Interface total polymer concentration

In the example given in Figure 9.2, the total polymer concentration in the middle of the interface is about 9.5%, instead of 10% in the bulk. As expected, the theory predicts that this depletion of polymer at the interface increases (the excess decreases) as the total concentration increases (Figure 9.4). 

FIGURE 9.4 Depletion of total polymer concentration at the center of the interface versus total polymer concentration for five degrees of incompatibility. For further details, see the caption of Fignre 9.2. 

The amount of polymer depleted from the interface region, enriching the bulk of the phases, can be approximated by integrating the total polymer concentration along the distance from the center of the interface. The result for the example of Figure 9.2 is in Figure 9.6. 

FIGURE 9.7 Total polymer concentration far away from the interface in a phase-separated system of equal phase volumes, with one phase broken up into equally sized droplets. Overall concentration of each polymer is 5% (w/w). 

The homopolymer profile thickness was calculated numerically to increase exponentially with copolymer molecular weight and linearly with copolymer concentration. The increasing width (or decreasing slope) of the homopolymer profiles, as compared to the total polymer profiles (homopolymer plus copolymer segments), reflected the necessity to accommodate the increased amount of the copolymer at the interface. 

The vicinity of total reflection of a polymer solution - air interfaces is investigated using a neutron radiation. Experiments and calculations reveal a significant singular behaviour, from which the exact nature of the polymer concentration profile can be determined. 

We discuss here the use of neutron reflectivity at a polymer solution-air interface, for the experimental determination of the polymer concentration profile. The method consists of analyzing the neutron reflectivity near total reflection, as a function of the incident inverse wavelength k. This method was developed at the LLB in... 

Polymers can adsorb spontaneously from solution on to surfaces if the interaction between the polymer and the surface is more favorable than that of the solvent with the surface. For example, a polymer like poly(ethylene oxide) (PEO) is soluble in water but will adsorb on various hydrophobic surfaces and on the water/air interface. This is the case of equilibrium adsorption where the concentration of the polymer monomers increases close to the surface with respect to their concentration in the bulk solution. We discuss this phenomenon at length both on the level of a single polymer chain (valid only for extremely dilute polymer solutions), see Section II, and for polymers adsorbing from (semidilute) solutions, see Section III. In Fig. 2a we schematically show the volume fraction profile (p(z) of monomers as a function of the distance z from the adsorbing substrate. In the bulk, i.e., far away from the substrate surface, the volume fraction of the monomers is (p], whereas, at the surface, the corresponding value is (p > (p]. The theoretical models address questions in relation to the polymer conformations at the interface, the local concentration of polymer in the vicinity of the surface, and the total amount of adsorbing polymer chains. In turn, the knowledge of the polymer interfacial behavior is used to calcu-... 

The phyllosilicate particles present a very high aspect ratio of width/thickness, in the order of 10-1000 and the complete exfoliation of the layered silicate in the polymer matrix is the main goal for the successful development of clay-based nanocomposites. For very low concentrations of particles, the total interface between polymer and layered silicates is much greater than that in conventional composites. Depending on the strength of the interfacial interaction, four types of morphology are possible in nanocomposites (Fig. 2) [24] ... 

Figure S.6. Schematic representation of a poljrmer concentration profile as a function of distance 2 from the interface. The upper curve gives the overall segment concentration c(z), the lower curve the concentration c (z) due to non-adsorbed chains. Both curves approach the bulk solution concentration c at large 2. The hatched area is the polymer surface excess r , the sum of the shaded and hatched areas represents the total...

A nonelectrochemical method also sensitive to the presence of water is infrared spectroscopy with multiple internal reflection, applied by Nguyen and coworkers to study the swelKng of an organic coating at the metal-polymer interface in situ [58]. The integration of the stretching vibration of water was used as a measure of the water uptake at the interface. Stratmarm and coworkers measured the increase of the water concentration at the Fe-alkyd-polymer interface by means of single attenuated total infrared reflection spectroscopy (ATIRS) [59]. An ultrathin Fe film was evaporated onto a ZnSe crystal and coated with an alkyd primer. The authors concluded that no separate water film is... 

Macromolecular diffusion in the interface between the core and shell phases can be illustrated by a model composed of three parts core. A, the interface between the core and the shell, AB and the shell phase, B as shown in Figure 3.44. It is assumed here that the core phase is totally covered by the shell phase. The PMMA/PVAc latex is phase-separated at high temperature [97]. During phase separation of the interfacial phase, polymer A in the core does not diffuse out and polymer B in the shell does not diffuse into the AB and core phases. The parameters C(r, t) and co(r, t) are the concentrations of polymer A and polymer B which diffuse into the core and shell phases, respectively. 

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