bluuebunny/crossref_metadata_2025_split huggingface dataset:
Block copolymers and liquid crystalline block copolymers: A bird's‐eye view
Authors: Galli Giancarlo 
Published: March 2011

AbstractBlock copolymers and liquid crystals are separately known to order at different length scales. Various types of molecular interactions in liquid crystalline block copolymers determine complex phase behaviors and states of order, and thereby can provide a way of tailoring the material properties. Examples of liquid crystalline block copolymers will be discussed as they may offer unique opportunities for both theoretical and experimental research.
Block copolymers with liquid crystalline segments
Authors: Schulze Uwe , Reichelt Norbert , Schmidt Hans‐Werner 
Published: March 2011

AbstractThis paper describes the synthesis and characterization of polystyrene‐block‐poly(2,2'‐dimethyl‐4,4'‐biphenylene phenylterephthalate)‐block‐polystyrene and of poly(ethylene glycol)‐black‐poly(2,2'‐dimethyl‐4,4'‐biphenylene phenylterephthalate)‐block‐poly (ethylene glycol) block copolymers. The ABA‐triblock copolymers were synthesized by condensation reaction of telechelic poly(2,2'‐dimethyl‐4,4'‐biphenylene phenylterephthalate) with ω‐hydroxy polystyrene and ω‐hydroxy poly(ethylene glycol) methyl ether of different molecular weights prepared by anionic polymerization. Some aspects of the liquid crystalline behavior and the phase transitions with respect to the block copolymer composition will be discussed.
Multiple length scale self‐organization in liquid crystalline block copolymers
Authors: Ober Christopher K. , Wang Jianguo , Mao Guoping , Kramer Edward J. , Chen John T. , Thomas Edwin L. 
Published: March 2011

AbstractA series of block copolymers were prepared consisting of a block of poly(styrene) and a block in which a mesogenic group was attached by polymer analogous chemistry to a flexible backbone. Two types of mesogenic groups which produced a range of mesophases were investigated: (i) an azobenzene mesogenic group and (ii) a semifluorinated group. Organization caused by liquid crystallinity and phase separation leads to simultaneous organization on a variety of length scales. Comparison of the ordering behavior of these two types of mesogenic groups and more conventional flexible chain diblocks are made.
Tandem interactions in the self‐assembly of ionic block copolymers
Authors: Moffitt Matthew , Eisenberg Adi 
Published: March 2011

AbstractThe aim of the present review is to show how the phenomena of block copolymer self‐assembly and interactions of ionic (or ionizable) groups in polymer systems can be combined to produce materials with versatile and unique behavior. In our discussion, we consider two classes of tandem interactions. First, block copolymers containing short ionic blocks and long nonionic blocks are investigated in organic media. In systems of this type, block copolymer self‐assembly and short‐range electrostatic interactions act in tandem, forming regular and highly‐stable spherical structures. Next, we consider ionic (or ionizable) block copolymers dissolved in aqueous media. In this case, block copolymer self‐assembly acts in tandem with the hydrophilic nature of the soluble blocks, resulting in a wide range of unique morphologies.
Effect of flow on topological interactions in polymers
Authors: Marrucci Giuseppe , Ianniruberto Giovanni 
Published: March 2011

AbstractThe dynamics of concentrated polymers of high molecular mass is dominated by topological interactions (or entanglements). The nonlinear effects shown by these systems in fast flows are still poorly understood, however. We have recently noted that a mechanism of convective constraint release should play a significant role in the nonlinear range, and preliminary calculations have been made both for a simple dumbbell model and for the tube model of Doi and Edwards. Here we show that further elaboration of the simple dumbbell model can predict quite complex rheological behaviours such as those observed by Navard and coworkers in semi‐dilute solutions of ultrahigh molecular mass polymers.
Influence of a liquid crystalline block on the microdomain structure of block copolymers
Authors: Thomas Edwin L. , Chen John T. , O'Rourke Mary Jane E. , Ober Christopher K. , Mao Guoping 
Published: March 2011

AbstractWe report on the phase behavior and microdomain structure of two types of diblock copolymers containing a liquid crystal (LC) block joined to a flexible coil block. Consideration of the symmetry groups of the liquid crystalline phases and of the block copolymer microdomain structures provides a rationale for predicting the possible types of liquid crystalline block copolymer morphologies. Both previously reported and newly discovered structural types are identified. Possible organizational schemes are developed for the mesogens and periodic disclination defects with respect to the intermaterial dividing surfaces separating the liquid crystalline and flexible coil domains. The first type of copolymer investigated has a rod‐like LC block whereas the second type copolymer has a side chain LC block. Five different rod‐coil diblocks based on poly(hexyl isocyanate‐b‐styrene) P(HIC‐b‐S) were synthesized by anionic polymerization. Wavy lamellae, zig‐zag and arrowhead microdomain morphologies corresponding to smectic‐C and smectic‐O structures were observed depending on the composition. These layered phases have the director (PHIC chain axis) tilted at various orientations with respect to the layer normal. Side‐chain LC diblocks based on functionalized poly(isoprene‐b‐styrene) P(I‐b‐S) were also investigated. These polymers were synthesized using polymer analogous chemistry from P(I‐b‐S) precursors. Three different mesogenic groups were attached to the PI blocks: one based on biphenyl benzoate and two based on azobenzene. The microdomain structures found for the functionalized poly(isoprene side‐chain LC‐b‐styrene) P(ILC‐b‐S) diblocks are typical of traditional coil‐coil diblocks (lamellae and cylinders). However, these morphologies possess an additional smectic layering of the mesogens within the microdomains of the LC block. In the case of the rod‐coil diblocks, the transformation from an initially isotropic state to the final microphase separated solid state occurs via nematic and then smectic liquid crystalline states, whereas for the side‐chain LC‐coil cases, the microphase separation transition occurs prior to development of orientational order. The long‐range microdomain order of LC block‐coil block copolymers can extend over very large distances due to the influence of the orientational ordering of the LC block.
Liquid crystals 100 years later. What are the new concepts used in the design of molecular, macromolecular and supramolecular liquid crystals?
Authors: Percec Virgil 
Published: March 2011

AbstractA brief discussion of selected synthetic strategies pursued in the field of molecular, macromolecular and supramolecular liquid crystals is made by reviewing some tandem historical events of the past 100 years of activity in this field. This survey will try to suggest the rational for the discovery, evolution and investigation of some of these new concepts. Also a brief and speculative forecast of the future of this field will be presented.
Design and construction of supramolecular and macromolecular architectures by tandem interactions
Authors: Rowan Alan E. , Sommerdijk Nico A. J. , Reek Joost N. H. , Zwanenburg Binne , Feiters Martinus C. , Nolte Roeland J. M. 
Published: March 2011

AbstractThe self‐assembling behaviour of several molecular building blocks are used to construct a variety of chiral and nonchiral supra‐molecular and macromolecular architectures. These structures can be finely tuned by slight changes in e.g. the shape of the building blocks, the pH and by the addition of guest molecules.
Spatial configuration of chain molecules incorporated in liquid crystals and thermodynamic significance
Authors: Abe Akihiro 
Published: March 2011

AbstractThe conformation of chain molecules participating variously in the formation of liquid crystalline mesophase has been elucidated. Two examples are mentioned: (1) the side chain flanking the α‐helical backbone of polypeptides, and (2) the spacer joining mesogenic units in mainchain liquid crystals. Flexible segments play an important role in determining thermodynamic properties of these systems.
Direct synthesis of aromatic polyamides
Authors: Russo Saverio , Mariani Alberto , Mazzanti Sabina L. E. 
Published: March 2011

AbstractThe synthesis of aromatic polyamides, namely poly(p‐phenylenetere‐phthalamide) and poly(p‐benzamide), via phosphorylation reaction has been thoroughly investigated. The effect of reaction temperature, concentration of monomers and reactants, type and concentration of salts, amount of the activator and its stepwise addition have been considered and the optimum reaction conditions found. The resultant synthesis of the above polymers, also in connection with the high purification techniques of all components of the reaction mixture, allowed to reach the highest molecular weights obtained so far by this synthetic way.
Synthesis and properties of polyesters containing naphthalenetetracarboxylic imide
Authors: Kim Woo‐Sik , Kim Sang‐Youl , Park Nam‐Kyu 
Published: March 2011

AbstractPoly(ethylene naphthalates) containing small contents of N, N'‐bis(ω‐hydroxypropyl)naphthalene‐1, 4, 5, 8‐tetracarboxylic imide(HPNTI) unit as the photostabilizing component, which are stable to ultraviolet lights, were synthesized from dimethyl naphthalate, ethylene glycol, and HPNTI. The polyesters obtained were characterized by fluorescence spectroscopy and measurements of molecular weights and thermal properties.
Hydroboration, haloboration and phenylboration polymerizations
Authors: Chujo Yoshiki 
Published: March 2011

AbstractA polyaddition between diene and monoalkylborane produced a polymer consisting of C‐B bonds in the main chain. The resulting organoboron polymers can be used as a novel type of reactive polymers. On the other hand, hydroboration polymerization of dicyano compounds produced air‐stable poly(cyclodiborazane)s having B‐N four‐membered rings via dimerization of iminoborane species. Poly(organoboron halide)s were prepared either by haloboration polymerization between diynes and boron tribromide or by hydroboration polymerization of dienes with monobromoborane. Furthermore, phenylboration polymerization of diynes or diisocyanates gave new organoboron mainchain polymers.
Synthesis and properties of polyamides containing imidazoline rings
Authors: Chen Leo‐Wang , Kuo Yao‐Hsing 
Published: March 2011

AbstractThe novel polyamide containing an imidazoline ring(PAI) was synthesized by a two‐stage melt polymerization of dimethyl terephthalate (DMT) with diethylenetriamine (DETA) or triethylenetetramine (TETA). The heat resistance of PAI was superior to that of polyamide which was synthesized only in the first‐stage reaction and didn't contain imidazoline ring. Their chemical structures were identified by infrared spectroscopy and NMR. The optimum condition for production was studied by varying several reaction factors, including the contents of H2O and H3PO4, the reaction temperature and the reaction time at second‐stage reaction under vacuum. According to study of the characteristics of solution behavior of PAI, both the viscosity and the degree of cyclization could be described by equation of magnified image in m‐cresol at 30°C.
Syndiospecific polymerizations of styrene with siloxane‐bridged dinuclear titanocenes and mao catalyst systems
Authors: Lee Dong‐Ho , Yoon Keun‐Byoung , Noh Seok‐Kyun , Woo Sang‐Sun 
Published: March 2011

AbstractThe syndiotactic polymerizations of styrene are carried out with dinuclear titanocenes such as tetramethyldisiloxanediylbis(cyclopentadienyltitanium trichloride), Cl3Ti‐CpSi(CH3)2‐O‐Si(CH3)2Cp‐TiCl3 (1), hexamethyltrisiloxanediylbis(cyclopentadienyltitanium trichloride), Cl3Ti‐CpSi(CH3)2‐O‐Si‐(CH3)2‐0‐Si(CH3)2Cp‐TiCl3 (2) and hexamethyl‐trisiloxanediylbis(dicyclopentadienyltitanium dichloride), Cl2CpTi‐CpSi(CH3)2‐O‐Si‐(CH3)2‐O‐Si(CH3)2Cp‐TiCpCl2 (3) in the presence of modified methylaluminoxane (MMAO). Although the catalyst activity of dinuclear titanocenes is lower than that of the corresponding mononuclear titanocenes CpTiCl3 and Cp2TiCl2, the former produce polystyrene of higher weight‐average molecular weight and higher syndiotactic index than the latter. Among the dinuclear titanocenes examined, 2 has the largest catalyst activity. In addition, the copolymerizations of styrene and ethylene are carried out with 2.
Toward uniform polymer architecture through stereospecific living polymerization and chromatographic separation technique
Authors: Hatada Koichi , Nishiura Takafumi , Kitayama Tatsuki , Ute Koichi 
Published: March 2011

AbstractIsotactic (it‐) and syndiotactic (st‐) poly(methyl methacrylate)s (PMMAs) were fractionated into uniform PMMAs (without molecular weight distribution) by supercritical fluid chromatography (SFC). The SFC technique was applied to the isolation of uniform it‐ and st‐PMMAs with a hydroxy group (it‐ and st‐PMMA‐OH) at the chain end. Equimolar amounts of uniform it‐ and st‐PMMA‐OHs were coupled with sebacoyl dichloride to form uniform stereoblock PMMA. The reaction of uniform st‐PMMA‐OH with methacryloyl chloride gave uniform PMMA macromonomer with methacryloyl group at the chain end. The resulting uniform macromonomer was polymerized radically and the products were fractionated into uniform comblike polymers (1mer to 4mer) by means of gel‐permeation chromatography (GPC). The uniform st‐PMMA‐OH was reacted with 1, 3, 5‐benzenetricarbonyl trichloride to form uniform st‐tri‐armed star polymer. Some of the properties of these uniform stereoregular polymer architectures were studied.
Synthesis of gel type dispersion polymers via living dispersion polymerization (LDP)
Authors: Kim Kwang Ung , Kim Jungahn , Ahn Young Hye , Im Sung Soon 
Published: March 2011

AbstractA gel type disperse polystyrene/divinylbenzene (DVB) copolymer was successfully prepared in hydrocarbon via ‘living dispersion polymerization (LDP)’ method. Characterization of the dispersed polymers was performed by a combination of size‐exclusion chromatographic and transmission electron microscopic analyses. Poly(t‐butylstyryl)lithium with 3,5 × 104 g/mol of molecular weight was used as a steric stabilizing moiety in the living dispersion polymerization. The particle size of the dispersed polymers was able to be controlled by both the mole ratio of the concentration of poly(t‐butylstyryl)lithium to n‐butyllithium and the amount of monomer to over 2 μm.
Radical/cation transformation polymerization and its application to the preparation of block copolymers
Authors: Kamachi Mikiharu , Guo Hai‐Qing , Kajiwara Atsushi 
Published: March 2011

Abstractp‐Methoxystyrene (MOS), butyl vinyl ether (BVE), and N‐vinylcarbazole (VCZ) were polymerized in high yield by azoinitiators such as 2, 2'‐azodiisobutyronitrile (AIBN) in the presence of electron acceptors such as Ph2I+PF6−. An electron paramagnetic resonance (ESR) study of the model radicals of the propagating radical showed the transformation of the radical to the corresponding cation in the presence of the electron acceptors. In the case of BVE, the polymer formation was caused by cationic species produced by the transformation of the initiating radical. The polymerizations of MOS and VCZ were ascribed to the transformation of the growing radical to the corresponding cation during the propagation step which was classified as the radical/cation transformation polymerization. Block copolymers of MOS/cyclohexene oxide (1, 2‐epoxycyclohexane) (CHO) and VCZ/CHO were effectively prepared by the radical/cation transformation polymerization of the appropriate monomers in the presence of AIBN, electron acceptor and CHO. The formation of block copolymers was characterized by turbidimetry, thin‐layer chromatography, and solubility tests.
Preparation of copoly(amide‐imide)s via direct polycondensation
Authors: Choi Kil‐Yeong , Hong Young‐Taik 
Published: March 2011

AbstractPreparation of various kinds of copoly(amide‐imide) was carried out via direct polycondensation of trimellitic anhydride (TMA) with the corresponding diamine mixture in the presence of an equimolar amount of thionyl chloride (TC) as a condensing agent followed by thermal imidization. The resulting copoly(amide‐imide)s had inherent viscosities in the range of 41 to 68 mL g−1 and glass transition temperatures of 215°C to 291°C. These copoly(amide‐imide)s had relatively good thermomechanical properties. That is, the initial decomposition temperature (IDT) and tensile strength were 350–409°C and 104–121 MPa, respectively. The melt viscosities of the copoly(amide‐imide)s measured at 345°C under a frequency of 102 rad s−1 were in the range of 4.8 × 102 ∼ 4.5 ˜ 103 Pa s depending on comonomers, which are somewhat lower than that commerciallized PAI with 5.6 × 103 Pa s.
Controlled macromolecular synthesis by the nucleophile/lewis acid binary systems
Authors: Aida Takuzo , Takeuchi Daisuke , Sugimoto Hiroshi , Inoue Shohei 
Published: March 2011

AbstractAmphiphilic initiator systems consisting of bulky nucleophiles as propagating species and bulky electrophiles (Lewis acids) as monomer activators bring about high‐speed living anionic polymerization of polar vinylic and heterocyclic monomers to give narrow molecular weight distribution (MWD) polymers.
Partially imidized poly[(amic ester)‐alt‐imide]: A novel polyimide pregursor
Authors: Lee Myong‐Hoon , Park Jiwoong , Rhee Suh Bong 
Published: March 2011

AbstractPartial imidization of poly[(amic ester)‐alt‐(amic acid)], a precursor for the “strictly alternating” copolyimides, was performed via selective chemical imidization of amic acid units in the copolymer precursor. The resulting, poly[(amic ester)‐alt‐imide], showed superior properties such as an excellent solution stability, good processibility and improved optical transparency, which are essential for the use as a precursor for the polyimide.
Formation, structure and properties of polymer networks
Authors: Dutton S. , Stepto R. F. T. , Taylor D. J. R. 
Published: March 2011

AbstractThe systematic study of intramolecular reaction and gel points together with measurements of moduli of trifunctional and tetrafunctional end‐linked networks show that gel points are always delayed and network imperfections always result from the intramolecular reaction which must occur when such networks are formed. The quantitative interpretation and prediction of gel points and moduli directly from reactant structures and reaction conditions are discussed.
Relationship between structure and conformation in liquid crystalline polymers
Authors: Hardouin F. , Lecommandoux S. 
Published: March 2011

AbstractOur studies on the nematic phase of different kinds of thermotropic liquid crystalline polymers tend to focus on the following question: what about the anisotropy of the backbone conformation in the orientational medium imposed by its mesogenic groups ? By means of small angle neutron scattering (SANS) different features are qualitatively and quantitatively discussed. In the case of liquid crystal side chain polymers, the chain anisotropy is essentially driven by thermodynamical, structural and chemical considerations. In addition, in the case of liquid crystal main chain polymers, hairpin defects are observed for sufficiently long polymers.
Structure evolution and properties in a rigid polyimide prepared from its flexible poly(amic acid) precursor
Authors: Ree Moonhor , Woo Sung Ho , Shin Tae Joo , Kim Kyungjun , Chang Heesook , Zin Wang Cheol , Lee Ki‐Bong , Park Yong Joon 
Published: March 2011

AbstractSoluble poly(p‐phenylene biphenyltetracarboxamic acid) precursor was converted to the polyimide by thermal imidization at various conditions. The structure evolution being occurred during its thermal imidization over 25–400°C was investigated as a function of imidization temperature and time by X‐ray scattering with synchrotron radiation sources of Pohang Accelerator Laboratory in Korea and with conventional radiation sources. In addition, properties in the polyimide films were investigated by dynamic mechanical thermal analysis, stress‐strain analysis, prism coupling, and residual stress analysis.
Fluorescence study on dynamics of liquid‐crystalline polymers
Authors: Horie Kazuyuki , Huang Hsuwen 
Published: March 2011

AbstractFluorescence measurements of various main‐chain liquid‐crystalline (LC) polyesters, poly[oxybiphenyl‐4, 4'‐diyloxy(2, 5‐dihexadecyloxy)‐1, 4‐pyromellitoyl] (B‐C16), poly[(ethylene terephthalate)‐co‐(p‐oxybenzoate)] (PET40/OBA60), poly(oxybiphenyl‐4, 4'‐diyloxy‐1, 10‐decanedioyl) (PB‐10), low‐molecular‐weight LC bis(p‐hexyloxyphenyl) terephthalate (PP6), and a lyotropic LCP, poly(sulfo‐1, 4‐phynelene 3'‐nitroterephthalate) (PSPNT), were carried out to investigate their dynamics and intermolecular interaction changes.
Structure and thermodynamics of polymeric liquids: Polymer kirkwood integral equation method
Authors: Gan Hin Hark , Eu Byung Chan 
Published: March 2011

AbstractA statistical mechanical theory is employed to predict the structural and thermodynamic properties of polymeric liquids. The theory consists of a coupled set of self‐consistent integral equations for the pair correlation functions which relates the polymer structure to molecular interaction potentials. In this article, the essentials of the method are reviewed and the results are shown in comparison with other theories and simulation data. Quantitative agreements are found between the results of the theory and those of the simulations for a wide range of density and temperature.
High performance liquid chromatography characterization of macromolecules
Authors: Chang Taihyun , Lee Hee Cheong , Lee Wonmok 
Published: March 2011

AbstractA new method, temperature gradient interaction chromatography(TGIC) is employed for the characterization of macromolecules. Fine and reproducible control of interaction between polymer chains and the alkyl chain bonded silica packing material can be achieved by varying the temperature of the column. This method provides a far superior resolution to the conventional size exclusion chromatography. In addition, this method has a high sample loading capacity to be effective for preparative purpose. Furthermore, this method can be used to characterize binary polymer mixtures, where one component of a polymer mixture is separated by the size exclusion mechanism and the other is by the interaction mechanism simultaneously from single isocratic elution.
The thermal behaviors of latexes: Wet latex glass transition temperatures
Authors: Lee Do Ik , Walker Lynn C. , Kan Charles S. 
Published: March 2011

AbstractThe thermal behaviors of latexes were studied by using MicroCal MC‐2 Scanning Calorimeter which is a differential scanning micro‐calorimeter capable of handling fluids under pressure. The MC‐2 unit was found to be uniquely capable of measuring not only the glass transition temperatures (Tg's) of wet latexes, but also the extent of annealing (enthalpy relaxation) that has a profound impact on the deformability of latex particles and, in turn, the film formation of latexes. The effects of polar monomers, the neutralization of carboxylated latexes, and coalescing agents on the wet latex Tg's were also studied.
Polymer processing research in industry: Role of academic‐industrial cooperation for fundamental research
Authors: Hyun Kun Sup 
Published: March 2011

AbstractUnderstanding how polymers will process in such as extruders, injection molding machines, and dies can be met through academic‐industry cooperation. With declining R&D budgets and globalization of businesses, this cooperation is extremely valuable for continuing fundamental research in polymer processing and fabrication technologies. This paper illustrates some examples and suggests how industry can best benefit from these programs