Solvent polymer-bearing surfaces

Shear interactions between polymer-bearing solid surfaces have been studied in some detail for the case of polymer brushes, and there is an emerging understanding of the mechanism that governs these forces.More limited results have been reported for adsorbed polymers in near- solvents and for telechelic brushes.Figure 7 schematically summarizes the shear forces in these cases. 

Zhao and Brittain [280-282] reported the LCSIP of styrene on planar silicon wafers using surface modifications of 2-(4-(ll-triethoxysilylundecyl)phenyl-2-methoxy-propane or 2-(4-trichlorosilylphenyl)-2-methoxy-d3-propane respectively. Growth of PS brushes from these SAMs has been successfully achieved factors that influence PS thickness included solvent polarity, additives and TiC concentration. Sequential polymerization by monomer addition to the same silicate substrate bearing the Hving polymer chains resulted in thicker PS films. FTIR-ATR studies using a deuterated initiator indicated that the initiator efficiency is low, and the... 

Over the last 10 years there have been a large number of experimental, theoretical and numerical simulations on the properties of polymer brushes. The static properties of polymer brushes are now very well understood and have been reviewed extensively elsewhere [26-29]. In this article I will concentrate on more recent results for polymer brushes in a shear flow. Accordingly, the next section on the static properties will be brief. In Section III, the hydrodynamic penetration depth for the solvent into the brush will be discussed for shear flow past the brush and for two surfaces approaching each other. In Section IV, the normal and shear forces between two surfaces bearing end-grafted chains will be discussed. Two processes, interpenetration and compression, are found to occur concurrently. The origin of the reduced friction observed in recent SFA ex-... 

The shape of the experimental isotherm (Fig. 3.38) is qualitatively similar to that found by van Vliet [226] with foam films from aqueous solutions of polyvinyl alcohol. It is also characteristic of the interaction energy as a function of the distance between two mica surfaces bearing grafted polymer brushes in good solvent as determined with Surface Force Apparatus (SFA) [e.g. 242],... 

In some applications, it is also desirable to graft various molecules bearing OH groups or amine groups to the polysiloxane backbone. An example for a successful introduction of such a molecule has been shown by the grafting of cinchonidine. This molecule is well known to afford enantioselective reduction on metallic surfaces. The aim was first to use such a polymer to stabilize metal nanoparticles in organic solvents as well as to study the catalytic activities of such system. 

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