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Homogeneous nucleation and fractionated crystallization in block copolymers

Titelangaben

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

Volltext

Link zum Volltext (externe URL): Volltext

Abstract

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.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Zusätzliche Informationen: ISI:000174818600030
Keywords: ETHYLENE/ALPHA-OLEFIN COPOLYMERS; POLYMER BLENDS; POLYETHYLENE
Institutionen der Universität: Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Lehrstuhl Makromolekulare Chemie II
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie > Lehrstuhl Makromolekulare Chemie II > Lehrstuhl Makromolekulare Chemie II - Univ.-Prof. Dr. Andreas Greiner
Profilfelder > Advanced Fields > Polymer- und Kolloidforschung
Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Chemie
Profilfelder
Profilfelder > Advanced Fields
Titel an der UBT entstanden: Nein
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
Eingestellt am: 16 Apr 2015 07:18
Letzte Änderung: 16 Apr 2015 07:18
URI: https://eref.uni-bayreuth.de/id/eprint/10414