Color transitions in monolayers of a polymerizable single-chain diacetylenic lipid

We report on the polymerization kinetics of floating and supported monolaye rs of the lipid ethyl morpholine pentacosadiynoic amide. The in situ absorp tion measurements on a floating monolayer at the air/water interface enable d us to study the reaction kinetics of the diacetylenic W-triggered photopo lymerization. The rate constants for a first-order consecutiven reaction M --> B --> R (monomer to blue polymer to red polymer) were determined. The m echanical action of the atomic force microscope (AFM) tip had an immense im pact on the scanned regions of the deposited film, changing locally the pro perties of the monolayer toward the red, fluorescing moiety. Distinct level s of fluorescence were observed which were contributed to distinct levels o f interaction of the AFM tip with the monolayer. The results suggest that t he spectral shift arises from a slight rearrangement in the packing of the side chains in the polymeric backbone.