Process for controlling reaction stoichiometry during polymerization of thermoplastic resins

A process for preparing a thermoplastic polymer to achieve a predetermined polymer target stoichiometry, wherein a thermoplastic polymer is made from at least one first monomer having a first reactive end group and at least one second monomer having a second reactive end group, by reaction of the first reactive end group with the second reactive end group and has a glass transition temperature of greater than 130° C., and comprising the steps of:

• (a) selecting a polymer target stoichiometry, ST, based on a target incorporated part-moles of a first reactive end group of at least one first monomer, AT, and a target incorporated part-moles of a second reactive end group of at least one second monomer, BT, wherein
• ST=[AT/BT]−1;
• (b) calculating an initial polymer formulation stoichiometry, SI, by determining an offset factor, λ, and calculating the polymer formulation stoichiometry based on the following formula:
• SI=ST+λ,
• wherein the offset factor is determined by experimentally determining an amount of a member selected from the group consisting of unreacted first monomers, unreacted second monomers, and combinations thereof, of a calibration sample thermoplastic polymer made by reacting the at least one first monomer and the at least one second monomer;
• (c) determining part-moles of the first reactive end group of the at least one first monomer to be initially charged to a reactor, AI, and part-moles of the second reactive end group of the at least one second monomer to be initially charged to the reactor, BI, based on the following formula:
• SI=[AI/BI]−1;
• (d) reacting an amount of the at least one first monomer and an amount of the at least one second monomer as determined from step (c) in the reactor containing at least one organic solvent and forming a reaction mixture having solids in an amount that is more than 5 weight percent, based on the weight of the reaction mixture;
• (e) obtaining a sample from the reaction mixture after a period of time sufficient to allow for reaction of the at least one first monomer and the at least one second monomer to form the thermoplastic polymer;
• (f) separating the sample into a soluble phase and an insoluble phase comprising the thermoplastic polymer;
• (g) determining a first reactive end group concentration of the at least one first monomer in the thermoplastic polymer as measured in part-moles (AR), a second reactive end group concentration of the at least one second monomer in the thermoplastic polymer as measured in part-moles (BR), a first reactive end group concentration of the at least one first monomer in the soluble phase as measured in part-moles (XR), and a second reactive end group concentration of the-at least one second monomer in the soluble phase as measured in part-moles (YR);
• (h) determining a reaction stoichiometry for the sample, SR, based on the following formula:
• SR=[AR/BR]−1;
• (i) determining a value of ST−SR;
• (j) selecting from,
• (i) if ST−SR≦0, adding to the reaction an amount of part-moles of the second reactive end group of the at least one second monomer, based on the following formula:
• B
• C
• =
• α
• *
• B
• I
• 
• (
• 1
• +
• S
• R
• 1
• +
• S
• T
• -
• 1
• )
• +
• β
• *
• X
• R
• ,
• wherein Bc is part-moles of the second reactive end group of the at least one second monomer for addition to the reaction, BI is the part-moles of the second reactive end group of the at least one second monomer initially charge to the reactor, SR is the reaction stoichiometry for the sample, ST is the polymer target stoichiometry, XR is part-moles of the first reactive end group of the at least one first monomer in the soluble phase of the sample, α is a constant ranging from 1 to 20;
• β is a constant ranging from 0 to 1;
• or
• (ii) if ST−SR>0, adding to the reaction an amount of part-moles of the first reactive end group of the at least one first monomer, based on the following formula:
• AC=BI*δ(ST−SR)+εYR
• wherein AC is the part-moles of the first reactive end group of the at least one first monomer for addition to the reaction, BI is the part-moles of the second reactive end group of the at least one second monomer initially charged to the reactor, SR is the reaction stoichiometry for the sample, ST is the polymer target stoichiometry, YR is the part-moles of second reactive end group of the at least one second monomer in the soluble phase of the sample, δ is a constant ranging from 1 to 20, and ε is a constant ranging from 0 to 1;
• and;
• (k) forming the thermoplastic polymer with a final stoichiometry, SF.