Polymer grafting onto polyurethane backbone via Diels–Alder reaction

The aliphatic polyurethane with pendant anthracene moieties (PU‐anthracene) was prepared from polycondensation of anthracen‐9‐yl methyl 3‐hydroxy‐2‐(hydroxymethyl)‐2‐methylpropanoate (anthracene diol), 1 with hexamethylenediisocyanate in the presence of dibutyltindilaurate in CH₂Cl₂ at room temperature for 10 days. Thereafter, the PU‐anthracene (M_n,GPC = 12,900 g/mol, M_w/M_n = 1.87, relative to PS standards) was clicked with a linear α‐furan protected‐maleimide terminated‐poly(methyl methacrylate) (PMMA‐MI) (M_n,GPC = 2500 g/mol, M_w/M_n = 1.33), or ‐poly(ethylene glycol) (PEG‐MI) (M_n,GPC = 550 g/mol, M_w/M_n = 1.09), to result in well‐defined PU‐graft copolymers, PU‐g‐PMMA (M_n,GPC = 23800 g/mol, M_w/M_n = 1.65, relative to PS standards) or PU‐g‐PEG (M_n,GPC = 11,600 g/mol, M_w/M_n = 1.45, relative to PS standards) using Diels–Alder reaction in dioxane/toluene at 105 °C. The Diels–Alder grafting efficiencies were found to be over 93–99% using UV spectroscopy. Moreover, the structural analyses and the thermal transitions of all copolymers were determined via ¹H NMR and DSC, respectively. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 521–527     

Diels‐alder click reaction for the preparation of polycarbonate block copolymers

The Diels‐Alder reaction as a click reaction strategy is applied to the preparation of well‐defined polycarbonate (PC)‐block copolymers. A well‐defined α‐anthracene‐terminated polycarbonate (PC‐anthracene) is prepared using 9‐anthracene methanol as an initiator in the ring opening polymerization of benzyl 5‐methyl‐2‐oxo‐1,3‐dioxane‐5‐carboxylate in CH₂Cl₂ at room temperature for 5 h. Next, a well‐defined α‐furan protected maleimide‐terminated‐poly(ethylene glycol) (PEG₁₁‐MI or PEG₃₇‐MI), ‐poly(methyl methacrylate) (PMMA₂₆‐MI), and ‐poly(ε‐caprolactone) (PCL₂₇‐MI) were clicked with the PC‐anthracene at reflux temperature of toluene to yield their corresponding PC‐based block copolymers (PC‐b‐PEG, PC‐b‐PMMA, and PC‐b‐PCL). The homopolymer precursors and their block copolymers were characterized by using the GPC, NMR and UV analysis. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

A route toward multifunctional polyurethanes using triple click reactions

The aliphatic polyurethane with pendant alkyne, perfluorophenyl, and anthracene moieties (PU‐anthracene) was prepared from polycondensation of anthracene, alkyne, and perfluorophenyl functional‐diols with hexamethylenediisocyanate in the presence of dibutyltindilaurate (DBTL) in CH₂Cl₂ at room temperature for 10 days. Thereafter, the PU‐(anthracene‐co‐alkyne‐co‐perfluorophenyl) (M_n,GPC = 15,400 g/mol, M_w/M_n= 1.37, relative to PS standards) was sequentially clicked with benzyl azide, octylamine, and 4‐(2‐hydroxyethyl)?10‐oxa‐4‐azatricyclo[5.2.1.02,6]dec‐8‐ene‐3,5‐dione (adduct alcohol) via copper‐catalyzed azide‐alkyne cycloaddition, active ester substitution and Diels–Alder reactions, respectively, to finally yield PU‐(hydroxyl‐co‐benzyltriazole‐co‐octylamine). The PUs were characterized using ¹H NMR, GPC, and DSC. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 480–486     

Multiarm star polymers with peripheral dendritic PMMA arms through Diels–Alder click reaction

Dendritic 2‐ and 4‐arm PMMA‐based star polymers with furan‐protected maleimide at their focal point, (PMMA)_2n‐MI and (PMMA)_4n‐MI were efficiently clicked with the peripheral anthracene functionalized multiarm star polymer, (α‐anthryl functionalized‐polystyrene)_m‐poly(divinyl benzene) ((α‐anthryl‐PS)_m‐polyDVB) through the Diels–Alder reaction resulting in corresponding multiarm star block copolymers: (PMMA)_2n‐(PS)_m‐polyDVB and (PMMA)_4n‐(PS)_m‐polyDVB, respectively. Molecular weights (M_w,TDGPC), hydrodynamic radius (R_h), and intrinsic viscosity (η) of the multiarm star polymers were determined using three‐detection GPC (TD‐GPC). The high efficiency of this methodology to obtain such sterically demanding macromolecular constructs was deduced using ¹H‐NMR and UV–vis spectroscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

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     

Graft copolymers via ROMP and Diels–Alder click reaction strategy

Anthracene‐functionalized oxanorbornene monomer and oxanorbornenyl polystyrene (PS) with ω‐anthracene end‐functionalized macromonomer were first polymerized via ring‐opening metathesis polymerization using the first‐generation Grubbs' catalyst in dichloromethane at room temperature and then clicked with maleimide end‐functionalized polymers, poly(ethylene glycol) (PEG)‐MI, poly(methyl methacrylate) (PMMA)‐MI, and poly(tert‐butyl acrylate) (PtBA)‐MI in a Diels–Alder reaction in toluene at 120 °C to create corresponding graft copolymers, poly(oxanorbornene)‐g‐PEG, poly(oxanorbornene)‐g‐PMMA, and graft block copolymers, poly(oxanorbornene)‐g‐(PS‐b‐PEG), poly(oxanorbornene)‐g‐(PS‐b‐PMMA), and poly(oxanorbornene)‐g‐(PS‐b‐PtBA), respectively. Diels–Alder click reaction efficiency for graft copolymerization was monitored by UV–vis spectroscopy. The dn/dc values of graft copolymers and graft block copolymers were experimentally obtained using a triple detection gel permeation chromatography and subsequently introduced to the software so as to give molecular weights, intrinsic viscosity ([η]) and hydrodynamic radius (R_h) values. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Sequential double polymer click reactions for the preparation of regular graft copolymers

In this study, graft copolymers with regular graft points containing polystyrene (PS) backbone and poly(methyl methacrylate) (PMMA), poly(tert‐butyl acrylate) (PtBA), or poly (ethylene glycol) (PEG) side chains were simply achieved by a sequential double polymer click reactions. The linear α‐alkyne‐ω‐azide PS with an anthracene pendant unit per chain was produced via atom transfer radical polymerization of styrene initiated by anthracen‐9‐ylmethyl 2‐((2‐bromo‐2‐methylpropanoyloxy)methyl)‐2‐methyl‐3‐oxo‐3‐(prop‐2‐ynyloxy) propyl succinate. Subsequently, the azide–alkyne click coupling of this PS to create the linear multiblock PS chain with pendant anthracene sites per PS block, followed by Diels–Alder click reaction with maleimide end‐functionalized PMMA, PtBA, or PEG yielded final PS‐g‐PMMA, PS‐g‐PtBA or PS‐g‐PEG copolymers with regular grafts, respectively. Well‐defined polymers were characterized by ¹H NMR, gel permeation chromatography (GPC) and triple detection GPC. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Block‐brush copolymers via ROMP and sequential double click reaction strategy

We report an efficient way, sequential double click reactions, for the preparation of brush copolymers with AB block‐brush architectures containing polyoxanorbornene (poly (ONB)) backbone and poly(ε‐caprolactone) (PCL), poly(methyl methacrylate) (PMMA) or poly(tert‐butyl acrylate) (PtBA) side chains: poly(ONB‐g‐PMMA)‐b‐poly(ONB‐g‐PCL) and poly(ONB‐g‐PtBA)‐b‐poly(ONB‐g‐PCL). The living ROMP of ONB affords the synthesis of well‐defined poly(ONB‐anthracene)₂₀‐b‐poly (ONB‐azide)₅ block copolymer with anthryl and azide pendant groups. Subsequently, well‐defined linear alkyne end‐functionalized PCL (PCL‐alkyne), maleimide end‐functionalized PMMA (PMMA‐MI) and PtBA‐MI were introduced onto the block copolymer via sequential azide‐alkyne and Diels‐Alder click reactions, thus yielding block‐brush copolymers. The molecular weight of block‐brush copolymers was measured via triple detection GPC (TD‐GPC) introducing the experimentally calculated dn/dc values to the software. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Multiarm star block copolymers via Diels‐Alder click reaction

Two types of multiarm star block copolymers: (polystyrene)_m‐poly(divinylbenzene)‐poly(methyl methacrylate)_n, (PS)_m‐polyDVB‐(PMMA)_n and (polystyrene)_m‐poly(divinylbenzene)‐poly(tert‐butyl acrylate)_k, (PS)_m‐polyDVB‐(PtBA)_k were successfully prepared via a combination of cross‐linking and Diels–Alder click reactions based on “arm‐first” methodology. For this purpose, multiarm star polymer with anthracene functionality as reactive periphery groups was prepared by a cross‐linking reaction of divinyl benzene using α‐anthracene end functionalized polystyrene (PS‐Anth) as a macroinitiator. Thus, obtained multiarm star polymer was then reacted with furan protected maleimide‐end functionalized polymers: PMMA‐MI or PtBA‐MI at reflux temperature of toluene for 48 h resulting in the corresponding multiarm star block copolymers via Diels–Alder click reaction. The multiarm star and multiarm star block copolymers were characterized by using ¹H NMR, SEC, Viscotek triple detection SEC (TD‐SEC) and UV. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 178–187, 2009     

Heterograft brush copolymers via romp and triple click reaction strategies involving CuAAC,diels–alder,and nitroxide radical coupling reactions

In this study, an equimolar mixture of oxanorbornenyl‐anthracene (ONB‐anthracene), oxanorbornenyl‐bromide (ONB‐Br), and oxanorbornenyl tosylate (ONB‐OTs) was polymerized via ring opening metathesis polymerization using the first generation Grubbs' catalyst in CH₂Cl₂ at room temperature to form poly(ONB‐anthracene‐co‐ONB‐Br‐co‐ONB‐OTs)₁₀ copolymer as a main backbone. Next, this main backbone was sequentially clicked with a furan protected maleimide‐terminated poly(methyl methacrylate), 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐terminated poly(ethylene glycol), and alkyne‐terminated poly(ε‐caprolactone) (PCL₂₀‐alkyne) via Diels–Alder, nitroxide radical coupling, and copper‐catalyzed azide‐alkyne cycloaddition, respectively, to yield a poly(ONB‐g‐PMMA‐co‐ONB‐g‐PEG‐co‐ONB‐g‐PCL)₁₀ heterograft brush copolymer © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Dynamic light scattering studies of atactic and syndiotactic poly(methyl methacrylate)s in dilute theta solution

The present article considers the coil‐to‐globule transition behavior of atactic and syndiotactic poly(methyl methacrylates), (PMMA) in their theta solvent, n‐butyl chloride (nBuCl). Changes in Rh in these polymers with temperature in dilute theta solutions were investigated by dynamic light scattering. The hydrodynamic size of atactic PMMA (a‐PMMA‐1) in nBuCl (M_w: 2.55 × 10⁶ g/mol) decreases to 61% of that in the unperturbed state at 13.0°C. Atactic PMMA (a‐PMMA‐2) with higher molecular weight (M_w: 3.3 × 10⁶ g/mol) shows higher contraction in the same theta solvent (α_η = R_h(T)/R_h (θ) = 0.44) at a lower temperature, 7.25°C. Although syndiotactic PMMA (s‐PMMA) has lower molecular weight than that of atactic samples (M_w: 1.2 × 10⁶), a comparable chain collapse was observed (α_η = 0.63) at 9.0°C. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2253–2260, 1999     

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,structure, and property of well‐defined polymethylene‐based diblock copolymers by a combination of living polymerization of ylides and atom transfer radical polymerization

A combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) was used successfully in the design and synthesis of well‐defined polymethylene‐b‐poly(methyl methacrylate) (PM‐b‐PMMA) and polymethylene‐b‐poly(n‐butyl acrylate) (PM‐b‐Pn‐BuA). Tripolymethylene borane were firstly synthesized by living polymerization of dimethylsulfoxonium methylides and then oxidated quantitatively through trimethylamine‐N‐oxide dihydrate to provide a series of low‐polydispersity hydroxyl‐terminated polymethylenes (PM‐OHs) with different molecular weight. Subsequently, such polymers were converted into polymethylene‐based macroinitiators (PM‐MIs, M_n(GPC) = 1900–10,400 g/mol; M_w/M_n = 1.12–1.23) in ～100% conversion. ATRPs of methyl methacrylate and n‐butyl acrylate were successfully conducted using PM‐MI to produce well‐defined diblock copolymers of PM‐b‐PMMA and PM‐b‐Pn‐BuA, respectively. The GPC traces indicated the successful extension of PMMA and Pn‐BuA segment (M_n(GPC) of PM‐b‐PMMA = 3980–10,100 g/mol; M_w/M_n = 1.16–1.22; M_n of PM‐b‐Pn‐BuA = 7400–9200 g/mol; M_w/M_n = 1.14–1.18). Atomic force microscopy (AFM) was used to characterize the structures of the precipitated PM‐b‐PMMA micelles, which were formed in toluene. The blend of LDPE/PMMA was prepared with PM‐b‐PMMA as compatibilizer. The scanning electron microscopy (SEM) results showed that the compatibilization of the LDPE/PMMA was improved greatly by the incorporation of PM‐b‐PMMA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5671–5681, 2009     

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     

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     

Thermal‐initiated reversible addition–fragmentation chain transfer polymerization of methyl methacrylate in the presence of oxygen

A novel reversible addition–fragmentation chain transfer polymerization (RAFT) of methyl methacrylate (MMA) in the presence of oxygen was carried out for the first time without added chemical initiators. The polymerization was mediated by 2‐cyanoprop‐2‐yl 1‐dithionaphthalate (CPDN) or cumyl dithionaphthalenoate (CDN) as RAFT agent. The polymerization demonstrated the features of a living/controlled radical polymerization. The polymerization rate increased with oxygen concentration. Polymers with molecular weight M_n up to 520,000 g/mol, polydispersity M_w/M_n ～1.46 and RAFT efficiency M_n,th/M_n,GPC ～1.026 in the case of CPDN and M_n ～331,500 g/mol, M_w/M_n ～1.35, and M_n,th/M_n,GPC ～1.137 in the case of CDN were obtained. The possible mechanism of the thermal‐initiated RAFT polymerization of MMA in the presence of oxygen was discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3343–3354, 2006     

Encapsulation of nanomaterials using an intermediary layer cross‐linkable ABC triblock copolymer

For the preparation of core‐shell nanoparticles containing functional nanomaterials, a photo‐cross‐linkable amphiphilic ABC triblock copolymer, poly(ethylene glycol)‐b‐poly(2‐cinnamoyloxyethyl methacrylate)‐b‐poly(methyl methacrylate) (PEG‐PCEMA‐PMMA), was synthesized. This triblock copolymer was then used to encapsulate Au nanoparticles or pyrene. The triblock copolymer of PEG‐b‐poly(2‐hydroxyethyl methacrylate)‐b‐PMMA (PEG‐PHEMA‐PMMA) (M_n = 15,800 g/mol, M_w/M_n = 1.58) was first synthesized by activators generated by electron transfer atom transfer radical polymerization. Its middle block was then functionalized with cinnamoyl chloride. The degrees of polymerization of the PEG, PHEMA, and PMMA blocks were 45, 13, and 98, respectively. PMMA‐tethered Au nanoparticles (with an average diameter of 3.0 nm) or pyrene was successfully encapsulated within the PEG‐PCEMA‐PMMA micelles. The intermediary layers of the micelles were then cross‐linked by UV irradiation. The spherical structures of the PEG‐PCEMA‐PMMA micelles containing Au nanoparticles or pyrene were not changed by the photo‐cross‐linking process and they showed excellent colloidal stability. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4963–4970, 2009     

Novel,biodegradable, functional poly(ester‐carbonate)s by copolymerization of trans‐4‐hydroxy‐L‐proline with cyclic carbonate bearing a pendent carboxylic group

Water‐soluble poly(ester‐carbonate) having pendent amino and carboxylic groups on the main‐chain carbon is reported for the first time. This article describes the melt ring‐opening/condensation reaction of trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L ‐proline (N‐CBz‐Hpr) with 5‐methyl‐5‐benzyloxycarbonyl‐1,3‐dioxan‐2‐one (MBC) at a wide range of molar fractions. The influence of reaction conditions such as catalyst concentration, polymerization time, and temperature on the number average molecular weight (M_n) and molecular weight distribution (M_w/M_n) of the copolymers was investigated. The polymerizations were carried out in bulk at 110 °C with 3 wt % stannous octoate as a catalyst for 16 h. The poly(ester‐carbonate)s obtained were characterized by Fourier transform infrared spectroscopy, ¹H NMR, differential scanning calorimetry, and gel permeation chromatography. The copolymers synthesized exhibited moderate molecular weights (M_n = 6000–14,700 g mol^?1) with reasonable molecular weight distributions (M_w/M_n = 1.11–2.23). The values of the glass‐transition temperature (T_g) of the copolymers depended on the molar fractions of cyclic carbonate. When the MBC content decreased from 76 to 12 mol %, the T_g increased from 16 to 48 °C. The relationship between the poly(N‐CBz‐Hpr‐co‐MBC) T_g and the compositions was in approximation with the Fox equation. In vitro degradation of these poly(N‐CBz‐Hpr‐co‐MBC)s was evaluated from weight‐loss measurements and the change of M_n and M_w/M_n. Debenzylation of 3 by catalytic hydrogenation led to the corresponding linear poly(ester‐carbonate), 4 , with pendent amino and carboxylic groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2303–2312, 2004     

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 block copolymers via Diels Alder reaction of maleimide‐ and anthracene‐end functionalized polymers

A number of diblock copolymers were successfully prepared by Diels–Alder reaction, between maleimide‐ and anthracene‐end functionalized poly (methyl methacrylate) (PMMA), polystyrene (PS), poly(tert‐butyl acrylate) (PtBA), and poly(ethylene glycol) (PEG) in toluene, at 110 °C. For this purpose, 2‐bromo‐2‐methyl‐propionic acid 2‐(3,5‐dioxo‐10‐oxa‐4‐azatricyclo[5.2.1.02,6]dec‐8‐en‐4‐yl)‐ethyl ester, 2 , 9‐anthyrylmethyl 2‐bromo‐2‐methyl propanoate, 3 , and 2‐bromo‐propionic acid 2‐(3,5‐dioxo‐10‐oxa‐4‐azatricyclo[5.2.1.02,6]dec‐8‐en‐4‐yl)‐ethyl ester, 4 , were used as initiators in atom transfer radical polymerization, in the presence of Cu(I) salt and pentamethyldiethylenetriamine (PMDETA), at various temperatures. On the other hand, PEG with maleimide‐ or anthracene‐end functionality was achieved by esterification between monohydroxy PEG and succinic acid monoathracen‐9‐ylmethyl ester, 1 , or 4‐maleimido‐benzoyl chloride. Thus‐obtained PMMA‐b‐PS, PEG‐b‐PS, PtBA‐b‐PS, and PMMA‐b‐PEG block copolymers were characterized by ¹H NMR, UV, and GPC. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1667–1675, 2006