Melt and solid-state structures of polydisperse polyolefin multiblock copolymers

Sheng Li, Richard A. Register, Jeffrey D. Weinhold, Brian G. Landes

Research output: Contribution to journalArticle

57 Scopus citations

Abstract

Crystallization in polydisperse ethylene-octene multiblock copolymers, polymerized via chain shuttling chemistry, is examined using two-dimensional synchrotron small- and wide-angle X-ray scattering on flow-aligned specimens. The multiblocks are composed of alternating crystalline (hard) blocks of low 1-octene content and amorphous (soft) blocks of high 1-octene content; the block lengths and the number of blocks per chain are characterized by most-probable distributions. These polymers self-assemble into lamellar domain morphologies in the melt, and the melt morphology is retained in the solid state. Despite extensive mixing between hard and soft blocks, the high crystallinity (>50%) of the hard blocks leads to an alignment of the crystallites within the domain structure, with the orthorhombic polyethylene c-axis generally perpendicular to the lamellar domain normal. The interlamellar domain spacings exhibited by the multiblocks, which exceed 100 nm, are estimated to be 5 times larger than those in near-monodisperse block copolymers having a similar chemical composition and a number-average molecular weight equivalent to the multiblock's "constituent diblock" repeating unit. This swelling factor exceeds the value of 3 previously reported for analogous polydisperse olefin diblock copolymers, due to the lower segregation strength and enhanced phase mixing of the multiblocks studied here.

Original languageEnglish (US)
Pages (from-to)5773-5781
Number of pages9
JournalMacromolecules
Volume45
Issue number14
DOIs
StatePublished - Jul 24 2012

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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