Briefly discuss the key difference between the step-growth

Question

1. Briefly discuss the key difference between the step-growth (e.g., condensation) polymerization and the chain-growth (e.g., free-radical) polymerization. (20%)

2. Consider the polymeization of styrene in toluene solution, initiated by di{ert-butylperoxide. For a solution containing 0.04 mole of initiator and 2 mole of monomer per liter, the initial rates of initiation R, and of propagation Ro are found to be 1.6 x 10^-10 and 6.4 x 10^-7 mole/L.s, respectively. (30%)

a) Calculate the values of (fk_d) and of (k_p/k_t^1/2).

b) Calculate the initial kinetic chain length, under the assumption that no transfer occurs.

3. Show by chemical equations the polymeization of acrylamide (H₂C:CHCONH₂) initiated by the thermal decomposition of potassium persulfate (K₂S₂O₈). (15%)

4. What is the difference between HIPS and ABS in terms of chemical compositions? (15%)

5. Briefly compare and contrast the suspension polymerization and the emulsion polymerization in terms of the polymerization processes and mechanisms. (20%)