Steric interaction energy

For example, to calculate the steric interaction energy, we simply sum up the number of receptor atoms that are within a specific distance (i.e., 5 A) away from any ligand... 

To determine the steric interaction energy for two parallel plates at a separation, h, the mixing free energy per unit area A, G /A, for the approach of two sterically stabilized particles fi om infinite separation to a separation,... 

FIGURE 10.23 The distance dependence of the steric interaction energy of latex particles stabilized by poly(vinyl alcohol) in water (1) 500 nm, (2) 100 nm, and (3) 10 nm. The elastic modulus is 1.4 x 10 nm . Data from Sonntag [45]. 

Calculate the steric interaction energy between the two spheres given in problem 1. Use Table 10.7 for the value of the relevant Flory-Huggins x parameter. 

A. Samat, R. Guglielmetti, Y. Ferre, H. Pommier, and J. Metzger, Conformational study of the open forms of benzothiazoline spiropyrans by estimation of the steric interaction energy and the electronic stability of the system (EHT [extended Huckel theoryl Method),./. Chim. Phys. 69, 1202-1210 (1972). 

An approximate expression first derived by Fisher (see Ref. [32] p. 460) for the adsorbed polymer steric interaction energy AGpoi t etween two spheres is ... 

The conformations of the molecules in the polymer layer and the resulting steric interaction energy can be calculated by means of a numerical self-consistent field model. The free energy of the polymer layers then is minimized by considering all possible conformations (including adsorbed segments) of the chains. We will not discuss the theory because it can rarely... 

The physical bases of these theoretical predictions are quite straightforward. At very low surface coverages, the steric interactional energy is... 

Fig. 12.4. The distance dependence of the steric interaction energy for two spheres of radius stabilized by polymer layers with different segment density distribution functions I, exponential 2, constant 3, Gaussian 4, radial Gaussian (after Smitham and Napper, 1979).

At present then, it is uncertain to what extent these three factors conjugation/hyperconjugation, hybridization, and polar attractions, (in addition to small steric interaction energies) are responsible for variations in hydrogenation heats. 

The relative stability of molecular addition compounds of the donor-acceptor type has been widely studied. H.C. Brownand his co-workers have carried out a great deal of work on boron addition compounds, with a view to establishing the magnitude of steric interaction energies. Other workershave investigated gallium, indiuxx, and thallium addition compounds to elucidate additional favors which affect relative acceptor, and donor properties. 

Stabilization of Polymer Colloid Dispersions 3.6.3 The steric interaction energy Vj... 

Figure 2. Theoretical calculation of the dependence of the steric interaction energy Ester (a) and the total interaction energy Et (b) on interparticle distance for different values of polymer layer thickness. Reproduced from Ref [32] with kind permission of Elsevier.

It is a frequent task in colloid science to prevent the collapse of solutions of particles in the face of van der Waals attraction. Electrostatic repulsion by surface charges and steric repulsion by grafted polymers frequently serve this purpose. In the case of soft membranes, the repulsion resulting from out-of-plane fluctuations is in principle capable of overcoming van der Waals attraction. This has been shown theoretically for fluid and solid membranes. The pure steric interaction energy drops as l/z for the former if due to undulations and approximately as the third power of 1/z for the latter,z being the mean spacing. 

The adsorption of polymers at the surface of emulsion droplets is often an important factor, with a great impact on their stability. The particular interaction energy per unit film area, however, depends on the solvent quality with respect to the polymer. Thus, for theta solvents, the steric interaction energy / (A) can be calculated using the theory of Dolan and Edwards ... 

In a poor solvent one can observe a minimum in the steric interaction energy at separations close to the polymer layer thickness. This minimum is due to the attraction between the polymer segments in a poor solvent. At smaller separations, strong steric repulsion between the adsorbed layers appears. This interesting case can be treated only numerically. 

In the Onsager model, attractive intermolecular forces are not taken into account, rather only the steric interaction energy between two rods is considered. The third term in Eq. (2.6) is an orientational entropy (Sor) and the last term stands for the packing entropy (Sp) related to the excluded volume between two rods. As a model of rigid rods we take a spherocylinder, consisting of cylinder of diameter D and length I capped with two hemispheres. The function Pj is the excluded volume of the spherocylinders and depends on the angle p(0,0 ) between two spherocylinders ... 

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