You're looking for the full paper or solution manual for "Polymer Physics" by Rubinstein and Eisenberg. Here's some information:
He wrote the derivation from scratch. When he finished, the entropy formula was correct, but more than that—he understood why the 3 was in the numerator. It came from the three dimensions of space, each direction a leash on the chain's freedom. polymer physics rubinstein solution manual
The core difficulty lies in the scaling approach. Rubinstein and Colby eschew detailed, messy algebra in favor of scaling relations (e.g., ( R \sim N^\nu ), where ( R ) is the size of a polymer coil and ( N ) is the number of monomers). This method requires intuitive leaps: ignoring constants, focusing on power laws, and understanding the physical crossover between different regimes (theta solvents, good solvents, melts). You're looking for the full paper or solution
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The solution manual for "Polymer Physics" by Rubinstein and Eisenberg is not publicly available for free. However, you can find some resources: Rubinstein, M
If you have a specific problem or chapter from Rubinstein & Colby, I can help work through the reasoning and solution directly. Would that be useful for you?
Verify the Scaling: If the solution results in a scaling relationship (e.g.,