LANGMUIR-BLODGETT MONOLAYERS AND MULTILAYERS OF STEARIC-ACID AND STEARYL AMINE

For mixed monolayers it has long been shown that the addition of stear ic acid facilitates the transfer of Langmuir-Blodgett monolayers and m ultilayers otherwise difficult to transfer. Mixed monolayers of steari c acid (SA) and stearyl amine (SAm) have been studied with the aim bot h of obtaining monolayers appropriate for transfer and of defining the parameters relevant to the latter. The spreading isotherms of SA and SAm in several molar ratios on a subphase at pH 5.5 and T = 20-degrees -allowed determination of the complete miscibility of the two componen ts. Moreover the comparison of the transfer ratios between the mixture s and the pure components proves that the mixtures, and in particular the equimolecular mixture, show an improved transferability. The hyste resis isotherms show that the improved transferability can be attribut ed to improved surface rheological properties of SAm monolayer to whic h SA had been added. The Fourier transform IR spectra of transferred m ultilayers and the spectra of the monolayer of each component and of t heir mixtures in equimolecular ratio obtained by electron spectroscopy for chemical analysis show that, beyond the favourable disposition of the hydrophobic chains, interactions between the carboxilic and amini c functional groups are responsible for the improved transferability.