Molecular Architecture of Multiblock Copolymers Synthesized by the Chain Shuttling Technology

Recent advances in the characterization of ethylene/1-octene-based statistical multiblock copolymers (MBCs) synthesized via chain shuttling copolymerization are illustrated. The Perspective focuses on the peculiarity of MBC systems that consists in the nonuniform chain architecture of these intriguing systems due to compositional heterogeneity occurring at inter- and intra-chain level. In the first part, the effect of dispersity on the phase behavior and properties of MBCs and block copolymers in general is discussed along with the consequences of crystallization of one of the blocks on microphase separation, domain spacing, and morphology. In the second part, the main results achieved in the elucidation of details of the chain microstructure in terms of average length of the blocks and block length distribution are presented. It is shown that solvent and thermal fractionation techniques, coupled with other techniques such as transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) represent powerful tools to elucidate the inter- and intra-chain heterogeneous composition of the MBCs. Guidelines on how to establish structure/properties relationships for such polydisperse systems are also provided.