Comb-like macromolecules were adsorbed on 1 mica and imaged by scanning force microscopy in real time as they underwent a transition from an extended worm-like conformation to globuli and vice versa. The conformational transition was effected by coadsorption of ethanol and water molecules. Coadsorption of the small molecules allowed manipulation of the adherence and spreading of the macromolecules, thus effecting the reptation like stretching and collapse of the single molecules.