Polymers silica-poly chain adsorption

Adsorption of block copolymers onto a surface is another pathway for surface functionalization. Block copolymers in solution of selective solvent afford the possibility to both self-assemble and adsorb onto a surface. The adsorption behavior is governed mostly by the interaction between the polymers and the solvent, but also by the size and the conformation of the polymer chains and by the interfacial contact energy of the polymer chains with the substrate [115-119], Indeed, in a selective solvent, one of the blocks is in a good solvent it swells and does not adsorb to the surface while the other block, which is in a poor solvent, will adsorb strongly to the surface to minimize its contact with the solvent. There have been a considerable number of studies dedicated to the adsorption of block copolymers to flat or curved surfaces, including adsorption of poly(/cr/-butylstyrcnc)-ft/od -sodium poly(styrenesulfonate) onto silica surfaces [120], polystyrene-Woc -poly(acrylic acid) onto weak polyelectrolyte multilayer surfaces [121], polyethylene-Wocfc-poly(ethylene oxide) on alkanethiol-patterned gold surfaces [122], or poly(ethylene oxide)-Woc -poly(lactide) onto colloidal polystyrene particles [123],... 

Cationic Polymers., The relation between zeta potential and flocculation by a polymer has been studied by Rjes (3IS), who pointed out that as soon as a colloidal particle is coated with polymer it bears the same charge as the polymer and is redispersed. Similar studies by Ries and Meyers (316) involved the use of microphoresis and electron microscope observations of model colloids and polymeric flocculants. Polyamine type flocculants appeared to extend out from the particle surface for a distance of 20-300 A. Flocculation occurs simultaneously through charge neutralization and bridging of polymer chains from particle to particle then excess polymer reverses the potential and redispersion occurs. Adsorption of poly [(1,2-dimethylvinylpyridinium) methylsulfate] on silica was similarly studied by Shyluk (317), who concluded that the polymer chains lay flat along the surface when no excess polymer was present. 

This work deals with the statistical description of poly(dimethylsiloxane) chains adsorbed upon the surface of silica particles within silica-siloxane mixtures. In these systems, the incorporation of fumed silica into the PDMS polymer melt is obtained by mechanical mixing. Subsequently, the adsorption which occurs through the formation of hydrogen bonds between the oxygen atoms on the polymer chains and the silanol groups located on the silica s surface is a solvent free or melt adsorption process. Consequently, the law of adsorption observed from these systems is specific to such a process. 

J.P. Cohen-Addad, P. Huchot, P. Jost, A. Pouchelon. Hydroxyl or methyl terminated poly(dimethylsiloxane) chains kinetics of adsorption on silica in mechanical mixtures. Polymer, 30,143-146,1989. 

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