Multiple Segmental Processes in Polymers with cis and trans Stereoregular Configurations.

Altering the stereochemistry of a single double bond in the side group of a polymer resulted in systems with unprecedented local dynamics. These include (i) the appearance of three segmental processes in the cis -polymers all with Vogel-Fulcher-Tammann (VFT) temperature dependence, (ii) the low steepness index associated with fragility, m , and (iii) the lowest pressure coefficient of T g , d T g /d P , ever reported for polymers. We show that it is the inability of the cis -polymer to pack the side groups efficiently that controls the dynamics. Furthermore, the trans -polymers have the ability to crystallize. The wealth of dynamics reflects the cis / trans stereochemistry and the presence of different dipoles at specific positions sampling both the side group and backbone dynamics.