Study On Terminated Products Of RAFT Polymerization By Polymer Chromatography Method

The Reversible Addition-Fragmentation chain Transfer polymerization (RAFT) isone of the research focuses in living radical polymerization, which has broadapplication prospect. The deep research on RAFT polymerization mechanism plays avital role in further development of RAFT polymerization and for more expansiveapplication.In this paper, the BDB-prepared polystyrene (PSt) was extended with methylacrylate in a specially-designed chain extension reaction, in which the living PStchains were extended and transformed into block copolymer, but the remaining deadPSt chains (D-PSt) will keep constant and can be separated and quantified by highperformance liquid chromatography. The systematic experimental investigation of theeffect of various polymerization parameters on the mass fraction of dead species(fD-PSt) in RAFT-prepared polystyrene (PSt) was implemented. The results clearlydemonstrated the initiator concentration, RAFT agent concentration and conversionhave an effect on proportional of fD-PSt, respectively.Using BCBD with carbazole as Z group to prepare PSt-RAFT andP(St-BA)-RAFT, which extended with methyl acrylate into block copolymer. Theresults of isolating the termination products of dead polymer confirmed that the theintermediate free radicals participated in the cross termination reaction. Theproportion of the cross-termination was estimated and the low proportion wasexplained by a series of theories.Collecting the dead species by silica column chromatography, and tests of HPLCand GPC were implemented in different wavelength. The results indicated themolecular weight of dead species was close to PSt-RAFT and the PDI of dead specieswas higher than the latter due to the complex components.