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Random isotropic structures and possible glass transitions in diblock copolymer melts

Zhang, Cheng-Zhong and Wang, Zhen-Gang (2006) Random isotropic structures and possible glass transitions in diblock copolymer melts. Physical Review E, 73 (3). Art. No. 031804. ISSN 1539-3755. https://resolver.caltech.edu/CaltechAUTHORS:ZHApre06

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Abstract

We study the microstructural glass transition in diblock-copolymer melts using a thermodynamic replica approach. Our approach performs an expansion in terms of the natural smallness parameter—the inverse of the scaled degree of polymerization [overline N]—which allows us to systematically study the approach to mean-field behavior as the degree of polymerization increases. We find that in the limit of infinite chain length, both the onset of glassiness and the vitrification transition (Kauzmann temperature) collapse to the mean-field spinodal, suggesting that the spinodal can be regarded as the mean-field signature for glass transitions in this class of microphase-separating system. We also study the order-disorder transition (ODT) within the same theoretical framework; in particular, we include the leading-order fluctuation corrections due to the cubic interaction in the coarse-grained Hamiltonian, which has been ignored in previous studies of the ODT in block copolymers. We find that the cubic term stabilizes both the ordered (body-centered-cubic) phase and the glassy state relative to the disordered phase. In melts of symmetric copolymers the glass transition always occurs after the order-disorder transition (below the ODT temperature), but for asymmetric copolymers, it is possible for the glass transition to precede the ordering transition.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1103/PhysRevE.73.031804DOIArticle
ORCID:
AuthorORCID
Zhang, Cheng-Zhong0000-0001-8825-7158
Wang, Zhen-Gang0000-0002-3361-6114
Additional Information:© 2006 The American Physical Society (Received 16 March 2005; published 15 March 2006) This work was supported by the National Science Foundation through the Center for the Science and Engineering of Materials at Caltech.
Funders:
Funding AgencyGrant Number
NSFUNSPECIFIED
Subject Keywords:polymer melts; polymer blends; random processes; glass transition; polymerisation; vitrification; phase separation; order-disorder transformations; fluctuations; vitreous state
Issue or Number:3
Record Number:CaltechAUTHORS:ZHApre06
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:ZHApre06
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3803
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:14 Jul 2006
Last Modified:28 Feb 2020 00:24

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