Good solvent regime

M molar mass), where I and III are the tricritical or -regions. Here, the chain molecules exhibit an unperturbed random coil confirmation. In contrast, I and II are the critical or good solvent regimes, which are characterized by structural fluctuations in direction of an expanded coil conformation. According to the underlying concept of critical phenomena, the phase boundaries have to be considered as a continuous crossover and not as discontinuous transitions. 

At sufficiently high temperatures, the solvent is gbbd, with three regimes. There is a dilute good solvent regime at concentrations... 

Force Versus Extension Behavior in the Good Solvent Regime... 

U) At lower x values, steric repulsion dominates the chains tend to swell. We enter the good solvent regime when we cross a certain line L. Beyond L the excluded volume parameter n = (1 — 2x)o dominates the interactions. Returning to the free energy expression, eq. (III.8)... 

The nearly good solvent regimes described by eq. (IV.52) can be described more physically in terms of spatial correlations. The basic idea is that for small v, a short portion of a chain, with a number p of monomers must be nearly ideal. We see this from the perturbation expansion [eq. (1.42)] where we find no effect of v if n/a (p ) < 1. There is a certain value of p[(p = gB beyond which excluded volume effects... 

On the scale of the star as a whole, the crossover, from the 0 regime to the good solvent regime, can be estimated from the condition of swelling of the outermost coronal blob, f(kstar)r[Pg.61]

Figure 3.4 Concentration regimes oaicuiated for PS dissolved in a good solvent. Regimes I, diiute II, semi-dilute unentangled III, semi-dilute entangled IV, concentrated unentangled and V, concentrated entangled. Reprinted with permission of Graessley (1980). Copyright 1980. Elsevier.

SAWs with nearest-neighbor attraction (—> theta point). The transition of polymer conformation from the high-temperature (good-solvent) regime to the theta point to the collapsed regime is well modeled by the self-avoid-... 

The polymer molecules attached to the surface are in the good solvent regime. That is, the monomers of the polymer chains like to be in contact with the solvent molecules. This is usually modeled as the athermal limit. 

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