Polymers Between Two Surfaces

Horn, R. G., and Israelachvili, J. N., Molecular organization and viscosity of a thin film of molten polymer between two surfaces as probed by force measurements. Macromolecules, 21, 2836-2841 (1988). 

These predictions are in better agreement with the results of Luckham and Klein [21] who observed an extended force profile between two surfaces coated with polyelectrolyte and supposed the non-equilibrium character of polymer adsorption. 

Another source of attraction between two surfaces is possible when the surfaces are immersed in a solution of a nonadsorbing polymer (e.g., a polymer that does not adsorb on, or is repelled by, the surfaces). Although this force is generally weak, it can play a significant role in destabilization of colloidal particles under certain circumstances. 

FIG. 13.17 Depletion attraction between two surfaces immersed in a polymer solution. 

Friction Between Two Surfaces Answer the following questions or discuss statements (a) Two clean, highly polished steel surfaces when brought into contact appear to stick as if having very high coefficient of friction, (b) Would the dynamic coefficient of friction between steel and a polymer increase or decrease with increasing surface... 

More detailed electrostatic interaction in aqueous media between two surfaces grafted with ionic polymer chains was measured with the use of AFM [100]. The AFM tip surface was modified by graft polymerization of a cationic monomer after being coated with a cyanoacrylate polymer. Figure 41 illustrates the plausible scheme employed in the experiment. A... 

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-... 

Solution Thermodynamics in Spin Coating. A polymer solution confined between two surfaces (thin film) may show substantial differences in thermodynamic properties when compared to those in bulk [145] this is because surface effects (important in thin films) may influence fhe phase equilibrium as well as the kinetics of demixing. Surface effects are important because they may lead to... 

The structure of the filler particle surfaces and of the polymer surface characterised hy their fractal dimensions, affects the interfacial adhesion in composites. To explain the structural effect let us introduce the concept of the accessibility of the sites on these surfaces to form adhesion joints (physical or chemical). As a first approximation the degree of such accessibility may be defined as a difference of the fractal dimensions of two surfaces. The higher is this difference the lower is the accessibility of the surface and the less is the adhesion [21]. Suppose that the filler particle has a very rough surface with dimensions which are close to the Euclidean dimension d = 3 (for example, AI2O3 particles) [33], whereas the polymer surface is very smooth, i.e., dp = d = 2. In this case the contact between two surfaces is possible only at the apexes of the rough surface of the filler and the result could be very low adhesion. In other words, the disparity of the dimensions determines the inaccessibility of the greater part of the filler particle for the formation of adhesion bonds [21]. 

---