Ex uno plures ("out of one, many"): new paradigms for expanding the range of polyolefins through reversible group transfers.

The "mature" status presently enjoyed by polyolefins prepared with homogeneous (soluble) single-site catalysts through the transition-metal-catalyzed coordination polymerization of ethene and 1-alkenes brings with it a common impression that it is now routinely possible to obtain, with a high degree of confidence, any desired stereochemical microstructure or copolymer composition through iterative optimization employing a set of mutationally related synthetic derivatives generated from an initial molecular design. The dominant reliance on this "one catalyst, one material" strategic approach to discovery is intrinsically self-limiting, however, owing to the limited pool of molecular structures that can be reasonably synthesized and drawn upon. Recently, non-chain-terminating, reversible group-transfer processes have been purposefully introduced to olefin coordination polymerization. These processes, which are highly competitive with propagation, can be controlled externally and now provide the basis for new "one catalyst, many materials" paradigms that have the potential to greatly expand the reach of polyolefin materials for the 21st century.