Authors Reihs, T. ; Müller, M. ; Lunkwitz, K.
Title Deposition of polyelectrolyte ccmplex nano-particles at silica surfaces characterized by ATR-FTIR and SEM
Date 02.01.2003
Number 10993
Abstract We report on the adsorption of preformed polyelectrolyte complex (PEC) particles at silica surfaces. PEC dispersions were prepared by mixing poly(diallyldimethylammonium chloride) (PDADMAC) optionally with two maleic acid copolymers: sodium poly(maleic acid-co-propylen) (PMA-P) or sodium poly(maleic acid-co-α-methylstyrene) (PMA-MS). Stable colloid nanoparticles were formed as it was characterized by PCS and turbidity. ATR-FTIR spectroscopy was used to study the adsorbed amount of the PECs and SEM and AFM were applied for the lateral characterization of the PEC layers. The influence of surface pretreatment (i), polyanion (ii), pH (iii) and PEC centrifugation (iv) on the adsorption behavior was studied. Different pretreatments of the silicon substrate, i.e. cleaning in sulfuric acid, ‘piranha’ solution or multilayer deposition caused different adsorbed amounts, whereby additionally a linear dependence of the adsorbed amount on the bulk PEC concentration was found. Deposition of PEC-PDADMAC/PMA-P resulted in flat highly deformed adsorbed particles, whereas the adsorbed PEC-PDADMAC/PMA-MS formed spherical caps on the surface. The adsorbed amount obtained at pH=9 was significantly higher compared to that at pH=6. Centrifugation of the PEC dispersion resulted in a monodisperse coacervate fraction for PMA-MS containing PECs showing also a low polydispersity in the adsorbed state. Using silicon surfaces modified by polyanion terminating polyelectrolyte multilayers, the highest adsorbed amount of PECs was found, whereby additionally no deformation of the adsorbed PECs was observed. Furthermore consecutive deposition of oppositely charged PEC particles resulted in a complete surface coverage. From these findings we outline the potential of PEC nanoparticles, which might be compared in properties and applications to latex systems.
Publisher Colloids and Surfaces A: Physicochemical and Engineering Aspects
Citation Colloids and Surfaces A: Physicochemical and Engineering Aspects 212 (2003) 79-95

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