Oxyanion-initiated Polymerization Of Stimuli-response Amphiphilic Copolymer

Oxyanion-initiated polymerization of methacrylates has been studied. The monomers used in this work included methyl methacrylate (MMA), (dimethamino)ethyl methacrylate (DMAEMA), 2,2,2-trifluoroethyl methacrylate (TFEMA), 2, 2, 3, 4, 4, 4-Hexafluorobuthyl methacrylate (HFBMA). The initiator was potassium benzyl alcoholate. A series of well-defined, benzyloxy-capped AB or BA diblock copolymers with narrow molecular weight distribution, such as BzO-PDMAEMA-b-PMMA and BzO-PMMA-b-PDMAEMA, have been synthesized by the sequential addition of the alternative monomers. The results of GPC and ¹H NMR measurements show that oxyanion-initiated polymerization possess the substantial feature of "living" anion polymerization, not only suitable for tertiary amino-substituted methacrylates, but also for methyl methacrylate. The micellization behavior of the diblock copolymer BzO-PDMAEMA-b-PMMA in aqueous solution were investigated by the measurement of surface tension, fluorescence probe, conductivity. The particle sizes of micelles were determined by laser light scattering studies. These results showed that they had excellent surface activity, and the behavior of solution changed with length of hydrophobic and hydrophilic segments and pH values of solution.Two kinds of hydrocarbon-fluorocarbon hybrid amphiphilic block copolymers with narrow molecular weight distribution were synthesized via oxyanion-initiated polymerization, such copolymers as BzO-PDMAEMA-b-PTFEMA and BzO-PDMAEMA-b-PHFBMA. The structures were characterized by ¹H NMR, ¹⁹F NMR. From ¹H NMR and GPC analyses, the molecular weights and molecular weight distribution were obtained. These research works showed that fluorinated amphiphilic block copolymers could be prepared successfully through oxyanion-initiated polymerization. We studied their solution behavior and found that fluorocarbons chain would affect the properties of the block copolymers compared with the same structures of the hydrocarbon block copolymers. This new discovery would benefit to synthesis of fluorinated amphiphilic block copolymers.