Free Radical Copolymerization

[Allcock-307] shows this equation using f for m and F for M.

is the molar fraction of the first monomer in the polymer.
is the molar fraction of the second monomer in the polymer.
is the feed molar fraction of the first monomer.
is the feed molar fraction of the second monomer.
is the reactivity ratio of the first monomer.
is the reactivity ratio of the second monomer.

k(11) is the probability that a polymer chain ending with a monomer 1 radical will be attacked by a monomer 1
k(12) is the probability that a polymer chain ending with a monomer 1 radical will be attacked by a monomer 2
k(21) is the probability that a polymer chain ending with a monomer 2 radical will be attacked by a monomer 1
k(22) is the probability that a polymer chain ending with a monomer 2 radical will be attacked by a monomer 2

Some statements:

If multiplied by is less than one, then there will be a tendency for the monomers to alternate.
If multiplied by equals one, then there will be a random distribution of monomers.
If multiplied by is greater than one, then there will be a tendency to give blocks of homopolymeric sequences.

The reference I used didn't specify, but the equations above have an assumption or two build in that the author didn't allude to (continuous feed to maintain a steady state concentration? something else?)

Last Update- January 21, 1995- wld