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http://hdl.handle.net/11375/21361
Title: | Field-Induced Phase Transitions of Block Copolymers |
Authors: | Sun, Youhai |
Advisor: | Shi, A.-C. |
Department: | None |
Keywords: | field-induced, phase transitions, block copolymers, soft materials, ordered structures, linear response theory |
Publication Date: | 2007 |
Abstract: | <p> Block copolymers are a class of soft materials which can self-assemble into a variety of ordered structures. One method to induce new structures is the application of an external field such as an electric field. Previously, studies of the field-induced phase transitions are based on the assumption that the structural change follows certain symmetry pattern or simply using real-space numerical methods. The goal of the current project is to develop a simple analytic method to predict the structural change. Our approach is based on a linear response theory, in which the external field is taken as a perturbation and the lowest-order contribution to the solution is computed. We applied our method to the Landau-Brazovskii theory which is valid close to the order-disorder transition point of diblock copolymers. The result shows that there will be an additional term to the order parameter as a response to the external field. The structural change can be predicted by a new Fourier expansion of the order parameter. As an example, we examined the structural change of a body-centered cubic phase under an applied electric field.</p> |
URI: | http://hdl.handle.net/11375/21361 |
Appears in Collections: | Digitized Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Sun_Youhai_2007_Masters..pdf | 1.65 MB | Adobe PDF | View/Open |
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