Structural Investigation at Nanometric Length Scale of Ethylene/1-Octene Multiblock Copolymers from Chain-Shuttling Technology

Abstract

The chain-shuttling technology has emerged as a powerful tool for the efficient production of ethylene/1-octene multiblock copolymers (EOBCs) characterized by a statistical distribution in block length (BL) and numbers of blocks per chain (BN) (blockiness) and unique properties of elastomers with high melting temperature and low density. The crystallization properties and the morphology at nanometric length scales of some commercial grades of EOBC samples are analyzed. The samples are characterized by alternating soft and hard blocks and similar molecular characteristics, including the octene concentration in the hard and soft blocks, the fraction of hard blocks, and the melting temperature of ∼120 °C. Differences occur for the molecular mass of the hard (MH ≈ 2 or 3 kg/mol) and soft (MS, from 3 to 5 times MH) block and BN (in the range of 2–17). Small-angle X-ray scattering (SAXS) measurements, coupled with differential scanning calorimetry thermal analysis of isothermally crystallized samples, indicate ...