bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and absorbency of gelatin-graft-poly(sodium acrylate-co-acrylamide) superabsorbent hydrogel with saltand pH-responsiveness properties
Authors: Pourjavadi Ali , Sadeghi Mohammad , Mahmodi Hashemi Mohammad , Hosseinzadeh Hossein 
Published: August 2014

AbstractIn this article, we synthesize a novel gelatin-based superabsorbent hydrogel via graft copolymerization of mixtures of acrylic acid (AA) and acrylamide (AAm) onto gelatin backbones. The polymerization reaction was carried out in an aqueous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N'-methylene bisacrylamide (MBA) as a crosslinker. The hydrogel structures were confirmed by FTIR spectroscopy. The effect of grafting variables, i.e. concentration of MBA and APS, AA/AAm weight ratio, and reaction time and temperature, was systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The swelling behavior of these absorbent polymers was also investigated in various salt solutions. Results indicated that the swelling capacity decreased with an increase in the ionic strength of the swelling medium. Furthermore, the swelling of superabsorbing hydrogels was examined in solutions with pH values ranging between 1.0 and 13.0. It showed a reversible pH-responsive behavior at pHs 2.0 and 7.0. This on-off switching behavior makes the synthesized hydrogels an excellent candidate for controlled delivery of bioactive agents. Finally, the swelling kinetics of the synthesized hydrogels with various particle sizes was preliminarily investigated.
Preparation and Characterization of Core-Shell Latex Containing PDMS in the Shell
Authors: Zhang Baotan , Liu Bailing , Cao Shunsheng , Deng Xiaobo 
Published: August 2014

AbstractIn this paper, the composite latex particles with a polyacrylate (PA) core and a polydimethylsiloxane (PDMS) shell via 3-(methacryloxypropyl)- trimethoxy silane (MPS) as the medium to link the core and shell were prepared by semicontinuous seeded emulsion polymerization and were characterized by transmission electron microscopy (TEM), FT-IR, particle size analyzer and X-ray photoelectron spectroscopy (XPS). The TEM images indicated that the particles containing organic siloxane (D-40) displayed an evident core/shell structure. Additionally, the study by FT-IR and XPS also revealed that D4 could be grafted onto the surface of polyacrylate core because there appeared the characteristic peaks of Si-O-Si group and Si 2s and Si 2p in the spectra of FT-IR and XPS respectively. Besides, the atomic ratio of C/Si on the surface of the core/shell particles (D-40) was close to the ratio of C/Si in the latex of pure PDMS that could prove the PA particles were fully covered by PDMS and the properties of PDMS should be embodied in a maximal level. In order to testify the result, the surface properties of the films produced from the core/shell particles were also investigated by the static contact angle method. Compared with the copolymer of PA, the core/shell particles were more effective to create hydrophobic surface, so, the introduction of D4 was capable of obvious increase in water repellency.
Synthesis of Well-defined Carbazole Group Labelled Polymer via RAFT Polymerization and Study on the Optical Properties
Authors: Zhou Di , Zhu Xiulin , Zhu Jian , Hu Lihua , Cheng Zhenping 
Published: August 2014

AbstractBenzyl 9H-carbazole-9-carbodithioate (BCC) was synthesized and characterized. The single-crystal structure of BCC was first reported. The RAFT polymerizations of styrene and acrylates using BCC as the RAFT agent under conventional polymerization conditions were investigated. The results showed that the BCC was an effective RAFT agent for the polymerizations of styrene and acrylates. The well-controlled polymers were labelled with carbazole group, which was confirmed by 1H NMR and the chain extension of the obtained polymer. Azo modified poly(methyl acrylate) (PMA) was synthesized through a postpolymerization azo-coupling scheme. The optical properties of obtained polymer were also characterized. The results showed that the carbazole group labelled polymer exhibited fluorescence and the azo polymer exhibited UV absorption behaviour in N,N-dimethyl formamide (DMF).
Preparation of a Novel Cellular Fiber: Control of Cell Density of the Fiber
Authors: Linfeng Guo , Xiong Chunyan , Zhu Jiangjiang , Wang Yimin 
Published: August 2014

AbstractA new cellular fiber was obtained by a post-treatment of spun fibers. Cellular polymers such as poly(ethylene terephthalate) show great promise for different engineering applications due to their high density property. Recent study has shown that some high density cellular polymers possess long fatigue life and/or equivalent strengths as compared with commercial-type neat polymers. However, only few studies have focused on the process of cellular polymer fibers to date. In this paper, the effect on a cellular structure of cellular PET fibers (hereafter called “CPET fibers”) subjected to different forming processes is discussed. An ultra saturating gas method was used to fabricate the CPET fibers with different cell densities. Inert gas nitrogen (N2) was saturated in PET fiber at high pressure to form a polymer/gas system. A pressure vessel was then discharged and polymer/gas solutions were foamed at a temperature controlled medium. The effect on the fiber’s cellular structure, particularly on the fiber cell density with different processing parameters such as pressure, saturation time, foaming temperature and time was investigated in detail. Experimental results showed that the cell density of the CPET fibers increased with increasing the pressure, saturation time, foaming temperature and time. The saturation time and pressure are key factors that affect the density of cells formed inside the CPET fibers. The foaming time however showed no substantial influence on the cell density of the fibers when held longer than 10s.
HPLC separation of ibuprofen and mefenamic acid using molecularly imprinted polymer as stationary phase
Authors: Hung Chin-Yin , Huang Yun-Tzu , Huang Han-Hung , Hwang Ching-Chiang 
Published: August 2014

AbstractA simple high-performance liquid chromatographic method for the assay of ibuprofen and mefenamic acid in tablets is described. This method was developed by using self-prepared molecularly imprinted polymers (MIPs) as the stationary phase. MIPs are synthesized using non-covalent method by the free radical polymerization of template, functional monomer and an excess of crosslink monomers resulting in organic materials. The resulting bulk material was then ground into 25~44μm particles and packed into analytical columns. The effect of functional monomers/crosslinking ratio and the concentration of acetonitrile in the mobile phase were studied. Ibuprofen and mefenamic acid were efficiently resolved on the polymer. The retention time of ibuprofen and mefenamic acid were approximately 19.69±0.36min and 46.27±1.23min, respectively. Linearity was observed from 3.13-8.33g/l for ibuprofen and 0.3-0.9g/l for mefenamic acid, with the coefficients of determination (r2) of 0.9977 and 0.9958. The limits of detection (LOD) of ibuprofen and mefenamic acid were found to be respectively 0.42g/l and 0.06g/l, while the limits of quantitation (LOQ) were 1.41g/l and 0.20g/l, respectively. The self-prepared MIP was successfully applied to the commercial tablet analysis and the result showed a good accuracy with -1.33 ~ -1.8% and -0.8 ~ +1.33% for ibuprofen and mefenamic acid.
Role of magnesium complexes in the anionic polymerization of hexano-6-lactam
Authors: Arnoldová Petra , Brus Jiří , Prokopová Irena , Brožek Jiří 
Published: August 2014

AbstractThe course of anionic hexano-6-lactam polymerization initiated with magnesium compounds differs in some parameters from that initiated with lactam alkali salts. This may be attributed to the coordination of magnesium compounds with functional groups on polymer chains. Supposed coordination effects were proved on model compounds of N-ethylacetamide and N-butyryl-hexano-6-lactam with magnesium bromide. Based on interpretation of Raman and NMR spectra, the interaction between magnesium bromide and both types of ligands as an electron donating coordination of carbonyl groups was proposed. N-butyryl-hexano-6-lactam is more distinctly coordinated to magnesium atom through the carbonyl group located in the cyclic constitution unit.
High-throughput experimentation applied to atom transfer radical polymerization: Automated optimization of the copper catalysts removal from polymers
Authors: Zhang Huiqi , Abeln Caroline H. , Fijten Martin W. M. , Schubert Ulrich S. 
Published: August 2014

AbstractCombinatorial chemistry and high-throughput experimentation have drawn great attention in recent years because of their significant advantages in increasing the research productivity. One of the emerging fields is their application in polymer science. Herein we describe the high-throughput optimization of purification conditions for polymers prepared via atom transfer radical polymerization using an automated synthesizer. The effects of the column materials, column lengths and eluent volumes on the purification efficiency as well as the molecular weights of the obtained purified polymers were systematically investigated for the first time. The optimum purification conditions for the removal of copper catalysts are provided. As a result an online high-throughput purification workflow using SPE cartridges is now available for the utilization in automated parallel synthesizers for ATRP screening experiment.
Atom transfer rearrangement radical polymerization of (2,4,6-trihalophenolato) Fe(II) / Ce(III) / Ce(IV) complexes in solid state
Authors: Çelik Güler Bayraklı , Sultan Wadie , Kısakürek Duygu 
Published: August 2014

AbstractThe synthesis of poly(dihalophenylene oxide)s by thermal decomposition of Fe(II), Ce(III) and Ce(IV) phenolato complexes with pyridine as neutral ligands were achieved at different temperature ranges (140o - 250oC) with different time intervals (3 - 48 hr) via atom transfer rearrangement radical polymerization (ATRRP). The complexes were characterized by FTIR, DSC, UV-Visible, mass spectroscopy, magnetic susceptibility and elemental analyses. Structural analyses of polymers were performed by 1H and 13C-NMR, FTIR spectroscopic analyses, Tg by DSC and the molecular weights by viscometrical method. 1H-NMR spectra of polymers are quite similar in pattern except the relative intensities of two main peaks, all having branched structures. The lowest percent conversion values were observed for polymers synthesized from Fe(III) complexes compared to Ce(III) and Ce(IV) complexes. The glass transition temperature of the polymers were quite high indicating they are rigid polymers (162o to 187 oC).
Ethylene Polymerization over Transition Metal Supported Catalysts. III. Vanadium
Authors: Matos Inês , Zhang Yingjun , Fonseca Isabel , Lemos Francisco , Lemos Manda , Freire Filipe , Fernandes Anabela C. , Botelho do Rego Ana M. , Valente Anabela , Mano João F. , Henriques Rui T. , Marques Maria M. 
Published: August 2014

AbstractThe polymerization of ethylene in the presence of vanadium catalysts supported on zeolite NaY, HY and charcoal was examined. The catalysts were prepared by the incipient wetness method and characterized by a variety of techniques to determine the oxidation state of the vanadium species inside the zeolite. In all the catalysts that were prepared vanadium is not in a single oxidation state. These catalysts were active in the polymerization of ethylene with activities of the order of magnitude 105 gPE/molV.[M].h for the zeolite catalysts and 103 gPE/molV.[M].h for the charcoal systems. No polymer could be obtained in the absence of alkylaluminum or aluminoxane in the experimental conditions used. The kinetics of ethylene polymerization reactions using the vanadium catalysts was studied. A kinetic model based on a proposed mechanism for these reactions was used to fit the experimental data. The application of this model resulted in very good fittings and the kinetic rate constants of each elementary step could be estimated. Since the polyethylene that was produced is closely bound to the zeolite catalysts, the thermal and mechanical properties of the PE/zeolite composites were measured, indicating that the presence of zeolite improved the mechanical properties of the polymers produced.
The Synthesis and Crystallization of Poly(vinylidene fluoride) in Supercritical CO2
Authors: Shi Zhendong , Zheng Zhen , Su Xiaoli , Wang Xinling 
Published: August 2014

AbstractA series of poly(vinylidene fluoride)s (PVDFs) is synthesized in supercritical carbon dioxide (sc-CO2). The influences of polymerization pressure, molecular weight distribution and H-H defect concentration on the crystallization of PVDF have been studied in combination with differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXRD) and Fourier transform infrared spectroscopy (FT-IR) measurements. The result shows that the morphology, molecular weights, polydispersity and head-to-head (H-H) defect concentrations of the PVDFs are affected by the reaction pressure and good solubility generated from sc-CO2. Especially, the sc-CO2 polymerization has greatly improved the crystallization mode of the obtained PVDFs such as the complete degree of crystallinity, crystallinity and the crystal phase. This will create more comprehensive application fields for PVDF.
Water expandable polystyrene (WEPS): Part 4. Synthesis of the water expandable blend of polystyrene and poly(2,6- dimethyl-1,4-phenylene ether)
Authors: Snijders Emile A. , Nelissen Laurent , Lemstra Piet J. 
Published: August 2014

AbstractIn previous studies, we discussed the use of water as an environmentally benign blowing agent for foaming of polystyrene beads, resulting in so-called WEPS, viz. water expandable polystyrene foam. Several grades of precursors to WEPS have been prepared by varying the water content and the molar mass, to control the melt strength of the polystyrene matrix. Additionally, we have used (endcapped) poly(2,6-dimethyl-1,4-phenylene ether) (PPE) to control both the meltviscosity and the glass transition temperature Tg. The advantage of using the blend PS/PPE is that the processing window for foaming is increased in view of the difference between the Tg and the boiling point of water. Using the novel WEPS route with some adjustments, for the first time a water expandable homogeneous blend of polystyrene and end-capped PPE was successfully obtained.
Mechanical properties of thin microcellular PET sheet
Authors: Guan Rong , Banglong Xiang , Yinglin Li , Zhaoxin Xiao , Deping Lu , Gongwu Song 
Published: August 2014

Abstract In this paper, the thin microcellular poly(ethylene terephthalate)(PET) sheets, having the controlled structures, were prepared by compression molding. The effects of the processing conditions on the microcellular PET tensile properties have been investigated. By comparing the importance of the individual processing parameters, the saturation time was the most important factor to determine tensile modulus, whereas the saturation time and the upper-plate temperature were the most important processing parameters that influence the tensile strength and specific tensile strength. The effects of the microstructure on the tensile properties of microcellular PET were also investigated systematically. The results indicated that the tensile modulus and strength increased with increasing foam density, but decreased slightly with increasing cell size. Following the experimental data, a new model was built to relate the tensile modulus and tensile strength with the foam density and the cell size.
A new way of step-mass-thermal transferring to control phase inversion for polyacrylonitrile(PAN)/DMSO/water system
Authors: Bing-Xin Jiang , Huan-Qin Zhu , Zhan-He Du , Cheng-Xun Wu 
Published: August 2014

AbstractThe step-mass-thermal transferring meant that for PAN/DMSO/water system, the kinetic of phase inversion and droplet ripening was controlled by employing several consecutive coagulation baths with different concentrations and temperatures. In this way, the morphology of fiber could be adjusted based on modelling. The phase diagram of PAN/DMSO/water was calculated based on Flory-Huggins theory. The mass and thermal transferring was calculated according to Fick’s second law and Fourier heat equation respectively.
Novel blocked functionality copolymers as surface coatings in DNA microarray technology
Authors: Viganò M. , Levi M. , Chiari M. , Damin F. , Turri S. 
Published: August 2014

AbstractNew copolymers made of 2-(dimethyl amino) ethyl methacrylate (DMAEM) and isocyanate ethyl methacrylate blocked with methyl ethyl ketoxime (IEMB) was synthesized in various composition ratios in order to obtain water reducible copolymers after acidification. They were characterized by infrared spectroscopy, chemical titration for the determination of amine equivalent weight, and by differential scanning calorimetry (DSC). Calorimetric analysis showed the presence of a former broad endothermal peak followed by a latter, stronger exothermal one, which can be respectively attributed to the deblocking of isocyanate groups and to their subsequent reactions. Some copolymer compositions were dip coated onto microscope glass slides and surfaces were characterized by static and dynamic contact angles, revealing a clear effect of the salifying agent and a likely surface rearrangement of polar groups while in contact with water. Finally, oligonucleotides surface immobilization and molecular recognition capability of the coated glass slides were positively assessed by hybridization tests with fluorescently labelled complementary probes.
Preparation of polyaniline/Fe2O3 composite dispersions in the presence of dodecylbenzene sulfonic acid
Authors: Yan Wu , Shuangxi Xing , Shengyu Jing , Teili Zhou , Chun Zhao 
Published: August 2014

AbstractWe reported a chemical approach for the in-situ preparation of conducting polyaniline (PANI)/Fe2O3 composite dispersions using dodecylbenzene sulfonic (DBSA) acid both as dopant and surfactant. The PANI/Fe2O3 composite dispersions were characterized by X-ray diffraction, UV-vis and FT-IR spectra and conductivity measurement. The dispersions showed good stability and existed without precipitate for at least half a year. The gas-sensing behavior of the composite film to 100 ppm of NH3 was studied through monitoring the change of the resistance.
Preliminary testing of silicone-urethane elastomers as substrates in human cell culture
Authors: Lewandowska-Szumieł Malgorzata , Kozakiewicz Janusz , Mrówka Piotr , Jurkowska Agnieszka , Sienkiewicz-Łatka Edyta , Przybylski Jarosław , Okrój Wiesława , Walkowiak Bogdan 
Published: August 2014

AbstractSilicone-urethanes, polymers combining the characteristics of two widely used biomaterials, i.e. polyurethanes and silicones, are highly valued in many applications, including medical implants. To assess properties of these materials in contact with living cells, a set of different silicone-urethane materials, candidates for tissue engineering scaffolds, was synthesized and characterized. Two different oligomeric siloxane diols: Tegomer-2111 (Teg) and KF-6001 (KF), and two different types of diisocyanate, MDI and IPDI, were used in synthesis. Blood platelets adhesion to surfaces of selected materials showed a higher thrombogenicity of material based on Teg. Human fibroblasts were used in in vitro biocompatibility tests. The viability of cells cultured on silicone-urethanes was tested by XTT assay. Teg-based silicone-urethanes showed a significantly higher biocompatibility than those based on KF. Materials based on MDI compared to IPDI were found to be significantly more favoured by cells, not necessarily due to the type of diisocyanate but maybe also because of the necessity of using potentially toxic catalyst which accompanies the use of IPDI. Our studies indicate that silicone-urethanes are potent materials for tissue engineering products development. On the basis of the observations performed in cell culture, Tegomer- 2111 as oligomeric siloxane diol and MDI as diisocyanate are recommended as starting materials for silicone-urethane scaffolds synthesis.
Second-order nonlinear optical properties of polyphosphazenes containing multi-dipolar and imidazolebased chromophores
Authors: Yang Pan , Xiaozhen Tang 
Published: August 2014

AbstractThe synthesis and second-order nonlinearity study of several new polyphosphazenes were described, which are composed of a new type of Yshaped nonlinear optical (NLO) chromophores attached onto polyphosphazene. They were obtained via a post-azo coupling reaction. The resulting materials were characterized by means of 1H NMR, 31P NMR, FT-IR, UV-vis, GPC and DSC. Chromophore contents up to 14 mol% have been realized. The polymers have high glass-transition temperatures, good optical transparency, and the poled film of P3- P8 revealed a resonant d33 value in the range of 11-42 pm/V by second harmonic generation (SHG) measurements.
Guar gum as filler in unsaturated polyester composites
Authors: Shenoy Mohan , D’Melo Dawid John 
Published: August 2014

AbstractGuar gum is a natural polysaccharide that has been explored for various applications. However, there is a limited number of studies in which guar gum has been used as a filler in a polymer. The effect of acetylation of guar gum on its properties as a filler in an unsaturated polyester matrix was studied. The rheology of the uncured composition indicated increased polymer-filler interaction with increased ester content. The tensile and flexural properties increased with the acetylation degree of guar gum; however the impact resistance of the composites was reduced. Excessive esterfication of guar gum was detrimental to the mechanical properties of the composites due to reduced hydrogen bonding resulting in the filler phase having lower integrity. The chemical properties of the composites were also studied as well as the effects of acetylation. Thus, an increase in the hydrophobic nature of guar gum resulted in an increase in the polymer-filler adhesion and interaction but at the same time reduced the hydrogen bonding leading to reduced cohesion of the filler particles. This resulted in reduced mechanical properties of the composites as compared to lower acetylated guar gum based composites.