Langmuir films of an oligo(p-phenylene vinylene) functionalized with a diaminotriazine headgroup

A detailed investigation is presented on the Langmuir film characteristics of a novel substituted oligo(p-phenylene vinylene) with a diaminotriazine headgroup, namely, 6-[4-{4-(3,4,5-tridodecyloxystyryl)-2,5-bis[(S)-2-methylbutoxy]styryl}-2,5-bis[(S)-2-methylbutoxy]styryl]phenyl-2,4-diamino-1,3,5-triazine (OPVT). The films were characterized by recording surface pressure (pi -A) and surface potential(DeltaV-A) isotherms, in addition to Brewster angle microscopy (BAM). The limiting mean molecular area indicates formation of a monomolecular Langmuir film of OPVT at the air-water interface. The dependence of a plateau transition in the pi -A isotherm on experimental conditions is studied. The critical area for the increase in surface potential revealed the interaction of OPVT molecules even at a large area per molecule, supported by BAM images. On the basis of the data, we propose a model for the organization of OPVT molecules at different stages of film compression.