Morphology of adsorption anionic polyelectrolytes to mica substrate in different environment visualized by atomic force microscopy

We have observed the morphology of an anionic polyelectrolyte (partially hydrolyzed polyacrylamide) (HPAM) adsorbed to mica surface in different environment using atomic force microscopy with molecular resolution. HPAM molecules deposited on the mica surface from aqueous solution at natural pH were observed to form a nanostructured network. However, the nanostructured network-to-globule conformational transition on mica can be directly visualized when the mica substrate with the predeposited HAPM molecules was immersed into chloroform. Meanwhile, necklace-like globule conformation on mica can be obtained in the presence of NaCl.