Melt and Solid-State Structures of Polydisperse Polyolefin Multiblock Copolymers

Journal Article · Tue Oct 23 04:00:00 EDT 2012 · Macromolecules

DOI:https://doi.org/10.1021/ma300910m· OSTI ID:1047918

Li, Sheng; Register, Richard A; Weinhold, Jeffrey D; Landes, Brian G ^[1]

---

1. Dow

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.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: NSFINDUSTRY
• OSTI ID: 1047918
• Journal Information: Macromolecules, Journal Name: Macromolecules Journal Issue: (14) ; 07, 2012 Vol. 45
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
ALIGNMENT
ALKENES
CHAINS
CHEMICAL COMPOSITION
CHEMISTRY
COPOLYMERS
CRYSTALLIZATION
DOMAIN STRUCTURE
MOLECULAR WEIGHT
MORPHOLOGY
POLYETHYLENES
POLYMERS
POLYOLEFINS
SCATTERING
SEGREGATION
SWELLING
SYNCHROTRONS