I'm working on the RAFT copolymerization of MPC and NIPAm monomer, but I'm not sure how to calculate the total conversion from proton NMR? Is it an average of conversions of two monomers or just counts all the components together using a conventional equation polymer/(monomer+polymer)?
For a copolymer, I would report this: the OVERALL conversion (counting all components together) and the INDIVIDUAL conversion of each monomer.
This gives a sense of the composition of the polymer, and possibly the homogeneity of the polymer. For example, assume you mixed monomer A and monomer B at 1:1. The conversion of A is 0.95 and of B is 0.50. (Overall is 0.725.) A discrepancy like this tells you that A is much more reactive than B. In a conventional radical polymerization, with chains being initiated and terminated throughout the course of the reaction, chains formed early will be richer in A and chains formed late will be richer in B as A is used up. For RAFT this may be more complex.
Dear all, the question needs a lot of special events to be answered correctly, by a rich background expert. First there is a confusion betwween the polymerization reaction conversion (which can simply determined by the mass ratio of product to reacanta) and how much of the two monomers have been consumed by polymerization. The first thing to know prior to the copolymerization reaction is the reactivity ratios of both monomers. If you use conventional monomers be sure that these laters are known in textbooks and publications. For NMR, it is a powerful tool to determine the average MW, sequence distribution and tacticity, and chains end groups. The following links provide additional information. My Regards
https://doi.org/10.5254/1.3539131
https://www.degruyter.com/document/doi/10.1515/epoly-2018-0010/html
https://link.springer.com/chapter/10.1007/978-3-662-08982-8_4#citeas
https://www.researchgate.net/publication/239273215_Copolymers_of_N-cyclohexylacrylamide_and_n-butyl_acrylate_Synthesis_characterization_monomer_reactivity_ratios_and_mean_sequence_length/figures?lo=1&utm_source=google&utm_medium=organic