Polyurea and film composed of at least one monomolecular layer of a polyurea

摘要

A polyurea of the general formula ##STR1## where X and Y are. independently of one another, a divalent radical whose chain contains in each case at least two carbon atoms, and A and B are, independently of one another, H or (C.sub.1 -C.sub.26)alkyl, and n is an integer greater than 4, which polyurea contains at least one (C.sub.6 -C.sub.26) alkyl group per repeating unit, is prepared by reacting the diamine NHA-X-NHB with roughly the equimolar amount of a diisocyanate OCN-Y-NCO. The polyurea is suitable for preparing ordered monomolecular LB films on a base (film-substrate-system). For this purpose it is dissolved in a volatile organic solvent which is not miscible with water, the solution is spread at the water/air interface, and the layer formed is compressed after the solvent has evaporated and it is transferred to a solid layer base by the Langmuir-Blodgett technique.