Characteristic Ratios of Model Polydienes and Polyolefins

Homogeneous anionic polymerization offers several unique advantages in the polymerization of diene monomers. Polymers prepared by this method possess extremely narrow molecular weight distributions and are free of branching. The microstructure of the polymer may be controlled by the choice of polymerization conditions. Amorphous polyolefins can be obtained by hydrogenation of diene polymers. Polyolefins prepared in this manner retain the desirable characteristics of the parent material, i.e., narrow molecular weight distributions and an absence of branching. Hence these polymers are ideal models for testing molecular theories. Several series of model polydienes and polyolefins have been prepared by the aforementioned techniques. These polymers have been carefully characterized, with particular emphasis on determining the effect of molecular architecture on chain stiffness as defined by the characteristic ratio. Glass transition temperatures are also reported.