Pyroelectric superlattices based on copolysiloxane/calix[8]arene alternatelayer LB films

The pyroelectric effect in alternate layer LB superlattices incorporating i nteracting lamellae of carboxyl and amino moieties has been investigated. T hree distinct systems have been studied, namely (a) a copolysiloxane carbox ylic acid/aliphatic amine alternate multilayer, (b) a calix[8]arene carboxy lic acid/calix[8]arene amine alternate multilayer, and (c) a hybrid system consisting of a copolysiloxane carboxylic acid/calix[8]arene amine multilay er. In all superlattices there occurs proton transfer between acid and amin e moieties leading to a temperature-dependent electric polarisation which i s reinforced by added contributions from dipolar reorientation effects. Thi s paper describes how the pyroelectric coefficient can be enhanced by utili sing a hybrid alternate layer LB film superlattice containing a 50:50 copol ysiloxane substituted with polar aromatic side-chains terminated with carbo xyl groups, which is co-deposited with a calix[8]arene molecular basket sub stituted with primary amine groups. The pyroelectric activity of the copoly siloxane acid/calix[8]arene amine system is substantially higher and stable over a wider temperature range than either of the other two superlattices, giving a pyroelectric coefficient of 10.3 mu C m(-2) K-1 at 25 degrees C. (C) 1999 Elsevier Science S.A. All rights reserved.