Star polymer with crosslinked core and water‐soluble poly(N‐hydroxyethylacrylamide)‐arms: Synthesis by arm‐first method using ATRP and characterizations by SEC‐MALS and SAXS measurement in water

Core crosslinked star (CCS)‐polymers with water‐soluble arms composed of poly(N‐hydroxyethylacrylamide) (PHEAA) are described. N‐Hydroxyethylacrylamide was polymerized by the atom transfer radical polymerization consisting of ethyl 2‐chloropropionate, copper(I) chloride (CuCl), and tris[2‐(dimethylamino)ethyl]amine in an ethanol/water mixed solvent at 20 °C. The obtained PHEAA‐arms were subsequently coupled using N,N′‐methylenebisacrylamide as the crosslinking agent and sodium L ‐ascorbic acid (AscNa) as the reaction activator. A total of 17 representative coupling reactions with diverse conditions are discussed together with the characterizations of the products mainly by size exclusion chromatograph equipped with the multiangle laser light scattering detector (SEC‐MALS). Consequently, the coupling reactions provided CCS‐polymers with PHEAA‐arms (CCS‐PHEAAs) having weight averaged‐molecular weights determined by SEC‐MALS (M_w,MALS) ranging from 63.8 kg mol^?1 to 832 kg mol^?1, which corresponded to the average arm‐number (N_arm) ranging from 4.1 to 42, respectively. CCS‐PHEAA with the M_w,MALS of 250 kg mol^?1 was isolated and characterized by small angle X‐ray scattering measurements in 0.05 M NaNO₃ aq. at 25 °C, which was shown to possess a star‐shaped structure and exist as single molecules with a radius of gyration at the infinite dilution condition (<R_g²>_z,0^1/2) of 74 ± 4 Å. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A Simply Synthesized,Tough Polyarylene with Transient Mechanochromic Response

A simple and high‐yielding route to tough polyarylenes of the type poly(meta,meta,para‐phenylene) (PmmpP) is developed. PmmpP is tough even in its as‐synthesized state which has an intermediate molar mass of M_w≈60 kg mol^?1 and exhibits outstanding mechanical properties at further optimized molecular weight of M_w=96 kg mol^?1, E=0.9 GPa, ?=300 %. Statistical copolymers with para,para‐spiropyran (SP) are mechanochromic, and the toughness allows mechanochromism to be investigated. Strained samples instantaneously lose color upon force release. DFT calculations show this phenomenon to be caused by the PmmpP matrix that allows build‐up of sufficiently large forces to be transduced to SP, and the relatively unstable corresponding merocyanine (MC) form arising from the aromatic co‐monomer. MC units covalently incorporated into PmmpP show a drastically reduced half life time of 3.1 s compared to 4.5 h obtained for SP derivatives with common 6‐nitro substitution.     

Dielectric,thermal, and mechanical properties of CeO2‐filled HDPE composites for microwave substrate applications

Cerium oxide‐filled high density polyethylene (HDPE) composites for microwave substrate applications were prepared by sigma‐blend technique. The HDPE was used as the matrix and the dispersion of CeO₂ in the composite was varied up to 0.5 by volume fraction, and the dielectric properties were studied at 1 MHz and microwave frequencies. The variations of thermal conductivity (k_eff), coefficient of thermal expansion (α_c) and Vicker's microhardness with the volume fraction of the filler were also measured. The relative permittivity (ε_eff) and dielectric loss (tan δ) were found to increase with increase in CeO₂ content. For 0.4 volume fraction loading of the ceramic, the composite had ε_eff = 5.7, tan δ = 0.0068 (at 7 GHz), k_eff = 2.6 W/m °C, α_c = 98.5 ppm/°C, Vicker's microhardness of 18 kg/mm² and tensile strength of 14.6 MPa. Different theoretical approaches have been used to predict the effective permittivity, thermal conductivity, and coefficient of thermal expansion of composite systems and the results were compared with the experimental data. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 998–1008, 2010     

Biaxial extension measurements on bimodal elastomeric networks

Bimodal elastomeric networks were prepared by tetrafunctionally endlinking mixtures of short and long hydroxyl-terminated poly (dimethylsiloxane) chains having number-average molecular weights of 500 and 18,000 g/mol^?1, respectively, over a composition range of 0–98 mol % of the short chains. Biaxial extension (compression) measurements were carried out by inflation of circular sheets of these materials at 23°C. The unimodal network (0 mol % short chains) showed the same behavior reported by other workers for noncrystal-lizable networks: as the compression increased, the reduced stress or modulus [f*] went through a rather slight maximum followed by a gradual leveling off to the rupture point. The bimodal networks, however, showed much more pronounced maxima with another, significant increase in [f*] at very high compressions. This final increase is presumably due to non-Gaussian effects from the very limited extensibility of the short chains, and thus parallels the upturns in [f*] frequently reported for bimodal networks at very high elongations.     

Preparation and Thermal Chemical Property of Complexes of Zinc Nitrate with Trytophan

IntroductionZincisanessentialtraceelementtothelife .Manydiseasesarousedfromadeficiencyofzincelementhavere ceivedconsiderableattention .L α Aminoacidsarebasicunitsofproteins .L α Trytophanisoneoftheeightspeciesofaminoacidsindispensableforlife ,whichhastobeab sorbedfromfoodbecauseitcannotbesynthesizedinthehumanbody .InviewofthecomplexesofL α trytophanandessentialelementsasaddictiveswidelyusedinsuchfieldsasfoodstuff,medicineandcosmetic ,1 3theyhaveabroadenprospectforapplications .Briefly ,ab…     

Elastic behavior of bimodal poly(dimethylsiloxane) networks

The rubberlike elastic behavior of bimodal poly(dimethylsiloxane) (PDMS) networks was investigated by the Monte Carlo simulation method and enumeration calculation method on the basis of the rotational‐isomeric‐state (RIS) model. These bimodal PDMS networks consist of short chains (chain length from 10 to 20) as well as long chains (chain length equal to 150). For long PDMS chains, through generating many PDMS conformations in the equilibrium state using the Monte Carlo simulation method we can obtain the average Helmholtz free energy and the average energy. For short PDMS chains with chain lengths from 10 to 20, as the total number of conformations is only from 6.56 × 10³ to 3.87 × 10⁸, we adopt the enumeration calculation method. The deformation is partitioned nonaffinely between the long and short chains, and this partitioning can be determined by requiring the free energy of the deformed network to be minimized. Chain dimensions and thermodynamic statistical properties of bimodal PDMS networks at various elongation ratios are discussed. We find that elastic force f increases with elongation ratio λ; the energy contribution f_u to elastic force is significant, and the ratio of ranges from 0.15 to 0.36 at T = 343 K. In the meantime, elastic force f increases with the average energy 〈U〉. The energy change in the process of tensile elongation is taken over, which has been ignored in previous theories. Our calculations may provide some insights into the phenomena of rubberlike elasticity of bimodal networks. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 105–114, 2002     

Formation of triblock copolymers via a tandem enhanced spin capturing—nitroxide‐mediated polymerization reaction sequence

The preparation of ABA‐type block copolymers via tandem enhanced spin capturing polymerization (ESCP) and nitroxide‐mediated polymerization (NMP) processes is explored in‐depth. Midchain alkoxyamine functional polystyrenes (M_n = 6200, 12,500 and 19,900 g mol^?1) were chain extended with styrene as well as tert‐butyl acrylate at elevated temperature NMP conditions (T = 110 °C) generating a tandem ESCP‐NMP sequence. Although the chain extensions and thus the block copolymer formation processes function well (yielding in the case of the chain extension with styrene number average molecular weights of up to 20,800 g mol^?1 (PDI = 1.22) when the 6200 g mol^?1 precursor is used and up to 67,500 g mol^?1 (PDI = 1.36) when the 19,900 g mol^?1 precursor is used and 21,600 g mol^?1 (PDI = 1.17) as well as 37,100 g mol^?1 (PDI = 1.21) for the tert‐butyl acrylate chain extensions for the 6200 and 12,500 g mol^?1 precursors, respectively), it is also evident that the efficiency of the block copolymer formation process decreases with an increasing chain length of the ESCP precursor macromolecules (i.e., for the 19,900 g mol^?1 ESCP precursor no efficient chain extension with tert‐butyl acrylate can be observed). For the polystyrene‐block‐tert‐butyl acrylate‐block‐polystyrene polymers, the molecular weights were determined via triple detection SEC using light scattering and small‐angle X‐ray scattering. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Unexpected Molecular Weight Dependence to the Physical Aging of Thin Polystyrene Films Present at Ultra‐High Molecular Weights

The physical aging behavior, time‐dependent densification, of thin polystyrene (PS) films supported on silicon are investigated using ellipsometry for a large range of molecular weights (MWs) from M_w = 97 to 10,100 kg mol^?1. We report an unexpected MW dependence to the physical aging rate of h < 80‐nm thick films not present in bulk films, where samples made from ultra‐high MWs ≥ 6500 kg mol^?1 exhibit on average a 45% faster aging response at an aging temperature of 40 °C compared with equivalent films made from (merely) high MWs ≤ 3500 kg mol^?1. This MW‐dependent difference in physical aging response indicates that the breadth of the gradient in dynamics originating from the free surface in these thin films is diminished for films of ultra‐high MW PS. In contrast, measures of the film‐average glass transition temperature T _g(h) and effective average film density (molecular packing) show no corresponding change for the same range of film thicknesses, suggesting physical aging may be more sensitive to differences in dynamical gradients. These results contribute to growing literature reports signaling that chain connectivity and entropy play a subtle, but important role in how glassy dynamics are propagated from interfaces. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1224–1238     

Activity and stability spontaneously enhanced toward ethylene polymerization by employing 2‐(1‐(2,4‐dibenzhydrylnaphthylimino)ethyl)‐6‐(1‐(arylimino)ethyl) pyridyliron(II) dichlorides

A series of 2‐(1‐(2,4‐dibenzhydrylnaphthylimino)ethyl)‐6‐(1‐(arylimino)ethyl)pyridyliron(II) complexes ( Fe1 ? Fe5 ) was synthesized and characterized. The molecular structure of the representative Fe2 was determined by single‐crystal X‐ray diffraction, revealing a distorted pseudo‐square‐pyramidal geometry around the iron center. On activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all these iron complex precatalysts performed with high activities (up to 1.58 × 10⁷ g (PE) mol^?1 (Fe) h^?1) toward ethylene polymerization, producing highly linear polyethylenes with high molecular weight and bimodal distribution, which was in accordance with high temperature ¹³C NMR, high T _m values (T _m ～130 °C) and the GPC curves of the obtained polyethylenes. Meanwhile, DFT calculation results also showed the good correlation between net charges on iron and experimental activities. Compared with previous bis(imino)pyridyliron analogues, the current iron complexes containing the benzhydrylnaphthyl groups exhibited relatively higher activities and better thermal‐stability at elevated temperatures, especially at 80 °C as the industrial operating temperature, and still showed high activities toward ethylene polymerization up to 8.57 × 10⁶ g (PE) mol^?1 (Fe) h^?1 in the presence of co‐catalyst MMAO. In addition, these iron complex precatalysts all exhibited long lifetimes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 988–996     

Synthesis and properties of the polythiourethanes obtained by the cationic ring‐opening polymerization of cyclic thiourethanes

The cationic ring‐opening polymerization of a five‐membered thiourethane [3‐benzyl‐1,3‐oxazolidine‐2‐thione (BOT)] with boron trifluoride etherate afforded the corresponding polythiourethane with a narrow molecular weight distribution in an excellent yield. The molecular weight of the polymers could be controlled by the feed ratio of the monomer to the initiator. A kinetic study of the polymerization revealed that the polymerization rate of BOT (1.3 × 10^?2 L mol^?1 min^?1) was two times larger than that of the six‐membered thiourethane [3‐benzyltetrahydro‐1,3‐oxazolidine‐2‐thione (BTOT); 6.8 × 10^?3 L mol^?1 min^?1], and the monomer conversion obeyed the first‐order kinetic equation. These observations, along with the successful results in the two‐stage polymerization, supported the idea that this polymerization proceeded in a controlled manner. Block copolymerizations of BOT with BTOT were also carried out to afford the corresponding di‐ and triblock copolymers with narrow molecular weight distributions. The order of the 5% weight loss temperatures was as follows: poly(3‐benzyltetrahydro‐1,3‐oxazolidine‐2‐thione) [poly(BTOT)] > poly(BTOT₅₄‐b‐BOT₄₆) > poly(3‐benzyl‐1,3‐oxazolidine‐2‐thione) [poly(BOT)]. This indicated that an increase in the BTOT unit content raised the decomposition temperature. The order of the refractive indices was poly(BOT) > poly(BTOT₅₄‐b‐BOT₄₆) > poly(BTOT₅₄‐b‐BOT₄₆‐b‐BTOT₅₀) > poly(BTOT); this was in accord with the order of the sulfur content in the polymer chain. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4795–4803, 2006     

Viscoelastic properties of an organic hybrid of chlorinated polyethylene and a small molecule

The dynamic mechanical properties of an organic hybrid consisting of chlorinated polyethylene (CPE) and N,N‐dicyclohexyl‐2‐benzothiazolyl sulfenamide (DZ) were investigated. All the CPE/DZ hybrids showed a single loss tangent (tan δ) peak in the mechanical spectra. The peak area under the tan δ/temperature curves around the mechanical loss peak was examined to characterize the damping properties of the CPE/DZ hybrids. We found that there exists a bending point in the relation between the glass‐transition temperature (T_g) and DZ content and that the value of T_g is saturated in the higher DZ contents, suggesting that excess DZ molecules show self‐aggregation and are reorganized. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1341–1347, 2000     

Functionalization of surface‐grafted polymethylhydrosiloxane thin films with alkyl side chains

Thin films of crosslinked polymethylhydrosiloxane (PMHS) have been grafted on silica using the sol–gel process allowing further functionalization by effective quantitative hydrosilylation of SiH groups by olefins within the network. Postfunctionalization gives the polysiloxane network with n‐alkyl side chains. The PMHS coating was prepared by room temperature polycondensation of a mixture of methyldiethoxysilane HSiMe(OEt)₂ monomer and triethoxysilane HSi(OEt)₃ (TH) as crosslinker. The surface‐attached films are chemically stable and covalently bonded to the silica surface. Subsequently, films were functionalized without delamination. We showed by FTIR spectroscopy how the crosslinking ratio and the molecular size of the alkenes precursors influence the extent of the hydrosilylation reaction of SiH groups in the PMHS network. We have determined that quasi‐full olefin addition catalyzed by a platinum complex occurred within soft networks of less than 5% TH with 1‐alkenes CH₂?CH(CH₂)_n‐2CH₃ of various alkyl chain lengths (n = 5, 11, 17). Powders of PMHS gel were also modified with 1‐alkenes by hydrosilylation. The SiH groups within the soft gel (5% crosslinked) were fully functionalized as shown by ²⁹Si and ¹H solid‐state NMR. The structure of functionalized polysiloxane with n‐octadecyl and n‐dodecyl side chains was studied by FTIR, wide angle X‐ray diffraction, and DSC showing crystallization of the long n‐alkyl chains in the network. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3546–3562, 2008     

Synthesis and ethylene polymerization of 8‐(fluorenylarylimino)‐5,6,7‐trihydroquinolylnickel chlorides: Tailoring polyethylenes by adjusting fluorenyl position and adduct Et2Zn

A series of 8‐(arylimino)‐5,6,7‐trihydroquinolines ligand pendant fluorenyl group at N‐aryl ring, and their nickel complexes ( Ni1 ? Ni5 ) have been prepared and characterized. Once activated with Et₂AlCl, the complexes Ni1 , Ni2 , and Ni3 bearing ligands from para‐fluorenylaniline produced unimodal polyethylenes; on the contrary complexes Ni4 and Ni5 gave bimodal polyethylenes due to steric influence of ligands from ortho‐fluorenyl anilines. With a increment of Et₂Zn/ Ni4 ratio from 0 to 400, the distinct bimodel polyethylenes were obtained with molecular weights shifted from 14.3 to 57.6 kg·mol^?1; apart shiftment to higher molecular weights, the portion of low molecular weight decreased along with higher portion of high molecular weight. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1910–1919     

Preparation and microstructural analysis of poly(lactic‐alt‐glycolic acid)

Alternating copolymers of glycolic (G) and lactic (L) acid were prepared by the condensation of the preformed dimers: L_LG and L_racG. By size exclusion chromatography (THF, PS standards), poly(L_LG) exhibited a molecular weight (M_n) of 15.6 kg mol^?1, with a weight average molecular weight (M_w) of 26.9 kg mol^?1 and a PDI of 1.72. The M_n for poly(L_racG) was 9.2 kg mol^?1, with a M_w of 12.9 kg mol^?1 and a PDI of 1.40. The NMR spectra of poly(L_LG) were consistent with an isotactic microstructure. NMR spectra of the racemic poly(L_racG) were consistent with an atactic structure. The methylene region of the ¹H NMR spectrum showed a tetrad level of resolution of the nearby stereochemical relationships, for example, iii. Resonances for other groups in both the ¹H and ¹³C NMR spectra gave only a triad level of resolution. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4704–4711, 2008     

Estimation of Dimerisation Constants from Complexatin-Induced Displacements of 1H-NMR Chemical Shifts: Dimerisation of Caffeine

The determination of the dimerisation constant (K^D) for the weak self-association of a compound C in dilute solution according to the equilibrium, 2C?C₂ is described. The method uses chemical shifts measured on a series of solutions of C at different concentrations: the optimum K^D is defined by a linear regression best-fit procedure, which simultaneously determines optimum values for δ_o and also for δ_∞, the intrinsic chemical shifts for nuclei in the monomer and dimer species. The dimerisation of caffeine in D₂O is used as a model to demonstrate the working of the method and the quality of results obtained. The most probable value of K_D for caffeine at 30.5° is found in the range 5.5–6.0 kg solution · mol^?1, and the enthalpy and entropy of dimerisation are found to be ΔH^? = ?15.1 kJ · mol^?1 and ΔS^? = ?35.3 J · °C^?1 · mol^?1, respectively. The influence of small errors in δ_o on the confidence limits of K^D is discussed.     

Electric,dielectric, and dynamic mechanical behavior of carbon black/styrene‐butadiene‐styrene composites

The conductivity of styrene‐butadiene‐styrene block copolymers containing different amounts of extraconductive carbon black (CB) was investigated as a function of the mold temperature. The composites exhibited reduced percolation thresholds (between 1.0 and 2.0 vol % CB). The dynamic mechanical analysis characterization revealed that the glass‐rubber‐transition temperatures of both segments were not affected by the CB addition, although the damping of the polybutadiene phase displayed a progressive drop with an increase in the CB concentration. The normalized curves of tan δ/tan δ_max (where tan δ represents the value of the loss tangent at any measurement temperature and tan δ_max represents the loss tangent peak value at the corresponding temperature T_max) versus T/T_max (where T is the temperature and T_max is the maximum temperature), corresponding to both polystyrene and polybutadiene phases as well as the activation energy related to the glass‐rubber‐transition process, did not present any significant change with the addition of CB. The dielectric analysis revealed the presence of two relaxation peaks in the composite containing 1.5 vol % CB, the magnitude of which was strongly influenced by the frequency, being attributed to interfacial Maxwell‐Wagner‐Sillars relaxations caused by the presence of different interfaces in the composite. The mechanical properties were not affected by the presence of CB at concentrations of up to 2.5 vol %. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2983–2997, 2003     

Nonlinear rheological behavior of silica filled solution‐polymerized styrene butadiene rubber

The reinforcement and nonlinear viscoelastic behavior have been investigated for silica (SiO₂) filled solution‐polymerized styrene butadiene rubber (SSBR). Experimental results reveal that the nonlinear viscoelastic behavior of the filled rubber is similar to that of unfilled SSBR, which is inconsistent with the general concept that this characteristic comes from the breakdown and reformation of the filler network. It is interesting that the curves of either dynamic storage modulus (G′) or loss tangent (tan δ) versus strain amplitude (γ) for the filled rubber can be superposed, respectively, on those for the unfilled one, suggesting that the primary mechanism for the Payne effect is mainly involved in the nature of the entanglement network in rubbery matrix. It is believed there exists a cooperation between the breakdown and reformation of the filler network and the molecular disentanglement, resulting in enhancing the Payne effect and improving the mechanical hysteresis at high strain amplitudes. Moreover, the vertical and the horizontal shift factors for constructing the master curves could be well understood on the basis of the reinforcement factor f(φ) and the strain amplification factor A(φ), respectively. The surface modification of SiO₂ causes a decrease in f(φ), which is ascribed to weakeness of the filler–filler interaction and improvement of the filler dispersion. However, the surface nature of SiO₂ hardly affects A(φ). © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2594‐2602, 2007     

Synthesis and characterization of novel alternating fluorinated copolymers bearing oligo(ethylene oxide) side chains

The synthesis and characterization of novel poly(CTFE‐g‐oligoEO) graft copolymers [chlorotrifluoroethylene (CTFE) and ethylene oxide (EO)] are presented. First, vinyl ether monomers bearing oligo(EO) were prepared by transetherification of ω‐hydroxyoligo(EO) with ethyl vinyl ether catalyzed by a palladium complex in 70–84% yields. Two vinyl ethers of different molecular weights (three and 10 EO units) were thus obtained. Then, radical copolymerization of the above vinyl ethers with CTFE led to alternating poly(CTFE‐alt‐VE) copolymers that bore oligo(OE) side chains in satisfactory yields (65%). These original poly(CTFE‐g‐oligoEO) graft copolymers were characterized by ¹H, ¹⁹F, and ¹³C NMR spectroscopy. Their molecular weights reached 19,000 g mol^?1, and their thermal properties were investigated while their glass transition temperatures ranged between ?42 and ?36 °C. Their thermogravimetric analyses under air showed decomposition temperatures of 270 °C with 10% weight loss (T_d,10%). These novel copolymers are of potential interest as polymer electrolytes in lithium ion batteries, showing room temperature conductivities ranging from 4.49 × 10^?7 to 1.45 × 10^?6 S cm^?1 for unplasticized material. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Organocatalyzed ring‐opening polymerization of cyclic butylene terephthalate oligomers

In this study, various organic compounds, with different activation modes, have been tested as catalysts for the ring‐opening polymerization (ROP) of cyclic butylene terephthalate oligomers (CBT) in bulk at 210 °C, using tert‐butylbenzyl alcohol (tBnOH) as initiator. Among them, 1,3,5‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) appeared to be the most efficient, achieving high monomer conversions in short reaction times (within minutes). Analysis by size‐exclusion chromatography (SEC) of the poly(butylene terephthalate) (PBT) synthesized using this catalyst also showed that the polymerization follows the expected theoretical M _n trend for molecular weights up to 50 kg·mol^?1. Chain‐end fidelity relatively to the alcohol initiator has been confirmed by MALDI‐TOF mass spectroscopy, which showed that all polymer chains possess the tert‐butylbenzyl moiety as chain‐end. Finally, to demonstrate the potential of this system for the synthesis of PBT‐based block copolymers, a monomethyl ether poly(ethylene glycol) (PEG) of 5000 g·mol^?1 has been employed as initiator for the ROP of CBT. A PEO‐b‐PBT block copolymer of 15,000 g·mol^?1 could thus been obtained, as confirmed by the shift of the SEC traces towards higher molecular weights and the same diffusion coefficient determined for ¹H NMR signals of the PEO block and the PBT block. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1611–1619     

A minimal amount of acrylonitrile turns the nitroxide‐mediated polymerization of methyl methacrylate into an almost ideal controlled/living system

Nitroxide‐mediated controlled/living free‐radical polymerization of methyl methacrylate initiated by the SG1‐based alkoxyamine BlocBuilder was successfully performed in bulk at 80–99 °C with the help of a very small amount of acrylonitrile (AN, 2.2–8.8 mol %) as a comonomer. Well‐defined PMMA‐rich P(MMA‐co‐AN) copolymers were prepared with the number‐average molar mass, M_n, in the 6.1–32 kg mol^?1 range and polydispersity indexes as low as 1.24. Incorporation of AN in the copolymers was demonstrated by ¹H and ¹³C NMR spectroscopy, and its effect on the chain thermal properties was evaluated by DSC and TGA analyses. Investigation of chain‐end functionalization by an alkoxyamine group was performed by means of ³¹P NMR spectroscopy and chain extensions from a P(MMA‐co‐AN)‐SG1 macroinitiator. It demonstrated the very high proportion of SG1‐terminated polymer chains, which opened the door to block copolymer synthesis with a high quality of control. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 34–47, 2010