New approach to block copolymerization of ethylene with polar monomers by the unique catalytic function of organolanthanide complexes

This paper describes the first examples of ABA‐ and AB‐type block copolymerizations of a nonpolar monomer, in this case ethylene, with polar monomers, such as methyl methacrylate (MMA), ϵ‐caprolactone (CL), and 2,2‐dimethyltrimethylene carbonate (DTC), initiated by the unique catalytic function of rare earth metal complexes [Sm(II) and Ln(III) (Ln = Y, Sm)] as initiators. The Sm(II) species conducts the ABA‐type triblock copolymerization, leading to poly(MMA‐co‐ethylene‐co‐MMA), poly(CL‐co‐ethylene‐co‐CL), or poly(DTC‐co‐ethylene‐co‐DTC) by the efficient catalysis of racemic Me₂Si(C₅H₂‐2‐Me₃Si‐4‐tBu)₂Sm(THF)₂ ( 1 ) or meso Me₂Si(Me₂SiOSiMe₂)(C₅H₂‐3‐tBu)Sm(THF) ( 2b ). The resulting block copolymers are completely insoluble in THF and CHCl₃, but the homopolymers of MMA, CL, and DTC are freely soluble in these solvents. TEM profiles provide direct evidence for the block copolymerizations, where the spheric morphology of homogeneously dispersed polar polymers was observed. Ln(III) species, such as racemic Me₂Si(C₅H₂‐2‐Me₃Si‐4‐tBuMe₂Si)YH ( 5 ) and Me₂Si(C₅H₂‐2‐Me₃Si‐4‐tBu)SmH ( 6 ), afford AB‐type block copolymers between ethylene and MMA or CL, whose TEM images reveal the homogeneous dispersion of poly(MMA) or poly(CL) units in the polyethylene region. The ABA‐ and AB‐type block copolymers demonstrate high break stress and high tensile modulus as compared with their corresponding blended polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4095–4109, 2000     

Biodegradation of copolymers composed of optically active L‐lactide and (R)‐ or (S)‐1‐methyltrimethylene carbonate

Random copolymerizations of L ‐lactide with (R)‐, (S)‐, or rac‐1‐methyltrimethylene carbonate with bis(pentamethylcyclopentadienyl) samarium‐methyl tetrahydrofuranate [(C₅Me₅)₂SmMe(THF)] as a novel initiator provided high molecular weight polymers with low polydispersities. Biodegradation of the resulting polymers with tricine and {N‐[tris(hydroxymethyl)methyl]‐2‐aminoethane sulfonic acid (TES) buffers as well as activated sludge showed only a small weight loss, whereas the polymer with proteinase K revealed high biodegradability independent of the optical activity of 1‐methyltrimethylene carbonate. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3916–3927, 2001     

Enzymatic degradations of copolymers of L-lactide with cyclic carbonates

Syntheses and biodegradation of random copolymers of L -lactide (L -LA) with trimethylene carbonate (TMC), 1,1-dimethyltrimethylene carbonate (1,1-DTMC) and 2,2-dimethyltrimethylene carbonate (2,2-DTMC) were investigated at various monomer ratios using SmMe(C₅Me₅)₂THF as an initiator at 80 °C for 24 h in toluene. Enzymatic degradation of these polymers were performed using cholesterol esterase, lipoprotein lipase, and proteinase K. Poly(TMC) was effectively biodegraded by cholesterol esterase and lipoprotein lipase, while poly(2,2-DTMC) and all the copolymers were hardly degraded using these enzymes. Biodegradations of poly(L -LA-co-TMC) (97:3) and poly(L -LA-co-2,2,DTMC) (95:5) show rapid degradations using TES buffer, a compost and proteinase K. The physical properties of these copolymers were also examined.

Enzymatic degradation of L -LA/2,2-DTMC copolymers by proteinase K in Tricine buffer (pH 8.0) at 37 °C: a 98:2, b 82:18, c 100:0, d 66:34, e 34:66, f 0:100.     

Rare‐earth‐metal‐initiated polymerizations of (meth)acrylates and block copolymerizations of olefins with polar monomers

The organo‐rare‐earth‐metal‐initiated living polymerization of methyl methacrylate (MMA) was first discovered in 1992 with (C₅Me₅)₂LnR (where R is H or Me and Ln is Sm, Yb, Y, or La) as an initiator. These polymerizations provided highly syndiotactic (>96%) poly(methyl methacrylate) (PMMA) with a high number‐average molecular weight (M_n > 1000 × 10³) and a very narrow molecular weight distribution [weight‐average molecular weight/number‐average molecular weight (M_w/M_n) < 1.04] quantitatively in a short period. Bridged rare‐earth‐metallocene derivatives were used to perform the block copolymerization of ethylene or 1‐hexene with MMA, methyl acrylate, cyclic carbonate, or ?‐caprolactone in a voluntary ratio. Highly isotactic (97%), monodisperse, high molecular weight (M_n > 500 × 10³, M_w/M_n < 1.1) PMMA was first obtained in 1998 with [(Me₃Si)₃C]₂Yb. Stereocomplexes prepared by the mixing of the resulting syndiotactic and isotactic PMMA revealed improved physical properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 1955–1959, 2001     

Isothiourea‐based lewis pairs for homopolymerization and copolymerization of 2,2‐dimethyltrimethylene carbonate with ε‐caprolactone and ω‐pentadecalactone

In this study, the homopolymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and its copolymerizations with ε‐caprolactone (CL) were carried out in detail using the isothiourea‐based Lewis pairs comprised 2,3,6,7‐tetrahydro‐5H‐thiazolo(3,2‐a)pyrimidine and magnesium halides (MgX₂) with benzyl alcohol (BnOH) as the initiator. The copolymerization of DTC and CL via one‐pot addition produced randomly sequenced copolymers. On the other hand, a well‐defined linear poly(ε‐caprolactone)–block–poly(2,2‐dimethyltrimethylene carbonate) (PCL‐b‐PDTC) diblock copolymer was prepared by simple sequential ring‐opening polymerization of CL and DTC. In addition, poly(ω‐pentadecalactone)–block–PDTC diblock copolymer was successfully prepared by the same strategy. Moreover, PDTC–poly(ethylene glycol) (PEG)–PDTC triblock copolymer was synthesized in the presence of PEG 2000. The effects of different polymerization conditions on the polymerization reactions have been systematically discussed. The resulting polymers were characterized by the ¹H and ¹³C NMR spectra, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF MS). The block copolyester structures were confirmed by the ¹³C NMR spectroscopy and DSC characterizations. These results indicated that the supposed mechanism was a dual catalytic mechanism. The proposed mechanism involved activation of the monomer via coordination to the MgX₂, and the initiator alcohol was deprotonated by base. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2349–2355     

Tunable poly(hydroxyl urethane) from CO2‐Based intermediates using thiol‐ene chemistry

CO₂‐based, crosslinked poly(hydroxyl urethane)s (PHUs) are accessed via a set of efficient reactions based on the addition chemistry of thiol‐ene and amines‐cyclic carbonates. This strategy to utilize 5‐membered cyclic carbonates produced from CO₂ is robust, facile, modular, and atomically efficient in nature. The thiol‐ene reaction was utilized to access bis(cyclic carbonate), tris(cyclic carbonate), and tetrakis(cyclic carbonate) in quantitative yield from 4‐vinyl‐1,3‐dioxolan‐2‐one and thiols. Multi‐functional cyclic carbonates were simply mixed with diethylenetriamine and/or 1,6‐diaminohexane to generate crosslinked PHUs from 25 to 80 °C. These materials are easy to scale‐up and are potential candidates in many applications such as coatings, binders, and resins. The resulting polymers have glass transition temperatures between ?1 and 16 °C and thermal decomposition temperatures from 190 to 230 °C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

In situ ethylene homopolymerization and copolymerization catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonite

Ethylene homopolymerizations and copolymerizations were catalyzed by zirconocene catalysts entrapped inside functionalized montmorillonites that had been rendered organophilic via the ion exchange of the interlamellar cations of layered montmorillonite with hydrochlorides of L ‐amino acids (AAH⁺Cl^?) or their methyl esters (MeAAH⁺Cl^?), with or without the further addition of hexadecyltrimethylammonium bromide (C₁₆H₃₃N⁺Me₃Br^?; R₄N⁺Br^?). In contrast to the homogeneous Cp₂ZrCl₂/methylaluminoxane catalyst for ethylene homopolymerizations and copolymerizations with 1‐octene, the intercalated Cp₂ZrCl₂ activated by methylaluminoxane for ethylene homopolymerizations and copolymerizations with 1‐octene proved to be more effective in the synthesis of polyethylenes with controlled molecular weights, chemical compositions and structures, and properties, including the bulk density. The effects of the properties of the organic guests on the preparation and catalytic performance of the intercalated zirconocene catalysts were studied. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2187–2196, 2003     

Polymeric ruthenium bipyridine complexes: New potential materials for polymer solar cells

Methyl methacrylate‐containing bipyridine monomers were synthesized with a hydoxy‐functionalized bipyridine. The 4′‐methyl group of the 2,2′‐bipyridine was used to introduce hydoxy‐functionalized alkyl spacers of two different lengths. Two, different synthetic routes were applied for the preparation of the hydoxy‐functionalized bipyridine via a bromo‐(C₇ spacer) or a silylated‐(C₃ spacer) intermediate. A copolymer of poly(methyl methacrylate) with bipyridine units in the side chains was prepared by free‐radical copolymerization and characterized with ¹H NMR, ultraviolet–visible, and IR spectroscopy as well as gel permeation chromatography. The bipyridine units of the copolymer were reacted with ruthenium bipyridine precursors. The resulting graft copolymers displayed promising photophysical and electrochemical properties, opening interesting perspectives for applications in the field of solar‐cell devices. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 374–385, 2004     

Synthesis and characterization of well‐defined diblock and triblock copolymers of poly(N‐isopropylacrylamide) and poly(ethylene oxide)

Well‐defined diblock and triblock copolymers composed of poly(N‐isopropylacrylamide) (PNIPAM) and poly(ethylene oxide) (PEO) were successfully synthesized through the reversible addition–fragmentation chain transfer polymerization of N‐isopropylacrylamide (NIPAM) with PEO capped with one or two dithiobenzoyl groups as a macrotransfer agent. ¹H NMR, Fourier transform infrared, and gel permeation chromatography instruments were used to characterize the block copolymers obtained. The results showed that the diblock and triblock copolymers had well‐defined structures and narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight < 1.2), and the molecular weight of the PNIPAM block in the diblock and triblock copolymers could be controlled by the initial molar ratio of NIPAM to dithiobenzoate‐terminated PEO and the NIPAM conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4873–4881, 2004     

Synthesis and characterization of novel poly(ester‐carbonate)s by copolymerization of trans‐4‐hydroxy‐L‐proline with cyclic carbonate

The melt ring‐opening/condensation reaction of trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L‐proline (N‐CBz‐Hpr) with cyclic carbonate [trimethylene carbonate (tri‐MC) or tetramethylene carbonate (tetra‐MC)] at a wide range of molar fractions in the feed produced new degradable poly(ester‐carbonate)s. The influence of reaction conditions such as polymerization time and temperature on the yield and inherent viscosity of the copolymers was investigated. The polymerizations were carried out in bulk at 140 °C with 1.5 wt % stannous octoate as a catalyst for 30 h. The poly(ester‐carbonate)s obtained were characterized by Fourier transform infrared spectroscopy, ¹H NMR, differential scanning calorimetry, gel permeation chromatography, and Ubbelohde viscometry. The copolymers synthesized exhibited moderate molecular weights with rather narrow molecular weight distributions. The values of the glass‐transition temperature (T_g) of the copolymers depend on the molar fractions of cyclic carbonate. For the poly(N‐CBz‐Hpr‐co‐tri‐MC) system, with a decreased tri‐MC content from 93 to 16 mol %, the T_g increased from ?10 to 60 °C. Similarly, for the poly(N‐CBz‐Hpr‐co‐tetra‐MC) system, when the tetra‐MC content decreased from 80 to 8 mol %, the T_g increased from ?18 to 52 °C. The relationship between the poly(N‐CBz‐Hpr‐co‐tri‐MC) T_g and the compositions was in approximation with the Fox equation. In vitro degradation of these poly(N‐CBz‐Hpr‐co‐tri‐MC)s was evaluated from weight‐loss measurements. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1435–1443, 2003     

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     

Synthesis of α,ω‐di(iodo)PVC and of four‐arm star PVC with identical active chain ends by SET‐DTLRP of VC initiated with bifunctional and tetrafunctional initiators

Na₂S₂O₄‐catalyzed single‐electron transfer – degenerative chain transfer‐mediated living radical polymerization (SET‐DTLRP) of VC initiated with the bifunctional initiators 1,2‐bis(iodopropionyloxy)ethane, dimethyl 2,5‐diiodohexanedioate, and bis(2‐methoxyethyl)‐2,5‐diiodohexanedioate as well as the tetrafunctional initiator pentaerythritol tetrakis(2‐iodopropionate) is reported. This SET‐DTLRP was performed in water at ambient temperature in the presence of polyvinyl alcohol and hydroxypropyl methylcellulose surfactants and provides methods for the synthesis of α,ω‐di(iodo)PVC with two identical active chain ends and of four‐arm star PVC with four identical active chain ends. These difunctional and tetrafunctional derivatives of PVC are also macroinitiators for the synthesis of ABA triblock copolymers and four‐arm star block copolymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 635–652, 2009     

New soluble functional polymers by free‐radical copolymerization of methacrylates and bipyridine ruthenium complexes

The luminescent complex [4‐(3‐hydroxypropyl)‐4′‐methyl‐2,2′‐bipyridine]‐bis(2,2′‐bipyridine)‐ruthenium(II)‐bis(hexafluoroantimonate) and its methacrylate derivative were successfully synthesized and fully characterized by two‐dimensional ¹H and ¹³C{¹H} NMR techniques [correlation spectroscopy (COSY) and heteronuclear multiple‐quantum coherence experiment (HMQC)], as well as matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry. The respective labeled methyl methacrylate‐ruthenium(polypyridyl) copolymers were obtained by free‐radical copolymerization with methyl methacrylate and were characterized utilizing NMR, IR, and UV–visible spectroscopy and gel permeation chromatography. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3954–3964, 2003     

Syntheses of trimethoxysilyl‐endcapped polylactones via 3‐mercaptopropyl trimethoxysilane

Monofunctional polylactones were prepared by Bu₂Sn(OMe)₂‐initiated ring‐opening polymerization of ε‐caprolactone (εCL) followed by acylation with bromoacetylbromide. Telechelic polylactones and polylactides were prepared via ring‐expansion polymerization with 2,2‐dibutyl‐2‐stanna‐1,3‐dioxepane (DSDOP) or 2,2‐dibutyl‐2‐stanna‐pentaoxacyclotridecane (Bu₂SnTEG) as cyclic initiator. In situ combination of the polymerization with condensation by means of bromoacetylbromide yielded polylactones having bromoacetate endgroups. These endgroups were subjected to nucleophilic substitution with 3‐mercaptopropyl trimethoxysilane (3‐MPTMS). Analogous experiments were conducted with dl‐lactide. The telechelic trimethoxysilyl‐endcapped polylactones were characterized by viscosity, ¹H and ¹³C NMR‐spectroscopy, and MALDI‐TOF mass spectrometry. The mass spectra revealed small amounts of cyclic oligolactones as byproducts in all samples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3667–3674, 2005     

Ethylene/1-hexene copolymerizations by syndioselective metallocenes: Direct comparison of Me2C(Cp)(Flu)ZrMe2 with Et(Cp)(Flu)ZrMe2

Copolymerizations of ethylene with 1-hexene have been carried out by using two metallocenes: highly syndiospecific isopropylidene(1-η⁵-cyclopentadienyl)(1-η⁵-fluorenyl)-dimethylzirconium (Me₂C(Flu)(Cp)ZrMe₂, 1) and less syndiospecific (1-fluorenyl-2-cyclopentadienylethane)-dimethylzirconium (Et(Flu)(Cp)ZrMe₂, 2), in the presence of [Ph₃C][B(C₆F₅)₄] as a cocatalyst. The effect of different types of bridges on the catalytic activity and comonomer reactivity was reported. The ethano bridged 2 compound of a smaller dihedral angle showed much higher activity than the 1 compound in the ethylene homo- and copolymerizations. The catalytic activities of the two compounds were enhanced about twice when a suitable amount of 1-hexene comonomer is present in the feed. The copolymerization of ethylene with 1-hexene revealed a noticeable influence of the type of bridge on the relative reactivity of the 1-hexene. ¹³C-NMR analysis of copolymers showed that compound 1 is characterized by lower r_E, taken as an index of ethylene reactivity, and higher reactivity of 1-hexene. The bridge also affects the distribution of the 1-hexene along the copolymer chain, investigated through their product of reactivity ratios, r_Er_H. The thermal properties and the density of copolymers were not affected by the type of bridge of the metallocenes, but mainly depended on 1-hexene content in the copolymer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2763–2772, 1999     

Synthesis and characterization of biodegradable block copolymers of ϵ-caprolactone and D,L-lactide initiated by potassium poly(ethylene glycol)ate

Poly(D ,L -lactide)–poly(ϵ-caprolactone)–poly(ethylene glycol)–poly(ϵ-caprolactone)–poly(D ,L -lactide) block copolymer (PLA–PCL–PEG–PCL–PLA) was prepared by copolymerization of ϵ-caprolactone (ϵ-CL) and D ,L -lactide (D ,L -LA) initiated by potassium poly(ethylene glycol)ate in THF at 25°C. The copolymers with different composition were synthesized by adjusting the mole ratio of reaction mixture. The resulted copolymers were characterized by ¹H-NMR, ¹³C-NMR, IR, DSC, and GPC. Efforts to prepare copolymers with the corresponding structure of PCL–PLA–PEG–PLA–PCL and D ,L -lactide/ϵ-caprolactone random copolymers were not successful. © 1997 John Wiley & Sons, Inc.     

Synthesis and characterization of well‐defined ABC‐type triblock copolymers via atom transfer radical polymerization and stable free‐radical polymerization

An asymmetric difunctional initiator 2‐phenyl‐2‐[(2,2,6,6 tetramethylpiperidino)oxy] ethyl 2‐bromo propanoate ( 1 ) was used for the synthesis of ABC‐type methyl methacrylate (MMA)‐tert‐butylacrylate (tBA)‐styrene (St) triblock copolymers via a combination of atom transfer radical polymerization (ATRP) and stable free‐radical polymerization (SFRP). The ATRP‐ATRP‐SFRP or SFRP‐ATRP‐ATRP route led to ABC‐type triblock copolymers with controlled molecular weight and moderate polydispersity (M_w/M_n < 1.35). The block copolymers were characterized by gel permeation chromatography and ¹H NMR. The retaining chain‐end functionality and the applying halide exchange afforded high blocking efficiency as well as maintained control over entire routes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2025–2032, 2002     

Cinnamate‐functionalized poly(ester‐carbonate): Synthesis and its UV irradiation‐induced photo‐crosslinking

A functionalized cyclic carbonate monomer containing a cinnamate moiety, 5‐methyl‐5‐cinnamoyloxymethyl‐1,3‐dioxan‐2‐one (MC), was prepared for the first time with 1,1,1‐tri(hydroxymethyl) ethane as a starting material. Subsequent polymerization of the new cyclic carbonate and its copolymerization with L ‐lactide (LA) were successfully performed with diethyl zinc (ZnEt₂) as initiator/catalyst. NMR was used for microstructure identification of the obtained monomer and copolymers. Differential scanning calorimetry (DSC) was used to characterize the functionalized poly(ester‐carbonate). The results indicated that the copolymers displayed a single glass transition temperature (T_g) and the T_g decreased with increasing carbonate content and followed the Fox equation, indicative of a random microstructure of the copolymer. The photo‐crosslinking of the cinnamate‐carrying copolymer was also demonstrated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 161–169, 2009     

Synthesis of branched polypropylene with isotactic backbone and atactic side chains by binary iron and zirconium single‐site catalysts

This article reports the use of a binary single‐site catalyst system for synthesizing comb‐branched polypropylene samples having isotactic polypropylene (iPP) backbones and atactic polypropylene (aPP) side chains from propylene feedstock. This catalyst system consisted of the bisiminepyridine iron catalyst {[2‐ArN?C(Me)]₂C₅H₃N}FeCl₂ [Ar = 2,6‐C₆H₃(Me)₂] ( 1 ) and the zirconocene catalyst rac‐Me₂Si(2‐MeBenz[e]Ind)₂ZrCl₂ ( 2 ). The former in situ generated 1‐propenyl‐ended aPP macromonomer, whereas the latter incorporated the macromonomer into the copolymer. The effects of reaction conditions, such as the catalyst addition procedure and the ratio of 1 / 2 on the branching frequency, were examined. Copolymer samples having a branching density up to 8.6 aPP side chains per 1000 iPP monomer units were obtained. The branched copolymers were characterized by ¹³C NMR and differential scanning calorimetry. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1152–1159, 2003     

Multiblock poly(4‐vinylpyridine) and its copolymer prepared with cyclic trithiocarbonate as a reversible addition–fragmentation transfer agent

The polymerization of 4‐vinylpyridine was conducted in the presence of a cyclic trithiocarbonate (4,7‐diphenyl‐[1,3]dithiepane‐2‐thione) as a reversible addition–fragmentation transfer (RAFT) polymerization agent, and a multiblock polymer with narrow‐polydispersity blocks was prepared. Two kinds of multiblock copolymers of styrene and 4‐vinylpyridine, that is, (ABA)_n multi‐triblock copolymers with polystyrene or poly(4‐vinylpyridine) as the outer blocks, were prepared with multiblock polystyrene or poly(4‐vinylpyridine) as a macro‐RAFT agent, respectively. GPC data for the original polymers and polymers cleaved by amine demonstrated the successful synthesis of amphiphilic multiblock copolymers of styrene and 4‐vinylpyridine via two‐step polymerization. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2617–2623, 2007