We report a high-resolution X-ray lineshape study of main-chain smectic polymers. The results indicate that the layer ordering differs fundamentally from the algebraic decay typical for other smectic liquid-crystalline systems. The lineshapes are best described by broad squared Lorentzians indicating some form of short-range correlations. However, several higher harmonics are observed, which excludes simple liquid-like short-range order. This behaviour is tentatively attributed to a random field of defects associated with entangled hairpins in the main-chain polymer structure.

Eur. Phys. J. E

Muresan, A., Ostrovskii, B. I., Sánchez-Ferrer, A., Finkelmann, H., & de Jeu, W. H. (2006). Main-chain smectic liquid-crystalline polymers as randomly disordered systems. Eur. Phys. J. E, 19, 385–388. doi:10.1140/epje/i2005-10077-7