bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Relationship between Craze Structure and Molecular Weight in Polystyrene as Revealed by µSAXS Experiments
Authors: Zafeiropoulos Nikolaos E. , Davies Richard J. , Schneider Konrad , Burghammer Manfred , Riekel Christian , Stamm Manfred 
Published: September 2006

AbstractSummary: The phenomenon of crazing in polymers has received considerable attention in the past as it is thought to play a pivotal role in determining the performance of polymers under load. One aspect of particular interest has been the interconnection between molecular structure, craze characteristics, and macromechanical properties. In the present study, three different grades of polystyrene (PS) with different molecular weights have been systematically investigated in situ with synchrotron radiation microfocus small‐angle X‐ray scattering (µSAXS). The results suggest that there are different mechanisms operating in PS samples with low and very high molecular weights, compared to those of medium‐to‐high molecular weight. Previously it was thought that, above the critical molecular weight of entanglement, the effect of molecular weight on PS's mechanical behaviour at room temperature was negligible.Craze evolution as a function of strain in PS.imageCraze evolution as a function of strain in PS.
Efficient Homogeneous Chemical Modification of Bacterial Cellulose in the Ionic Liquid 1‐N‐Butyl‐3‐methylimidazolium Chloride
Authors: Schlufter Kerstin , Schmauder Hans‐Peter , Dorn Susann , Heinze Thomas 
Published: September 2006

AbstractSummary: Bacterial cellulose (BC), a unique type of cellulose, with high degree of polymerization of 6 500 could be dissolved easily in the ionic liquid 1‐N‐butyl‐3‐methylimidazolium chloride. For the first time, well‐soluble BC acetates and carbanilates of high degree of substitution (up to a complete modification of all hydroxyl groups) were accessible under homogeneous and mild reaction conditions. Characterization of the new BC derivatives by NMR and FTIR spectroscopy shows an unexpected distribution of the acetyl moieties in the order O‐6 > O‐3 > O‐2.13C NMR spectrum (DMSO‐d6) of a cellulose acetate with a DS of 2.25 synthesized in 1‐N‐butyl‐3‐methylimidazolium chloride.image13C NMR spectrum (DMSO‐d6) of a cellulose acetate with a DS of 2.25 synthesized in 1‐N‐butyl‐3‐methylimidazolium chloride.
The Effect of [CuI]/[CuII] Ratio on the Kinetics and Conformation of Polyelectrolyte Brushes by Atom Transfer Radical Polymerization
Authors: Cheng Nan , Azzaroni Omar , Moya Sergio , Huck Wilhelm T. S. 
Published: September 2006

AbstractSummary: The atom transfer radical polymerization of [2‐(methacryloyloxy)ethyl]trimethylammonium chloride (METAC) has been studied under different [CuI]/[CuII] ratios. The reaction kinetics is followed by ellipsometry and quartz crystal microbalance and it was found that the reaction speed influences the grafting density of the polymer brushes. High [CuI]/[CuII] ratios, i.e., fast polymerizations, lead to less dense polymer brushes.Plot of the frequency change of wet brushes on a QCM crystal (Δf) versus the dry thickness of brushes synthesized at different [CuI]/[CuII] ratios.imagePlot of the frequency change of wet brushes on a QCM crystal (Δf) versus the dry thickness of brushes synthesized at different [CuI]/[CuII] ratios.
Prediction of chemotherapeutic response of colorectal liver metastases with dynamic gadolinium‐DTPA‐enhanced MRI and localized 19F MRS pharmacokinetic studies of 5‐fluorouracil
Authors: van Laarhoven H. W. M. , Klomp D. W. J. , Rijpkema M. , Kamm Y. L. M. , Wagener D. J. Th. , Barentsz J. O. , Punt C. J. A. , Heerschap A. 
Published: September 2006

AbstractSystemic chemotherapy is effective in only a subset of patients with metastasized colorectal cancer. Therefore, early selection of patients who are most likely to benefit from chemotherapy is desirable. Response to treatment may be determined by the delivery of the drug to the tumor, retention of the drug in the tumor and by the amount of intracellular uptake, metabolic activation and catabolism, as well as other factors. The first aim of this study was to investigate the predictive value of DCE‐MRI with the contrast agent Gd‐DTPA for tumor response to first‐line chemotherapy in patients with liver metastases of colorectal cancer. The second aim was to investigate the predictive value of 5‐fluorouracil (FU) uptake, retention and catabolism as measured by localized 19F MRS for tumor response to FU therapy. Since FU uptake, retention and metabolism may depend on tumor vascularization, the relationship between 19F MRS and the DCE‐MRI parameters kep, Ktrans and ve was also examined (1). In this study, 37 patients were included. The kinetic parameters of DCE‐MRI, kep, Ktrans and ve, before start of treatment did not predict tumor response after 2 months, suggesting that the delivery of chemotherapy by tumor vasculature is not a major factor determining response in first‐line treatment. No evident correlations between 19F MRS parameters and tumor response were found. This suggests that in liver metastases that are not selected on the basis of their tumor diameter, FU uptake and catabolism are not limiting factors for response. The transfer constant Ktrans, as measured by DCE‐MRI before start of treatment, was negatively correlated with FU half‐life in the liver metastases, which suggests that, in metastases with a larger tumor blood flow or permeability surface area product, FU is rapidly washed out from the tumor. Copyright © 2006 John Wiley & Sons, Ltd.
The effect of initiator system on acrylate emulsion copolymerization with higher hydroxyl monomer content
Authors: Zhang Fa‐Ai , Yu Cai‐Li , Zhu Xing‐Hua , Wei Chun 
Published: September 2006

AbstractThe influence of the initiator (ammonium persulfate, APS) and APS/reducer system on the acrylate emulsion copolymerization of methyl methacrylate/butyl acrylate/acrylic acid/hydroxylethyl methacrylate (HEMA) was studied. The initiator level, reaction temperature, reducer type and reducer level on the effect of polymerization rate, particle size and size distribution were investigated. It was found that with the existence of hydrophilic monomer HEMA, polymerization rate increased but the particle size decreased and the size distribution became narrowed with the increase of initiator level, reaction temperature and reducer sodium hydrogen carbonate (NaHSO3) level. The APS/NaHSO3 system had better initiation efficiency than the APS/FeSO4 system. Copyright © 2006 John Wiley & Sons, Ltd.
Organosilicon ion‐exchange and complexing adsorbents
Authors: Voronkov M. , Vlasova N. , Pozhidaev Yu. , Belousova L. , Grigoryeva O. 
Published: September 2006

AbstractLong and systematic investigations of the present authors in the creation of organosilicon adsorbents, ion‐exchange and complexing agents are summarized. A wide series of such adsorption materials were synthesized by hydrolytic polycondensation and oxidizing hydrolytic polycondensation of organosilicon monomers of general formula X3SiQY and X3SiQZQSiX3, where X = Cl, AlkO; Q = alkylene C1–C3, phenylene; Y and Z = carbofunctional ionic and complexing groups. In this way, it was possible to obtain polyorganylsilsesquioxanes with carbofunctional groups such as Y = SH, SO3H, S(CH2)2NH2, SCH2COOH, NHC(O)CH3, NHC(S)CH3, NHC(NH)NH2, NHC(NH)NHC(NH)NH2, Z=S, SS, S(CH2)2S, NHC(O)NH, NHC(S)NH, NHSSNH, NHS(O)NH, NHS(O2)NH, NHC(SO2)NH, NHC(NH)NH, NHC(S)S− · NH3+, etc., which turned out to be very effective ion‐exchange and complexing adsorbents. These adsorbents have a crosslinked silsesquioxane structure. The three‐dimensional structure of the polyorganylsilsesquioxane skeleton of these adsorbents provides for their high thermal and chemical stability. They are stable up to 230–270°C and do not lose their adsorption activity in 10–18 mol/l H2SO4 at 100°C and in boiling concentrated HCl. The ion‐exchange and complexing properties of organosilicon adsorbents were studied on 50 elements of the Periodical system. Effective adsorbents toward noble metals, rare, rare‐earth and toxic elements have been found. The practical application of organosilicon adsorbents is described. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis of polymerizable amphiphiles with critical packing parameters systematically varied
Authors: Li M. H. , Yang W. L. , Qian J. , Wang C. C. , Fu S. K. 
Published: September 2006

AbstractIn this paper the design and synthesis of a group of polymerizable amphiphiles with different ratios of the number of hydrophilic heads and the number of hydrophobic tails are reported. The head/tail number ratio could be viewed as an approximate equivalent of the critical packing parameter. The synthetic procedure was optimized to be extendable. The design is expected to furnish a robust library of polymerizable amphiphiles for formation and immobilization of surfactant phases. Copyright © 2006 John Wiley & Sons, Ltd.
Lightly crosslinked, mesomorphic networks obtained through the reaction of dimeric, liquid‐crystalline epoxy–imine monomers and heptanedioic acid
Authors: Ribera David , Giamberini Marta , Serra Angels , Mantecón Ana 
Published: September 2006

AbstractWe reacted various dimeric, liquid‐crystalline epoxy–imine monomers, differing in the length of the central aliphatic spacer or the dipolar moments, with heptanedioic acid. The resulting systems showed a liquid‐crystalline phase in some cases, depending on the dimer and on the reaction conditions. The systems were characterized with respect to their mesomorphic properties and then were submitted to dynamic mechanical thermal analysis in both fixed‐frequency and frequency‐sweep modes in the shear sandwich configuration. The arrangement in the liquid‐crystalline phase seemed to be mainly affected both by the polarization of the mesogen and by the reaction temperature, which favored the liquid‐crystalline arrangement when it was lying in the range of stability of the dimer mesophase. In agreement with other recent literature data, dynamic mechanical thermal analysis results suggested that the presence of the mesogen directly incorporated into the main chain increased the lifetimes of the elastic modes both in the isotropic phase and in the liquid‐crystalline phase with respect to side‐chain liquid‐crystalline elastomers and that the time–temperature superposition principle did not hold through the liquid‐crystalline‐to‐isotropic transition. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44:6270–6286, 2006
Synthesis, characterization, and electrical properties of polypyrrole/multiwalled carbon nanotube composites
Authors: Wu Tzong‐Ming , Lin Shih‐Hsiang 
Published: September 2006

AbstractSize‐controllable polypyrrole (PPy)/multiwalled carbon nanotube (MWCNT) composites have been synthesized by in situ chemical oxidation polymerization directed by various concentrations of cationic surfactant cetyltrimethylammonium bromide (CTAB). Raman spectra, FTIR, SEM, and TEM were used to characterize their structure and morphology. These results showed that the composites are core (MWCNT)–shell (PPy) tubular structures with the thickness of the PPy layer in the range of 20–40 nm, depending on the concentration of CTAB. Raman and FTIR spectra of the composites are almost identical to those of PPy alone. The electrical conductivities of these composites are 1–2 orders of magnitude higher than those of PPy without MWCNTs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6449–6457, 2006
Synthesis of novel boron‐containing epoxy–novolac resins and properties of cured products
Authors: Martín C. , Lligadas G. , Ronda J. C. , Galià M. , Cádiz V. 
Published: September 2006

AbstractEpoxy–novolac resins were synthesized by modifying a commercial novolac resin with epichlorohydrin. These epoxy–novolac resins were characterized and further modified with different contents of bis(benzo‐1,3,2‐dioxa‐borolanyl)oxide or bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxa‐borolanyl)oxide. The boron‐containing epoxy–novolac resins were autocatalytically crosslinked or crosslinked with BF3MEA and their thermal stability and flame retardancy were determined by thermogravimetric analysis and limiting oxygen index (LOI) values. These LOI values for the bis(benzo‐1,3,2‐dioxa‐borolanyl)oxide derivatives were higher than the boron‐free novolac resins, which shows the benefit of the presence of boron. To test the role of boron in the enhancement of flammability, scanning electronic microscopy and energy‐dispersive X‐ray spectroscopy images were made. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6332–6344, 2006
A3‐type star polymers via click chemistry
Authors: Altintas O. , Yankul B. , Hizal G. , Tunca U. 
Published: September 2006

AbstractWe report a simple preparation of three‐armed (A3‐type) star polymers based on the arm‐first technique, using a click‐reaction strategy between a well‐defined azide‐end‐functionalized polystyrene, poly(tert‐butyl acrylate), or poly(ethylene glycol) precursor and a trisalkyne‐functional initiator, 1,1,1‐tris[4‐(2‐propynyloxy)phenyl]ethane. The click‐reaction efficiency for A3‐type star formation has been investigated with gel permeation chromatography measurements (refractive‐index detector). The gel permeation chromatography curves have been split with the deconvolution method (Gaussian area), and the efficiency of A3‐type star formation has been found to be 87%. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6458–6465, 2006
Amphiphilic conetworks. II. Novel two‐step synthesis of poly[2‐(dimethylamino)ethyl methacrylate]–polyisobutylene, poly(N‐isopropylacrylamide)–polyisobutylene, and poly(N,N‐dimethylacrylamide)–polyisobutylene hydrogels
Authors: Toman Luděk , Janata Miroslav , Spěváček Jiří , Brus Jiří , Sikora Antonín , Látalová Petra , Holler Petr , Vlček Petr , Dvořánková Barbora 
Published: September 2006

AbstractAmphiphilic polymer conetworks consisting of hydrophilic poly[2‐(dimethylamino)ethyl methacrylate], poly(N‐isopropylacrylamide), or poly(N,N‐dimethylacrylamide) and hydrophobic polyisobutylene chains were synthesized with a novel two‐step procedure. In the first step, a methacrylate‐multifunctional polyisobutylene crosslinker was prepared by the cationic copolymerization of isobutylene with 3‐isopropenyl‐α,α‐dimethylbenzyl isocyanate. In the second step, the methacrylate‐multifunctional polyisobutylene crosslinker, with a number‐average molecular weight of 8200 and an average functionality of approximately 4 per chain, was copolymerized radically with 2‐(dimethylamino)ethyl methacrylate, N‐isopropylacrylamide, or N,N‐dimethylacrylamide into transparent amphiphilic conetworks containing 42–47 mol % hydrophilic monomer. The synthesized conetworks were characterized with solid‐state 13C NMR spectroscopy and differential scanning calorimetry. The amphiphilic nature of the conetworks was proved by swelling in both water and n‐heptane. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6378–6384, 2006
Synthesis and properties of noncoplanar rigid‐rod aromatic polyhydrazides and poly(1,3,4‐oxadiazole)s containing phenyl or naphthyl substituents
Authors: Liou Guey‐Sheng , Hsiao Sheng‐Huei , Fang Yi‐Kai 
Published: September 2006

AbstractTwo new phenyl‐ and naphthyl‐substituted rigid‐rod aromatic dicarboxylic acid monomers, 2,2′‐diphenylbiphenyl‐4,4′‐dicarboxylic acid (4) and 2,2′‐di(1‐naphthyl)biphenyl‐4,4′‐dicarboxylic acid (5), were synthesized by the Suzuki coupling reaction of 2,2′‐diiodobiphenyl‐4,4′‐dicarboxylic acid dimethyl ester with benzeneboronic acid and naphthaleneboronic acid, respectively, followed by alkaline hydrolysis of the ester groups. Four new polyhydrazides were prepared from the dicarboxylic acids 4 and 5 with terephthalic dihydrazide (TPH) and isophthalic dihydrazide (IPH), respectively, via the Yamazaki phosphorylation reaction. These polyhydrazides were amorphous and readily soluble in many organic solvents. Differential scanning calorimetry (DSC) indicated that these hydrazide polymers had glass transition temperatures in the range of 187–234 °C and could be thermally cyclodehydrated into the corresponding oxadiazole polymers in the range of 300–400 °C. The resulting poly(1,3,4‐oxadiazole)s exhibited Tg's in the range of 252–283 °C, 10% weight‐loss temperature in excess of 470 °C, and char yield at 800 °C in nitrogen higher than 54%. These organo‐soluble polyhydrazides and poly(1,3,4‐oxadiazole)s exhibited UV–Vis absorption maximum at 262–296 and 264–342 nm in NMP solution, and their photoluminescence spectra showed maximum bands around 414–445 and 404–453 nm, respectively, with quantum yield up to 38%. The electron‐transporting properties were examined by electrochemical methods. Cyclic voltammograms of the poly(1,3,4‐oxadiazole) films cast onto an indium‐tin oxide (ITO)‐coated glass substrate exhibited reversible reduction redox with Eonset at −1.37 to −1.57 V versus Ag/AgCl in dry N,N‐dimethylformamide solution. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6466–6483, 2006
Characteristic properties of film prepared from poly(L‐lactide)‐grafted dextran of a relatively high sugar unit content as a degradable biomaterial
Authors: Ouchi Tatsuro , Kontani Tomohiro , Aoki Rie , Saito Toshifumi , Ohya Yuichi 
Published: September 2006

AbstractTo develop novel biomedical soft materials with degradability, amphiphilic poly(L‐lactide)‐grafted dextrans (Dex‐g‐PLLAs) of relatively high sugar unit contents were synthesized with the trimethylsilyl protection method. The characteristic properties of solution‐cast films prepared from the obtained Dex‐g‐PLLAs were investigated. The water absorption and degradation rate of the Dex‐g‐PLLA films increased with increasing sugar unit content. The morphology of the bulk phase and top surface of the Dex‐g‐PLLA films was evaluated with transmission electron microscopy and atomic force microscopy, respectively. The bulk phase of the Dex‐g‐PLLA films with a sugar unit content of 16–25 wt % was found by transmission electron microscopy to form a lamellar type of phase‐separated structure composed of approximately 80–100‐nm‐wide nanodomains because of their amphiphilic and branched structures. The hydrophobic top surface for a Dex‐g‐PLLA film with a sugar unit content of 25 wt % covered with PLLA segments was confirmed by atomic force microscopy phase images to be easily converted to a wettable top surface covered with hydrophilic dextran aggregates showing an 8–10‐nm‐wide honeycomb pattern by means of annealing in water. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6402–6409, 2006
Experimental and theoretical investigation of anomalous sorption kinetics in the methanol vapor–poly(methyl methacrylate) system at 35 °C
Authors: Dimos V. , Sanopoulou M. 
Published: September 2006

AbstractNon‐Fickian sorption kinetics of methanol vapor in a poly(methyl methacrylate) film of 8 μm, at 35 °C, are presented. The behavior of the system was studied in series of interval absorption runs. The relevant diffusion and viscous relaxation processes were studied by kinetic analysis of the sorption kinetic curves, using the relaxation‐dependent solubility model. The sorption isotherm concaves upward at high activities, typical to Florry–Huggins behavior, while it exhibits a convex‐upward curvature at low methanol vapor activities, indicating sorption in the excess free volume of the polymer matrix. Thermodynamic diffusivity presents a complex functional dependence on the concentration, while relaxation rate is found to be a function of concentration as well as of concentration interval. Relaxation rate becomes increasingly concentration‐dependent as the effective glass transition of the system is approached. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3173–3184, 2006
Rheological study on structural transition in polyethersulfone‐modified bismaleimide resin during isothermal curing
Authors: Liu Xiaoyun , Zhan Guozhu , Yu Yingfeng , Li Shanjun 
Published: September 2006

AbstractThe structural transition in the polyethersulfone (PES)‐modified bismaleimide resin, 4,4′‐bismaleimidodiphenylmethane (BDM), during isothermal curing was studied by using rheological technique, different scanning calorimetry (DSC), and time resolved light scattering (TRLS). Comparing with the cure of neat bismaleimide, two separate tan δ crossover points were observed because of the phase separation during curing the blends of PES/BDM. These two structural transitions stemmed from the fixing of phase structure of the system and the chemical crosslinking of bismaleimide, respectively. The effect of curing temperature and the PES content on structural transition was discussed and found that the occurrence of two structural transition exhibited the different dependency of curing temperature and PES content. The relaxation exponent n and gel strength S were also found to be temperature‐dependent and composition‐dependent. Moreover, the relaxation exponent n of the second structural transition is much lower than that of the first structural transition in the PES/bismaleimide blends. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3102–3108, 2006
Assessment of thermal expansion coefficient of methylsilsesquioxane thin film
Authors: Kim B. R. , Son J. M. , Ko M. J. 
Published: September 2006

AbstractFor the methylsilsesquioxane film whose optical birefringence is almost zero, it was recently reported that its vertical thermal expansion coefficient (CTE) was approximately one order of magnitude larger than the lateral CTE. Though the birefringence is not an absolute predictor of anisotropic behavior, the discrepancy in both the CTEs was so remarkable that it was essential to investigate whether the anisotropy was intrinsic property or not. If the effect of Poisson's ratio is considered in the calculation of the vertical CTE and when elastic modulus measured by surface acoustic wave spectroscopy is used in the assessment of the lateral CTE, both the CTEs are coincident with each other. Therefore, it can be concluded that the discrepancy in the CTEs can be attributed to a higher in‐plane polymer chain orientation but it can also arise from the misleadingly assumed modulus and Poisson's ratio. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3109–3120, 2006
Polyaniline/iron nanocomposites prepared by cryomilling
Authors: Zhu Y. G. , Li Z. Q. , Gu J. J. , Zhang D. , Tanimoto T. 
Published: September 2006

AbstractThe polyaniline/iron nanocomposites with both conducting and magnetic properties have been prepared by cryomilling (high‐energy ball milling under cryogenic temperature), in which the average size of iron grains attains 20 nm. Enhanced coercivity of 206 Oe and decreased conductivity of 0.1 S cm−1 at room temperature have been obtained for the nanocomposites containing 10% volume fraction of iron in polyaniline after cryomilling for 20 h. The high value of the coercivity could be considered due to the presence of a fraction of single‐domain particles in the nanocomposites. The low value of the conductivity could be considered due to the dedoping of conducting polyaniline with the cryomilling time. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3157–3164, 2006