title: New 2-in-1 polyelectrolyte step-by-step film buildup without solution alternation: from PEDOT-PSS to polyelectrolyte complexes.
abstract: Although never emphasized and increasingly used in organic electronics, PEDOT-PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)) layer-by-layer (lbl) film construction violates the alternation of polyanion and polycation rule stated as a prerequisit for a step-by-step film buildup. To demonstrate that this alternation is not always necessary, we studied the step-by-step construction of films using a single solution containing polycation/polyanion complexes. We investigated four different systems: PEDOT-PSS, bPEI-PSS (branched poly(ethylene imine)-poly(sodium 4-styrene sulfonate)), PDADMA-PSS (poly(diallyl dimethyl ammonium)-PSS), and PAH-PSS (poly(allylamine hydrochloride)-PSS). The film buildup obtained by spin-coating or dipping-and-drying process was monitored by ellipsometry, UV-vis-NIR spectrophotometry, and quartz-crystal microbalance. The surface morphology of the films was characterized by atomic force microscopy in tapping mode. After an initial transient regime, the different films have a linear buildup with the number of deposition steps. It appears that, when the particles composed of polyanion-polycation complex and complex aggregates in solution are more or less liquid (case of PEDOT-PSS and bPEI-PSS), our method leads to smooth films (roughness on the order of 1-2 nm). On the other hand, when these complexes are more or less solid particles (case of PDADMA-PSS and PAH-PSS), the resulting films are much rougher (typically 10 nm). Polycation/polyanion molar ratios in monomer unit of the liquid, rinsing, and drying steps are key parameters governing the film buildup process with an optimal polycation/polyanion molar ratio leading to the fastest film growth. This new and general lbl method, designated as 2-in-1 method, allows obtaining regular and controlled film buildup with a single liquid containing polyelectrolyte complexes and opens a new route for surface functionalization with polyelectrolytes.
authors.affiliation: Centre National de la Recherche Scientifique, Institut de Science des Matériaux de Mulhouse, LRC 7228-UHA, 15 rue Jean Starcky, BP 2488, 68057 Mulhouse cedex, France.
authors.forename: Christine
authors.initials: C
authors.lastname: de Saint-Aubin
authors.forename: Joseph
authors.initials: J
authors.lastname: Hemmerlé
authors.forename: Fouzia
authors.initials: F
authors.lastname: Boulmedais
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Vallat
authors.forename: Michel
authors.initials: M
authors.lastname: Nardin
authors.forename: Pierre
authors.initials: P
authors.lastname: Schaaf
mesh_terms: D018625:Microscopy, Atomic Force; D011073:Polyamines / Q000737:chemistry*; D000071228:Polyelectrolytes; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D058525:Quartz Crystal Microbalance Techniques; D012996:Solutions; D055672:Static Electricity; D013499:Surface Properties; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D011073:Polyamines; D000071228:Polyelectrolytes; D011108:Polymers; D011137:Polystyrenes; D012996:Solutions; D013876:Thiophenes; C533756:poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)