Synthesis of new amphiphilic diblock copolymers containing poly(ethylene oxide) and poly(α‐olefin)

This article discusses an effective route to prepare amphiphilic diblock copolymers containing a poly(ethylene oxide) block and a polyolefin block that includes semicrystalline thermoplastics, such as polyethylene and syndiotactic polystyrene (s‐PS), and elastomers, such as poly(ethylene‐co‐1‐octene) and poly(ethylene‐co‐styrene) random copolymers. The broad choice of polyolefin blocks provides the amphiphilic copolymers with a wide range of thermal properties from high melting temperature ～270 °C to low glass‐transition temperature ～?60 °C. The chemistry involves two reaction steps, including the preparation of a borane group‐terminated polyolefin by the combination of a metallocene catalyst and a borane chain‐transfer agent as well as the interconversion of a borane terminal group to an anionic (? O^?K⁺) terminal group for the subsequent ring‐opening polymerization of ethylene oxide. The overall reaction process resembles a transformation from the metallocene polymerization of α‐olefins to the ring‐opening polymerization of ethylene oxide. The well‐defined reaction mechanisms in both steps provide the diblock copolymer with controlled molecular structure in terms of composition, molecular weight, moderate molecular weight distribution (M_w/M_n < 2.5), and absence of homopolymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3416–3425, 2002     

Toward one‐pot olefin/thiophene block copolymers using an in situ ligand exchange

Block copolymers containing both conducting and insulating segments are of interest due to their enhanced electrical properties arising from their increased crystallization. Yet few methods exist for generating these copolymers, because the reaction conditions for synthesizing each block are often incompatible. Herein, efforts toward identifying a one‐pot, living polymerization method for synthesizing block copolymers of 1‐pentene and 3‐hexylthiophene is described. An in situ ligand exchange enables the optimal catalyst to be utilized for synthesizing each block. Even under these conditions, however, only homopolymers are observed. Computational studies modeling the ligand exchange reveal that the added stabilizing ligands likely inhibit propagation of the second block. These results suggest an ancillary ligand‐based “goldilocks” effect wherein catalysts that are stable yet still reactive are required. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1601–1605     

Synthesis and Characterization of Novel Biodegradable Di‐ and Tri‐Block Copolymers Based on Ethylene Carbonate Polymer as Hydrophobic Segment

Synthesis of novel amphiphilic biodegradable block copolymers based on ethylene carbonate is reported in this study. Polyethylene glycol monomethyl ether (MeO‐PEO) and polyethylene glycol (PEG) of varying molar masses are used as macro‐initiator for ring‐opening polymerization of ethylene carbonate in the presence of sodium stannate trihydrate as a heterogeneous transesterification catalyst. Earlier elution of block copolymer from macro‐initiator in size exclusion chromatography (SEC) indicated the successful synthesis of the block copolymers. Ratios of both types of blocks are varied systematically. Liquid chromatography at critical conditions is used for the analysis of the non‐critical individual blocks, and if there are any critical segments that are not attached to the non‐critical block. To the best of our knowledge, this is the first report on the synthesis of ethylene carbonate‐based amphiphilic block copolymers. Chromatographic critical conditions of the ethylene carbonate polymer are also reported for the first time. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1887–1893     

Highly active bifunctional cobalt‐salen complexes for the synthesis of poly(ester‐block‐carbonate) copolymer via terpolymerization of carbon dioxide,propylene oxide,and norbornene anhydride isomer: Roles of anhydride conformation consideration

This article describes an efficient synthetic route of defined reactive polyester‐block‐polycarbonate copolymers, utilizing a bifunctional SalenCoNO₃ complex as catalyst for the single‐step terpolymerization of norbornene anhydride (NA), propylene oxide, and carbon dioxide. The geometric isomer of NA plays an important role in polymerization efficacy and the resulting polymer microstructure, including carbonate content, sequence isomer of polycarbonate moiety, and molecular weight. A hydroxyl‐functionalized polyester–polycarbonate block copolymer was synthesized by a thiol‐ene reaction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 789–795     

Propylene polymerizations with a binary metallocene system—Chain shuttling caused by trimethylaluminium between active catalyst centers

Propylene was polymerized at varying trimethylaluminium (TMA) concentration with a homogeneous binary metallocene catalyst system activated by methylaluminoxane (MAO) in an attempt to better understand interactions between active catalyst sites and to clarify the role of the TMA as a chain shuttling agent. TMA‐free polymerization conditions were obtained by chemical treatment of MAO solution with 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT). A binary catalyst system consisting of catalyst precursors diphenylmethyl(cyclopentadienyl)(9‐fluorenyl)zirconium dichloride ( 1 ) producing high M_w syndiotactic polypropylene and rac‐dimethylsilylbis(4‐tert‐butyl‐2‐methyl‐cyclopentadienyl)zirconium dichloride ( 2 ) producing low M_w isotactic polypropylene was investigated. At the studied polymerization conditions, chain shuttling between the active catalysts caused by TMA was confirmed. The chain shuttling reactions caused changes in catalyst activity, molecular weights, melting behavior, and polymer microstructure. We propose that TMA is capable to transfer a growing polymer chain from catalyst 2 to catalyst 1 , and a stereoblock copolymer is formed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1364–1376, 2007     

Direct transesterification of poly(methyl acrylate) for functional polyacrylate syntheses

Post‐polymerization modification is an important synthetic method to produce macromolecules with various chemical and physical properties. With this technique, functional groups of polymer molecules within the same structural scaffold can be varied, and thus, accurate research on structure‐property relationships is possible. To add practicality, the direct post‐polymerization of commodity polymers has been pursued, but only limited success has been realized. In this report, a study on various transesterification methods for the synthesis of functional polyacrylates beginning with a poly(methyl acrylate) (PMA), one common acrylate polymer, is presented. The Zn‐based catalytic system, a combination of Zn₄(OCOCF₃)₆O and 4‐dimethylaminopyridine with instant methanol removal, exhibited the highest reactivity among many catalysts and conditions. Assorted alcohols were reacted with PMA to produce the corresponding polyacrylates. This method was successfully extended to post‐polymerization modification of a PMA‐containing block copolymer, PS‐b‐PMA and synthesis of acrylate copolymers with functional group density control. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2554–2560     

End‐group modification of poly(2,6‐dimethyl‐1,4‐phenylene ether) and in situ synthesis of poly(2,6‐dimethyl‐1,4‐phenylene ether)‐b‐poly(ethylene terephthalate) block copolymer

The preparation of poly(2,6‐dimethyl‐1,4‐phenylene ether)‐b‐poly(ethylene terephthalate) block copolymer was performed by the reaction of the 2‐hydroxyethyl modified poly(2,6‐dimethyl‐1,4‐phenylene ether) (PPE‐EtOH) with poly(ethylene terephthalate) (PET) by an in situ process, during the synthesis of the polyester. The yield of the reaction of the 2‐hydroxyethyl functionalized PPE‐EtOH with PET was close to 100%. A significant proportion of the PET‐b‐PPE‐EtOH block copolymer was found to have short PET block. Nevertheless, the copolymer structured in the shape of micelles (20 nm diameter) and very small domains with 50–200 nm diameter, whereas unmodified PPE formed much larger domains (1.5 μm) containing copolymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3985–3991, 2008     

Cu(0)/2,6‐bis(imino)pyridines catalyzed single‐electron transfer‐living radical polymerization of methyl methacrylate initiated with poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)

A series of 2,6‐bis(imino)pyridines, as common ligands for late transition metal catalyst in ethylene coordination polymerization, were successfully employed in single‐electron transfer‐living radical polymerization (SET‐LRP) of methyl methacrylate (MMA) by using poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) (P(VDF‐co‐CTFE)) as macroinitiator with low concentration of copper catalyst under relative mild‐reaction conditions. Well‐controlled polymerization features were observed under varied reaction conditions including reaction temperature, catalyst concentration, as well as monomer amount in feed. The typical side reactions including the chain‐transfer reaction and dehydrochlorination reaction happened on P(VDF‐co‐CTFE) in atom‐transfer radical polymerization process were avoided in current system. The relationship between the catalytic activity and the chemical structure of 2,6‐bis(imino)pyridine ligands was investigated by comparing both the electrochemical properties of Cu(II)/2,6‐bis(imino)pyridine and the kinetic results of SET‐LRP of MMA catalyzed with different ligands. The substitute groups onto N‐binding sites with proper steric bulk and electron donating are desirable for both high‐propagation reaction rate and C? Cl bonds activation capability on P(VDF‐co‐CTFE). The catalytic activity of Cu(0)/2,6‐bis(imino)pyridines is comparable with Cu(0)/2,2′‐bipyridine under the consistent reaction conditions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4378–4388     

Synthesis of star‐shaped poly(D,L‐lactic acid‐alt‐glycolic acid)‐b‐poly(L‐lactic acid) with the poly(D,L‐lactic acid‐alt‐glycolic acid) macroinitiator and stannous octoate catalyst

Two types of three‐arm and four‐arm, star‐shaped poly(D,L ‐lactic acid‐alt‐glycolic acid)‐b‐poly(L ‐lactic acid) (D,L ‐PLGA50‐b‐PLLA) were successfully synthesized via the sequential ring‐opening polymerization of D,L ‐3‐methylglycolide (MG) and L ‐lactide (L ‐LA) with a multifunctional initiator, such as trimethylolpropane and pentaerythritol, and stannous octoate (SnOct₂) as a catalyst. Star‐shaped, hydroxy‐terminated poly(D,L ‐lactic acid‐alt‐glycolic acid) (D,L ‐PLGA50) obtained from the polymerization of MG was used as a macroinitiator to initiate the block polymerization of L ‐LA with the SnOct₂ catalyst in bulk at 130 °C. For the polymerization of L ‐LA with the three‐arm, star‐shaped D,L ‐PLGA50 macroinitiator (number‐average molecular weight = 6800) and the SnOct₂ catalyst, the molecular weight of the resulting D,L ‐PLGA50‐b‐PLLA polymer linearly increased from 12,600 to 27,400 with the increasing molar ratio (1:1 to 3:1) of L ‐LA to MG, and the molecular weight distribution was rather narrow (weight‐average molecular weight/number‐average molecular weight = 1.09–1.15). The ¹H NMR spectrum of the D,L ‐PLGA50‐b‐PLLA block copolymer showed that the molecular weight and unit composition of the block copolymer were controlled by the molar ratio of L ‐LA to the macroinitiator. The ¹³C NMR spectrum of the block copolymer clearly showed its diblock structures, that is, D,L ‐PLGA50 as the first block and poly(L ‐lactic acid) as the second block. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 409–415, 2002     

In situ synthesis of nano‐assemblies of the high molecular weight ferrocene‐containing block copolymer via dispersion RAFT polymerization

The in situ synthesis of the nano‐assemblies of the high molecular weight ferrocene‐containing block copolymer of poly(ethylene glycol)‐block‐poly(4‐vinylbenzyl ferrocenecarboxylate) (PEG‐b‐PVFC) via dispersion reversible addition‐fragmentation chain transfer (RAFT) polymerization was discussed. Taking the advantage of the accelerated polymerization rate of the dispersion RAFT polymerization, the nano‐objects of the well‐defined PEG‐b‐PVFC diblock copolymer with the polymerization degree (DP) of the ferrocene‐containing PVFC block up to 300 were prepared. It was found that the morphology of the PEG‐b‐PVFC diblock copolymer nano‐assemblies was dependent on the DP of the PEG and PVFC blocks, and nanospheres favorably formed in the case of the long PEG block and vesicles containing a thick and porous membrane were formed in the case of the short PEG block and long PVFC block, respectively. Our results demonstrate that the dispersion RAFT polymerization is an effective way to prepare the high molecular weight ferrocene‐containing block copolymer with interesting morphologies. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 900–909     

Synthesis of four‐armed poly(ε‐caprolactone)‐block‐poly(ethylene oxide) by diethylzinc catalyst

Biodegradable, amphiphilic, four‐armed poly(?‐caprolactone)‐block‐poly(ethylene oxide) (PCL‐b‐PEO) copolymers were synthesized by ring‐opening polymerization of ethylene oxide in the presence of four‐armed poly(?‐caprolactone) (PCL) with terminal OH groups with diethylzinc (ZnEt₂) as a catalyst. The chemical structure of PCL‐b‐PEO copolymer was confirmed by ¹H NMR and ¹³C NMR. The hydroxyl end groups of the four‐armed PCL were successfully substituted by PEO blocks in the copolymer. The monomodal profile of molecular weight distribution by gel permeation chromatography provided further evidence for the four‐armed architecture of the copolymer. Physicochemical properties of the four‐armed block copolymers differed from their starting four‐armed PCL precursor. The melting points were between those of PCL precursor and linear poly(ethylene glycol). The length of the outer PEO blocks exhibited an obvious effect on the crystallizability of the block copolymer. The degree of swelling of the four‐armed block copolymer increased with PEO length and PEO content. The micelle formation of the four‐armed block copolymer was examined by a fluorescent probe technique, and the existence of the critical micelle concentration (cmc) confirmed the amphiphilic nature of the resulting copolymer. The cmc value increased with increasing PEO length. The absolute cmc values were higher than those for linear amphiphilic block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 950–959, 2004     

Synthesis of diblock copolymers containing poly(N‐vinylcarbazole) by reversible addition‐fragmentation chain transfer polymerization

The reversible addition‐fragmentation chain transfer (RAFT) polymerization of N‐vinylcarbazole (NVK) mediated by macromolecular xanthates was used to prepare three types of block copolymers containing poly(N‐vinylcarbazole) (PVK). Using a poly(ethylene glycol) monomethyl ether based xanthate ( PEG‐X ), the RAFT polymerization of NVK proceeded in a controlled way to afford a series of PEG‐b‐PVK with different PVK chain lengths. Successive RAFT polymerization of NVK and vinyl acetate (VAc) with a small molecule xanthate ( X1 ) as the chain transfer agent was tested to prepare PVK‐b‐PVAc. Though both monomers can be homopolymerized in a controlled manner with this xanthate, only by polymerizing NVK first could give well‐defined block copolymers. The xanthate groups in the end of PVK could be removed by radical‐induced reduction using tributylstannane, and PVK‐b‐PVA was obtained by further hydrolysis of PVK‐b‐PVAc under basic conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Linear and four‐armed poly(l‐lactide)‐block‐poly(d‐lactide) copolymers and their stereocomplexation with poly(lactide)s

Linear and four‐armed poly(l ‐lactide)‐block‐poly(d ‐lactide) (PLLA‐b‐PDLA) block copolymers are synthesized by ring‐opening polymerization of d ‐lactide on the end hydroxyl of linear and four‐armed PLLA prepolymers. DSC results indicate that the melting temperature and melting enthalpies of poly (lactide) stereocomplex in the copolymers are obviously lower than corresponding linear and four‐armed PLLA/PDLA blends. Compared with the four‐armed PLLA‐b‐PDLA copolymer, the similar linear PLLA‐b‐PDLA shows higher melting temperature (212.3 °C) and larger melting enthalpy (70.6 J g^?1). After these copolymers blend with additional neat PLAs, DSC, and WAXD results show that the stereocomplex formation between free PLA molecular chain and enantiomeric PLA block is the major stereocomplex formation. In the linear copolymer/linear PLA blends, the stereocomplex crystallites (sc) as well as homochiral crystallites (hc) form in the copolymer/PLA cast films. However, in the four‐armed copolymer/linear PLA blends, both sc and hc develop in the four‐armed PLLA‐b‐PDLA/PDLA specimen, which means that the stereocomplexation mainly forms between free PDLA molecule and the inside PLLA block, and the outside PDLA block could form some microcrystallites. Although the melting enthalpies of stereocomplexes in the blends are smaller than that of neat copolymers, only two‐thirds of the molecular chains participate in the stereocomplex formation, and the crystallization efficiency strengthens. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1560–1567     

Synthesis of water‐dispersible,fluorinated particles with grafting sulfonate chains by the core crosslinking of block copolymer micelles

Fluorinated polymer particles with grafting sulfonate chains, which showed high dispersion stability in aqueous media, were synthesized by the crosslinking of block copolymer micelles. A crosslinkable block copolymer, poly[(2,3,4,5,6‐pentafluorostyrene)‐co‐4‐(1‐methylsilacyclobutyl)styrene]‐b‐poly(neopentyl 4‐styrenesulfonate), composed of a statistical copolymer segment of 2,3,4,5,6‐pentafluorostyrene with 4‐(1‐methylsilacyclobutyl)styrene and a neopentyl 4‐styrenesulfonate segment, was prepared by the nitroxy‐mediated living radical polymerization of a 2,3,4,5,6‐pentafluorostyrene/4‐(1‐methylsilacyclobutyl)styrene mixture and neopentyl 4‐styrenesulfonate. The block copolymer formed micelles with a poly[(2,3,4,5,6‐pentafluorostyrene)‐co‐4‐(1‐methylsilacyclobutyl)styrene] core in acetonitrile, which were crosslinked via the ring‐opening reaction of silacyclobutyl groups in the core by a treatment with a platinum catalyst. The deprotection of sulfonate groups in the micelle corona by exposure to trimethylsilyl iodide and a treatment with aqueous HCl, followed by neutralization with aqueous NaOH, provided a polymer particle with polymer chains of sodium 4‐styrenesulfonate grafted on its surface. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1316–1323, 2007     

Block copolymers by chemoenzymatic cascade polymerization: A comparison of consecutive and simultaneous reactions

The synthetic parameters for the chemoenzymatic cascade synthesis of block copolymers combining enzymatic ring‐opening polymerization (EROP) and atom transfer radical polymerization (ATRP) in one pot were investigated. A detailed analysis of the mutual interactions between the single reaction components revealed that the ATRP catalyst system could have a significant inhibiting effect on the enzyme activity. The inhibition of the enzyme was less pronounced in the presence of multivalent ligands such as dinonyl bipyridine, which thus could be used in this reaction as an ATRP catalyst. Moreover, the choice of the ATRP monomer was investigated. Methyl methacrylate interfered with EROP by transesterification, whereas t‐butyl methacrylate was inert. Block copolymers were successfully synthesized with this cascade approach by the activation of ATRP after EROP by the addition of the ATRP catalyst and, with lower block copolymer yields, by the mixing of all the components before the copolymerization. Adetailed kinetic analysis of the reactions and the structure of the block copolymers showed that the first procedure proceeded smoothly to high block copolymer yields, whereas in the latter a noteworthy amount of the poly(t‐butyl methacrylate) homopolymer was detected. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4290–4297, 2006     

Facile synthesis of graft copolymers containing rigid poly(dialkyl fumarate) branches by macromonomer method

Graft copolymers show microphase separated structure as seen in block copolymers and have lower intrinsic viscosity than block copolymers because of a branching structure. Therefore, considering molding processability, especially for polymers containing rigid segments, graft copolymers are useful architectures. In this work, graft copolymers containing rigid poly(diisopropyl fumarate) (PDiPF) branches were synthesized by full free‐radical polymerization process. First, synthesis of PDiPF macromonomers by addition‐fragmentation chain transfer (AFCT) was investigated. 2,2‐Dimethyl‐4‐methylene‐pentanedioic acid dimethyl ester was found to be an efficient AFCT agent for diisopropyl fumarate (DiPF) polymerization because of the suppression of undesired primary radical termination, which significantly took place when common AFCT agent, methyl 2‐(bromomethyl)acrylate, was used. Copolymerization of PDiPF macromonomer with ethyl acrylate accomplished the generation of the graft copolymer having flexible poly(ethyl acrylate) backbone and rigid PDiPF branches. The graft copolymer showed a microphase separated structure, high transparency, and characteristic thermal properties to PDiPF and poly(ethyl acrylate). © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2474–2480     

Synthesis and characterization of block copolymers from 2‐vinylnaphthalene by anionic polymerization

The anionic polymerization of 2‐vinylnaphthalene (2VN) has been studied in tetrahydrofuran (THF) at ?78 °C and in toluene at 40 °C. 2VN polymerization in THF, toluene, or toluene/THF (99:1 v/v) initiated by sec‐butyllithium (sBuLi) indicates living characteristics, affording polymers with predefined molecular weights and narrow molecular weight distributions. Block copolymers of 2VN with methyl methacrylate (MMA) and tert‐butyl acrylate (tBA) have been synthesized successfully by sequential monomer addition in THF at ?78 °C initiated by an adduct of sBuLi–LiCl. The crossover propagation from poly(2‐vinylnaphthyllithium) (P2VN) macroanions to MMA and tBA appears to be living, the molecular weight and composition can be predicted, and the molecular weight distribution of the resulting block copolymer is narrow (weight‐average molecular/number‐average molecular weight < 1.3). Block copolymers with different chain lengths for the P2VN segment can easily be prepared by variations in the monomer ratios. The block copolymerization of 2VN with hexamethylcyclotrisiloxane also results in a block copolymer of P2VN and poly(dimethylsiloxane) (PDMS) contaminated with a significant amount of homo‐PDMS. Poly(2VN‐b‐nBA) (where nBA is n‐butyl acrylate) has also been prepared by the transesterification reaction of the poly(2VN‐b‐tBA) block copolymer. Size exclusion chromatography, Fourier transform infrared, and ¹H NMR measurements indicate that the resulting polymers have the required architecture. The corresponding amphiphilic block copolymer of poly(2VN‐b‐AA) (where AA is acrylic acid) has been synthesized by acidic hydrolysis of the ester group of tert‐butyl from the poly(2VN‐b‐tBA) copolymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4387–4397, 2002     

Synthesis of poly(cyanurate)s by a novel polyaddition of bis(epoxide)s with triazine dichloride

Poly(cyanurate)s (P‐1–P‐4) containing triazine groups in the main chain and pendant chloromethyl groups in the side chain were synthesized by the polyaddition of bis(epoxide)s with 2,4‐dichloro‐6‐(diphenylamino)‐s‐triazine (DPAT) using quaternary onium salts as catalysts. The polyaddition of diglycidyl ether of bisphenol‐A (DGEBA) with DPAT proceeded smoothly in chlorobenzene at 100 °C for 12 h to give P‐1 with M_n = 19,000 in a 92% yield, when tetrabutylammonium chloride (TBAC) was used as a catalyst. However, no reaction occurred without a catalyst or with triethylamine alone under the same reaction conditions. Polyadditions of other bis(epoxide)s with DPTA also proceeded smoothly using 5 mol % of TBAC as a catalyst in chlorobenzene to produce corresponding polymers (P‐2≈P‐4) in high yields under similar reaction conditions. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4006–4012, 2000     

Hyperbranched block copolymer from AB2 macromonomer: Synthesis and its reaction‐induced microphase separation in epoxy thermosets

In this contribution, we reported the synthesis of a hyperbranched block copolymer composed of poly(ε‐caprolactone) (PCL) and polystyrene (PS) subchains. Toward this end, we first synthesized an α‐alkynyl‐ and ω,ω′‐diazido‐terminated PCL‐b‐(PS)₂ macromonomer via the combination of ring‐opening polymerization and atom transfer radical polymerization. By the use of this AB₂ macromonomer, the hyperbranched block copolymer (h‐[PCL‐b‐(PS)₂]) was synthesized via a copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition (i.e., click reaction) polymerization. The hyperbranched block copolymer was characterized by means of ¹H nuclear magnetic resonance spectroscopy and gel permeation chromatography. Both differential scanning calorimetry and atomic force microscopy showed that the hyperbranched block copolymer was microphase‐separated in bulk. While this hyperbranched block copolymer was incorporated into epoxy, the nanostructured thermosets were successfully obtained; the formation of the nanophases in epoxy followed reaction‐induced microphase separation mechanism as evidenced by atomic force microscopy, small angle X‐ray scattering, and dynamic mechanical thermal analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 368–380