| Abstract: | A statistical model for the stereospecific polymerization of vinly monomers on Ziegler-Natta catalytic systems is presented. The basic assumptions of the model are: (a) the catalytic centers are asymmetric, so that at a given catalytic center the monomer CH2?CHR is inserted into the chain with two different rates according to the two different configurations of the opening carbon atom having the R group; (b) the insertion of a monomeric unit in the growing chain is affected also by interactions with the previous monomeric unit. Isotactic, syndiotactic, atatic, or stereoblock polymers are obtained according to the relative values of the two energy parameters expressing these two effects. |
