bluuebunny/crossref_metadata_2025_split huggingface dataset:
Swelling studies and adsorption of safranin T by acrylamide/maleic acid/methylene-bis-acrylamide based hydrogels
Authors: Velásquez Cristóbal Lárez , Ramírez Marvelis , Millán Enrique , Medina Arelis 
Published: August 2014

AbstractSwelling studies of an acrylamide/maleic acid/methylene-bis-acrylamidebased hydrogel prepared by free radical polymerization (weight ratio of 90/10/3) are presented. Water penetration mechanism was studied by using two classical definitions, i.e., Crank (FC = Wt/Weq) and Karadag (FK = (Wt-Wo)/Wo), of the water fraction into the hydrogel (F). An anomalous water penetration mechanism (0.5<n<1.0) was obtained by employing both definitions and Buckley equation (F = ktn); however, using the combined Peppas and Sahlin equation (F = k1t1/2 + k2t) pointing out that swelling occurs in two stages: at first controlled by diffusion and relaxation contributions and then defined mainly by the diffusion contribution. Hydrogel was also studied as a system for the adsorption of cationic dye Safranin. Results show that this system perfectly fit to a Langmuir isotherm and the dye adsorption process stops when coverage of all active sites on the hydrogel has been achieved. Interestingly, adsorption process does not seem to be affected even though the hydrogel concurrently suffers the well known collapse phenomenon.
Enhanced copper-catalyzed “click” reaction between homopolymers with terminal azide and alkyne groups in the presence of water
Authors: Liu Zhilei , He Guping , Hu Jiwen , Sun Jianping , Liu Guojun , Li Yinhui , Xiao Dingshu , Tu Yuanyuan 
Published: August 2014

AbstractWe report here that the efficiency of the click chemistry between the terminal azide and alkyne groups of different polymer chains could be drastically increased with the addition of an optimum amount of water into a reaction system. That is, the efficiency was only slightly promoted by the addition of a small amount of water into the reaction mixture. However, the reaction efficiency was increased dramatically near the water volume fraction to lead the reaction mixture into nanosized phase separation. Further increasing in water content caused the polymer(s) to undergo macroscopic phase separation and the click reaction efficiency was decreased once again. The enhanced efficiency of click coupling reaction including conversion and rate was also demonstrated via in-situ 1H-NMR. The reaction kinetics as well as reaction rate constant for these reaction system with typical water content were also evaluated. This finding on enhanced click reaction is of practical value, because click reactions in polymer synthesis are generally more difficult to be carried out and proceed relative slowly at low yield in most case because of the strong steric hindrance effect from “large and long” polymer chains, as compared to “click” reactions which are employed for preparation of the low molecular weight organic compounds.
The effect of P-chiral center on helical conformation of optically active N-propargylphosphonamidates
Authors: Lu Lihua , Mo Jiaoli , Yang Qiang , Zhang Liqun , Wang Weimin , Yue Dongmei 
Published: August 2014

AbstractNovel chiral and achiral N-propargylphosphonamidate monomers [HC=CCH2NH(P=O)R1R2,where 1: R1=CH3,R2=NHC(CH3)32: R1=CH3,R2 =NHC5H93:R1=OPh,R2=NHC(CH3)3, 4:R1=R2=OPh] were synthesized by successive condensation in order to study the helical conformation properties of N-phosphonamidates. One diastereomer was successfully separated from the other in the cases of monomer 1-3(named 1a-3a) according to the single peak in the 31P NMR spectra. Polymerizations of the monomers 1-4 were carried out with (nbd)Rh+[η6-C6H5B-(C6H5)3] as catalyst in CHCl3 yielding the polymers with number-average molecular weights of 1300-22400. Poly(1a)-poly(3a) and poly(4) were characterized by UV and CD spectroscopy. Poly(1a)- poly(3a) showed an intense positive CD signal at 325 nm based on the conjugated polyacetylene backbone while poly(4) showed no peak there, indicating that the polymers had a helical structure with predominantly one-handed screw sense because of P-chiral centre sole contribution.
Synthesis and characterization of poly(St-co-DVB)/montmorillonite nanocomposites by suspension polymerization
Authors: Ji Jiaming , Cao KeSheng , Tang Hua , Li ChangSheng 
Published: August 2014

AbstractPoly(styrene-co-divinylbenzene)/organic montmorillonite (OMMT) nanocomposites were prepared by suspension polymerization. OMMT was prepared by ion exchange method between sodium montmorillonite (SMMT) and cetyltrimethyl ammonium bromide (CTAB) in an aqueous solution. The character and structure of OMMT was revealed by XRD and FT-IR. The microstructure of polymer/OMMT nanocomposites was characterized by XRD, TEM and SEM. The thermal stability of polymer/OMMT nanocomposites was studied by TG and DTG. Also the effect of the amount of OMMT and divinylbenzene (DVB) on the thermal stability of polymer/OMMT nanocomposites has been discussed in this paper. It was observed that the crosslinked polymer/clay nanocomposites exhibited better thermal stability than pure polystyrene and polystyrene/clay nanocomposites under the experimental conditions.
Preparation of poly(methyl methacrylate) nano-latexes via UV irradiation in the presence of iron aqueous solution
Authors: Zhang Hong , Zang Limin , Luo Jiahe , Guo Jinshan 
Published: August 2014

AbstractThe UV-initiated emulsion polymerization of methyl methacrylate (MMA) in the presence of FeCl3 was studied. The photopolymerization presented high efficiency even though using a small percentage of photoinitiator. The entire polymerization could be performed within 10 min and displayed a conversion higher than 90% at ambient temperature. The particle sizes could be tuned in the range of 20-90 nm. The effects of content of initiator and emulsifying agent upon the reaction conversion, distribution of molecular weight, diameter of particles and glass-transition temperature were examined. 1H-NMR technique was used to investigate the structural properties of PMMA.
Synthesis, characterization of pyridine-based polyimides and their use as glucose oxidase immobilization media
Authors: Paşahan Aziz , Köytepe Süleyman , Ekinci Ergun 
Published: August 2014

AbstractA novel diamine monomer, containing 2,6-diaminopyridine, bis-pdimethylaminophenyl- 2,6-pyridine (S26DAP), was prepared from 4- (dimethylamino)benzaldehyde and 2,6-diaminopyridine. The monomer was characterized by FT-IR, NMR and elemental analyzer. The monomer was then utilized to prepare polyimides with dianhydrides such as pyromellitic dianhydride (PMDA), 3,3’,4,4’-benzophenonetetracarboxylic dianhyride (BPDA), 4,4’- oxydiphthalic anhydride (ODPA) and 3,3’,4,4’-biphenyltetracarboxylic dianhydride (BTDA) by the one-step method; synthesis of polyimides, followed by thermal imidization. The polyimides were characterized by FT-IR, GPC with intrinsic viscosity and adhesive properties also being evaluated. The polyimides exhibited high Tg (°C) (186-209 °C), good thermal stability and good adhesive properties. Medium to high molecular weight polymers were attained, with inherent viscosities near or higher than 1.05-1.32 dL/g, the solubility in dipolar aprotic solvents of the polyimides were much better than that of the aromatic polyimides. Furthermore, chemically synthesized polyimides were used for immobilization of glucose oxidase (GOx). The amperometric responses of the prepared GOx-polyimide-coated electrodes to glucose were examined at a potential of 0.7 V in PBS solution by means of TB technique. The results show that polyimide (S26DAP-PI-4) can be used for immobilization of glucose oxidase.
A comparative study of the reactivity of three plant oil methyl esters with divinylbenzene by FTIR spectroscopy
Authors: Jin Fuqiang , Wang Bo , Hu Suqin , Wang Jianmei , Cai Feipeng , Yang Gai 
Published: August 2014

AbstractPoly(divinylbenzene) microspheres were prepared by seed swelling polymerization of divinylbenzene in the presence of tung oil methyl esters, linseed oil methyl esters and soybean oil methyl esters, respectively. FTIR spectroscopy was used to characterize the polymers for investigating the reactivity of the three plant oil methyl esters. Results showed that tung oil methyl esters had strongest reactivity with divinylbenzene, and soybean oil methyl esters had weakest reactivity of the three oil methyl esters in the polymerization. These results were related with the fatty acid compositions of the oils.
UV-Curable organic-inorganic hybrid films based on tetraethylorthosilicate oligomer and special acrylated polyester
Authors: He Jianyun , Xiong Jinping , Xia Bingqian 
Published: August 2014

AbstractOrganic-inorganic hybrid films were prepared using tetraethylorthosilicate (TEOS) oligomer and special acrylated polyester (SAP) via a UV-curing process. TEOS oligomers were prepared in the presence of water and ethanol using hydrochloric acid as the catalyst and characterized using 1H NMR, 29Si NMR and MALDI-TOF mass spectra. Special acrylated polyester was synthesized by 1,4-cyclohexane dimethanol, neopentyl glycol, 1,4-butanediol, maleic anhydride, adipic acid, and acrylic acid. Hybrid films were cured by UV light and the thermal properties, dynamic mechanical properties, and tensile properties of the hybrid films were evaluated as the function of TEOS oligomer content. The morphology of the hybrid films was examined using atomic force microscopy (AFM). The microscopy and dynamic mechanical data indicated that the hybrid films were heterogeneous materials with various inorganic particle sizes dispersed within the organic matrix. The results indicated that after incorporating the TEOS oligomer, the strength and thermal stability of the hybrid films were enhanced.
Observation of oxygen inhibited layer of organic dental resin by confocal Raman-microscopy
Authors: Robin Jean Baptiste , Durand Jean Cédric , Derely Loic , Jacquot Bruno , Cuisinier Frédéric , Robin Jean-Jacques 
Published: August 2014

AbstractThis study investigated degrees of conversion of oxygen inhibited layer (OIL) of organic dental resins for restoration using Confocal-Raman spectroscopy. The aim was to determine which laser is adapted to determine the degrees of conversion of OIL and to measure variations of thickness and degrees of conversion in OIL with respect to monomers proportions. Bis-GMA (bis-phenol A glycidyl dimethacrylate) and TEGDMA (triethylene glycol dimethacrylate) based resins with various ratio of an equimolecular mixture of camphorquinone/EDMAB (ethyl (4-dimethyl amino) benzoate) were studied with different lasers by confocal- Raman spectroscopy. Results show that this technique is adapted for the non destructive measurement of OIL. The Thickness of OIL is not correlated with the proportions of Bis-GMA and TEGDMA in the resin and was close to 3-4μm. Thickness of OIL is very thin without inorganic fillers (3 or 4 μm). Inorganic fillers might be responsible of greater OIL in composite resins.
Monte Carlo simulation of chromatin fibre confined in a nanochannel
Authors: Cao Qianqian , Zuo Chuncheng , Ma Yanhong , Li Lujuan 
Published: August 2014

AbstractWe study 30-nm chromatin fibre restricted in a nanofluidic channel with square cross-section using Monte Carlo (MC) simulations. The chromatin fibre is modelled as cylinders-on-a-string with six alterable angles. The effects of the channel width and Emax on the configuration of the chromatin fibre are investigated in detail. Our results show that the channel width has a considerable influence on conformational characteristics of the chain. It is found that at large Emax, the chromatin fibre undergoes a conformational transition from stretched state to coiled state with increasing the channel width. Additionally, the influence of the channel width is lowered with enhancing Emax. At small values of the channel width, the chains for different Emax exhibit a similar structure, namely, a stretched conformation
Effects of nanoparticles in cells infected by Toxoplasma gondii
Authors: Leyke Silja , Köhler-Sokolowska Wanda , Paulke Bernd-Reiner , Presber Wolfgang 
Published: August 2014

AbstractCore-shell model drug carriers on 2 nanoscale size levels have been applied in cell culture studies, focused on Toxoplasmosis therapy. In synthesis, a seed of Rhodamin B-labelled polystyrene latex particles was coated by polybutyl cyanoacrylate under physical inclusion of 2 different, new drugs against Toxoplasmosis. Drug-loaded as well as drug-free core-shell model drug carriers were added to a cell culture of human macrophages, infected by Toxoplasma gondii, following an infection plan. Drug release from the carriers had been studied before by enzymatic degradation by means of pork liver esterase. Particle size decrease by degradation was investigated in a UV/VIS spectrometer via transmission measurements. Drug release profiles were obtained by HPLC studies. The dynamics in the population of infected human macrophages, Toxoplasma gondii as well as model drug carrier numbers were registered by a FACS (fluorescence-activated cell sorter). As main result, the drug-free references in the 2 series of core-shell model drug carriers achieved ca.85% of the observed maximum in Toxoplasmosis therapy efficiency. These data were correlated with an immune stimulant effect on the side of the human macrophages, caused by the cell uptake of colloidal substrate, foreign to the body.
Investigation of the surface properties of POSS-modified polyacrylate by inverse gas chromatography
Authors: Zou Qi-chao , Yu Huan , Chen Hao 
Published: August 2014

AbstractThe surface properties of poly(methyl methacryl-ate-co-n-butyl methacrylate-co-cyclopentyl methacryloxy propyl-polyhedral oligomeric silsesquioxane) (poly(MMA-co -BMA-co-POSSMA)) were studied by means of inverse gas chromatography (IGC) using 10 non-polar and polar solvents as the probes. Thermodynamic parameters of adsorption, such as the dispersive component of the surface energy, the specific interaction contribution to the free energy of adsorption and the acid/base constants of polymer surface were determined. It was found that incorporation of POSSMA into polymer resulted in increasing interactions between polymers and solvents, dispersive component of surface free energy of polymer and acidity of the surfaces of the polymers. The more the POSSMA were embedded, the larger the dispersive component of the surface free energy was, and the acidic character of the polymer surface was more obvious.
Preparation of new FI-type catalyst for polymerization of ethylene
Authors: Sandaroos Reza , Damavandi Saman , Goldani Mohammad Taghi 
Published: August 2014

AbstractA new FI-type Zr-based catalyst of bis[N-(3,5-dicumylsalicylidene)- anthracylaminato]zirconium(IV) dichloride was found to display a moderate ethylene polymerization activity of 42×104 g PE/mmol Zr. h with a viscosity average molecular weight (Mv) of 56×104 at the monomer pressure of 4 bars and temperature of 30 °C. HOMO (the highest occupied molecular orbital) and LUMO (the lowest unoccupied molecular orbital) energy level of the anionic phenoxyimine ligands, were calculated using HF/6-31G method. Plurality of the fused aromatic rings on the catalyst structure decreased the energy gap between the HOMO and LUMO, but could not increase the activity. The highest activity of the catalyst was obtained at about 30 °C following a sharp decrease at higher temperature. The catalyst showed the high activity at about [Al]:[Zr]=80000:1 molar ratio and further addition did not affect the activity of the catalyst. Experimental results revealed that low HOMO energy level is not a necessity to reach high activity of the catalyst. Despite low HOMO energy level, the prepared catalyst displayed moderate polymerization activity. Either the activity of the catalyst or the viscosity average molecular weight of the obtained polymer was affected by the hydrogen concentration slightly. However, activity of the catalyst showed higher sensitivity to amount of hydrogen and increased with increasing the hydrogen concentration. Higher monomer pressure increased productivity, crystallinity and the Mv values of the resulting polymer. Some specification of the obtained polymer was studied.
Biomedical applications of electrically conductive polymeric systems
Authors: Jagur-Grodzinski Joseph 
Published: August 2014

AbstractProperties of the electrically conductive polymers (ECPs) enable introduction of several novel applications in various fields, among others, as biomedical materials. Their use as scaffolds for tissue engineering and recovery of damaged neural tissues is especially advantageous. They may also be used for the electrically induced drug release and delivery, and as very sensitive biosensors for clinical applications. Another use is the detection and precision of the biologically important chemical materials. They have been shown to modulate and accelerate activities of the nerve, skeletal, muscle, and bone cells. Cell growth, migration and adhesion, may be stimulated by applying electric potential. Synthesis of DNA, secretion of proteins, and transformations of stem cells may be enhanced. Clinical analysis using ECP-based biosensors make possible the precise determination of the exact composition of individual DNA molecules, and thus enable early detection and treatment of genetically related diseases. Electrochemical (EC) approach of ECP-sensors enables precise determination of concentrations of several biologically important chemicals.
Organoclay/thermotropic liquid crystalline polymer nanocomposites. Part I: Effects of concentration on morphology, liquid crystallinity and thermal properties
Authors: Tang Youhong , Gao Ping , Ye Lin , Zhao Chengbi , Lin Wei 
Published: August 2014

AbstractThermotropic liquid crystalline polymer (TLCP) nanocomposites with different organoclay contents were prepared by a method combining ultrasonication, centrifugation and solution casting methods. The effects of organoclay concentration on morphology, liquid crystallinity and thermal properties of nanocomposites were characterized. Molecular level interactions existed in nanocomposites. With a small amount of organoclay (nominal 3.0 wt %), it was enough to change TLCP properties with enhanced thermal stability though with a small negative effect on liquid crystallinity. When high concentration organoclay was added, thermal stability decreased and liquid crystallinity lost with shearinduced phase separation occurrence.
Condensation between guanidine hydrochloride and diamine/multi-amine and its influence on the structures and antibacterial activity of oligoguanidines
Authors: Wei Dafu , Guan Yong , Ma Qiangxiang , Zhang Xi , Teng Zheng , Jiang Hua , Zheng Anna 
Published: August 2014

AbstractThe polycondensation of guanidine hydrochloride and diamine leads to various types of oligoguanidines, including linear and branched/cyclic types, which constitutes the mixture of oligoguanidines exhibiting efficient biocidal activities. In the present work, a series of polyhexamethylene guanidine hydrochloride (PHMG) were prepared by varying the mole ratio of hexamethylenediamine to guanidine hydrochloride and the reaction conditions, and their antibacterial activities were investigated. The contents of linear and branched/cyclic types in the mixture varied with different reaction conditions, and more branched/cyclic types led to more efficient antibacterial activity. Other oligoguanidines PDMG and PMXMG were synthesized using guanidine hydrochloride and decamethylenediamine and 1,3- benzenedimethanamine, respectively. Their chemical structures were similar to PHMG’s while the antibacterial activities were slightly different from PHMG’s. Further when the polycondensation were conducted between guanidine hydrochloride and multi-amine, such as diethylenetriamine or trithylenetetramine, the chemical structures of products were completely different from the above oligoguanidines. A new five-membered ring structure was observed, and the fivemembered ring structure further decreased the antibacterial activities.
Interfacial synthesis and characterization of L-lysinederived optically active poly(hydrazide-imide)s
Authors: Zahmatkesh Saeed , Banaei Alireza , Yazdanpanah Ashkbous 
Published: August 2014

AbstractSix novel poly(hydrazide-imide)s (PHIa-f) were prepared from the reaction of a novel L-lysine-derived chiral diacid, ethyl L-lysine-N,N'-ditrimellitoyl diacide (1), with six synthetic dihydrazides by interfacial polycondensation. These polymers have inherent viscosities in the range of 0.23 to 0.42 dl g-1, display optical activity, and are readily soluble in polar aprotic solvents. They start to decompose (T10%) above 248 ºC and display glass-transition temperatures at 164.37-210.20 0C All of the above polymers were fully characterized by UV, FT-IR and 1H NMR spectroscopy, elemental analysis, TGA, DSC, inherent viscosity measurement and specific rotation.
Dynamic lattice liquid (DLL) model in computer simulation of the structure and dynamics of polymer condensed systems
Authors: Blim Anna , Kowalczyk Tomasz 
Published: August 2014

AbstractThis review presents the use of Dynamic Lattice Liquid (DLL) model proposed by Pakula and coworkers. In the model polymer liquids are represented as dense systems of macromolecules. The model fulfils requirements of the local continuity and excluded volume conditions. The use of the model for numerical simulations of simple liquids, colloidal particles systems, solutions of linear polymers, branched like bottle-brush or star shaped polymers is described. The use of simulations for the prediction of the properties of the systems and their experimental validation is described. The model is presented as an universal tool for investigation of different systems that provides good agreement between numerical and experimental results for a broad range of the systems and conditions.
Preparation of a novel superhydrophobic PMMA surface with nanostructure and its blood compatibility
Authors: Wang Xiaobo , Yang Ningbo , Xu Qi , Mao Chun , Hou Xiaomei , Shen Jian 
Published: August 2014

AbstractSuperhydrophobic poly(methylmethacrylate) (PMMA) surface with nanostructure was prepared effectively via phase separation and selective solvent method. It is proposed that the cooperation of the nanostructure of PMMA surface and the surface group reorientation leads to the superhydrophobicity of PMMA surface. The superhydrophobic PMMA surface with nanostructure was characterized by scanning electron microscope (SEM) and water contact angle (WCA) measurements. The blood compatibility of the superhydrophobic PMMA surface with nanostructure was evaluated by platelet-rich plasma (PRP) and fresh human whole blood contacting experiments using pure flat PMMA film as the control. These two experiments demonstrated that blood compatibility of the superhydrophobic PMMA surface with nanostructure is better than that of the pure flat PMMA film. The significance of this research lies in that it will greatly broaden the application range of materials that can be used as biomaterials by fabrication of superhydrophobic surfaces.