The aim of this report is to present a method for preparation of multilayer films for colorimetric sensor from PDA vesicles using the PEM technique, that the change of its color is also observable visually. In this work, the blue phase of poly(10,12-pentacosadiynoic acid) vesicles were successfully immobilized into a film state by the layer-by-layer deposition with a polycationic polymer, chitosan. A linear relationship between the number of double layers and the electronic absorbance of the film indicating a well defined deposition. The thin blue films obtained have infinite stability when kept in water. The multilayer film displayed solvatochromic response to ethanol by switching its color from blue to red at 60% (w/w) aqueous ethanol solution while the vesicles in aqueous solution were found to change its color at 50% (w/w) ethanol content. The difference in response of the PDA vesicles in PEM film when compared to the vesicles dispersed in the aqueous solution is probably due to the electrostatic nature of the thin film which tends to repel less polar solvents. Thermochromic properties of the vesicles solution and the PEM film gave the same transition temperature at 70oC.
Journal: TechConnect Briefs
Volume: 1, Technical Proceedings of the 2006 NSTI Nanotechnology Conference and Trade Show, Volume 1
Published: May 7, 2006
Pages: 27 - 30
Industry sector: Advanced Materials & Manufacturing