PC Painter and MM Coleman Fundamentals of Polymer Science (2nd Edition, CRC Press)

Chapter 4 (pgs 83-93 only)

Concepts that you must know:

1. Definition of 'extend of reaction' (p), also as a probability.
2. Statistics of Polycondensation: average molecular weights (Mn, Mw) as a function of the 'extend of reaction' (p), polydispersity as function of p
3. Mole fraction & Weight fraction of x-mers in polycondensation
4. Understand and know how to apply equations 4.5 (4.25), 4.28, and 4.29. That is, given the p [directly, or indirectly by providing the concentrations of functional groups (initial and concentration at p)] you should be able to calculate x_n, x_w, and polydispersity (x_w/ x_n).

Exercises:

1. *Go through the derivations of Mn(p) (pg. 86), and Mn(p,r) (pg. 88)
2. *Go through the derivation of the Mole fraction & Weight fraction (pg. 89-91)
3. *Do "study question" 4 (pg. 105); make sure you can address 4c

Interactive Module:
You need the Flash Player (v.6 or later) plugin (which can be obtained free from here)
The files are extremely small (typically half a minute with a modem) and can be run directly from this web-page.

1. Start by showing one curve (mole/weight fraction) at a time and observe how each curve changes with p (move the slider). Plot both curves and compare their shapes and positions. (can you connect it back to the definitions of Mn and Mw from chapter 1?)
2. Comment on how the values of Mw, Mn, and d depend on the "extend of the reaction" (p).
3. Which molecule size has the largest mole fraction at any instant in the reaction (p)? Which molecule size has the largest weight fraction at any instant in the reaction (p)? Comment on the two!