Brush adsorption

Fig. 8. Schematic representation of the possible conformations of adsorbed (co)polymers prepared using macromonomer technique a brush adsorption of graft copolymer b terminally-attached adsorption c the mushroom-brush transition for strongly overlapping chains proposed by de Gennes [130] and Alexander [155]...

In cases when the two surfaces are non-equivalent (e.g., an attractive substrate on one side, an air on the other side), similar to the problem of a semi-infinite system in contact with a wall, wetting can also occur (the term dewetting appHes if the homogeneous film breaks up upon cooHng into droplets). We consider adsorption of chains only in the case where all monomers experience the same interaction energy with the surface. An important alternative case occurs for chains that are end-grafted at the walls polymer brushes which may also undergo collapse transition when the solvent quality deteriorates. Simulation of polymer brushes has been reviewed recently [9,29] and will not be considered here. 

Highly branched polymers, polymer adsorption and the mesophases of block copolymers may seem weakly connected subjects. However, in this review we bring out some important common features related to the tethering experienced by the polymer chains in all of these structures. Tethered polymer chains, in our parlance, are chains attached to a point, a line, a surface or an interface by their ends. In this view, one may think of the arms of a star polymer as chains tethered to a point [1], or of polymerized macromonomers as chains tethered to a line [2-4]. Adsorption or grafting of end-functionalized polymers to a surface exemplifies a tethered surface layer [5] (a polymer brush ), whereas block copolymers straddling phase boundaries give rise to chains tethered to an interface [6],... 

The aim of this review is to demonstrate the potential of surface forces measurement as a novel means for investigating surfaces and complex soft systems by describing our recent studies, which include cluster formation of alcohol, polyion adsorption, and polyelectrolyte brushes. 

Halperin A (1999) Polymer brushes that resist adsorption of model proteins design parameters. Langmuir 15 2525-2533 Haynes CA, Norde W (1994) Globular proteins at solid-liquid interfaces. Colloid Surf B 2 517-566... 

In this article I review some of the simulation work addressed specifically to branched polymers. The brushes will be described here in terms of their common characteristics with those of individual branched chains. Therefore, other aspects that do not correlate easily with these characteristics will be omitted. Explicitly, there will be no mention of adsorption kinetics, absorbing or laterally inhomogeneous surfaces, polyelectrolyte brushes, or brushes under the effect of a shear. With the purpose of giving a comprehensive description of these applications, Sect. 2 includes a summary of the theoretical background, including the approximations employed to treat the equifibrium structure of the chains as well as their hydrodynamic behavior in dilute solution and their dynamics. In Sect. 3, the different numerical simulation methods that are appHcable to branched polymer systems are specified, in relation to the problems sketched in Sect. 2. Finally, in Sect. 4, the appHcations of these methods to the different types of branched structures are given in detail. 

Fig. 27a-c. Conformations of cylindrical brushes upon adsorption on a surface a extended coil b two-dimensional helix c globule... 

The data demonstrate clearly the importance of the interaction of the subunits of brush like molecules with the substrate. In the case shown in Fig. 31, the structure was formed on a liquid substrate. Detailed studies of the molecular conformation affected by adsorption on a solid substrate have been possible with the monodendron jacketed polymers discussed before [87]. It has been... 

Polymer brushes were found to minimize adsorption of proteins by the soft or steric repulsion of the flexible yet immobihzed macromolecules [179], although a generally valid explanation of the protein resistant properties of some hydrophihc brushes is not available. A similar explanation can be formulated for the improvement of the colloidal stability of particle suspensions, when polymer brush-type layers are bound to small particles. This and other intriguing features of polymer brushes prompted a remarkable experimental and theoretical research activity in order to understand and exploit the unique properties of polymer brushes. 

Fig. 9.19 Preparation of polymer brushes on solid surfaces by a) chemical grafting of end-functionalized linear polymers or selective adsorption of asymmetric block copolymers and b) by surface-initiated polymerization (SIP) using initiator functions on the solid surface. The depicted SAM bearing to-functionalities...

Keywords Gradient Polymer brush Self-assembly Nanoparticles Protein adsorption... 

Fig. 10 Plots of Le/f-cw vs. dimensionless graft density a (1) PS brushes prepared by adsorption of PS-polydimethylsiloxane block copolymers (Mw,ps = 60000) and 0 (Mw,ps = 169000) [21,22]. (2) PEO brushes prepared by adsorption of PEO-PS block copolymers A (Mw.peo = 30800) and V (Mw.peo = 19600) [201]. (3) PMMA brushes prepared by surface-initiated ATRP (M = 31 300 267400). Data reprocessed from [116,117]...

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