ИСТИНА

Saturated vapour surroundings affect strongly the conformation of macromolecules adsorbed onto hard substrates. Variation of vapour composition may induce conformational transitions of single individual macromolecules: collapse or extension depending on the vapour nature. The same is valid for ultrathin polymer films spreading or dewetting in different vapours. The vapour-induced morphology transformations on a substrate may be observed directly using scanning force microscopy (SFM). Brush-like macromolecules are very convenient for such observations. Yet, some progress has been achieved with visualization of single linear flexible molecules during vapour-induced motion, see Fig. below. The driving force of the transformations is related to the competition in spreading between the polymer layer and co-adsorbed layer of vapour phase molecules (surface tension balance). This model has been verified in experiments with different macromolecules, different vapours and different substrates.