SYNTHESIS OF POLYBUTADIENE-<I>b</I>-POLY[2-(DIMETHYLAMINO)ETHYL METHACRYLATE] AMPHIPHILIC BLOCK COPOLYMER BY MECHANISM TRANSFORMATION

Abstract

A amphiphilic block copolymer of polybutadiene((PB)-b-poly[2-(dimethylamino))ethyl methacrylate](PDMAEMA) was synthesized by transformation of living anionic polymerization into atom transfer radical polymerization(ATRP).The macroinitiator,PB containing the 2-bromoisobutyryl end group(PB-Br) was attempted by anionic polymerization of butadiene with butyllithium initiator,then the living PB was chain extended with propylene oxide(PO) and terminated by 2-bromoisobutyryl bromide(BriBBr).By using PB-Br with controlled molecular weight(M_(n) = 5.7×10~(3)),high bromine content(the bromating efficiency,92.1%) and low polydispersity(M_(w)/M_(n) = 1.07) as macroinitiator and CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine(PMDETA) as catalyst and ligand,ATRP of hydrophilic DMAEMA was realized at 50℃.Kinetics studies reveal a controlled/living polymerization for DMAEMA.The GPC curve of the diblock copolymer indicates a successful initiation and growth of the second block,showing a symmertrical peak due to the removal of uninitiated marcoinitiator.Microphase separation behavior of the diblock copolymer was studied by DSC technique.The properties of the PB-Br and amphiphilic block copolymer PB-b-PDMAEMA were characterized by()~1H-NMR,FTIR in detail.Polydispersity of the diblock copolymer remained low(M_(w)/M_(n)= 1.27) for ATRP of DMAEMA.Estimated by()~1H-NMR,the resulting copolymer was expressed as PB_((10))-b-PDMAEMA_((23)).The results show that well-defined target products with controlled molecular weight and low dispersity were obtained.