STRUCTURE-DEPENDENT WETTABILITY OF HYDROPHOBIC MONOLAYER

Hydrophobic monolayer films of dimethyldioctadecyl-ammonium bromide (D MDOA) deposited on mica by Langmuir-Blodgett (LB) method have been stu died using Wilhelmy plate type wetting measurements, and atomic force microscopy (AFM). The structural change of DMDOA monolayer was observe d when exposed to salt solution. The effect of exposure time to aqueou s KBr salt solutions (immersion time) was especially investigated on s urface morphology and wettability of DMDOA films. AFM images have show n that the surface coverage of DMDOA monolayer is decreased with incre ase in KBr concentration, or in immersion time to KBr solution. The we tting measurements have demonstrated that the hydrophilicity of DMDOA sample is increased with decrease in surface coverage. Drastic hydroph ilisation was observed between 60% and 50% covered DMDOA samples.