Synthesis Of Hyperbranched Block Copolymer Via Click Reaction

Hyperbranched polymer is an important nonlinear polymer. They have many novel physical and chemical properties, such as high fluidity, low viscosity, good solubility and a large number of terminal groups, and broadly applied in catalysis, medicine carriers and nanometer materials. They have attracted polymer scientists’ considerable attention. Various novel hyperbranched polymers have been synthesized successfully. Paradoxically, the synthesis of intricate macromolecular structures generally benefits from exploitation of the simplest reactions available. This idea has leaded to the rapid adoption of "click chemistry" strategies in the field of macromolecule engineering. Therefore, these reactions are ideally suited to polymer-polymer reactions such as the coupling of many macromonomer. Atom transfer radical polymerization(ATRP) is a kind of useful method for the realization of living polymerization and syntheses of various structures, such as block copolymers, star-shaped polymer, graft copolymer and hyperbranched polymer.In this paper, the combination of atom transfer radical polymerization(ATRP) and "click chemistry" enabled us to prepare a hyperbranched polymer called "HyperMacs" with block structure via a one-pot reaction. The building polystyrene block synthesized using the initiator with one propargyl group and ATRP produced linear polymer chain with one bromine end-group, which were subsequently successive hydroxylation and esterification converted to two bromine end-group. The polystyrene was used as a macroinitiator to initiator other ATRP procedure produce the block structure. The terminal bromine groups of (C=C)-PSt-PtBA-Br2were substituted by N3via the reaction with sodium azide. Well-defined hyperbranched block copolymer have been successfully prepared by polymerization of polystyrenes-poly(t-butyl methacrylate) macromonomer, polymer containing one propargyl group at its one end and two terminal azide groups at the other end via click reaction.During our experiment we employed TLC to track the monomer’s synthesis procedure and the resulting polymers were characterized by FT-IR, GPC and1H NMR. The final hyperbranched polymer have high molecular weight up to Mn.GPC=8511and narrow molecular weight distributions (Mw/Mn=1.42).