In polymer nanocomposite synthesis by grafting from thechnique (RAFT or ATRP), we need to know the Molecular weight (Mn) of grafted polymer. Usually, we need to cleave the polymer from nanoparticle, and then subjected to GPC. I am wondering, if cleavage does'nt work, even with HF, can we assimilate the Mn of grafted polymer to the free one?
Hello
In case if the nanoparticle core can not be dissolved to get the free polymer for Mw analysis and also detachment of polymer does not work by hydrolysis of the anchoring group then possibly we can correlate the Mw of grafted polymer to the free one, but if the initiator (ATRP/RAFT) is attached to the particle then there is almost no possibility of getting free polymer.
In that case one can carry out the polymerization in identical reaction conditions one with the presence of ATRP initiator (not grafted) and polymer grafting in the same condition where the initiator is anchored on the particles. So the Mw of the polymer obtained in same conditions without particles can be correlated to the grafted polymer.
best of luck
Thank you Sushilkumar A. Jadhav for your answer. But I doubt with your last idea...I think I cannot do the same polymerization conditions, because I don't know the exactly amount of grafted initiator onto the nanoparticles. I can get it from TGA but this would be just an approximation.
You can figure out the initiator amount from the grafting density (which combines data from TGA/BET. Amount of grafted initiator can also be determined after the grafting reaction itself. You use a certain amount of initiator for grafting then recover the non grafted initiator (which remains in the supernatant liquid) , evaporate the solvent, dry the residue properly and weigh, the difference will be the grafting. Unless you use any other reagent but that also can be separated by chromatography. Alkoxysilane based grafting agents do not require additional reagents and the grafting by products are ethanol methanol etc. which can be easily separated.
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