Study Of RAFT Polymerization By Liquid Chromatography

The Reversible Addition-Fragmentation chain Transfer polymerization (RAFT)is one of the most promising living radical polymerization for industrialization, whichhas attracted more and more attention. Compared with other technology, PolymerChromatography has provided a relatively simple and effective method to study theRAFT polymerization.In this paper, we take BCBD with carbazole as Z group to prepare the blockcopolymer of PSt-b-PMA with different chain length of PMA. Conditions which cancompletely separate homopolymer PSt from block copolymer PMA-b-PSt areanalysised in normal-phase high performance liquid chromatography. Establishing aneffectively chromatography method to separate the block copolymer PSt-b-PMA fromthe homopolymer PSt. We verify the successful application of polymerchromatography on RAFT polymerization mechanism research.Chromatographic behaviour of low molar-mass polyesters (PMA) innormal-phase high performance liquid chromatography is studied. Based on this study,we establish a chromatography method to study the chain transfer constant of macro-RAFT agent (sPMA-RAFT) with different chain length through monitoring the RAFTpolymerization of N, N-dimethylacrylamide (DMAM), the result shows that the chainlength depandent of the sPMA-RAFT is not significant.Taking P2EHA prepared by RAFT polymerization as stabilizer, dispersionpolymerization of styrene in non-polar solvent is reserched by HPLC method. Byreversed-phase HPLC method, the homopolymer PSt, macro-RAFT agent of P2EHAand block copolymer P2EHA-b-PSt can be separated and detected quantitatively.Through this HPLC method, the dispersion polymerization process of St in hexane ismonitored, and the coversion of the macro-RAFT agent of P2EHA and its influenceon the nucleation and stability of the particles is studied. The experimental resultsshow that nucleation process is the mainly self-assembly of amphiphilic blockcopolymer of P2EHA-b-PSt, nuclear growth process occurs mainly in the swollenparticles. Due to the continuous nucleation of the block copolymer P2EHA-b-PSt, awide particle size distribution is appeared. With the macro-RAFT agent molecularweight and the solvent content of cyclohexane increasing, particle size of dispersionpolymerization products is gradually increasing.