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Nucleation of stable cylinders from a metastable lamellar phase in a diblock copolymer melt

Wickham, Robert A. and Shi, An-Chang and Wang, Zhen-Gang (2003) Nucleation of stable cylinders from a metastable lamellar phase in a diblock copolymer melt. Journal of Chemical Physics, 118 (22). pp. 10293-10305. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:WICjcp03

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Abstract

The nucleation of a droplet of stable cylinder phase from a metastable lamellar phase is examined within the single-mode approximation to the mean-field Landau–Brazovskii model for diblock copolymer melts. By employing a variational ansatz for the droplet interfacial profile, an analytic expression for the interfacial free energy of an interface of arbitrary orientation between cylinders and lamellae is found. The interfacial free energy is anisotropic and is lower when the cylinder axis is perpendicular to the interface than when the cylinders lie along the interface. Consequently, the droplet shape computed via the Wulff construction is lens like, being flattened along the axis of the cylinders. The size of the critical droplet and the nucleation barrier are determined within classical nucleation theory. Near the lamellar–cylinder phase boundary, where classical nucleation theory is applicable, critical droplets of size 30–400 cylinders across with aspect ratios of 4–10 and nucleation barriers of (30–40)kBT are typically found. The general trend is to larger critical droplets, higher aspect ratios, and smaller nucleation barriers as the mean-field critical point is approached.


Item Type:Article
Additional Information:©2003 American Institute of Physics. (Received 17 January 2003; accepted 13 March 2003) The authors would like to thank Professor Martin Grant for helpful comments. This work was supported by the Natural Sciences and Engineering Research Council of Canada, the Research Corporation, and an Ontario Premier’s Research Excellence Award. Z.G.W. acknowledges support by the U.S. National Science Foundation (Grant No. DMR-9970589(.
Subject Keywords:nucleation; polymer blends; polymer melts; free energy
Record Number:CaltechAUTHORS:WICjcp03
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:WICjcp03
Alternative URL:http://dx.doi.org/10.1063/1.1572461
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8777
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:15 Sep 2007
Last Modified:26 Dec 2012 09:42

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