Controlled Synthesis Of Multiblock Polymer

The synthesis and properties of block copolymers is always the attractive topic in polymer synthesis. In this thesis, well-defined multiblock polymers were prepared by combination of ATRP and RAFT.The relationship between polymerization condition and molecular weight, polydispersity of poly(methyl acrylate)(PMA) prepared by ethyl 2-bromopropionate(2-EBP) or diethyl meso-2,5-dibromoadipate(DEDBA)/CuBr/PMDETA in the presence of DPDTT was studied. Polymerization rate and block number of PMA was not affected by the type of initiator. A small amount of relative low molecular weight polymer was found, and the block number was lower than anticipated one. The reason is the generation of monoblock polymer by irreversible termination and ATRP_S process of trithiocarbonate initiated by complex of CuBr-PMDETA.Polymerization rate was enhanced by replacing TPMA with PMDETA as ligand. With respect to 2-EBP as initiator, block number of PMA was increased when using DEDBA as initiator, and be closer to anticipated on, because the irreversible termination was reduced resulting in the decrement of monoblock polymer. Furthurmore, no ATRPs process ocurrs when TPMA is applied as ligand.In general, well-defined multiblock polymers was prepared by combination of ATRP and RAFT polymerization. The molecular weight of block was controlled by the concentration of DPDTT and monomer conversion. The average block number of polymer was regulated by concentration ratio of DPDTT to ATRP initiator. This is a new method for precisely preparation of multiblock polymer.