![]() ![]() For polyelectrolytes of sufficiently low molar mass at pH 9, the growth of the multilayer can nevertheless be prevented for as much as five cycles of deposition. For such conditions, the molar mass of the polyelectrolyte plays a key role, with polyelectrolyte chains of larger molar mass adsorbing on a larger number of defects, resulting in stronger anchoring of the polyelectrolyte complex on the surfaces and faster subsequent growth of the multilayer. Because this is defect-driven growth, the multilayer is not continuous and is made of blobs or an open network of adsorbed strands. Once the polycation is adsorbed, multilayer growth ensues. At basic pH, PEO-silane monolayers undergo substantial hydrolysis leading to the formation of negatively charged defects in the monolayers, which then play the role of adsorption sites for the polycation. For acidic conditions (pH 3), the PEO-silane monolayers exhibit good polyelectrolyte repellency provided the polyelectrolytes bear no moieties that are able to form hydrogen bonds with the ether groups of the PEO chains. The ability of poly(ethylene oxide)-silane (PEO-silane) monolayers grafted onto silicon surfaces to resist the growth of polyelectrolyte multilayers under various pH conditions is assessed for different pairs of polyelectrolytes of varying molar mass. Resistance of poly(ethylene oxide)-silane monolayers to the growth of polyelectrolyte multilayers.īuron, Cédric C Callegari, Vincent Nysten, Bernard Jonas, Alain M ![]() It is found that the magnitude of the contribution per methylene group decreases as the hydrophobic character of the environment increases. The V of PHM shows a linear relationship with the number of methylene groups in the lateral chain. The PAA presents the smaller V, while the largest V value was for AMVP. The molar volume results allow us to discuss the effect of the carboxylic groups and the contributions from the comonomeric principal chain. These materials were investigated by density measurements in highly dilute aqueous solutions. Polymers like polymaleic acid-co-styrene, polymaleic acid-co-1-olefin, polymaleic acid-co-vinyl-2-pyrrolidone, and polyacrylic acid (abbreviated as MAS-n, PA-n-K2, AMVP, and PAA, respectively) were employed. In this work the partial molar volumes (V) of different anionic polyelectrolytes and hydrophobically modified polyelectrolytes (PHM) were measured. Salamanca, Constain Contreras, MartÃn Gamboa, Consuelo Partial molar volume of anionic polyelectrolytes in aqueous solution. Finally asymmetrical flow field flow fractionation coupled on line with static multi angle light scattering (AF4/MALS) evidences soluble PECs with very large average molar masses and size around 100 nm, in agreement with scrambled eggs multi-association between various polyelectrolyte chains. Isothermal titration calorimetry (ITC) indicates an endothermic formation of PEC with a binding constant around 10(5) L mol(-1). This atypical result is explained by the inaccessibility of some permanent cationic charge when screened by pH dependant cationic ones (due to the Hoffman alkylation). ![]() Electrophoretic mobility measurements have evidenced that insoluble PECs (neutral electrophoretic mobility) occurs for charge ratio between 0.6 (excess of polycation) and 1 (stoichiometry usual value) according to the pH. The formation of polyelectrolyte complexes (PECs) between carboxymethyl pullulan and DEAE Dextran, was investigated, in dilute solution, with emphasis on the effect of charge density ( molar ratio or pH) and molar masses. Le Cerf, Didier Pepin, Anne Sophie Niang, Pape Momar Cristea, Mariana Karakasyan-Dia, Carole Picton, Luc Formation of polyelectrolyte complexes with diethylaminoethyl dextran: charge ratio and molar mass effect.
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