Micelles possessing mixed cores and thermoresponsive shells fabricated from well‐defined amphiphilic ABC miktoarm star terpolymers

Amphiphilic ABC miktoarm star terpolymers consisting of polystyrene, poly(ε‐caprolactone), and poly(N‐isopropylacrylamide) arms, PS(‐b‐PNIPAM)‐b‐PCL, were synthesized via a combination of atom transfer radical polymerization, ring‐opening polymerization (ROP), and click chemistry. Difunctional PS bearing an alkynyl and a primary hydroxyl moiety at the chain end, PS‐alknyl‐OH, was prepared by reacting azido‐terminated PS with an excess of 3,5‐bis(propargyloxy)benzyl alcohol (BPBA) under click conditions. The subsequent ROP of ε‐caprolactone using PS‐alknyl‐OH macroinitiator afforded PS(‐alkynyl)‐b‐PCL copolymer bearing an alkynyl moiety at the diblock junction point. Target PS(‐b‐PNIPAM)‐b‐PCL amphiphilic ABC miktoarm star terpolymers were then prepared via click reaction between PS(‐alkynyl)‐b‐PCL and an excess of azido‐terminated PNIPAM (PNIPAM‐N₃). The removal of excess PNIPAM‐N₃ was accomplished by “clicking” onto alkynyl‐functionalized Wang resin. All the intermediate and final products were characterized by gel permeation chromatography, ¹H NMR, and FTIR. In aqueous solution, the obtained amphiphilic ABC miktoarm star terpolymer self‐assembles into micelles possessing mixed PS/PCL cores and thermoresponsive shells, which were further characterized by dynamic laser light scattering and transmission electron microscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1636–1650, 2009     

Synthesis of amphiphilic and thermoresponsive ABC miktoarm star terpolymer via a combination of consecutive click reactions and atom transfer radical polymerization

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)₂? NH, afforded difunctional PEG possessing an azido and a secondary amine moiety at the chain end, PEG‐NH? N₃. Next, the amidation of PEG‐NH? N₃ 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     

Dendrimer‐like miktoarm star terpolymers: A3‐(B‐C)3 via click reaction strategy

Two samples of dendrimer‐like miktoarm star terpolymers: (poly(tert‐butyl acrylate))₃‐(polystyrene‐poly(ε‐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 ε‐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     

One‐pot preparation of 3‐miktoarm star terpolymers via click [3 + 2] reaction

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 ε‐caprolactone (ε‐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 ε‐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(ε‐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     

One‐pot synthesis of ABC miktoarm star terpolymers by coupling ATRP,ROP, and click chemistry techniques

We report on the one‐pot synthesis of well‐defined ABC miktoarm star terpolymers consisting of poly(2‐(dimethylamino)ethyl methacrylate), poly(ε‐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 ε‐caprolactone (ε‐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     

ABC‐type hetero‐arm star terpolymers through “Click” chemistry

Hetero‐arm star ABC‐type terpolymers, poly(methyl methacrylate)‐polystyrene‐poly(tert‐butyl acrylate) (PMMA‐PS‐PtBA) and PMMA‐PS‐poly(ethylene glycol) (PEG), were prepared by using “Click” chemistry strategy. For this, first, PMMA‐b‐PS with alkyne functional group at the junction point was obtained from successive atom transfer radical polymerization (ATRP) and nitroxide‐mediated radical polymerization (NMP) routes. Furthermore, PtBA obtained from ATRP of tBA and commercially available monohydroxyl PEG were efficiently converted to the azide end‐functionalized polymers. As a second step, the alkyne and azide functional polymers were reacted to give the hetero‐arm star polymers in the presence of CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine ( PMDETA) in DMF at room temperature for 24 h. The hetero‐arm star polymers were characterized by ¹H NMR, GPC, and DSC. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5699–5707, 2006     

ABCD 4‐miktoarm star quarterpolymers using click [3 + 2] reaction strategy

Two samples of ABCD 4‐miktoarm star quarterpolymer with A = polystyrene (PS), B = poly(ε‐caprolactone) (PCL), C = poly(methyl methacrylate) (PMMA) or poly(tert‐butyl acrylate) (PtBA), and D = poly(ethylene glycol) (PEG) were prepared using click reaction strategy (Cu(I)‐catalyzed Huisgen [3 + 2] reaction). Thus, first, predefined block copolymers of different polymerization routes, PS‐b‐PCL with azide and PMMA‐b‐PEG and PtBA‐b‐PEG copolymers with alkyne functionality, were synthesized and then these blocks were combined together in the presence of Cu(I)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as a catalyst in DMF at room temperature to give the target 4‐miktoarm star quarterpolymers. The obtained miktoarm star quarter polymers were characterized by GPC, NMR, and DSC measurements. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1218–1228, 2008     

Preparation of H‐shaped ABCAB terpolymers by atom transfer radical coupling

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     

H‐shaped (ABCDE type) quintopolymer via click reaction [3 + 2] strategy

H‐shaped quintopolymer containing different five blocks: poly(ε‐caprolactone) (PCL), polystyrene (PS), poly(ethylene glycol) (PEG), and poly(methyl methacrylate) (PMMA) as side chains and poly(tert‐butyl acrylate) (PtBA) as a main chain was simply prepared from a click reaction between azide end‐functionalized PCL‐PS‐PtBA 3‐miktoarm star terpolymer and PEG–PMMA‐block copolymer with alkyne at the junction point, using Cu(I)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as a catalyst in DMF at room temperature for 20 h. The H‐shaped quintopolymer was obtained with a number–average molecular weight (M_n) around 32,000 and low polydispersity index (M_w/M_n) 1.20 as determined by GPC analysis in THF using PS standards. The click reaction efficiency was calculated to have 60% from ¹H NMR spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4459–4468, 2008     

Heteroarm H‐shaped terpolymers through click reaction

Heteroarm H‐shaped terpolymers, (polystyrene)(poly(methyl methacrylate))‐ poly(tert‐butyl acrylate)‐(polystyrene)(poly(methyl methacrylate)), (PS)(PMMA)‐PtBA‐(PMMA)(PS), and, (PS)(PMMA)‐poly(ethylene glycol)(PEG)‐(PMMA)(PS), through click reaction strategy between PS‐PMMA copolymer (as side chains) with an alkyne functional group at the junction point and diazide end‐functionalized PtBA or PEG (as a main chain). PS‐PMMA with alkyne functional group was prepared by sequential living radical polymerizations such as the nitroxide mediated (NMP) and the metal mediated‐living radical polymerization (ATRP) routes. The obtained H‐shaped polymers were characterized by using ¹H‐NMR, GPC, DSC, and AFM measurements. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1055–1065, 2007     

Quadruple click reactions for the synthesis of cysteine‐terminated linear multiblock copolymers

Synthesis of cysteine‐terminated linear polystyrene (PS)‐b‐poly(ε‐caprolactone) (PCL)‐b‐poly(methyl methacrylate) (PMMA)/or poly(tert‐butyl acrylate)(PtBA)‐b‐poly(ethylene glycol) (PEG) copolymers was carried out using sequential quadruple click reactions including thiol‐ene, copper‐catalyzed azide–alkyne cycloaddition (CuAAC), Diels–Alder, and nitroxide radical coupling (NRC) reactions. N‐acetyl‐L ‐cysteine methyl ester was first clicked with α‐allyl‐ω‐azide‐terminated PS via thiol‐ene reaction to create α‐cysteine‐ω‐azide‐terminated PS. Subsequent CuAAC reaction with PCL, followed by the introduction of the PMMA/or PtBA and PEG blocks via Diels–Alder and NRC, respectively, yielded final cysteine‐terminated multiblock copolymers. By ¹H NMR spectroscopy, the DP_ns of the blocks in the final multiblock copolymers were found to be close to those of the related polymer precursors, indicating that highly efficient click reactions occurred for polymer–polymer coupling. Successful quadruple click reactions were also confirmed by gel permeation chromatography. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A New Approach for the Synthesis of Miktoarm Star Polymers Through a Combination of Thiol–Epoxy “Click” Chemistry and ATRP/Ring‐Opening Polymerization Techniques

A new approach was developed for synthesis of certain A₃B₃‐type of double hydrophilic or amphiphilic miktoarm star polymers using a combination of “grafting onto” and “grafting from” methods. To achieve the synthesis of desired miktoarm star polymers, acetyl protected poly(ethylene glycol) (PEG) thiols (M_n = 550 and 2000 g mol^?1) were utilized to generate A₃‐type of homoarm star polymers through an in situ protective group removal and a subsequent thiol–epoxy “click” reaction with a tris‐epoxide core viz. 1,1,1‐tris(4‐hydroxyphenyl)ethane triglycidyl ether. The secondary hydroxyl groups generated adjacent to the core upon the thiol–epoxy reaction were esterified with α‐bromoisobutyryl bromide to install atom transfer radical polymerization (ATRP) initiating sites. ATRP of N‐isopropylacrylamide (NIPAM) using the three‐arm star PEG polymer fitted with ATRP initiating sites adjacent to the core afforded A₃B₃‐type of double hydrophilic (PEG)₃[poly(N‐isopropylacrylamide)] (PNIPAM)₃ miktoarm star polymers. Furthermore, the generated hydroxyl groups were directly used as initiator for ring‐opening polymerization of ε‐caprolactone to prepare A₃B₃‐type of amphiphilic (PEG)₃[poly(ε‐caprolactone)]₃ miktoarm star polymers. The double hydrophilic (PEG)₃(PNIPAM)₃ miktoarm star polymers showed lower critical solution temperature around 34 °C. The preliminary transmission electron microscopy analysis indicated formation of self‐assembly of (PEG)₃(PNIPAM)₃ miktoarm star polymer in aqueous solution. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 146–156     

PEG‐b‐PtBA‐b‐PHEMA well‐defined amphiphilic triblock copolymer: Synthesis,self‐assembly,and application in drug delivery

A series of well‐defined amphiphilic triblock copolymers, poly(ethylene glycol)‐b‐poly(tert‐butyl acrylate)‐b‐poly(2‐hydroxyethyl methacrylate) (PEG‐b‐PtBA‐b‐PHEMA), were synthesized via successive atom transfer radical polymerization (ATRP). ATRP of tBA was first initiated by PEG‐Br macroinitiator using CuBr/N,N,N′,N″,N′″‐pentamethyldiethylenetriamine as catalytic system to give PEG‐b‐PtBA diblock copolymer. This copolymer was then used as macroinitiator to initiate ATRP of HEMA, which afforded the target triblock copolymer, PEG‐b‐PtBA‐b‐PHEMA. The critical micelle concentrations of obtained amphiphilic triblock copolymers were determined by fluorescence spectroscopy using N‐phenyl‐1‐naphthylamine as probe. The morphology and size of formed aggregates were investigated by transmission electron microscopy and dynamic light scattering, respectively. Finally, an acid‐sensitive PEG‐b‐PtBA‐b‐P(HEMA‐CAD) prodrug via cis‐aconityl linkage between doxorubicin and hydroxyls of triblock copolymers with a high drug loading content up to 38%, was prepared to preliminarily explore the application of triblock copolymer in drug delivery. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and Aggregation Behavior of Multi‐Responsive Double Hydrophilic ABC Miktoarm Star Terpolymer

We report the first example of the synthesis and the “schizophrenic” micellization behavior of a multi‐responsive double hydrophilic ABC miktoarm star terpolymer. A well‐defined miktoarm star terpolymer consisting of poly(ethylene glycol), poly(2‐(diethylamino)ethyl methacrylate), and poly(N‐isopropylacrylamide) arms, PEG(‐b‐PDEA)‐b‐PNIPAM, was synthesized via the combination of atom transfer radical polymerization (ATRP) and click reaction. Containing pH‐responsive PDEA and thermo‐responsive PNIPAM arms, this novel type of miktoarm star terpolymer molecularly dissolves in aqueous solution at acidic pH and room temperature, but supramolecularly self‐assembles into PDEA‐core micelles at alkaline pH and room temperature, and PNIPAM‐core micelles at acidic pH and elevated temperatures. Most importantly, both types of micellar aggregates possess well‐solvated hybrid coronas.

     

3‐miktoarm star terpolymers using triple click reactions: Diels–Alder,copper‐catalyzed azide‐alkyne cycloaddition,and nitroxide radical coupling reactions

Well‐defined linear furan‐protected maleimide‐terminated poly(ethylene glycol) (PEG‐MI), tetramethylpiperidine‐1‐oxyl‐terminated poly(ε‐caprolactone) (PCL‐TEMPO), and azide‐terminated polystyrene (PS‐N₃) or ‐poly(N‐butyl oxanorbornene imide) (PONB‐N₃) were ligated to an orthogonally functionalized core ( 1 ) in a two‐step reaction mode through triple click reactions. In a first step, Diels–Alder click reaction of PEG‐MI with 1 was performed in toluene at 110 °C for 24 h to afford α‐alkyne‐α‐bromide‐terminated PEG (PEG‐alkyne/Br). As a second step, this precursor was subsequently ligated with the PCL‐TEMPO and PS‐N₃ or PONB‐N₃ in N,N‐dimethylformamide at room temperature for 12 h catalyzed by Cu(0)/Cu(I) through copper‐catalyzed azide‐alkyne cycloaddition and nitroxide radical coupling click reactions, yield resulting ABC miktoarm star polymers in a one‐pot mode. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation of ABC miktoarm star terpolymer containing poly(ethylene glycol), polystyrene,and poly(tert‐butylacrylate) arms by combining diels–alder reaction,atom transfer radical,and stable free radical polymerization routes

The ABC type miktoarm star terpolymer was prepared utilizing “core‐in” and “core‐out” methods via combination of Diels–Alder reaction (DA), stable free radical polymerization (SFRP), and atom transfer radical polymerization (ATRP). First, in DA reaction, poly(ethylene glycol)‐maleimide (PEG‐maleimide) precursor was reacted with succinic acid anthracen‐9‐ylmethyl ester 3‐(2‐bromo‐2‐methyl‐propionyloxy)‐2‐methyl‐2‐[2‐phenyl‐2‐(2,2,6,6‐tetramethyl‐piperidin‐1‐yloxy)‐ethoxy‐carbonyl]‐propyl ester, 8 , to give DA adduct, 9 , which has appropriate functional groups for SFRP and ATRP. Second, a previously obtained 9 was used as a macroinitiator for SFRP of styrene at 125 °C. As a third step, this PEG‐polystyrene (PEG‐PSt) precursor with a bromine functionality in the core was employed as a macroinitiator for ATRP of tert‐butylacrylate (tBA) in the presence of Cu(I)Br and pentamethyldiethylenetriamine at 80 °C to give ABC type miktoarm star terpolymer (PEG‐PSt‐PtBA) with controlled molecular weight and low polydispersity (M_w/M_n < 1.27). The obtained polymers were characterized by gel permeation chromatography and ¹H NMR. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 499–509, 2006     

Multiarm star triblock terpolymers via sequential double click reactions

Multiarm star triblock terpolymers were obtained by using two different click reactions sequentially: Cu(I) catalyzed azide–alkyne and Diels–Alder. The synthetic strategy is described as follows: (poly(methyl methacrylate))_n‐(polystyrene)_m‐poly(divinyl benzene)) ((PMMA)_n‐(PS)_m‐polyDVB) multiarm star diblock copolymer was first obtained from an azide–alkyne click reaction of (alkyne‐PS)_m‐polyDVB multiarm star polymer with α‐anthracene‐ω‐azide PMMA (anth‐PMMA‐N₃), followed by a Diels–Alder click reaction of the anthracene groups at the star periphery with α‐maleimide poly (tert‐butyl acrylate) (PtBA‐MI) or α‐maleimide poly(ethylene glycol) (PEG‐MI) leading to target (PtBA)_k‐(PMMA)_n‐(PS)_m‐polyDVB and (PEG)_p‐(PMMA)_n‐(PS)_m‐polyDVB multiarm star triblock terpolymers. The hydrodynamic diameter of individual multiarm star triblock terpolymers were measured by dynamic light scattering (DLS) to be ～24–27 nm in consistent with the atomic force microscopy (AFM) images on silicon substrates. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1557–1564, 2010     

Linear tetrablock quaterpolymers via triple click reactions,azide‐alkyne,diels–alder,and nitroxide radical coupling in a one‐pot fashion

Azide‐alkyne and Diels–Alder click reactions together with a click‐like nitroxide radical coupling reaction were used in a one‐pot fashion to generate tetrablock quaterpolymer. The various living polymerization generated linear polymers with orthogonal end‐functionalities, maleimide‐terminated poly(ethylene glycol) (PEG‐MI), anthracene‐ and azide‐terminated polystyrene, alkyne‐ and bromide‐terminated poly(tert‐butyl acrylate) or alkyne‐poly(n‐butyl acrylate), and tetramethylpiperidine‐1‐oxyl (TEMPO)‐terminated poly(ε‐caprolactone) (PCL‐TEMPO) were clicked together in a one‐pot fashion to generate PEG‐b‐PS‐b‐PtBA‐b‐PCL or PEG‐b‐PS‐b‐PnBA‐b‐PCL quaterpolymer using Cu(0), CuBr, and N,N,N′,N″,N″‐pentamethyldiethylenetriamine as catalyst in dimethyl formamide at 80 °C for 36 h. Linear precursors and target quaterpolymers were analyzed via ¹H NMR and gel permeation chromatography. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,surface properties,and morphologies of poly[methyl(3,3,3‐trifluoropropyl)siloxane]‐b‐polystyrene‐b‐poly(tert‐butyl acrylate) triblock copolymers by a combination of anionic ROP and ATRP

A series of well‐defined poly[methyl(3,3,3‐trifluoropropyl)siloxane]‐b‐polystyrene‐b‐poly(tert‐butyl acrylate) (PMTFPS‐b‐PS‐b‐PtBA) triblock copolymers were prepared by a combination of anionic ring‐opening polymerization of 1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane (F₃), and atom transfer radical polymerization (ATRP) of styrene (St) and tert‐butyl acrylate (tBA), using the obtained α‐bromoisobutyryl‐terminal PMTFPS (PMTFPS‐Br) as the macroinitiators. The ATRP of St from PMTFPS‐Br, as well as the ATRP of tBA from the obtained PMTFPS‐b‐PS‐Br macroinitiators, has typical characteristic of controlled/living polymerization. The results of contact angle measurements for the films of PMTFPS‐b‐PS‐b‐PtBA triblock copolymers demonstrate that the compositions have an effect on the wetting behavior of the copolymer films. For the copolymer films with different compositions, there may be different macroscale or nanoscale structures on the outmost layer of the copolymer surfaces. The films with high content of PtBA blocks exhibit almost no ordered microstructures on the outmost layer of the copolymer surfaces, even though they have microphase‐separated structures in bulk. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

ROMP‐NMP‐ATRP combination for the preparation of 3‐miktoarm star terpolymer via click chemistry

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