Polystyrene adsorption, interactions surfaces

These results confirm the existence of weak or labile floes at partial PVA coverage, particularly with the high-molecular-weight fully-hydrolyzed Vinol 325 and Vinol 350. In contrast, the partially-hydrolyzed Vinol 523, which is comparable in molecular weight to the Vinol 325, gave an adsorption isotherm with little scatter, indicating the absence of flocculation. Partially hydrolyzed PVA shows specific interactions with polystyrene surfaces (mentioned below), and the absence of flocculation in this case is consistent with the theory proposed by Clark and Lai (14) for bridging flocculation. 

Table III shows that the adsorption densities at the plateau region increase with increasing PVA molecular weight, despite the distribution of molecular weights for each sample. The adsorption density of Vinol 350 is given in parentheses because of the difficulty in establishing its exact value. For the fully hydrolyzed PVA s, which show no specific interactions with polystyrene surfaces, the increase in adsorption density is proportional to the 0.5 power of the molecular weight, in good agreement with theory, which predicts for weak surface interactions under...

Protein adsorption is the first event that takes place on material surfaces when blood or other body fluids are brought into contact with any material. Therefore, cell - material interactions must be discussed by taking into consideration the species and the nature of the protein adsorbed on the material surfaces. For instance, a series of cell-attachment and spreading experiments [11] of fibroblasts on the surface of modified polystyrene (TCP and Primaria) carried out in the presence of fetal calf serum (FCS) showed that FCS contains components which tend to decrease the attachment and spreading of fibroblast cells. The effect of these nonadhesive components was only evident when the FCS was depleted of vitronectin, showing that vitronectin overcomes the effect of these nonadhesive components and promotes cell-attachment and spreading on the polystyrene surface. Fibronectin, on the other hand, does not play a principal role in this fibroroblast adhesive process (Fig. 2). 

What is the driving force for protein adsorption Is the adsorption driven by overall energetic (enthalpic) interactions or does the entropic contribution prevail Do both entropic and enthalpic contributions play a major part in the adsorption process, the extent of each depending on the particular protein and surface in question An illuminating thermodynamic analysis given by Norde and Lyklema 62,66) for the adsorption of two different globular proteins (human serum albumin, HSA, and bovine pancreatic ribonuclease, RNase) on polystyrene latices will be presented. We believe this analysis has general validity. 

Recent investigations have shown that the behavior and interactions of surfactants in a polyvinyl acetate latex are quite different and complex compared to that in a polystyrene latex (1, 2). Surfactant adsorption at the fairly polar vinyl acetate latex surface is generally weak (3,4) and at times shows a complex adsorption isotherm (2). Earlier work (5,6) has also shown that anionic surfactants adsorb on polyvinyl acetate, then slowly penetrate into the particle leading to the formation of a poly-electroyte type solubilized polymer-surfactant complex. Such a solubilization process is generally accompanied by an increase in viscosity. The first objective of this work is to better under-stand the effects of type and structure of surfactants on the solubilization phenomena in vinyl acetate and vinyl acetate-butyl acrylate copolymer latexes. 

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],... 

When the composite-matrix is formed with a polystyrene solution as a dispersion medium, the self-assembly of silica particles is influenced by the adsorption of macromolecules on their surface. During adsorption, both solitary macromolecules and their aggregates transfer simultaneously onto the adsorbent surface. Depending on solution concentration, not only the conformation of adsorbed molecules but also the number and size of macromolecular aggregates in the solution change on adsorption. This leads to the formation of complex-shaped structures, which are linked by a system of nonvalent interactions and consist of polymeric-inorganic blocks[8,14] this is of interest in the preparation of a nanostructured medium (polystyrene-silica gel) as a precomposite for the fabrication of carbon structures in a matrix of silica particles. 

According to [15], the adsorption of PS on aerosil surface OH groups involves participation of benzene ring n electrons. Only each third aromatic ring undergoes interactions with the silica surface, therefore the adsorption layer has a bulk structure. 0.95mg/m2 of polystyrene is required for the formation of a monolayer on the surface of Si02 particles [15]. For the PS concentrations used in the present work, this corresponds approximately to C=1.5 g/100 mL, whereas the PS concentration of C=5,0 g/100 mL corresponds to about fourfold excess of polymer, and the PS concentration of C=0.25 g/100 mL is insufficient for the formation of a monolayer on the surface of SiC>2 particles. 

In the case of sulfate charged latexes, the adsorption of ODN was reported to be independent of salinity. Such behavior was attributed to the hydrophobic interaction between the aromatic bases of ODN and the hydrophobic domains on the polystyrene particle surface [23]. 

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