Curious to learn how much conc. of monomers are converting into polymer
Depending on the monomer and on the solvent used, IR or NMR can be an option. IR is more flexible and does not require deuterated solvents, but it is less accurate. Also, it is possible to measure the conversion by means of DSC, but it is less straightforward. If the polymerization has been stopped, TGA could even be an option.
I think you should think about NMR as it has always been used most times to get a quantitative measure of monomer conversion.
Agreeing with the prvious colleagues: spectroscopic method provide more information, but DSC conversion or sometimes even dilatormetry can be used to get the converison rate (in the case of bulk polymerization).
There's a variety of suitable online methods that can be employed for the determination of monomer conversion, including those that are based on measurement of density or volumetric change, viscosity, and even ultrasound propagation velocity. However, the most practical and accurate ways to measure conversion are spectroscopic techniques, mainly FT-NIR and NMR. Conversion may also be determined directly by gas chromatography which is particularly applicable for monitoring reactions involving two or more monomers (copolymerization or IPN).
Hi , I think depending on monomer, polymer and polymerization type you can use some approaches. for example after that your reaction was finished, you can use your polymer weight yield percentage and amount of total starting monomer that you have. If you want to know conversion percentage during the reaction, TLC can help you for qualitative data. For example in addition polymerization for quantitative data when you have vinyl type monomer, during reaction progressing vinyl double bound eliminate and you can judge from it's NMR spectrum changes.
If you are working with vinyl monomers it is very simple. No need to use any instruments. Simply one can exactly measure the un reacted monomer by titrating with bromide/bromite mixture at regular intervals and calculate the rate of polymerization.
Page 27 in this document:
http://www.rsc.org/suppdata/py/c2/c2py20072d/c2py20072d.pdf
How to measure free monomer in emulsion polymerization reaction by bromine titration?
By using HNMR comparison of integral of polymer peak and monomer peak
% = integral polymer peak / integral monomer peak + integral polymer peak
see page 23
Another possibility is Gas Chromatography, if the boiling point of your monomer is within the operating range of the GC. You can add an internal standard to the polymerization mixture or use the polymerization solvent as a standard in order to calculate the monomer concentration versus the standard. As the polymerization proceeds, the monomer/standard ratio will decrease.
Another method is Size exlusion chromatography, where you can follow the evolution of the molecular weight of the polymer in time. Depending on which characterization techniques are available to you, you can determine the molecular weight of you polymer versus a standard (relative method) or if you have a light scattering setup you could obtain absolute molecular weights.
for example: Article One-Pot Automated Synthesis of Quasi Triblock Copolymers for...
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