bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dansyl Fluorescence and Local Structure of Dansyl‐Labeled Core‐Shell and Core‐Hair Type Microspheres in Solution
Authors: Horie Kazuyuki , Yamada Sadakazu , Machida Shinjiro , Takahashi Satoshi , Isono Yoko , Kawaguchi Haruma 
Published: February 2003

AbstractCore‐shell type microspheres with fluorescent dansyl groups at random sites in crosslinked poly(N‐isopropylacrylamide) (PNIPAM) shell chains and core‐hair type microspheres with dansyl groups at terminal sites of PNIPAM hair chains graft‐polymerized with living‐radical mechanism were prepared. Fluorescent spectra indicating the microenvironments of dansyl groups attached to the microspheres and their dependences on temperature and solvent compositions were compared to those of dansyl groups in PNIPAM bulk gels and in free solutions. Fluorescence peak wavelength of dansyl groups in the core‐shell type microspheres showed an extraordinary blue shift in water, suggesting that dansyl groups are incorporated in the semi‐interpenetrating polymer network (SIPN) region of the core‐shell boundary. This is supported by a confocal laser‐scanning fluorescence microscope (CLFM) image of a single particle for the core‐shell type microsphere. Dansyl groups at the chain ends of PNIPAN hairs of the core‐hair type microspheres in water are also located on the surface of hydrophobic cores.
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Hydrogen‐Bonding‐Directed Template Synthesis of Novel Stereo‐Regular Organo‐Bridged Ladder‐Like Polymethylsiloxane
Authors: Tang Huadong , Sun Jin , Zhou Xiaoshu , Fu Pengfei , Xie Ping , Zhang Rongben 
Published: February 2003

AbstractA novel stereo‐regular organo‐bridged ladder‐like polymethylsiloxane (LPMS) was synthesized by a stepwise coupling polymerization on the basis of an amido H‐bonding‐assisted self‐assembling template. The monomer N,N′‐bis{4‐[3‐(diethoxymethylsilyl)propoxy]‐phenyl}terephthalamide (M), prepared by hydrosilylation reaction at high temperature, was hydrolyzed in a dilute solution at a low temperature to form a ladder‐like supramolecular intermediate through amido H‐bonding interactions, which was further condensed to form the polymer LPMS. A combination of techniques including 1H NMR, 29Si NMR, and FT‐IR spectroscopies X‐ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to characterize the titled polymer LPMS, and the results indicate that the polymer possesses an ordered ladder‐like structure.
29Si NMR spectrum of the polymer LPMS.magnified image29Si NMR spectrum of the polymer LPMS.
Palladium‐Catalyzed Phosphonation of Polyphenylsulfone
Authors: Jakoby Kai , Peinemann K. V. , Nunes Suzana P. 
Published: February 2003

AbstractAn efficient synthetic procedure for the phosphonation of aromatic polymers was developed and is here exemplified for polyphenylsulfone. This procedure involved the bromination of the polymer and the subsequent bromine‐phosphorus exchange by means of a Pd(0)‐catalyzed PC coupling reaction. In the resulting product, the phosphonate ester pendant groups were attached to aromatic rings of the polymer chain without alkylene spacer units. A substitution degree of almost one phosphonate moiety per repeating unit of the polymer was achieved in the presence of Pd2(dba)3 · CHCl3 as catalyst at 120 °C. Polymers with free phosphonic acid groups were prepared by ester hydrolysis.
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On the Lamellar Crystal Structure of Nylons 6,8 and 8,10: A Study Combining Electron Microscopy and Energy Analysis
Authors: Bermúdez Marta , León Salvador , Alemán Carlos , Muñoz‐Guerra Sebastián 
Published: February 2003

AbstractLamellar crystals of nylon 6,8 and nylon 8,10 with chains in a fully extended conformation were obtained by crystallization in solution, and examined by electron and X‐ray diffraction. The same crystal structure appeared to be shared by both nylons crystallized in glycerin. This structure consisted of a mixture of α‐ and β‐forms with features similar to that previously described for lamellar crystals of nylon 4,6 grown in the same solvent. Crystallization of nylon 8,10 in hexane‐2,5‐diol afforded lamellar crystals with sheets stacked in the β‐form. A comparative energy evaluation of the different models that are feasible for the crystal structure of these nylons with fully extended chains indicated very small energy differences among them. The presence of different chain arrangements in the same lamellar crystal, as well as the crystallization of the same nylon in different crystal forms upon slight modification of the crystallization conditions, are fully consistent, therefore, with the results obtained in the energy analysis.
Nylon 8,10 crystals grown in hexane‐2,5‐diol at 150 °C. Inset: The respective electron diffraction patterns.magnified imageNylon 8,10 crystals grown in hexane‐2,5‐diol at 150 °C. Inset: The respective electron diffraction patterns.
Formation of Regular Hole Pattern in Polymer Films
Authors: Peng Juan , Han Yanchun , Fu Jun , Yang Yuming , Li Binyao 
Published: February 2003

AbstractOrdered macroporous materials recently have attracted much attention. A method that utilizes the condensation of monodisperse water droplets on a polymer solution is proposed for the preparation of honeycomb microporous films. Our results show that it is a general method that can be used for patterning a wide range of polymers. The presence of water vapor and polymer is necessary for the formation of regular holes in films. The formation of hexagonal packing instead of other kinds of packing takes place because the hexagonal packing has the lowest free energy. The formation mechanisms of regular hole pattern and imperfections in the hexagonal packing are proposed.Hexagonal hole structures in a PMMA film.magnified imageHexagonal hole structures in a PMMA film.
Model ω‐Functionalized Linear Polystyrenes with One, Two, and Three Sulfobetaine End Groups: Synthesis, Characterization, and Association Behavior
Authors: Sakellariou Giorgos , Pispas Stergios , Hadjichristidis Nikos 
Published: February 2003

AbstractThree series of ω‐functionalized polystyrenes (PS) with different molecular weights, the first consisting of dimethylamino end‐capped PSs and the other two of ω‐branched PSs end‐capped with two and three low‐molecular‐weight (Mn ∼ 500 g · mol−1) dimethylamino ω‐functionalized polybutadienes (PB), were synthesized by high‐vacuum anionic polymerization techniques using the functional initiator ([3‐(dimethylaminopropyl)]lithium) and chlorosilane linking chemistry. The ω‐dimethylamino polymers (precursors) were molecularly characterized by size‐exclusion chromatography, low‐angle laser light scattering (LALLS), membrane osmometry, and NMR spectroscopy. The characterization results indicate a high degree of molecular and structural homogeneity. The dimethylamino end groups were transformed to the highly polar sulfozwitterionic ones (see Figure) by reaction with cyclopropanosultone. The mono‐, di‐, and tri‐zwitterion capped polymers were found by LALLS, dynamic light scattering (DLS) and viscometry, to associate in carbon tetrachloride, a good nonpolar solvent for the PS tail. In contrast, results on dimethylamino‐capped precursors show no evidence of aggregation. Aggregation numbers increase in decalin compared with those in carbon tetrachloride. At constant molecular weight of the parental PS, the degree of association increases with increasing number of functional groups and for a given number of functional groups with decreasing molecular weight of the PS tail. Temperature‐dependent light scattering measurements in decalin indicate that aggregation persists at the highest temperature investigated.A schematic representation of the materials investigated in this study.magnified imageA schematic representation of the materials investigated in this study.
Low‐Temperature Polymerization of Olefins in the Presence of Titanium Monoamidinate/MAO Catalyst
Authors: Liguori Dario , Grisi Fabia , Sessa Irene , Zambelli Adolfo 
Published: February 2003

AbstractThis paper reports the predominantly syndiotactic‐specific polymerization of propylene in the presence of titanium monoamidinate/methylaluminoxane (MAO) catalysts. The same catalysts, depending on the reaction conditions, also promote either predominantly 1,4‐cis or 1,4‐trans polymerization of 1,3‐butadiene and polymerization of styrene either to highly syndiotactic or to stereoirregular polymer. Some preliminary information about the features of propylene polyinsertion is also reported.Expansion of the 20–24 ppm region of the 13C NMR spectrum of sample 2. The starred resonance at 21.75 ppm and the shoulders are not assigned.magnified imageExpansion of the 20–24 ppm region of the 13C NMR spectrum of sample 2. The starred resonance at 21.75 ppm and the shoulders are not assigned.
Combining ATRP of Methacrylates and ROP of L,L‐Dilactide and ε‐Caprolactone
Authors: Ydens Isabelle , Degée Philippe , Dubois Philippe , Libiszowski Jan , Duda Andrzej , Penczek Stanislaw 
Published: February 2003

AbstractCoupling atom transfer radical polymerization (ATRP) and coordination‐insertion ring‐opening polymerization (ROP) provided a controlled two‐step access to polymethacrylate‐graft‐polyaliphatic ester graft copolymers. In the first step, copolymerization of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) was carried out at 80 °C at high MMA concentration by using ethyl 2‐bromoisobutyrate and [NiBr2(PPh3)2] as initiator and catalyst, respectively. Kinetic and molar masses measurements, as well as 1H NMR spectra analysis of the resulting poly(MMA‐co‐HEMA)s highlighted the controlled character of the radical copolymerization, while the determination of the reactivity ratios attested preferential incorporation of HEMA. The second step consisted of the ROP of ε‐caprolactone or L,L‐dilactide, in THF at 80 °C, promoted by tin octoate (Sn(Oct)2) and coinitiated by poly(MMA‐co‐HEMA)s obtained in the first step. Once again, kinetic, molar mass, and 1H NMR data demonstrated that the copolymerization was under control and started on the hydroxyl functions available on the poly(MMA‐co‐HEMA) multifunctional macroinitiator.Comparison of the SEC traces for the poly(MMA‐co‐HEMA) macroinitiator P2 (line only), the polymethacrylate‐g‐PLA copolymer C2 (line marked by ○), and the polymethacrylate‐g‐PLA C3 (line marked by ▵).magnified imageComparison of the SEC traces for the poly(MMA‐co‐HEMA) macroinitiator P2 (line only), the polymethacrylate‐g‐PLA copolymer C2 (line marked by ○), and the polymethacrylate‐g‐PLA C3 (line marked by ▵).
Nanoscopic Polymer Particles with a Well‐Defined Surface: Synthesis, Characterization, and Properties
Authors: Ballauff Matthias 
Published: February 2003

AbstractWe review our recent work on polymeric latex particles having a well‐defined surface of grafted polymers. Two types of particles are discussed: i) particles with a thermosensitive shell, and ii) particles bearing a dense layer of linear polyelectrolyte chains on their surface (“spherical polyelectrolyte brush”). Both types of particles consist of a polystyrene core onto which either linear or crosslinked chains are grafted. The synthesis of these core–shell particles proceeds in a two‐step process which is reviewed in detail. In particular, we discuss the photo‐emulsion polymerization used for the synthesis of the spherical polyelectrolyte brushes. Most of the studies of these particles have been done in aqueous suspension. Here the equilibrium structure of the surface layer of the particles has been investigated by dynamic light scattering and by small‐angle X‐ray scattering. Results deduced from the flow behavior of the particles in dilute solution can directly be derived from static data. Very recent data refer to the interaction of the spherical polyelectrolyte brushes with solid interfaces. It is demonstrated that particles bearing positively charged polyelectrolyte chains interact strongly with negatively charged surfaces. The strong interaction that is directly evident from AFM studies can be used to generate 2D networks of the particles on the surface.
Schematic representation of the synthesis of defined spherical polyelectrolyte brushes.magnified imageSchematic representation of the synthesis of defined spherical polyelectrolyte brushes.
Block Copolymers: Past Successes and Future Challenges
Authors: Lodge Timothy P. 
Published: February 2003

AbstractBlock copolymers are the focus of a great deal of research activity in contemporary macromolecular science. This is attributable to a range of fascinating fundamental issues associated with understanding self‐assembly processes in both solution and in bulk, coupled to an adventitious convergence of substantial progress in synthetic versatility, developments in molecular and structural characterization, understanding of the factors that control phase behavior, and elucidation of the response of copolymer materials to external fields. It is argued that due to the rapid progress in these areas block copolymers now stand on the verge of a new generation of sophisticated materials applications, in which particular nanostructures will play a crucial role. This may be contrasted with the current billion dollar annual market for block copolymer materials, in which no substantial advantage is taken of any particular nanostructure. A variety of persistent challenges are identified that stand between block copolymers and widespread success in novel applications; foremost amongst these are issues concerned with processing.
Nuclear Magnetic Resonance Spectroscopy in Macromolecular Science
Authors: Spiess Hans Wolfgang 
Published: February 2003

AbstractA historical overview of the role of NMR spectroscopy in macromolecular science in general and its coverage in “Macromolecular Chemistry and Physics” in particular is given. In the early days physics‐application to study molecular dynamics, partial alignment of macromolecules and phase separation prevailed, deduced from broad‐line solid‐state NMR. Only somewhat later, high‐resolution NMR in solution was established as an important tool for elucidating the chain microstructure. In the future, these two aspects are expected to merge.
Side group liquid crystalline polymers: 2H NMR has elucidated alignment and dynamics of these complex materials.magnified imageSide group liquid crystalline polymers: 2H NMR has elucidated alignment and dynamics of these complex materials.
Hermann Staudinger Prize 2002
Authors: Mülhaupt Rolf 
Published: February 2003

AbstractThis section contains news of the macromolecular community all over the world. Articles about, for example, people, projects, and market trends are welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de. The editorial office decides which articles will be published.
Computer Simulations for Macromolecular Science
Authors: Kremer Kurt 
Published: February 2003

AbstractIn the context of a few characteristic examples, the perspectives of computational materials science for polymeric systems are being discussed. The examples chosen cover the range from atomistic/quantum models to coarse grained bead spring polymer models.Cartoon of the average chain conformations near the surface. Since the chains are relatively short and only the chain ends adsorb, there is no entanglement network, which would otherwise enhance the bulk adhesion to the surface. Black lines represent chains with both chain ends stuck to the surface, red lines represent chains with only one chain end stuck to the surface and the other in the bulk, and light blue lines represent chains in the bulk.29magnified imageCartoon of the average chain conformations near the surface. Since the chains are relatively short and only the chain ends adsorb, there is no entanglement network, which would otherwise enhance the bulk adhesion to the surface. Black lines represent chains with both chain ends stuck to the surface, red lines represent chains with only one chain end stuck to the surface and the other in the bulk, and light blue lines represent chains in the bulk.29
Multi‐Scale Analysis of Mechanical Properties of Amorphous Polymer Systems
Authors: Meijer Han E. H. , Govaert Leon E. 
Published: February 2003

AbstractUse of proper constitutive equations for the intrinsic behavior of glassy polymers (including yield, strain softening and hardening) allows nowadays for analyzing the mechanical response of homogeneous and heterogeneous polymer systems in great detail. Analyses are performed on both the periodic RVE, representative volume element, level and, via a MLFEM, multi‐level finite element method, also on the macroscopic level of e.g. a notched, scratched tensile test bar. Introduction of a failure criterion, in this case the critical tri‐axial stress that initiates crazing, allows for the prediction of brittle‐to‐tough transitions, both as a function of temperature as well as of the absolute critical local material thickness. The analyses give clear suggestions towards possible directions to optimize the microstructure in heterogeneous polymer systems in order to obtain the ultimate toughness of polymers.
Ductile deformation of mechanically rejuvenated polystyrene.magnified imageDuctile deformation of mechanically rejuvenated polystyrene.
Nanocomposites of Hairy‐Rod Macromolecules: Concepts, Constructs, and Materials
Authors: Wegner Gerhard 
Published: February 2003

AbstractThe rational construction of nanocomposites based on so‐called hairy‐rod macromolecules (HRM) is the objective of this review covering 15 years of extensive research at the Max Planck Institute for Polymer Research. HRM are described as shape‐persistent objects, which are processed into ultrathin films by the Langmuir–Blodgett protocol. Transfer of monolayers initially formed on the water surface to solid substrates is understood as a two‐dimensional analogue of an extrusion process giving rise to molecular orientation phenomena. The scope of HRM concerning chemical composition and molecular architecture is reviewed, and examples of how to obtain complex constructs having device functions are given. Recent work on hairy‐rod polyelectrolytes based on poly(p‐phenylene sulfonates)s is summarized as well, and their ability to form hierarchical superstructures in aqueous solution is presented.
Assembly process of multilayers of hairy‐rod macromolecules by the LB technique.magnified imageAssembly process of multilayers of hairy‐rod macromolecules by the LB technique.
90 Years of Polymer Latexes and Heterophase Polymerization: More vital than ever
Authors: Antonietti Markus , Tauer Klaus 
Published: February 2003

AbstractAn attempt is made to give an overview on the historical and possible future development of heterophase polymerization techniques in liquid continuous media to prepare polymer dispersions. Polymer latexes play an essential role in our daily life as they are present visibly or hidden in a variety of products such cosmetics, detergents, newspapers, or paints and lacquers. More than 10 million tons of polymers are produced by heterophase polymerization techniques worldwide yearly. The majority of heterophase polymerizations is carried out in water as continuous phase and hence, they are belong to green chemistry with increasing importance due to environmental reasons. The compartmentalization of the reaction volume into domains of colloidal size (between a few nm3 and μm3) is the characteristic feature and relates both to the problems and the potential promises of this class of polymers. Special emphasis is placed with regard to the development of new heterophase polymerization techniques, the adoption of new polymerization mechanism to the particular conditions of heterophase polymerization, the synthesis of block copolymers and nanoparticulate hybride structures, the development of new stabilizers and polymerization aids, and the usage of specialty latexes as model systems to learn more about complex matter.
Colloidal crystal made of monodisperse polystyrene latexes.magnified imageColloidal crystal made of monodisperse polystyrene latexes.
Biomacromolecules and Bio‐Related Macromolecules
Authors: Kobayashi Shiro , Uyama Hiroshi 
Published: February 2003

AbstractThe present article briefly reviews research developments in the area of biomacromolecules and bio‐related macromolecules, whose research papers have been published for several decades preferably in the Macromolecular Journals. The area covers the important classes of macromolecules, polysaccharides (cellulose, amylose, chitin, etc.), polyesters (poly(lactic acid), poly(hydroxyalkanoate)s, etc.), and phenolic polymers (lignin, urushi, etc.). These polymers and their derivatives are very important for scientific interests as well as for industrial applications. Their synthesis, structure, reactions, and properties are mainly mentioned, and important topics of the target polymers are selected and mostly chronologically reviewed.
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Catalytic Polymerization and Post Polymerization Catalysis Fifty Years After the Discovery of Ziegler's Catalysts
Authors: Mülhaupt Rolf 
Published: February 2003

AbstractDuring the 1950's the discoveries of Ziegler's organometallic catalyst systems and Natta's stereoselective olefin polymerization set the stage for extraordinary progress in polymer science and technology. Today advanced catalyst systems are available for catalytic carbon carbon bond formation by means of polyinsertion, metathesis, coupling reactions, and controlled radical polymerization. Modern catalytic olefin polymerization processes and polyolefins are environmentally friendly and meet the demands of a sustainable development. The architectures of homo‐ and copolymers based upon olefin, cycloolefin, diene, styrene and arene feed stocks are tailored as a function of single site catalysts' ligand frameworks. Polymer properties are varied over a very wide range, e.g., liquid/solid, rigid/soft, crystalline/amorphous/rubbery, permeable/impermeable, opaque/transparent, moldable/thermosetting, insulating/conducting. Advanced polymerization reaction engineering, copolymerization processes, reactor granule and reactor blend technologies, tailor‐made single site catalysts, catalyst blends and tandem catalysis improve property profiles, stability, morphology, and melt processing. Tuned cycloolefin polymers are new functional materials for electronic applications. Catalytic chain transfer (CCT) and atom transfer polymerization (ATRP) produce a variety of new functional polymers, reactive oligomers, and block copolymers. Aqueous polyolefin emulsions are obtained when catalytic olefin polymerization is performed in nanodroplets of catalyst miniemulsions. The scope of catalytic polymerization and post polymerization catalysis is progressing well beyond the frontiers of commodity polyolefin manufacturing. Advanced catalytic processes produce polar polymers such as polyethers, polyketones, polyesters, polycarbonates, polyamides, polyaramids, and polyimides. The new phosgene free polycarbonate syntheses are based upon the palladium catalyzed oxidative carbonylation. This overview highlights history, recent progress and modern trends in catalytic polymerization and catalytic polymer modification illustrated by selected examples.
Ziegler's glass reactor for performing his Mülheim low pressure ethylene polymerization. The reactor is on display at the Max Planck Institut für Kohlenforschung in Mülheim (this picture was made available by courtesy of G. Fink).magnified imageZiegler's glass reactor for performing his Mülheim low pressure ethylene polymerization. The reactor is on display at the Max Planck Institut für Kohlenforschung in Mülheim (this picture was made available by courtesy of G. Fink).