bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermally latent polyaddition and curing of Di‐ and tri‐functional hemiacetal esters with diepoxide by salen‐zinc complex with tunable catalytic activity and model and networking reactions
Authors: Komatsu Hiroyuki , Ochiai Bungo , Endo Takeshi 
Published: December 2007

AbstractSalen‐zinc complexes (Zn/1R) thermal‐latently catalyzed the polyaddition of a diepoxide (2) with a difunctional hemiacetal ester (3), which proceeded at moderate temperatures (100–150 °C) for curing of mixtures containing monomers and initiators. The catalytic activities of Zn/1R depended on the Lewis acidities of the complexes controlled by the electronic character of the salen ligands. For example, Zn/13,5‐Cl bearing four electron‐withdrawing chlorine atoms initiated the polyaddition at the lowest temperature (100 °C), and Zn/1OMe bearing two electron‐donating methoxy groups initiated the polyaddition at 120 °C. The Lewis acidities of the complexes were evaluated by NMR and IR spectroscopies and computational calculation. The polyadditions with the salen‐zinc complexes proceeded quantitatively at 150 °C, and the use of a tri‐functional hemiacetal ester (7) with 2 afforded the corresponding networked polymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1427–1439, 2008
Polysaccharide‐templated twisted assemble of 2‐anilinonaphthalene‐6‐sulfonic acid
Authors: Shimada Naohiko , Okobira Tadashi , Takeda Yoichi , Shinkai Seiji , Sakurai Kazuo 
Published: December 2007

AbstractSchizophyllan (SPG) is a natural β‐1,3‐glucan that forms a triple helix (t‐SPG) in neutral aqueous solutions and t‐SPG can be denatured to single chains (s‐SPGs) in DMSO or alkaline solutions. Exchanging the denatured solutions for neutral water leads the renaturation of the triple helix. We have reported that hydrophobic molecules can form a complex with s‐SPG when they are present in the renaturation process. Some of these, for example poly(dA) and polyaniline, were found to have aromatic amino moieties. This report demonstrates whether s‐SPG can interact with other aromatic amino compounds such as anilinonaphthalene sulfonic acid (ANS) derivatives. Enhanced fluorescence intensity and red‐shifted UV absorption spectra were observed in the mixture of s‐SPG and 2,6‐ANS or 2,6‐TNS. In the circular dichroism measurement, the positive Cotton effects appeared after mixing 2, 6‐ANS with s‐SPG. When the amino proton was replaced by the methyl group or used in intramolecular hydrogen bonds, any spectral changes were not observed. These results indicate that amino proton in the ANS derivatives plays a key role in the complexation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1440–1448, 2008
Branched polymer via free radical polymerization of chain transfer monomer: A theoretical and experimental investigation
Authors: Liu Jianhua , Wang Yusong , Fu Qi , Zhu Xiangyang , Shi Wenfang 
Published: December 2007

AbstractA simple mathematic model for the free radical polymerization of chain transfer monomers containing both polymerizable vinyl groups and telogen groups was proposed. The molecular architecture of the obtained polymer can be prognosticated according to the developed model, which was validated experimentally by homopolymerization of 4‐vinyl benzyl thiol (VBT) and its copolymerization with styrene. The chain transfer constant (CT) of telogen group in a chain transfer monomer is considered to play an important role to determine the architecture of obtained polymer according to the proposed model, either in homopolymerization or copolymerization. A highly branched polymer will be formed when the CT value is around unity, while a linear polymer with a certain extent of side chains will be obtained when the CT value is much bigger or smaller than unity. The CT of VBT was determined to be around 15 by using the developed model and 1H NMR monitored experiments. The obtained poly(VBT) and its copolymers were substantiated to be mainly consisted of linear main chain with side branching chains, which is in agreement with the anticipation from the developed model. The glass transition temperature, number average molecular weight, and its distribution of those obtained polymer were primarily investigated. This model is hopefully to be used as a strategy to select appropriate chain transfer monomers for preparing hyperbranched polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1449–1459, 2008
Propagation kinetics of free‐radical polymerizations in ionic liquids
Authors: Woecht Inga , Schmidt‐Naake Gudrun , Beuermann Sabine , Buback Michael , García Nuria 
Published: December 2007

AbstractPropagation rate coefficients,kp, of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) homopolymerizations were measured at ambient pressure in four ionic liquids (ILs): 1‐ethyl‐3‐methylimidazolium ([emim]) ethyl sulfate and [emim] hexyl sulfate as well as butyl‐3‐methylimidazolium ([bmim]) hexafluorophosphate and [bmim] tetrafluoroborate via the pulsed‐laser polymerization size‐exclusion chromatography technique. In passing from bulk polymerization at 40 °C polymerization in IL solution containing 20 vol % monomer,kpis enhanced by up to a factor of 4 with MMA and by a factor of 2 with GMA. This enhancement ofkpprimarily results from a lowering of activation energy upon partial replacement of monomer by ionic liquid species. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1460–1469, 2008
Fluorescent polymer particles incorporating pyrene derivatives
Authors: Tamai Toshiyuki , Watanabe Mitsuru , Maeda Hajime , Mizuno Kazuhiko 
Published: December 2007

AbstractFluorescent polymer particles incorporating pyrene and alkynylpyrenes were prepared by miniemulsion polymerization of styrene. The pyrenes were simply dissolved in styrene monomer and then added to the reaction mixture in a vessel, followed by ultrasonication and the polymerization. The pyrenes were incorporated in the polystyrene particles and gave monomer fluorescence emission. The fluorescent particles incorporating the alkynylpyrenes, which have high fluorescence quantum yield and short fluorescence lifetime, showed the same fluorescence emission intensity under air and nitrogen. The fluorescence of the alkynylpyrenes in the polymer particles will not be quenched by molecular dioxygen in contrast to that in organic solvents. Incorporation of fluorophore into polymer particles will protect the fluorophore from its undesirable interaction with oxygen, affording the particles highly fluorescent even under air. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1470–1475, 2008
Styrene/1,3‐butadiene copolymerization by C2‐symmetric group 4 metallocenes based catalysts
Authors: Napoli Mariagrazia , Ricciardi Rosa , Memoli Antonia , Longo Pasquale 
Published: December 2007

AbstractC2‐symmetric group 4 metallocenes based catalysts (rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]ZrCl2(1), rac‐[CH2(1‐indenyl)2]ZrCl2(2) and rac‐[CH2(3‐tert‐butyl‐1‐indenyl)2]TiCl2(3)) are able to copolymerize styrene and 1,3‐butadiene, to give products with high molecular weight. In agreement with symmetry properties of metallocene precatalysts, styrene homosequences are in isotactic arrangements. Full determination of microstructure of copolymers was obtained by 13C NMR and FTIR analysis and it reveals that insertion of butadiene on styrene chain‐end happens prevailingly with 1,4‐trans configuration. In the butadiene homosequences, using zirconocene‐based catalysts, the 1,4‐trans arrangement is favored over 1,4‐cis, but the latter is prevailing in the presence of titanocene (3). Diad composition analysis of the copolymers makes possible to estimate the reactivity ratios of copolymerization: zirconocenes (1) and (2) produced copolymers having r1 × r2 = 0.5 and 3.0, respectively (where 1 refers to styrene and 2 to butadiene); while titanocene (3) gave tendencially blocky styrene–butadiene copolymers (r1 × r2 = 8.5). The copolymers do not exhibit crystallinity, even when they contain a high molar fraction of styrene. Probably, comonomer homosequences are too short to crystallize (ns = 16, in the copolymer at highest styrene molar fraction). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1476–1487, 2008
Styrene‐ethylene co‐oligomerization with bis‐(diphenylphosphino)‐amine/chromium catalysts and the use of the co‐oligomerization products in copolymerization reactions with metallocenes
Authors: Du Toit Aletta , De Wet‐Roos Deon , Joubert Dawie J. , Van Reenen Albert J. 
Published: December 2007

AbstractEthylene‐styrene (or 4‐methylstyrene) co‐oligomerization using various bis(diphenylphoshino)amine ligands in combination with chromium is discussed. GC analysis of the reaction mixture shows that various phenyl‐hexene and phenyl‐octene isomers are formed either through cotrimerization or cotetramerization. It seems that the more bulky ligands display lower selectivity to co‐oligomerization and favor ethylene homo‐oligomerization. Subsequent copolymerization of the oligomerization reaction mixture using a metallocene polymerization catalyst results in a copolymer with a branched structure as indicated by Crystaf and 13C NMR analysis. Assignments of the 13C NMR spectrum are proposed from an APT NMR experiment combined with calculated NMR chemical shift data using additivity rules. An indication of the ability of the different co‐oligomerization products to copolymerize into the polyethylene chain could be established from these assignments. Unreacted styrene and the more bulky isomers, 3‐phenyl‐1‐hexene and 3‐phenyl‐1‐octene, are not readily incorporated while branches resulting from the other isomers present in the co‐oligomerization reaction mixture are detected in the NMR spectrum. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 1488–1501, 2008
High‐throughput kinetic analysis of acrylate and thiol‐ene photopolymerization using temperature and exposure time gradients
Authors: Johnson Peter M. , Stansbury Jeffrey W. , Bowman Christopher N. 
Published: December 2007

AbstractIn this work, a high‐throughput technique for evaluating photopolymers is developed to enable simultaneous measurement of the effects of temperature in combination with exposure time. Temperature and exposure time gradients were produced in orthogonal directions on a single sample, and subsequently sampled using Fourier transform infrared (FTIR) spectroscopy. The technique developed here allows for photopolymerization kinetics to be analyzed rapidly over a large range of industrially relevant temperatures, giving insight into the role temperature and the polymer's glass transition temperature have in dictating the photopolymerization kinetics. In the 70/30 wt % hexyl acrylate and hexanediol diacrylate system, conversion in samples below the glass transition temperature (TG) was 66 ± 2% after 12 s, significantly lower than the 93 ± 4% conversion at 12 s for samples polymerized at temperatures above the TG. In addition, a thiol‐ene system was analyzed to study the effect of temperature on the ene homopolymerization in allyl ether monomers, which leads to incomplete thiol conversion in stoichiometrically balanced systems. At a 60% thiol conversion, the allyl ether‐ene conversion at all temperatures is 65 ± 3% irrespective of initial formulation temperature, indicative of the homopolymerization behavior being nearly independent of temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1502–1509, 2008
Synthesis and properties of highly refractive polyimides derived from fluorene‐bridged sulfur‐containing dianhydrides and diamines
Authors: Terraza Claudio A. , Liu Jin‐Gang , Nakamura Yasuhiro , Shibasaki Yuji , Ando Shinji , Ueda Mitsuru 
Published: December 2007

AbstractHighly refractive and transparent polyimides (PIs) based on fluorene‐bridged and sulfur‐containing monomers have been developed. An aromatic dianhydride, 4,4′‐[p‐thiobis(phenylenesulfanyl)]diphthalic anhydride (3SDEA), was polymerized with several fluorene‐containing diamines, including commercially available 9,9′‐bis(p‐aminophenyl)fluorene (APF), 9,9′‐bis[4‐(p‐aminophenoxy)phenyl]fluorene (OAPF), and newly synthesized 9,9′‐bis[4‐(p‐aminophenyl)sulfanylphenyl]fluorene (ASPF) to afford series A PIs. Meanwhile, series B PIs were obtained from a new dianhydride, 4,4′‐[(9H‐fluorene‐9‐ylidene)bis(p‐phenylsulfanyl)]diphthalic anhydride (FPSP) and two aromatic diamines, ASPF and 4,4′‐thiobis[(p‐phenylenesulfanyl)aniline] (3SDA) via a two‐step polycondensation procedure. The PIs exhibit good thermal stabilities, such as relatively high glass transition temperatures in the range of 220–270 °C and high initial thermal decomposition temperatures (T10%) exceeding 490 °C. The 9,9′‐disubstituted fluorene moieties endow the PI films with good optical transparency. The optical transmittances of the PI films at 450 nm are all higher than 80% for the thickness of about 10 μm. Furthermore, the highly aromatic fluorene moiety and flexible thioether linkages in the molecular chains of the PIs provide them with high refractive indices of 1.6951–1.7258 and small birefringence of 0.0056–0.0070. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1510–1520, 2008
Synthesis of chalcone‐based fluorescent polymers: Diels‐Alder reaction of chalcones and their polymerization through ROMP
Authors: Kamakshi R. , Reddy B. S. R. 
Published: December 2007

AbstractRing opening metathesis polymerization (ROMP) was carried out on Diels‐Alder adducts formed from reactions between chalcones and cyclopentadiene. Most of the chalcones gave predominantly endo‐adducts and the exo‐adducts were obtained in good yields from reacting cyclopentadiene with furfurylidine acetone and N,N,diethylaminobenzylidine‐(4‐hydroxy)acetophenone. These exo‐adducts were subjected to ROMP using Grubbs catalyst, bis(tricyclohexylphosphine)benzylidinedichloride. The monomers and polymers were characterized using spectroscopic techniques like FT‐IR, 1HNMR. The polymers were characterized using TGA, DSC, and GPC. The polymers were found to possess fluorescent properties and poly[2‐(4‐diethylamino)phenyl‐3,5‐divinylcyclopentyl](4‐hydroxyphenyl) methanone was found to have good emissive property at two wavelengths. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1521–1531, 2008
Cyclic oligomer chemistry
Authors: Brunelle Daniel J. 
Published: December 2007

AbstractCyclic oligomers of engineering plastics such as polycarbonate and aromatic polyesters have been known for some time, being formed at very low levels during commercial manufacture. At GE Global Research, we have devised methods for high‐yielding and selective preparation of such cyclic oligomers, that are amenable to commercial manufacture. The mixtures of cyclic oligomers have melting points significantly lower than individual ring sizes, and have very low viscosities in the melt. Ring‐opening polymerization using appropriate initiators affords rapid reactions (2–6 min) without measurable exotherm, providing very high‐molecular‐weight polymers and without reaction byproducts. These materials have been scaled to commercial quantities, and have shown to be extremely useful for fabrication of glass and carbon fiber composites with high‐fiber fractions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1151–1164, 2008
Dynamic mechanical and rheological properties of binary S–(S/B)–S triblock copolymer blends
Authors: Thunga M. , Satapathy B. K. , Staudinger U. , Weidisch R. , Abdel‐Goad M. , Janke A. , Knoll K. 
Published: December 2007

AbstractThe rheology and dynamic mechanical properties of binary block copolymer blends consisting of a symmetrical triblock copolymer with thermoplastic elastomeric behavior (LN4) and an asymmetrical thermoplastic triblock copolymer (LN3) were investigated. TEM images of the blends show a systematic variation in the morphologies from worms (∼20–0 wt % LN3) to cylinders (∼60–30 wt % LN3) to lamellae (100–70 wt % LN3) as a function of LN3 content. DMA analysis has revealed that the increase in LN3 content leads to a decrease in miscibility between the PS end blocks and the S/B middle block. The frequency and temperature dependence of the storage modulus (G′), loss modulus (G″), and complex viscosity (|η*|) has been studied for LN4 (weakly segregated) and LN3 (strongly segregated) from their master curves. By comparing the rheological properties of these blend compositions at low‐frequency regime, it is observed that with the increase in LN3 content the shear modulus and complex viscosity increase. Blend compositions with 70–100 wt % of LN3 show nonterminal behavior at reduced frequencies due to the presence of highly ordered microdomains when compared to blends with ∼0–20 wt % of LN3 content. van Gurp–Palmen plots were constructed to observe the transition from liquid‐ to solid‐like behavior in the vicinity of order‐to‐disorder transition (ODT) temperature. ODT temperature increases as the thermoplastic LN3 content increases which are also confirmed by the Han plots. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 329–343, 2008
Mean‐field theoretical analysis of brush‐coated nanoparticle dispersion in polymer matrices
Authors: Harton Shane E. , Kumar Sanat K. 
Published: December 2007

AbstractThe equilibrium dispersion of nanoparticles with grafted polymer chains into polymer matrices, of the same chemical structure as the brush, is studied through the device of mean‐field theory. Our results show that the disperion of brush‐coated nanoparticles into a matrix polymer is improved with (i) decreasing particle radius and (ii) increasing brush chain length. Both of these aspects can be understood based on the fact that, unlike the case of planar surfaces, homopolymer chains end‐grafted to spherical nanoparticle surfaces tangentially spread away from the surface thus alleviating the packing frustration that is created by the relatively high grafting densities. This permits significant brush/matrix overlap, even at high grafting densities, a regime that has only recently become experimentally available due to advances in polymer synthesis (i.e., the “grafting‐to” methods). © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 351–358, 2008
Electrical and dielectric properties in carbon fiber‐filled LMWPE/UHMWPE composites with different blend ratios
Authors: Chen Qingyun , Xi Ying , Bin Yuezhen , Matsuo Masaru 
Published: December 2007

AbstractCarbon fiber (CF) filled low‐molecular‐weight polyethylene (LMWPE) and ultra‐high molecular weight polyethylene (UHMWPE) composites were prepared by the gelation from solution and the kneading in the melting state. The content of carbon fibers was fixed to be 23.5 vol %. The resistivity, positive temperature coefficient (PTC), and dielectric behaviors of the composites became more pronounced with increasing content of LMWPE with much higher thermal expansion than that of UHMWPE. The PTC effect became most significant, when the blend ratio of LMWPE to UHMWPE was 9/1. Beyond 9/1, the PTC effect was less pronounced. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) revealed that the UHMWPE and LMWPE chains within the composite crystallized independently by gelation from solution and were virtually unaffected by the presence of carbon fibers. Consequently, it was confirmed that carbon fibers selectively were localized in the mixed region of LMWPE and UHMWPE for the composite (3/1 and 6/1) and mainly in the region of LMWPE for the 9/1, 12/1, and 15/1 composites. This indicated that the content of carbon fibers within LMWPE region was the highest for the 9/1 composite and the 9/1 composite provides the most significant PTC effect. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 359–369, 2008
Phase behavior of a single polyethylene chain confined between two adsorption walls
Authors: Su Jiaye , Zhang Linxi 
Published: December 2007

AbstractThe phase behavior of a single polyethylene chain confined between two adsorption walls is investigated by using molecular dynamics simulations. In the free space, it is confirmed in our calculation that the isolated polymer chain exhibits a disordered coil state at high temperatures, and collapses into a condensed state at low temperatures, that is, the coil‐to‐globule transition, and the finite chain length effects are considered since the critical region depends on chain lengths. When the chain is confined between two attractive walls, however, the equilibrium properties not only depend on the chain length but also depend on the adsorption energy and the confinement. Mainly, we focus on the influence of polymer chain length, confinement, and adsorption interaction on the equilibrium thermodynamic properties of the polyethylene chains. Chain lengths of N = 40, 80, and 120 beads, distances between the two walls of D = 10, 20, 30, 50, and 90 Å, and adsorption energies of w = 1.5, 2.5, 3.5, 6.5, and 8.5 kcal/mol are considered here. By considering the confinement–adsorption interactions, some new folding structures are found, that is, the hairpin structure for short chain of N = 40 beads, and the enhanced hairpin or crystal like structures for long chains of N = 80 and 120 beads. The results obtained in our simulations may provide some insights into the phase behaviors of confined polymers, which can not be obtained by previous studies without considering confinement–adsorption interactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 370–387, 2008
Conformation study of poly(p‐dioxanone) fibers by polarized Raman spectroscopy, X‐ray diffraction, and conformation analysis
Authors: Jaidann Mounir , Brisson Josée 
Published: December 2007

AbstractThe molecular orientation distribution of poly(p‐dioxanone) (PPDX) uniaxially oriented commercial fibers was determined by polarized Raman spectroscopy and X‐ray diffraction. The order parameters 〈P200〉 and 〈P400〉 of the orientation distribution function were determined by polarized Raman spectroscopy. For the CO stretching band, the values of 〈P200〉 and 〈P400〉 obtained are equal to −0.40 ± 0.04 and 0.28 ± 0.04, respectively. These results clearly indicate that the carbonyl groups are highly oriented perpendicular to the fiber axis. X‐ray diffraction led to a fiber repeat value of 0.628 nm for these samples, and to 〈P200〉 and 〈P400〉 values of 0.93 and 0.82, respectively, for the c‐axis orientation, indicating a high orientation in the draw direction of the fibers. A Monte‐Carlo conformational search led to 20 low‐energy conformations, but only one of these was found compatible with both the fiber repeat and the angle between the CO bond and the fiber axis. This conformation, a 21 helix with a tg−ttg− succession of torsion angles, is proposed as the existing conformation in the crystalline state. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 406–417, 2008