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Star Terpolymers (star + terpolymer)
Selected AbstractsSynthesis of amphiphilic and thermoresponsive ABC miktoarm star terpolymer via a combination of consecutive click reactions and atom transfer radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2009Changhua Li Abstract Well-defined amphiphilic and thermoresponsive ABC miktoarm star terpolymer consisting of poly(ethylene glycol), poly(tert -butyl methacrylate), and poly(N -isopropylacrylamide) arms, PEG(- b -PtBMA)- b -PNIPAM, was synthesized via a combination of consecutive click reactions and atom transfer radical polymerization (ATRP). Click reaction of monoalkynyl-terminated PEG with a trifunctional core molecule bis(2-azidoethyl)amine, (N3)2NH, afforded difunctional PEG possessing an azido and a secondary amine moiety at the chain end, PEG- NHN3. Next, the amidation of PEG- NHN3 with 2-chloropropionyl chloride led to PEG-based ATRP macroinitiator, PEG(N3)Cl. The subsequent ATRP of N -isopropylacrylamide (NIPAM) using PEG(N3)Cl as the macroinitiator led to PEG(N3)- b -PNIPAM bearing an azido moiety at the diblock junction point. Finally, well-defined ABC miktoarm star terpolymer, PEG(- b -PtBMA)- b -PNIPAM, was prepared via the click reaction of PEG(N3)- b -PNIPAM with monoalkynyl-terminated PtBMA. In aqueous solution, the obtained ABC miktoarm star terpolymer self-assembles into micelles consisting of PtBMA cores and hybrid PEG/PNIPAM coronas, which are characterized by dynamic and static laser light scattering, and transmission electron microscopy. On heating above the phase transition temperature of PNIPAM in the hybrid corona, micelles initially formed at lower temperatures undergo further structural rearrangement and fuse into much larger aggregates solely stabilized by PEG coronas. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4001,4013, 2009 [source] ROMP-NMP-ATRP combination for the preparation of 3-miktoarm star terpolymer via click chemistryJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2009Aziz Gozgen Abstract A combination of ring opening metathesis polymerization (ROMP) and click chemistry approach is first time utilized in the preparation of 3-miktoarm star terpolymer. The bromide end-functionality of monotelechelic poly(N -butyl oxanorbornene imide) (PNBONI-Br) is first transformed to azide and then reacted with polystyrene- b -poly(methyl methacrylate) copolymer with alkyne at the junction point (PS- b -PMMA-alkyne) via click chemistry strategy, producing PS-PMMA-PNBONI 3-miktoarm star terpolymer. PNBONI-Br was prepared by ROMP of N -butyl oxanorbornene imide (NBONI) 1 in the presence of (Z)-but-2-ene-1,4-diyl bis(2-bromopropanoate) 2 as terminating agent. PS- b -PMMA-alkyne copolymer was prepared successively via nitroxide-mediated radical polymerization (NMP) of St and atom transfer radical polymerization (ATRP) of MMA. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 497,504, 2009 [source] One-pot synthesis of ABC miktoarm star terpolymers by coupling ATRP, ROP, and click chemistry techniquesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2009Yanfeng Zhang Abstract We report on the one-pot synthesis of well-defined ABC miktoarm star terpolymers consisting of poly(2-(dimethylamino)ethyl methacrylate), poly(,-caprolactone), and polystyrene or poly(ethylene oxide) arms, PS(- b -PCL)- b -PDMA and PEO (- b -PCL)- b -PDMA, taking advantage of the compatibility and mutual tolerability of reaction conditions (catalysts and monomers) employed for atom transfer radical polymerization (ATRP), ring-opening polymerization (ROP), and click reactions. At first, a novel trifunctional core molecule bearing alkynyl, hydroxyl group, and bromine moieties, alkynyl(OH)Br, was synthesized via the esterification reaction of 5-ethyl-5-hydroxymethyl-2,2-dimethyl-1,3-dioxane with 4-oxo-4-(prop-2-ynyloxy)butanoic acid, followed by deprotection and monoesterification of alkynyl(OH)2 with 2-bromoisobutyryl bromide. In the presence of trifunctional core molecule, alkynyl(OH)Br, and CuBr/PMDETA/Sn(Oct)2 catalytic mixtures, target ABC miktoarm star terpolymers, PS(- b -PCL)- b -PDMA and PEO(- b -PCL)- b -PDMA, were successfully synthesized in a one-pot manner by simultaneously conducting the ATRP of 2-(dimethylamino)ethyl methacrylate (DMA), ROP of ,-caprolactone (,-CL), and the click reaction with azido-terminated PS (PS- N3) or azido-terminated PEO (PEO- N3). Considering the excellent tolerability of ATRP to a variety of monomers and the fast expansion of click chemistry in the design and synthesis of polymeric and biorelated materials, it is quite anticipated that the one-pot concept can be applied to the preparation of well-defined polymeric materials with more complex chain architectures. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3066,3077, 2009 [source] Preparation of H-shaped ABCAB terpolymers by atom transfer radical couplingJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2009Xiaolan Luo Abstract H-shaped ABCAB terpolymers composed of polystyrene (PS) (A), poly(ethylene oxide) (PEO) (B), and poly(tert -butyl acrylate) (PtBA) (C) were prepared by atom transfer radical coupling reaction using ABC star terpolymers as precursors, CuBr and N,N,N,,N,,N,-pentamethyldiethylenetriamine (PMDETA) as catalysts, and nanosize copper as the reducing agent. The synthesis of 3-miktoarm star terpolymer PS-PEO-(PtBA-Br) involved following steps: (1) the preparation of PS with an active and an ethoxyethyl-ptotected hydroxyl group at the same end; (2) the preparation of diblock copolymer PS- b -PEO with ethoxyethyl-protected group at the junction point through the ring-opening polymerization (ROP) of EO; (3) after de-protection of ethoxyethyl group and further modification of hydroxyl group, tBA was polymerized by atom transfer radical polymerization using PS- b -PEO with 2-bromoisobutyryl functional group as macroinitiator. The H-shaped terpolymer could be successfully formed by atom transfer radical coupling reaction in the presence of small quantity of styrene, CuBr/PMDETA, and Cu at 90 °C. The copolymers were characterized by SEC, 1H NMR, and FTIR in detail. The optimized coupling temperature is 90 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 59,68, 2009 [source] Dendrimer-like miktoarm star terpolymers: A3 -(B-C)3 via click reaction strategyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2008Ozcan Altintas Abstract Two samples of dendrimer-like miktoarm star terpolymers: (poly(tert -butyl acrylate))3 -(polystyrene-poly(,-caprolactone))3 (PtBA)3 -(PS-PCL)3, and (PS)3 -(PtBA-poly(ethylene glycol)3 were prepared using efficient Cu catalyzed Huisgen cycloaddition (click reaction). As a first step, azido-terminated 3-arm star polymers PtBA and PS as core (A) were synthesized by atom transfer radical polymerization (ATRP) of tBA and St, respectively, followed by the conversion of bromide end group to azide. Secondly, PS-PCL and PtBA-PEG block copolymers with alkyne group at the junction as peripheral arms (B-C) were obtained via multiple living polymerization mechanisms such as nitroxide mediated radical polymerization (NMP) of St, ring opening polymerization (ROP) of ,-CL, ATRP of tBA. Thus obtained core and peripheral arms were linked via click reaction to give target (A)3 -(B-C)3 dendrimer-like miktoarm star terpolymers. (PtBA)3 -(PS-PCL)3 and (PS)3 -(PEG-PtBA)3 have been characterized by GPC, DSC, AFM, and SAXS measurements. (PtBA)3 -(PS-PCL)3 did not show any self-organization with annealing due to the miscibility of the peripheral arm segments. In contrast, the micro-phase separation of the peripheral arm segments in (PS)3 -(PtBA-PEG)3 resulted in self-organized phase-separated morphology with a long period of , 13 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5916,5928, 2008 [source] One-pot preparation of 3-miktoarm star terpolymers via click [3 + 2] reactionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2007Ozcan Altintas Abstract The preparation of 3-miktoarm star terpolymers using nitroxide mediated radical polymerization (NMP), ring opening polymerization (ROP), and click reaction [3 + 2] are carried out by applying two types of one-pot technique. In the first one-pot technique, NMP of styrene (St), ROP of ,-caprolactone (,-CL), and [3 + 2] click reaction (between azide end-functionalized poly(ethylene glycol) (PEG-N3)/or azide end-functionalized poly(methyl methacrylate) (PMMA-N3) and alkyne) are carried out in the presence of 2-(hydroxymethyl)-2-methyl-3-oxo-3-(2-phenyl-2-(2,2,6,6-tetramethylpiperidin-1-yloxy)ethoxy) propyl pent-4-ynoate, 2, as an initiator for 48 h at 125 °C (one-pot/one-step). As a second technique, NMP of St and ROP of ,-CL were conducted using 2 as an initiator for 20 h at 125 °C, and subsequently PEG-N3 or azide end-functionalized poly(tert -butyl acrylate (PtBA-N3) was added to the polymerization mixture, followed by a click reaction [3 + 2] for 24 h at room temperature (one-pot/two-step). The 3-miktoarm star terpolymers, PEG-poly(,-caprolactone)(PCL)-PS, PtBA-PCL-PS and PMMA-PCL-PS, were recovered by a simple precipitation in methanol without further purification. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3588,3598, 2007 [source] Reversible Hydrogels from an Ampholytic An(B -b- C)n Heteroarm Star Block TerpolymerMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 21 2008Nikoletta Stavrouli Abstract An asymmetric, amphiphilic, An(B- b -C)n heteroarm star block terpolymer bearing polystyrene and poly(2-vinyl pyridine)- block -poly(acrylic acid) arms, was synthesized by anionic polymerization, using an extending "in-out" method and a post polymerization deprotection reaction. Due to the pH-dependent protonation/deprotonation equilibrium of the P2VP/PAA blocks, a rich phase behavior was observed as a function of pH. At pH,=,2, the star terpolymers form a physical hydrogel through a solvent-induced sol/gel transition in a DMF/water solvent mixture. The gelation mechanism was attributed to a jamming effect mediated by increasing the dielectric permittivity of the medium. [source] | ||||||||||