Entropy confinement

This free energy still has a minimum at R — 0. The confinement entropy term is not strong enough to stabilize the collapse of the chain due to excluded volume attraction because Nb jP [Pg.116]

And now we can estimate confinement entropy. We will argue that this entropy is of order unity per each arc of the length A. Indeed, we can say each arc can bend to either right or left, which means the relevant number of conformations is estimated as where L/X is the number of arcs. 

The simple model in the previous paragraph demonstrates that as the confinement radius a is reduced, the confinement entropy increases dramatically. Furthermore, the confinement entropy scales linearly with polymer size, as defined by the number of Kuhn segments N, resulting in considerable... 

From (2.36) it follows that the confinement entropy is negative, as expected, because confinement leads to a decrease of the entropy. From the free energy (2.39) we obtain for the pressure of the chains inside the plates... 

We neglect the effect of chain contraction at high concentrations. Although the chain contraction decreases the confinement entropy, its effect is usually small (Problem 4.9). Therefore, we also use the confinement entropy of a single chain in the low concentration limit, k aSR Jdf, for the semidilute solution. 

The Thickness of a Polymer Adsorbed on a Surface Is a Balance Between Adsorption Energy and Confinement Entropy... 

The entropy that is lost upon confinement of a polymer chain to nanoscale dimensions depends on both chain size and confinement size. deGennes argued that this confinement entropy scales with the length of the chain and inversely with the confinement size [85] ... 

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