Synthesis and characterization of hyperbranched polystyrene via click reaction of AB₂ macromonomer

Abstract

Well‐defined hyperbranched polystyrenes have been successfully prepared by polymerization of AB2 macromonomer, polystyrene containing an azide group at its one end and two terminal propargyl groups at the other end via click reaction. For preparation of AB2 macromonomers, an ATRP initiator, bispropargyl 2‐bromosuccinate (BPBS) with two propargyl groups and one bromine group was synthesized by the successive bromination and esterification reaction of L‐aspartic acid. The resulting BPBS initiated the ATRP of St, and subsequently, the terminal bromine groups of (CH≡C)2‐PS‐Brs were substituted by N3 via the reaction with sodium azide resulting the AB2 macromonomer, (CH≡C)2‐PS‐N3 with various molecular weights. All intermediates and the resultant polymers were characterized by GPC, 1H NMR, FTIR, and MALLS methods. The polymerization kinetics study showed fast increase of DP at the initial stage of polymerization and then slow increase of their DP. The final “HyperMacs” have high‐molecular weight up to Mw,MALLS = 340,000 g/mol, their molecular weight distributions were moderately narrow (Mw/Mn = 1.47–1.65). The ratios of [η]H/[η]L of the HyperMacs formed in the polymerization system increased with evolution of polymerization. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 454–462, 2010

Long‐Chain Hyperbranched Polymers: Synthesis, Properties, and Applications

“…Interestingly, the multiple functional group–induced intra‐chain cyclization side reaction in the polymerization could be prevented if poly(ε‐caprolactone) precursor was completely threaded by α‐cyclodextrin (α‐CD) to form the rigid polypseudorotaxanes . Moreover, some other distinct processes were developed to convert linear polymer precursors into LCHBPs via this AB 2 manner …”

Well‐Defined Miktocycle Eight‐Shaped Copolymers Composed of Polystyrene and Poly(ε‐caprolactone): Synthesis and Characterization

“…Thus, two key points for this successful synthesis are preparation of the well‐defined linear diblock copolymer and selection of an efficient cyclization reaction to avoid troublesome purification procedure. Among the published cyclization reactions applied in preparation of cyclic polymers,10–19 the click reactions including Huisgen‐,29–33 Diels‐Alder,34 and thiol‐ene reactions35 have been well studied recently in the preparation of polymers with nonlinear architectures. Especially, the azide/alkyne “click” reaction displayed high reactivity (nearly quantitative yield), high tolerance of functional groups, insensitivity to solvents, and low susceptivity to side reactions 31.…”

Synthesis and temperature gradient interaction chromatography of model asymmetric star polymers by the “macromonomer” approach

“…Even the most careful use of anionic polymerisation results in some batch to batch variation in molecular weight. The 'macromonomer' approach, first reported by our group for the synthesis of complex dendritically branched polymers such as DendriMacs [33,38], HyperMacs [54][55][56] and more recently HyperBlocks [57], has become widely adopted as a useful route to make a variety of complex dendritic branched architectures with polymer segments between branch points [58][59][60][61][62][63][64][65][66][67]. In essence the 'macromonomer' approach involves the synthesis of the linear segments of a branched polymer by a living/controlled polymerisation mechanism such that the linear segments contain chain-end functionalities which allow the subsequent construction of branched polymers via coupling reactions between macromonomers.…”