I am working on NiPam polymerization and I am unsure of the necessary ratio of TEMED necessary to achieve the correct polymerization ratio for the reaction to occur. I am unable to use nitrogen gas to purge the oxygen from the solution.
The goal is to create a solution which is fairly solid. The monomer I am using is water and the NiPam is in powder form. The ratio of NiPam powder to monomer is close to 1:1.25.
I would immensely appreciate it if someone could give me the necessary percentage of TEMED necessary to carry out this reaction and the necessary temperature for the polymerization to occur.
Thank you so much
Dear Ani Reddy, I think you should rephrase the question. TEMED is a reducing agent, it can not used alone for polymerization, it must be used with an oxidazing agent such as one of the persulfate to form a redox couple. Generally a ratio of 1 is used.
Water is not a monomer, it is the solvent or reaction medium.
You are giving a ratio NiPam to monomer ? Is there a second monomer or you mean water ? If it is water you mean, you are using too much monomer, almost mass polymerization and not solution one.
Elimination of oxygen is a necissity if you are interested in kinetics and reproducible results. There are other means to eliminate O2. If not possible try to increase a bit the initiator concentration. My Regards
Dear Ani,
during the reaction TEMED acts as a stabilizing agent for radicals produced from initiators as Abdelkader already mentioned. Also, I strongly encourage you to deoxigenize your solution by any means necessary, as all processes including radicals will be strongly influenced by the presence of Oxygen and you will end up with everythng, but not what you've been aiming for.
Concerning your question about the temperature you should carry out the reaction, you have to take the dependence of the TEMED concentration into account. Also, since you will carry out the reaction in water, you will produce different types of polymer networks (from your question and the mentioned ratio, I assume that you are adding a cross-linker like BIS to your reaction). Using temperatures around RT (good solvent conditions) you will produce a hydrogel of macroscopic size (I guess you are aiming for that), if you elevate the temperature high above the LCST of PNIPAM you will need less TEMED (or none depending the temperature) to initiate your reaction, but you will end up with microgel particles, sized somewhere between 300-1000 nm diameter, dependent on your amount of NIPAM, BIS and initiator.
Since I assume you want to produce macrogels I will attach links to two papers, which produce them, to give you an idea of typical synthesis conditions.
Article The Internal Network Dynamics of Poly(NIPAM) Based Copolymer...
Article Small angle neutron scattering study on poly(N-isopropyl acr...
Dear all, additional information are depicted in the following RG link. My Regards
https://www.researchgate.net/post/What_is_APS_TEMED_ratio_in_polyNIPAM_polymerization/amp
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