Copolymerization

Aims

 * Statistical free radical copolymerization
 * Copolymer composition

Introduction

 * Polymerization of two or more monomers
 * Properties of the polymer depend on monomer composition and time

Statistical copolymerization

 * Monomers are consumed at different rates
 * Therefore the polymer composition changes during the reaction

 $$F_A = \frac{r_A f_A^2 + f_A f_B}{r_A f_A^2 + 2 f_A f_B + r_B f_B^2}$$


 * Defines the polymer composition at any moment in time.
 * FA = amount of monomer A in the polymer.
 * fA = amount of monomer A in the monomer feed.
 * FA + FB = 1
 * fA + fB = 1

 $$r_A = \frac{k_{AA}}{k_{AB}}$$ and $$r_B = \frac{k_{BB}}{k_{BA}}$$


 * Defines the relative rates of reaction.
 * Ratios are set for any pair of monomers.
 * No variation with solvent, concentration, temperature, etc.

rA > 1 → HOMO propagation preferred

rA < 1 → CROSS propagation preferred