Controlled/living Radical Polymerization Mediated By Xanthene-9-Thione&PEMTX

Controlled/living radical polymerization(CRP)have been used widely due to the obvious characteristics:To reduce the chain termination as much as possible,to keep the balance between free radicals and dormant species.Based on the previous learning of CMP and TKMP,the Thioxanthene-9-thione(TXT),selected as a free radical capture agent,was prepared at first(about yield of 60%).Primarily,the polymerization was carried out in the presence of MMA or St,ABVN,TXT and THF(to add as M:ABVN:TXT = 1:2:5).To modify this polymerization,it was necessary to alter the experiment conditions,such as changing solvent,monomer concentration,and the proportion between monomer and initiator.In addition,a model of small molecule thioether(PEMTX)was proposed,which was regarded as intermediate in the polymerization.After a series of experiment,the proper conditions of experiments were monomer concentration 30%(wt)at 65? in THF.For the monomer MMA,the conversion rate could get 100%after 24h,Mn increasing from 41 k to 68k with PDI at 1.6-1.7.For St,the results showed the molecular weight increased from 46k to 60k with PDI at 1.7-1.8.Last but not least,the characterization of NMR and GPC confirmed that PEMTX structure was added to the polymer chain.Although MMA and St polymerization can mediated by PEMTX,to gain better consequent,ABVN and PEMTX can be used at the same time to control monomer polymerization.The results was obviously showed that when the comdition was PEMTX:ABVN = 0.5:1,controlled and living characteristics can be observed.Espacially for St,the conversion rate could reach up to 47%after 48h,and molecular weight was increased from 16k to 29k.It was shown that polymerization can be initiated by PEMTX,and more free radicals can be gained if it had ABVN in the system.