Molecular organization of aminimides with long-alkyl chains on water surface

Three kinds of aminimide derivatives having long-chain hydrocarbons were prepared to investigate the formation of monomolecular films. The delocalization of the ionic structure, which is confirmed by FT-IR measurements, affected molecular organization on a water surface and adsorption behavior to hydrophilic glass substrates. Area per molecules of the aminimides estimated from π–A isotherms (ca. 0.5 nm2) were larger than that for the corresponding hydrazide (ca. 0.3 nm2) and fatty acid (ca. 0.2 nm2), thus the stability of a Langmuir film of aminimides was affected by a number of long-chain alkyl-substituted aminimides. FT-IR measurements using RAS method of transferred films onto gold substrates showed that CH2 stretching modes of hydrocarbon chains of the aminimides having two long-chain alkyls were in solid state, whereas that for the aminimides having one alkyl chain were in liquid state. These results suggested that the molecular organization of amphiphilic aminimides having the characteristic polar head required the enhancement of van der Waals interactions among hydrophobic tails for film stabilization. It was also observed that the adsorption of aminimides occurs more preferably with respect to the corresponding hydrazide and fatty acid due to electrostatic interactions between aminimides and a hydrophilic surface of substrates. The aminimides decomposed above 170 °C to produced isocyanates and amines. A paper modified with the aminimides having two long-chain alkyls showed high water-repellence by heat treatment at 200 °C for 10 min.