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Homogeneous nucleation and fractionated crystallization in block copolymers

Title data

Müller, Alejandro J. ; Balsamo, V. ; Arnal, M. L. ; Jakob, T. ; Schmalz, Holger ; Abetz, Volker:
Homogeneous nucleation and fractionated crystallization in block copolymers.
In: Macromolecules. Vol. 35 (9 April 2002) Issue 8 . - pp. 3048-3058.
ISSN 0024-9297
DOI: https://doi.org/10.1021/ma012026w

Official URL: Volltext

Abstract in another language

The confinement of crystallizable blocks within AB or ABC microphase-separated block copolymers in the nanoscopic scale can be tailored by adequate choice of composition, molecular weight, and chemical structure. In this work we have examined the crystallization behavior of a series of AB and ABC block copolymers incorporating one or two of the following crystallizable blocks: polyethylene, poly(epsilon-caprolactone), and poly(ethylene oxide). The density of confined microdomain structures (MD) within block copolymers of specific compositions, in cases where the MD are dispersed as spheres, cylinders, or any other isolated morphology, is much higher than the number of heterogeneities available in each crystallizable block. Therefore, fractionated crystallization takes place with one or several crystallization steps at decreasing temperatures. In specific cases, the clear observation of exclusive crystallization from homogeneous nuclei was obtained. The results show that, regardless of the specific morphological features of the MD, it is their vast number as compared to the number of heterogeneities present in the system that determines the fractionated character of the crystallization or in extreme cases homogeneous nucleation. The self-nucleation behavior was also found to depend on the composition of the copolymers. When the crystallizable block is confined into spheres or cylinders and exhibits homogeneous nucleation, the self-nucleation domain disappears. This is a direct consequence of the extremely high density of microdomain structures that need to be self-seeded (on the order of 10(15)-10(16)/cm(3)). Therefore, to increase the density of self-nuclei, the self-nucleation temperature has to be decreased to values so low that extensive partial melting is achieved, and some of the unmelted crystal fragments can be annealed, in some cases even before self-nucleation takes place.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: ISI:000174818600030
Keywords: ETHYLENE/ALPHA-OLEFIN COPOLYMERS; POLYMER BLENDS; POLYETHYLENE
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: 16 Apr 2015 07:18
Last Modified: 16 Apr 2015 07:18
URI: https://eref.uni-bayreuth.de/id/eprint/10414