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Fractionated crystallization and fractionated melting of confined PEO microdomains in PB-b-PEO and PE-b-PEO diblock copolymers

Title data

Castillo, R. V. ; Arnal, M. L. ; Müller, Alejandro J. ; Hamley, I. W. ; Castelletto, V. ; Schmalz, Holger ; Abetz, Volker:
Fractionated crystallization and fractionated melting of confined PEO microdomains in PB-b-PEO and PE-b-PEO diblock copolymers.
In: Macromolecules. Vol. 41 (12 February 2008) Issue 3 . - pp. 879-889.
ISSN 0024-9297
DOI: https://doi.org/10.1021/ma0718907

Official URL: Volltext

Abstract in another language

The confined crystallization of poly(ethylene oxide) (PEO) in predominantly spherical microdomains formed by several diblock copolymers was studied and compared. Two polybutadiene-b-poly(ethylene oxide) diblock copolymers were prepared by sequential anionic polymerization (with approximately 90 and 80 wt % polybutadiene (PB)). These were compared to equivalent samples after catalytic hydrogenation that produced double crystalline polyethylene-b-poly(ethylene oxide) diblock copolymers. Both systems are segregated into microdomains as indicated by small-angle X-ray scattering (SAXS) experiments performed in the melt and at lower temperatures. However, the PB-b-PEO systems exhibited a higher degree of order in the melt. A predominantly spherical morphology of PEO in a PB or a PE matrix was observed by both SAXS and transmission electron microscopy, although a possibly mixed morphology (spheres and cylinders) was formed when the PEO composition was close to the cylinder-sphere domain transitional composition as indicated by SAXS. Differential scanning calorimetry experiments showed that a fractionated crystallization process for the PEO occurred in all samples, indicating that the PE cannot nucleate PEO in these diblock copolymers. A novel result was the observation of a subsequent fractionated melting that reflected the crystallization process. Sequential isothermal crystallization experiments allowed us to thermally separate at least three different crystallization and melting peaks for the PEO microdomains. The lowest melting point fraction was the most important in terms of quantity and corresponded to the crystallization of isolated PEO spheres (or cylinders) that were either superficially or homogeneously nucleated. This was confirmed by Avrami index values of approximately 1. The isothermal crystallization results indicate that the PE matrix restricts the crystallization of the covalently bonded PEO to a higher degree compared to PB.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: ISI:000252944900055
Keywords: ETHYLENE/ALPHA-OLEFIN COPOLYMERS; ABC TRIBLOCK COPOLYMERS; BLOCK-COPOLYMERS; THERMAL FRACTIONATION; POLYETHYLENE-BLOCK; SELF-NUCLEATION; KINETICS; BEHAVIOR; OXIDE); POLYSTYRENE
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Macromolecular Chemistry II
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Macromolecular Chemistry II > Chair Macromolecular Chemistry II - Univ.-Prof. Dr. Andreas Greiner
Profile Fields > Advanced Fields > Polymer and Colloid Science
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Profile Fields
Profile Fields > Advanced Fields
Result of work at the UBT: No
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 15 Apr 2015 08:48
Last Modified: 15 Apr 2015 08:48
URI: https://eref.uni-bayreuth.de/id/eprint/10387