Preparation of a structural color forming system by polypeptide-based LB films

To prepare novel display systems like chameleon which change the color by stimuli, we prepared a structural color forming system by use of LB films consisting of polypeptide multilayers. We think this system change its color depending on the molecular structure like photochemical systems. Poly(gamma -hexyl-L-glutamate) (PHeLG) was used as the multilayer component and silicon was used as the substrate for reflection of incident light. PHeLG monolayers were transferred onto substrates hydrophobized with octadecyl trimethoxy silane (OTS). LB films with various layer numbers up to 160 layers were prepared and they showed different colors depending on the thickness of polypeptide layer due to interference of light. The structures of LB films were estimated by using AFM and Fr-IR spectroscopy. Interference colors were characterized by reflective visible spectra and compared with theoretical ones. Silicon wafer pre-colored by excessive oxidization was also used, and it was confirmed that only 10 or 20 layers of PHeLG could show the structural color. In this study, the base for preparation of chameleon-type display system was established. We will introduce photochemical moiety (azobenzene moiety, etc.) into this system and produce display systems which change their colors by optical stimuli. (C) 2001 Elsevier Science BN. All rights reserved.