e., they contain iso- as well as syndiotactic diads (see also Section 3.2). The bonds of real polymers, therefore, do not always follow in the same sequence, i.e., they can be ( + ) ( —) (-h) (—) ( —) (-h) ( + ) ( —), etc. The configurational defects make it necessary to bear in mind the randomness of the configuration when dealing with real structures. 

H. J. Cantow and O. Schnlz, Effect of chemical and conlignrational seqnence distribution on the miscibility of polymer blends - 1. blends of monotactic homopolymers, Polym. Bull., Vol. 15,449, 1986. 

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