Medium-range repulsions

Fig. 31 Overall interaction energy between two DNA-coated colloids, (a) Sketch of the interacting surfaces of two spheres of radius R0 separated by d. The maximum length of hybridized strands is 2L. (b) Total interaction energy as a function of d. It is the sum of the attractive I/DNA from the binding of accessible DNA strands, the repulsive I/rep from electrostatics and/or polymer steric effect, and the van der Waals attraction t/vdw. (c) For weak, short-range I/rep, particles which are unbound at high temperatures are irreversibly trapped in the van der Waals well after DNA hybridization at low temperatures, (d) For strong, medium-range I/rep, DNA binding produces a secondary minimum of reversible aggregation. Reproduced with permission from [138]...

SI formalism and the calculations based on it above. First, there is ample evidence that the medium-range osmotic repulsion of DLVO theory is basically correct [11], A theory does not become textbook without being able to explain some phenomena well. Therefore, there must be something correct, at least to a leading approximation, about the repulsive potential... 

There are other major objections to Crocker and Grier s claim [13, 14], one of which we consider in Chapter 7. First, there is the timescale of the measurements. The laser tweezer experiments measure transient collisions, whereas equilibrium in these dispersions usually takes weeks or months to achieve [17], Inspection of Figure 3.8 reveals that any transient experiment is going to be dominated by the medium-range strong repulsion. The minimum is so shallow that the true equilibrium nature of the forces takes weeks to reveal itself against the background of the Brownian motion. We also observed that when an n-butylammonium vermiculite gel had been compressed... 

Tablel.3 Optimized Pauli repulsions and their components (10 3E<,)fortheHe-He interaction in the medium range...

Coulomb or electric Very strong Attractive (+/-) or repulsive (same charges) Medium range (1/d )... 

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