Eur. Phys. J. E (2007) 24: 399-409
https://doi.org/10.1140/epje/i2007-10254-8

Regular Article

Order and strain in main-chain smectic liquid-crystalline polymers and elastomers

¹ FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam, The Netherlands
² Institute of Crystallography, Academy of Sciences of Russia, Leninsky prospect 59, 117333, Moscow, Russia
³ School of Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 30332, Atlanta, GA, USA
⁴ Institut für Makromolekulare Chemie, Universität Freiburg, D-79104, Freiburg, Germany

^* e-mail: dejeu@mail.pse.umass.edu

Received: 2 August 2007
Accepted: 10 December 2007
Published online: 21 January 2008

Abstract

The layer correlations in main-chain smectic liquid-crystal polymer and elastomer systems have been studied using high-resolution X-ray scattering. In contrast to side-chain smectic polymers, in main-chain systems the polymer chains are oriented parallel to the layer normal. As a result they couple directly to the lamellar structure and any polymer defect is translated into layer distortions. For the homopolymers the resulting X-ray lineshapes are well described by Lorentzians. This is interpreted as an average of algebraically decaying order in domains with dimensions of hundreds of nm and a wide dispersion of sizes. The elastomers show much broader peaks than the correponding polymers. This is attributed to strong non-uniform strain within the finite-size domains due to defects of the layer structure.