Specific effects of ions on the formation and properties of poly(allylamine hydrochloride)/poly(acrylic acid) multilayer

Abstract

Polielektrolitni kompleksi i višeslojevi poli(alilamin-hidroklorida) i poli(akrilne kiseline) pripravljeni su u vodenim otopinama NaF, NaCl, NaClO4, LiCl i (CH3)4NCl. Nastanak polielektrolitnih kompleksa po prvi puta istražen je visoko-razlučivom ultrazvučnom spektroskopijom. Ovom metodom ustanovljeno je da interpolielektrolitna neutralizacija rezultira ion-specifičnom agregacijom nabijenih koloidnih kompleksa. Analogan utjecaj iona određen je u slučaju odgovarajućih višeslojeva. Elipsometrom i mikroskopom atomskih sila utvrđeno je da debljina i hrapavost filma raste u nizu F − < Cl− < ClO4 − za anione odnosno (CH3)4N + < Na+ < Li+ za katione. Nadalje, ustanovljeno je da hidrofobnost višesloja također slijedi opisani trend za anione kada je polikation završni sloj filma. Zagrijavanjem polielektrolitnih višesloja tijekom njihove priprave potisnut je specifičan utjecaj iona na površinsku hrapavost i močivost zbog reorijentacije i migracije polimernih lanaca na međupovršini višesloj/zrak. Naposlijetku, provedeno istraživanje ukazuje na značajnu korelaciju između procesa interpolielektrolitne neutralizacije u otopini i na površini.Polyelectrolyte complexes and multilayers of poly(allylamine hydrochloride) and poly(acrylic acid) were prepared in aqueous solutions of NaF, NaCl, NaClO4, LiCl, and (CH3)4NCl. The formation of polyelectrolyte complexes was investigated for the first time by high-resolution ultrasonic spectroscopy. Using this method, it was established that interpolyelectrolyte neutralization results in ion-specific aggregation of charged colloidal complexes. Analogous influence of ions was observed in the case of corresponding multilayers. Using ellipsometer and atomic force microscope, it was determined that the thickness and roughness of the film increases in the sequence F− < Cl− < ClO4 − for anions and (CH3)4N + < Na+ < Li+ for cations. Furthermore, it was found that the hydrophobicity of the multilayer also follows the described trend for anions when a polycation is terminating layer of the film. By heating polyelectrolyte multilayers during their preparation, the specific influence of ions on surface roughness and wettability was suppressed due to the reorientation and migration of polymer chains at the multilayer/air interface. Finally, the conducted research indicates a significant correlation between the process of interpolyelectrolyte neutralization in solution and on the surface