Twist grain boundaries, which are widely observed in block copolymer samples of lamellar phases, have been investigated through both direct numerical solution and multiple scale analysis of a coarse-grained mesoscopic model equation. We show that the twist boundary profile can be well described by a pair of Ginzburg-Landau equations (amplitude equations) characterizing the slow evolution of the lamellae. The stability of the grain boundary configuration has been examined, and our results show that the boundary width, albeit varying with twist angle, is of order epsilon-1/4 , with epsilon the measure of the distance to the order-disorder threshold. We also study the motion of twist grain boundaries subjected to slow transverse modulations of lamellae, and obtain both analytically and numerically the traveling velocity of the boundary as well as its dependence on modulation wavenumber.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.101696 |
| Date | January 2006 |
| Creators | Zhang, Xusheng, 1980- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Physics.) |
| Rights | © Xusheng Zhang, 2006 |
| Relation | alephsysno: 002600203, proquestno: AAIMR32809, Theses scanned by UMI/ProQuest. |
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