Volume 44, Number 3, November I 1998
|Page(s)||302 - 308|
|Section||Condensed matter: structure, thermal and mechanical properties|
|Published online||01 September 2002|
Surface crinkling of strained diblock copolymer smectic thin films on striped substrates
Department of Applied Mathematics, Research School of Physical Sciences and Engineering, Australian National University - Canberra ACT, 0200, Australia
2 School of Chemistry, University of Sydney - NSW 2006, Australia
Accepted: 14 September 1998
We study theoretically the problem of a thin symmetric diblock copolymer melt or other smectic film placed on a chemically heterogeneous striped substrate. Recent experimental and numerical studies of this system have shown that the lamellae often align perpendicular to the substrate but that they also tend to crinkle or undulate. Here we show how this rippling can be understood as an instability caused by the intrinsic strain in the system. This instability is closely related to the classical Helfrich-Hurault instability which occurs when a smectic fluid is strained between two plates. However, unlike this instability, the critical strain scales as H-2 for thin films of thickness H. We also show that for a given thickness there is both an upper and a lower critical strain. For very thin films there is no crinkling, irrespective of the strain.
PACS: 61.41.+e – Polymers, elastomers, and plastics / 61.30.Jf – Defects in liquid crystals / 68.10.Cr – Surface energy (surface tension, interface tension, angle of contact, etc.)
© EDP Sciences, 1998
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.