Pyroelectric superlattices based on copolysiloxane/calixarene alternate layer LB films
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The pyroelectric effect in alternate layer LB superlattices incorporating interacting lamellae of carboxyl and amino moieties has been investigated. Three distinct systems have been studied, namely (a) a copolysiloxane carboxylic acid/aliphatic amine alternate multilayer, (b) a calixarene carboxylic acid/calixarene amine alternate multilayer, and (c) a hybrid system consisting of a copolysiloxane carboxylic acid/calixarene amine multilayer. In all superlattices there occurs proton transfer between acid and amine moieties leading to a temperature-dependent electric polarisation which is reinforced by added contributions from dipolar reorientation effects. This paper describes how the pyroelectric coefficient can be enhanced by utilising a hybrid alternate layer LB film superlattice containing a 50:50 copolysiloxane substituted with polar aromatic side-chains terminated with carboxyl groups, which is co-deposited with a calixarene molecular basket substituted with primary amine groups. The pyroelectric activity of the copolysiloxane acid/calixarene 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.