Chain walking

The potential applications of polymers formed by this reaction are diverse, from drug delivery to phase transfer agents, nanomaterials, and catalysis.

[1][3][4] Continuous research effort led to design of other ligands which provide CW polymerization catalysts upon complexation to late transition metals.

[7] As the vast majority of CW polymerization catalysts is based on late-transition metal complexes, having generally lower oxophilicity, these complexes were demonstrated also to provide copolymerisation of olefins with polar monomers like acrylates, alkylvinylketones, ω-alken-1-ols, ω-alken-1-carboxylic acids etc., which was the main initial intention of development of this class of catalysts.

At this second resting state, the ethylene molecule can insert to grow the polymer or dissociate inducing further chain walking.

Therefore, ethene only homopolymerization can provide branched polymer whereas the same mechanism leads to chain straightening in α-olefin polymerization.

Example of a nickel precatalyst that, upon activation with suitable cocatalyst (MAO, organoaluminiums), promotes chain walking.
Example of a palladium catalyst that promotes chain walking.
Structure of polymers obtained in CW polymerization of ethene vs. higher olefins
Mechanism of CW ethene polymerization leading to the formation of short chain branches