Questions from class - Lecture 6 Flashcards
What is the definition of a “blob”? How is the chain conformation inside a blob?
A blob is segment of the polymer of size ksi in which the chain statistics inside is unperturbed.
How can the chain conformation be determined in a scattering experiment?
From measuring the scattering intensity of the same concentration for many angles, and extrapolating to theta -> 0. The slope of the curve will give information of the radius of gyration, which tells us something about the conformation.
What is dilute/semidilute/concentrated polymer solution?
Dilute: concentration so low that the polymer molecules are far from eachother.
Semidilute: concentration is so that the polymers just start to touch.
Concentrated: concentration is so high that there is lot of entanglement.
How does phase diagrams of polymer solutions and polymer blends look like?
Polymer solution: It is very asymmetric, and has a molar mass-dependent phase boundary.
Polymer blends: more symmetric than polymer solutions.
Which type of model is used to calculate the entropy of mixing?
A simple lattice model is used.
How does the entropy of mixing of a polymer blend compare to the one of a regular solution?
The entropy of mixing in a polymer blend is much lower than for a regular solution.
