Journal of Polymer Science Part A: Polymer Chemistry

Cover image for Vol. 46 Issue 1

1 January 2008

Volume 46, Issue 1

Pages 1–382

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      Targeted delivery of proteins by nanosized carriers (pages 1–11)

      Roberto Solaro

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22388

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      Proteic drugs made available by proteomics are too powerful and short-lived in vivo to be delivered by conventional routes. Currently, intravenous administration of targeted protein nanocarriers appears to be the best possible delivery route. This highlight presents a critical overview of nanocarriers and targeting moieties employed by different research groups for the targeted delivery of proteins. Only active targeting of selected cell types has been considered because of unparalleled selectivity and efficacy. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

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    1. Synthesis of achiral PEG-PANI rod-coil block copolymers and their helical superstructures (pages 12–20)

      Lifeng Yan and Wei Tao

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22342

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      Achiral PEG-PANI rod-coil copolymers with different lengths of PANI segment have been synthesized, and it was found that the copolymer could form helical superstructures by π–π stacking induced self-assembly of the copolymers. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    2. Preparation of microcellular polysiloxane monoliths (pages 21–32)

      Marie-Thérèse Grosse, Michel Lamotte, Marc Birot and Hervé Deleuze

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22351

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      Stable W/O high internal phase emulsions containing vinyl- and hydrogenosiloxanes were polymerized to obtain microcellular polysiloxane monolith materials. The influence of various parameters (emulsion formulation, surfactant nature, crosslinker structure and crosslinking degree, porogen solvent) on the structure and the mechanical properties of the materials was investigated.

    3. A kind of novel nonmetallocene catalysts for ethylene polymerization (pages 33–37)

      Lifu Ma, Yaping Sheng, Qigu Huang, Yangfeng Zhao, Kunxue Deng, Junlong Li and Wantai Yang

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22354

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      Novel six nonmetallocene catalysts were performed for ethylene polymerization, methylaluminoxane (MAO) used as cocatalyst. The effects of polymerization conditions on performance behaviors were investigated as well. This polymer was characterized by 13C NMR, WAXD, GPC, and DSC. The result confirmed that the obtained polyethylene featured broad molecular weight distribution with MWD larger than 20, linear structure and lower melting temperature.

    4. A–B–A stereoblock copolymers of N-isopropylacrylamide (pages 38–46)

      Markus Nuopponen, Katriina Kalliomäki, Antti Laukkanen, Sami Hietala and Heikki Tenhu

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22355

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      Isotactic poly(N-isopropylacrylamide) (PNIPAM) is not water soluble. Triblock copolymers have been synthesized, which combine atactic and isotactic PNIPAMs. Figure shows the microcalorimetric endotherms of aqueous solutions of a PNIPAM stereoblock copolymer (□), and of an ordinary atactic PNIPAM (solid line).

    5. Enhancement of photocurrent of polymer-gelled dye-sensitized solar cell by incorporation of exfoliated montmorillonite nanoplatelets (pages 47–53)

      Chi-Wei Tu, Ken-Yen Liu, An-Ting Chien, Ming-Huei Yen, Ting Hsiang Weng, Kuo-Chuan Ho and King-Fu Lin

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22356

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      By using soap-free emulsion polymerization to prepare the exfoliated PNIPAAm-MMT nanocomposite latex, each exfoliated MMT nanoplatelet had a thickness of ∼ 1 nm, carried ∼ 1.8 cation/nm2, and acted like a two-dimensional electrolyte. The DSSC with the LiI/I2/tertiary butylpyridine electrolyte system gelled by this polymer nanocomposite had much higher photocurrent than that gelled by the neat resin, harvesting 5.4% solar energy to electricity conversion efficiency.

    6. Ethylene polymerization and copolymerization with a polar monomer using an α-iminocarboxamide nickel complex activated by trimethylaluminum (pages 54–59)

      Carlos L. P. Carone, Rubens Bisatto, Griselda B. Galland, Rene Rojas and Guillermo Bazan

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22357

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      An α-iminocarboxamide nickel complex was activated by trimethylaluminum and used in the polymerization of ethylene and its copolymerization with 10-undecen-1-ol. NMR spectroscopic studies did not show polar monomer incorporation. However, FTIR analyses suggest that the incorporation of a very small amount of comonomer affects the glass transition temperature, the degree of branching, and the mechanical properties of the materials.

    7. Synthesis of low-polydispersity poly(N-ethylmethylacrylamide) by controlled radical polymerizations and their thermal phase transition behavior (pages 60–69)

      Jian Xu, Xiaoze Jiang and Shiyong Liu

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22358

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      We report the first investigation of controlled radical polymerizations of N-ethylmethylacrylamide (EMA) by atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) processes. Thermal phase transitions of low-polydispersity PEMA homopolymers have been systematically investigated. The cloud point (CP) of PEMA lies between those of structurally similar PDMA and PDEA homopolymers, and varies in the temperature range of 58–68 °C, depending on the molecule weights, concentrations, and the hydrophobicity/hydrophilicity of end groups.

    8. Hyperbranched and thermally cross-linkable oligomer from a new 2,5,7-tri-functional fluorene monomer (pages 70–84)

      Lin-Ren Tsai and Yun Chen

      Article first published online: 21 NOV 2007 | DOI: 10.1002/pola.22359

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      A new hyperbranched oligomer (HOFV) with a weight- average molecular weight (Mw) of 2350 was prepared from 2-bromo-5,7-divinyl-9,9-dihexylfluorene (AB2) by the Heck reaction. Thermal curing of HOFV to form cross-linked HPFV was studied by IR, DSC, UV–vis spectra, NMR, AFM, and SEM. The terminal vinyl groups in HOFV almost disappeared after curing to provide smooth, homogeneous, and solvent-resistant film of HPFV. Two-layer PLED devices (ITO/PEDOT/HPFV/Ca/Al) exhibited maximal luminance and luminous efficiency of 1480 cd/m2 and 0.18 cd/A, respectively. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    9. Synthesis of poly(di[methylamine]ethyl methacrylate)-b-poly(cyclohexyl methacrylate)-b-poly(di[methylamine]ethyl methacrylate) amphiphilic triblock copolymers by ATRP: Condensed-phase and solution properties (pages 85–92)

      Alexandra Muñoz-Bonilla, David M. Haddleton, María L. Cerrada and Marta Fernández-García

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22360

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      This article provides a wide description of condensed phase and solution behavior of novel amphiphilic triblock copolymers PDMAE-b-PCH-b-PDMAE with poly(cyclohexyl methacrylate) as hydrophobic block and poly(di[methylamine]ethyl methacrylate), PDMAE, as hydrophilic blocks, which are successfully synthesized by controlled radical polymerization.

    10. Homo- and copolymerization of ethylene and norbornene with bis(β-diketiminato) titanium complexes activated with methylaluminoxane (pages 93–101)

      Yongfei Li, Haiyang Gao and Qing Wu

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22361

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      Bis(β-diketiminato) titanium complexes were synthesized and studied for catalytic polymerization of ethylene and norbornene. The complexes exhibited moderate activity for ethylene polymerization but low activity for norbornene polymerization in the presence of methylaluminoxane. Moreover, the catalytic systems also can promote copolymerization of ethylene and norbornene. The microstructure of the obtained copolymers is predominantly alternated or isolated norbornene units, and NN dyad and NNN triad norbornene sequences can be detected in copolymers with high incorporated content of norbornene.

    11. Combining atom-transfer radical polymerization and ring-opening polymerization through bifunctional initiators derived from hydroxy benzyl alcohol—Preparation and characterization of initiators, macroinitiators, and block copolymers (pages 102–116)

      Asawin Likhitsup, Anbanandam Parthiban and Christina L. L. Chai

      Article first published online: 21 NOV 2007 | DOI: 10.1002/pola.22362

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      A simple one-step procedure was developed for the preparation of bifunctional initiators by the esterification of various hydroxyl benzyl alcohols. Polystyrene macroinitiators were prepared by making use of these initiators under ATRP conditions. These macroinitiators were subsequently employed for the ring-opening polymerization of various lactides. Block copolymers of poly(styrene-b-lactide) of various compositions were prepared and characterized by IR and NMR spectroscopes, GPC, and thermal techniques.

    12. Novel designed polymer–acyclovir conjugates with linker-controlled drug release and hepatoma cell targeting (pages 117–126)

      Xia Li, Min Lu, Qi Wu, De-shui Lv and Xian-Fu Lin

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22363

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      Novel galactose-functionalized polymer–acyclovir conjugates with linker-controlled drug liberation and hepatoma cell targeting were facilely synthesized and fully characterized. In vitro release studies showed that the release rate could be widely controlled by changing the type of acyclovir-linked bond and the relative length of linker. The cell recognition experiments exhibited that the resulting conjugates had evident targeting function to hepG2 cells, and targeting ability was also in connection with the relative length of linker. By choosing appropriate linkers, cellular internalization of acyclovir could be well achieved. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    13. Highly stereo-efficient synthesis and luminescence properties of novel trans-regular vinylene– silylene–thiophene polymers (pages 127–137)

      Mariusz Majchrzak, Monika Ludwiczak, Malgorzata Bayda, Bronislaw Marciniak and Bogdan Marciniec

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22364

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      The first trans-stereo-regular vinylene-silylene-thiophene polymers 4 and 5 with perfect, consecutive silylene–arylene–silylene–vinylene linkage were obtained via silylative coupling polycondensation (SCP) of 2,5-bis(vinyldimethylsilyl)thiophene (2) or 5,5′-bis(vinyldimethylsilyl)-2,2′-bithiophene (3) catalyzed by ruthenium-hydride complex [RuHCl(CO)(PCy3)2] (1).

    14. NMR study of the nanomorphology in thin films of polymer blends used in organic PV devices: MDMO-PPV/PCBM (pages 138–145)

      R. Mens, P. Adriaensens, L. Lutsen, A. Swinnen, S. Bertho, B. Ruttens, J. D'Haen, J. Manca, T. Cleij, D. Vanderzande and J. Gelan

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22365

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      The disclosure of the nanomorphology of thin films in organic solar cells is of key importance for a better understanding of the occurring photovoltaic mechanisms. Hereto solid-state NMR relaxometry has been evaluated as a complementary technique to traditional microscopic techniques like AFM and TEM. Attention is focused on the influence of the blend composition and casting conditions on the resulting phase morphology. To demonstrate the applicability of NMR relaxometry in this field, MDMO-PPV/PCBM blends where used. In films prepared from blends in toluene with a PCBM content ≥70 wt %, a fraction of the PCBM is phase separated into crystalline domains, whereas the remaining part remains homogeneously mixed with the MDMO-PPV.

    15. Outer-sphere electron transfer metal-catalyzed polymerization of styrene using a macrobicyclic ligand (pages 146–154)

      Craig A. Bell, Michael R. Whittaker, Lawrence R. Gahan and Michael J. Monteiro

      Article first published online: 16 NOV 2007 | DOI: 10.1002/pola.22366

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      In this work, we use CuBr-catalyzed polymerizations of styrene in the presence of a macrobicyclic mixed donor (N and S) encapsulating ligand, NH2capten, in toluene at 60 and 100 °C. The macrobicyclic nature of the ligand ensures that a transition metal ion is effectively encapsulated (caged) within the three-dimensional cavity, resulting in activation of radicals through an outer-sphere electron transfer mechanism.

    16. Graft block copolymers of propargyl methacrylate and vinyl acetate via a combination of RAFT/MADIX and click chemistry: Reaction analysis (pages 155–173)

      Damien Quémener, Maude Le Hellaye, Carla Bissett, Thomas P. Davis, Christopher Barner-Kowollik and Martina H. Stenzel

      Article first published online: 21 NOV 2007 | DOI: 10.1002/pola.22367

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      Propagyl methacrylate-based polymer backbone is prepared via the reversible addition fragmentation chain transfer process. In parallel, an azide functionalized xanthate was employed to prepare narrow polydispersity poly(vinyl acetate). The two polymers are conjugated by Huisgen 1,3-dipolar cycloaddition to afford narrow polydispersity comb polymer. The study places special emphasis on following the copper catalyzed 1,3-dipolar cycloaddition via Fourier Transform Infrared Spectroscopy as well as via on-line UV/VIS photospectrometry. A suitable absorption band at 666 nm is identified as a promising sensor for following the click reaction kinetics, thus allowing for the rapid assessment of reaction completion in an on-line fashion.

    17. Novel amphiphilic triblocks fitted with photocrosslinkable termini, and their photocrosslinking to conetworks (pages 174–185)

      Yaohong Chen and J. P. Kennedy

      Article first published online: 19 NOV 2007 | DOI: 10.1002/pola.22368

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      Two new amphiphilic sequence-reversed triblocks, PEG-PDMS-PEG and PDMS-PEG-PDMS, fitted with photocrosslinkable HE3 termini were synthesized, characterized, photocrosslinked to amphiphilic conetworks (APCNs), and their properties studied. The sketch shows an APCN swollen with THF. The PEG/PDMS (blue/red) sequences can be reversed and the black patches indicate crosslinking/reinforcing sites formed of HE3 units. The mechanical properties of APCNs with crosslinks in hydrophobic domains were superior those with crosslinks in hydrophilic domains. Crosslinking/reinforcement increased by excess HE3. Water- swollen optically-clear APCNs exhibit properties appropriate for biomedical applications. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    18. Thermodynamic cloud point assays (pages 186–193)

      David E. Bergbreiter and Hui Fu

      Article first published online: 19 NOV 2007 | DOI: 10.1002/pola.22370

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      Analysis of cloud points and clouding curves using a melting point apparatus is a method to obtain a cloud point for polymers that have a lower critical solution temperature (LCST). Such assays also provide information about the effects of varying heating rates on LCSTs and similar stimuli-responsive phase separation behavior. Such assays can probe the effect of varying heating rates, the effect of polymer structure, and the effect of solution components on the breadth and progress of the phase transition process over a wide temperature range. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    19. The effect of structure on the thermoresponsive nature of well-defined poly(oligo(ethylene oxide) methacrylates) synthesized by ATRP (pages 194–202)

      Shin-Ichi Yamamoto, Joanna Pietrasik and Krzysztof Matyjaszewski

      Article first published online: 19 NOV 2007 | DOI: 10.1002/pola.22371

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      Statistical copolymers of di(ethylene glycol) methyl ether methacrylate (MEO2MA) and tri(ethylene glycol) methyl ether methacrylate (MEO3MA) were synthesized by atom transfer radical polymerization (ATRP). The lower critical solution temperature (LCST) of the polymers increased with the mole fraction of MEO3MA in the copolymer over the range of 26–52 °C. The average hydrodynamic diameter, measured by DLS varied with the LCST. Block copolymers of these two monomers were also prepared by ATRP. The LCST of these block copolymers shifted toward the LCST of the major segment from values measured for the statistical copolymers. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    20. Preparation and characterization of monodisperse superparamagnetic poly(vinyl alcohol) beads by reverse spray suspension crosslinking (pages 203–210)

      Chengli Yang, Yueping Guan, Jianmin Xing, Guobin Shan and Huizhou Liu

      Article first published online: 19 NOV 2007 | DOI: 10.1002/pola.22372

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      Monodisperse superparamagnetic poly(vinyl alcohol) (PVA) beads were prepared by reverse spray suspension crosslinking. The average diameter of the magnetic PVA beads is about 5 μm, and their specific saturation magnetization was found to be 12.8 emu/g. The magnetic PVA beads can potentially be used as a carrier for large-scale protein separation.

    21. Dramatic electronic effect of fluoro substituents on the olefin polymerization activity of mono β-diiminato titanium complexes (pages 211–217)

      Guangyong Xie and Changtao Qian

      Article first published online: 21 NOV 2007 | DOI: 10.1002/pola.22373

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      Titanium complexes with fluorine-containing β-diiminato ligands show dramatic electronic effects of fluoro-substituents on the olefin polymerization activity, which are extremely active catalyst precursors for ethylene polymerization and copolymerization of ethylene with 1-hexene. The molar percentage of 1-hexene incorporation and polymer microstructures can be modulated by the initial comonomer concentrations.

    22. Well-defined polycaprolactone precursors for low surface-energy polyurethane films (pages 218–227)

      T. Dikić, W. Ming, P. C. Thüne, R. A. T. M. van Benthem and G. de With

      Article first published online: 19 NOV 2007 | DOI: 10.1002/pola.22374

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      Well-defined oligomeric precursors have been synthesized via controlled ring-opening polymerization of ε-caprolactone and 4-tert-butyl-ε-caprolactone, and subsequently used to obtain low surface-energy polyurethane model coatings.

    23. Facile preparation of monodisperse hollow cross-linked chitosan microspheres (pages 228–237)

      Zhen Qian, Zhicheng Zhang, Haiming Li, Huarong Liu and Zhongqin Hu

      Article first published online: 21 NOV 2007 | DOI: 10.1002/pola.22375

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      A strategy for the fabrication of hollow crosslinked chitosan microspheres with carboxyl-functionalized polystyrene particles as template was proposed. It involves an initial cross-linking of chitosan followed by removal of the carboxyl-functionalized latexes. It is more convenient and effective than LbL assembly because the adsorption is just one-step. The potential of such materials in drug delivery or chromatography are currently under investigation.

    24. Preparation and characterization of 1,2,3-triazole-cured polymers from endcapped azides and alkynes (pages 238–256)

      Alan R. Katritzky, Nabin K. Meher, Sureyya Hanci, Reena Gyanda, Srinivasa R. Tala, Sindhu Mathai, Randolph S. Duran, Sophie Bernard, Firouzeh Sabri, Sandeep K. Singh, Jacek Doskocz and David A. Ciaramitaro

      Article first published online: 21 NOV 2007 | DOI: 10.1002/pola.22376

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      Various long chain hydroxyl-terminated polyols have been endcapped as alkynes and azides via tosylate, mesylate or nitrate intermediates. 1,3-Dipolar cycloaddition reactions of various alkynes and azides were studied to prepare triazole-cured polymers with degree of polymerization up to ≈29. Reactions under neat conditions were more convenient compared to reactions in the presence of solvent. Most of the reactions discussed went to completion between room temperature and 80 °C. All the endcapped polyols and triazole-cured polymers have been characterized by NMR spectroscopy, elemental analysis and gel permeation chromatography.

    25. Surfactant assisted polymerization of tetrafluoroethylene in supercritical carbon dioxide with a pilot scale batch reactor (pages 257–266)

      Alberto Giaconia, Onofrio Scialdone, Marco Apostolo, Giuseppe Filardo and Alessandro Galia

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22377

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      Chain-free radical polymerization of tetrafluoroethylene (TFE) was carried out in supercritical carbon dioxide, at 50 °C and 121–133 bar, with tertiary-amyl-per-pivalate (TAPPI) as a free radical initiator, with and without addition of perfluoropolyether carboxylate surfactants. A 5-L pilot scale batch reactor was used, obtained from the modification of an apparatus used for synthesis of fluoropolymers in conventional liquid media. Expanded fibrillated poly (TFE) was always obtained. Surfactant-free polymerizations led to a poly(TFE) mainly constituted by irregular shape 200–500 μm particles. When the FLUOROLINK® 7004H perfluoropolyether carboxylic acid was used, higher polymerization rates were observed and smaller quasi-spherical polymer particles were obtained.

    26. The “comonomer effect” in ethylene/α-olefin copolymerization using homogeneous and silica-supported Cp2ZrCl2/MAO catalyst systems: Some insights from the kinetics of polymerization, active center studies, and polymerization temperature (pages 267–277)

      Johannes A. M. Awudza and Peter J. T. Tait

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22378

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      The “comonomer effect” has been studied for polymerizations involving homogeneous (NS) and silica-supported (SS) Cp2ZrCl2/MAO catalyst systems in toluene. The study revealed that whereas there was a significant reduction of catalyst activity with increasing amount of the comonomer in the presence of the homogeneous catalyst, there was only a slight change in activity when the supported catalyst was used. Additionally, rate enhancement occurred at all temperatures for copolymerizations involving the supported catalysts but rate depression occurred with the homogeneous catalyst at high temperatures.

    27. Functionally terminated poly(methyl acrylate) by SET-LRP initiated with CHBr3 and CHI3 (pages 278–288)

      Gerard Lligadas, Janine S. Ladislaw, Tamaz Guliashvili and Virgil Percec

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22379

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      The single-electron transfer living radical polymerization (SET-LRP) of methyl acrylate initiated with bromoform (CHBr3) and iodoform (CHI3), and catalyzed by Cu(0)/Me6-TREN in DMSO at 25 °C is reported. A detailed kinetic and structural analysis is used to demonstrate that this is a reliable methodology to prepare poly(methyl acrylate) with active chain ends and controlled structure that can undergo subsequent functionalization to provide strategies for the synthesis of different block copolymers and other complex architectures.

    28. Photoinitiators with double and triple bonds (pages 289–301)

      Bernhard Seidl, Kadiriye Kalinyaprak-Icten, Norbert Fuß, Michael Hoefer and Robert Liska

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22380

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      Double and triple bonds were inserted into well known photoinitiators (PIs) for radical polymerization thus giving an absorption shifted up to 50 nm to the visible range of the spectrum. Mechanistic investigations identified hydrogen abstraction and α-cleavage as the main photochemical pathways. Photo-DSC experiments proofed that nearly all new compounds are suitable as PIs, although the high level of the commercial reference compounds could not been achieved.

    29. Preparation of 3-arm star polymers (A3) via Diels–Alder click reaction (pages 302–313)

      Aydan Dag, Hakan Durmaz, Gurkan Hizal and Umit Tunca

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22381

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      Diels–Alder click reaction was successfully applied for the preparation of 3-arm star polymers (A3) using furan protected maleimide end-functionalized polymers and trianthracene functional linking agent (2) at reflux temperature of toluene for 48 h. Well-defined furan protected maleimide end-functionalized polymers, poly(ethylene glycol) (PEG-MI), poly(methyl methacrylate) (PMMA-MI), and poly(tert-butyl acrylate) (PtBA-MI) were obtained by esterification or atom transfer radical polymerization. Obtained star polymers were characterized via NMR and GPC. Splitting of GPC traces of the resulting polymer mixture notably displayed that Diels–Alder click reaction was a versatile and a reliable route for the preparation of A3 star polymer. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    30. An efficient synthesis of telechelic poly (N-isopropylacrylamides) and its application to the preparation of α,ω-dicholesteryl and α,ω-dipyrenyl polymers (pages 314–326)

      Florence Segui, Xing-Ping Qiu and Françoise M. Winnik

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22382

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      Well-defined amphiphilic telechelic poly(N-isopropylacrylamides) bearing either cholesteryl or pyrenyl termini were prepared by chemical modification of telechelic dimercapto precursors which, themselves were obtained by RAFT polymerization of N-isopropylacrylamide in the presence of a symmetrical chain transfer agent. The synthetic procedures are straightforward, proceed in excellent yield, and lead to telechelic polymers with end-group functionality of 90% or higher, as judged from NMR and UV–vis spectroscopy measurements coupled with colorimetric assays. The dipyrenyl-polymers will serve as models in the study of the self-assembly of telechelic PNIPAMs bearing hydrophobic end groups using the intrinsic fluorescence of the termini, whereas self-assembled structures of the dicholesteryl-polymers may be suitable water-borne nanocarriers for hydrophobic materials. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    31. Surface modification of iron oxide nanoparticles by a phosphate-based macromonomer and further encapsulation into submicrometer polystyrene particles by miniemulsion polymerization (pages 327–340)

      Nancy Joumaa, Prisca Toussay, Muriel Lansalot and Abdelhamid Elaissari

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22383

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      A phosphate-based macromonomer (PAM200) was successfully used to disperse iron oxide nanoparticles in styrene. PAM200/styrene-based ferrofluids were then evaluated in styrene miniemulsion polymerization to form magnetic particles. The mechanisms leading to the formation of the magnetic particles (true miniemulsion polymerization and/or simple aggregation phenomenon) as well as the concomitant formation of small (ca. 100 nm) nonmagnetic particles are still to elucidate, but this study validates PAM200 as an efficient compatibilizing agent between hydrophilic maghemite and PS matrix. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

    32. Synthesis and characterization of water-soluble gold nanoparticles stabilized by comb-shaped copolymers (pages 341–352)

      De-Hui Han and Cai-Yuan Pan

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22384

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      The double hydrophilic comb-like copolymers, P(A-MPEO)-block-PNIPAM-SH, have been synthesized by two successive RAFT polymerizations of A-PEO and NIPAM. Very stable polymer-tethered gold nanoparticles in aqueous solution were prepared successfully by exchange reaction of citrate on the surface of gold particles with polymer chains in aqueous solution. During the reaction, solution color was changed from red of the citrate-coated gold particles to purple of the P(A-MPEO)-block-PNIPAM-tethered gold particles, and red shift in λmax on UV–vis absorption spectra was also observed. The comb-like copolymer and the composite particles are temperature-sensitive and may have potential stimuli-responsive applications.

    33. New polymer organogelators with L-isoleucine and L-valine as a gelation-causing segment: Organogelation by a combination of supramolecular polymer and conventional polymer (pages 353–361)

      Masahiro Suzuki, Ryosuke Yanagida, Chiho Setoguchi, Hirofusa Shirai and Kenji Hanabusa

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22385

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      New polymer organogelators, which are composed of poly(ethylene glycol), poly(propylene glycol), and poly(dimethylsiloxane)s as a polymer segment and L-isoleucine and L-valine derivatives as a gelation-causing segment, form organogels in many organic solvents and oils.

    34. Synthesis of densely grafted comblike copolymers (pages 362–372)

      Zhifeng Fu, Wuping Tao and Yan Shi

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22386

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      RAFT polymerization of a novel functional monomer, 2,3-di(2-bromoisobutyryloxy)ethyl acrylate (DBPPA), having two initiating groups for ATRP gave poly(DBPPA)s with controlled molecular weights and narrow molecular weight distributions. Well-defined comblike poly(DBPPA)-graft-polystyrenes carrying double branches in each repeating unit of backbone were prepared by using poly(DBPPA)s as macroinitiators for ATRP of styrene via “grafting from” approach. Poly(DBPPA)-graft-[polystyrene-block-poly(t-BA)]s and their hydrolyzed products poly(DBPPA)-graft-[polystyrene-block-poly(acrylic acid)]s were also successfully prepared.

    35. High molar mass ethene/1-olefin copolymers synthesized with acenaphthyl substituted metallocene catalysts (pages 373–382)

      Erkki Aitola, Kimmo Hakala, Hedvig Byman-Fagerholm, Markku Leskelä and Timo Repo

      Article first published online: 27 NOV 2007 | DOI: 10.1002/pola.22387

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      Ethene was copolymerized with 1-hexene and 1-hexadecene using MAO activated metallocenes bearing bulky acenaphthyl-cyclopentadienyl (1), acenaphthyl-fluorenyl (2) and fluorenyl-indenyl (3) ligands. Catalysts 1 and 2 showed conventional behavior in copolymerizations producing high molar mass copolymers whereas catalyst 3 showed synergetic comonomer effect in higher comonomer loads producing lower molar mass copolymers. According to the chain termination studies, the differences in polymerization behavior are proposed to have purely mechanistic origin.

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