Laterally attached liquid-crystalline polymers as stationary phases in reversed-phase high-performance liquid chromatography III. Effect of the localanisotropic order on the separation of polycyclic aromatic hydrocarbons

Specific stationary phases based upon non-liquid-crystalline polymers, liqu id-crystalline molecules and side-on fixed liquid-crystalline polymers (SO- LCP) have been synthesized for use as silica modified stationary phases in high-performance liquid chromatogaphy (HPLC). The mesogenic side group of t he SO-LCP was composed of three phenyl ring benzoate type with terminal alk oxy chains and was laterally linked to a polysiloxane backbone via an alkyl eater spacer arm. This study demonstrated that tile shape recognition of s tationary phases based upon SO-LCP towards the length-to-breath ratio (L/B) was strongly connected to the existence of a local liquid-crystalline orde r into the pores of silica gel, warranting the interest of the collective o rganization of mesomorphic materials in liquid chromatography. Furthermore, the chromatographic performances depended on the kind of anisotropic order and it was more advantageous to use smectic side-on liquid-crystalline pol ymer than nematic and obviously non-liquid-crystalline ones. Finally, for a series of polymers having the same mesomorphism, the larger the temperatur e stability range of the mesophase, the more pronounced the local order eff ect and the higher the shape recognition. (C) 2001 Elsevier Science B.V. AU rights reserved.