Independent Control of Elastomer Properties through Stereocontrolled Synthesis

In most synthetic elastomers, changing the physical properties by monomer choice also results in a change to the crystallinity of the material, which manifests through alteration of its mechanical performance. Using organocatalyzed stereospecific additions of thiols to activated alkynes, high‐molar‐mass elastomers were isolated via step‐growth polymerization. The resulting controllable double‐bond stereochemistry defines the crystallinity and the concomitant mechanical properties as well as enabling the synthesis of materials that retain their excellent mechanical properties through changing monomer composition. Using this approach to elastomer synthesis, further end group modification and toughening through vulcanization strategies are also possible. The organocatalytic control of stereochemistry opens the realm to a new and easily scalable class of elastomers that will have unique chemical handles for functionalization and post synthetic processing. Stereochemistry‐controlled stretching: Step‐growth polymerization using organocatalytic nucleophilic thiol–yne addition chemistry is demonstrated to produce elastomeric materials in which the stereochemistry of the double bond controls the mechanical properties of the materials independently of the monomers.