Title:	Giant-block twist grain boundary smectic phases
Authors:	Fernsler, J. Hough, L. Shao, R.F. Maclennan, J.E. Navailles, L. Brunet, M. Madhusudana, N.V. +6 Co-authors
Keywords:	liquid crystal chirality screw dislocation helix
Issue Date:	4-Oct-2005
Publisher:	The National Academy of Sciences
Citation:	Proceedings of the National Academy of Sciences of the U S A., 2005, Vol.102, p14191–14196
Abstract:	Study of a diverse set of chiral smectic materials, each of which has twist grain boundary (TGB) phases over a broad temperature range and exhibits grid patterns in the Grandjean textures of the TGB helix, shows that these features arise from a common structure: “giant” smectic blocks of planar layers of thickness lb > 200 nm terminated by GBs that are sharp, mediating large angular jumps in layer orientation between blocks (60° < Δ < 90°), and lubricating the thermal contraction of the smectic layers within the blocks. This phenomenology is well described by basic theoretical models applicable in the limit that the ratio of molecular tilt penetration length-to-layer coherence length is large, and featuring GBs in which smectic ordering is weak, approaching thin, melted (nematic-like) walls. In this limit the energy cost of change of the block size is small, leading to a wide variation of block dimension, depending on preparation conditions. The models also account for the temperature dependence of the TGB helix pitch.
Description:	Restricted Access. Please click on the alternative location for the open-access full text.
URI:	http://hdl.handle.net/2289/2313
ISSN:	0027-8424 1091-6490 (Online)
Alternative Location:	http://dx.doi.org/10.1073/pnas.0500664102
Copyright:	2005 The National Academy of Sciences
Appears in Collections:	Research Papers (SCM)

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