Polystyrene adsorption, interactions

The sorption of hydrocarbons proved to be a strongly exothermic process. This is not surprising because both the adsorption (pentane-polystyrene dispersion interactions) and the relaxation of strong inner stresses of the network result in heat generation. The temperature increase of the packing affects the sorption process in two different ways. First, it results in a considerable acceleration of the sorption process due to the facilitated diffusion of the sorbate molecules into the bead interior (the effective diffusion coefficient increases by 1 order of magnitude with the temperature... 

Hydrophilic interaction chromatography on Asahipak NH2P or Excel-pak CHA-P44 with pulsed amperometric detection has been used to fractionate malto-oligosaccharides.266 The Asahipak NH2P is a polyvinyl alcohol support with a polyamine bonded phase, and the Excelpak is a sulfonated polystyrene in the Zn+2 form. Amine adsorption of sialic acid-containing oligosaccharides was performed on a Micropak AX-5 column (Varian) using acetonitrile-water-acetic acid-triethylamine.267... 

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...

Ethyl cellulose and cellulose triacetate have been shown to form hydrogen bonded associates with dichloromethane (10,30). If this is so, then cellulose triacetate-dichloromethane interaction will be favored over polystyrene-cellulose triacetate interaction and thus no adsorption should be expected. 

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. 

These can be immobilized by either electrostatic adsorption on ion-exchangers [81] or sulfonated polystyrene [82], by hydrophobic interactions on organic polymers [83], by covalent binding to cellulose [68,84] and chloro-sulfonated polystyrene [71], or by entrapment in hydrogels [69,85]. Sol-gel based methods were established particularly for the preparation of fiber optic sensors [86-88]. 

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