Effects of pressure on systems with intrinsic orientational order

The dynamics of shape-persistent macromolecules have not been investigated to the same extent as of glass-forming liquids or amorphous polymers. Herein we investigate the dynamics of systems possessing intrinsic orientational order. Do such systems exhibit a glass transition and if yes, what is its origin? Do they show a dual relaxation scenario (alpha and beta-processes) as glass-forming liquids and polymers? If such processes exists what is their pressure dependence? Is the a-process controlled by temperature or by the available (free) volume? To answer these fundamental questions we employ some of the most common polymers exhibiting intrinsic orientational order, namely: (a) side-chain liquid crystalline polymers, (b) hairy-rod polymers and (c) synthetic polypeptides with alpha-helical secondary structure. We show that these molecularly diverse but shape-persistent macromolecules share some common features in their dynamic response. (C) 2004 Elsevier Ltd. All rights reserved.