Thin films of calix-4-resorcinarene deposited by spin coating and Langmuir-Blodgett techniques: determination of film parameters by surface plasmon resonance

Amphiphilic calix-4-resorcinarene (C-4-RA) has been deposited as thin films using both spin coating and Langmuir-Blodgett (LB) techniques. Both LB and spin-coated films were studied by surface plasmon resonance (SPR) using Kr etschmann's prism configuration, and their optical parameters have been eva luated. LB film thickness d obtained from SPR curve fitting procedure was p lotted as a function of the number of layers and from this, a bi-layer thic kness of 2.34 nm was determined. The thickness of spun films produced at a spinning speed of 2000 rpm is found to be equivalent to that of six to eigh t monolayer LB films. Both types of films were found to have a similar refr active index value of about 1.47, Using SPR technique, LB and spun films of C-4-RA of comparable thickness were found to respond in a similar manner w hen exposed to 400 ppm toluene vapour, indicating a structural similarity b etween films produced by "wet'' techniques, such as LB and spin coating. (C ) 1999 Elsevier Science S.A. All rights reserved.