bluuebunny/crossref_metadata_2025 huggingface dataset:
Copolymerization of Ethylene and 1-Hexene Catalyzed by the Zirconocene/Al(i-Bu)3/B(C6F5)3 Catalytic System
Authors: Zhang Puyu , Li Yonghong , Chai Yun
Published: August 2014

Copolymerizations of ethylene/1-hexene were conducted using different zirconocene/AlR3/B(C6F5)3 catalytic systems at 50°C. When AlEt3 was used as alkylate agent, very low copolymerization activity was observed with both bridged catalyst Et[Ind]2ZrCl2 and unbridged zirconocene Cp2ZrCl2 in-situ activated with B(C6F5)3. In appropriate Al/Zr mole ratio using Al(i-Bu)3, the catalytic activities of both zirconocene catalytic systems were similar to those of sophisticated zirconocene/methylaluminoxane(MAO) catalytic system. The catalytic activities, comonomer incorporation and molecular weight of the copolymer synthesized with Et[Ind]2ZrCl2/Al(i-Bu)3/B(C6F5)3 were higher than those obtained with Cp2ZrCl2/Al(i- Bu)3/B(C6F5)3. The effect of the concentration of 1-hexene on catalytic activity, copolymer molecular weight, and comonomer incorporation was investigated. The complicated “co-monomer effect”, together with an increase in comonomer incorporation, a decrease in the copolymer molecular weight, was found when the comonomer concentration was increased.
Correlation between morphology and NGM of 3,4- ethylenedioxythiophene (EDOT) in acetonitrile
Authors: del Valle María Angélica , Belén Camarada María , Díaz Fernando , East Gastón
Published: August 2014

The nucleation and growth mechanism (NGM) for the electro-oxidation of 3,4-ethylenedioxythiophene (EDOT) in acetonitrile on platinum and tin(IV) oxide electrodes was determined by analyzing the potentiostatic current-time transients inferred from electrocrystallization theory. The measurements were complemented by using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Preliminary studies performed to establish the working conditions for the potentiostatic technique using cyclic voltammetry (CV) demonstrated that under the working conditions employed herein the best potential scan-rate to obtain electrodeposits of poly(EDOT) was 50 mV·s-1. The prepared polymer displayed electrochromic properties and p- and n-doping, the p-doping being chemically reversible. In addition, it was observed that the electropolymerization mechanisms on both electrode materials were a combination of two contributions: progressive nucleation, followed by diffusion-controlled tridimensional growth, PN3Ddif; and instantaneous nucleation followed by three-dimensional growth under charge transfer control, IN3Dct. At shorter times, the IN3Dct contribution prevail giving rise to conical deposits, while at longer electrolysis times the polymeric deposit is made of granules, corresponding to the PN3Ddif mechanism. The electrode material has no effect at all on the global mechanism, but affects the time at which either contribution predominates. However, the morphological predictions made from the NGMs must be corroborated by other techniques before using the data to control the deposit to be prepared.
Modification of poly(butylene terephthalate) by reaction with 1,4-butane sultone; synthesis and thermal characterization of new telechelic PBT ionomers
Authors: Berti Corrado , Celli Annamaria , Marianucci Elisabetta , Vannini Micaela
Published: August 2014

New telechelic poly(butylene terephthalate) (PBT) ionomers, characterized by the presence of some aliphatic sulfonated chain ends, were prepared by reaction with the 1,4-butane sultone. Two methods of synthesis were compared and the final polymers, containing different percentages of ionic groups, were characterized, with particular attention to the thermal properties. Thermogravimetric analysis shows that the presence of ionic groups does not modify the thermal stability of PBT. The differential scanning calorimetry indicates that the crystalline phase and the crystallinity degree of PBT do not change in the presence of ionic chain ends, whereas the crystallization rate was found to be strongly modified. The ionomers crystallize at very high rate, due to the nucleating effect of the ionic aggregations formed in the melt.
The synergistic effect of dope concentration and jetdrawing on structure development of wet-spun poly(acrylonitrile)
Authors: Arbab Shahram , Mohammadi Naser , Noorpanah Parviz
Published: August 2014

Acrylic fibers are the major precursor of carbon fibers. In this work, the synergistic effect of polymer concentration and jet stretching on porosity, morphology and mechanical properties of wet-spun poly(acrylonitrile) fibers were studied and then the role of void size was elucidated. The results showed that the effect of jet stretching on fiber porosity is negligible below a threshold polymer concentration. Increasing polymer concentration up to 20 vol. % reduced the total porosity significantly but increased the nanometric void population slightly. On the other hand increasing polymer concentration and jet stretching simultaneously, improved mechanical properties as a result of a remarkable reduction in porosity. In addition, stretching shifted nanovoids distribution strongly toward smaller sizes. This was attributed to the effect of stretching and increasing polymer concentration on reducing the diffusion coefficient. Young's modulus of fibers also increased with decreasing overall porosity. Finally, strength-diameter correlation showed a good agreement with the Griffith's theory.
Synthesis, characterization and thermal crosslinking behavior of new poly(aryl ether sulfone)s based on naphthalene isomers
Authors: Ying Zhang , Yunhe Zhang , Yaming Niu , Ying Na , Zhenhua Jiang
Published: August 2014

Four new poly(aryl ether sulfone)s containing naphthalene rings were synthesized from 1,5- and 2,7-bis-(4-fluorosulfonyl)naphthalene isomers with different diphenols. These polymers exhibited high glass transition temperatures and good thermal stability. The glass transition temperatures ranged from 220 to 236°C and the 5% weight-loss temperatures were above 423°C. As the four polymers were treated at 300°C, the glass transition temperatures of polymer series a obviously increased and the polymers became insoluble in common organic solvents including NMP, DMAc, and chloroform, etc., but the series b did not, which indicate that a thermal crosslinking reaction via free radicals happened leading to crosslinked polymers
In-situ polymerization of EDOT in water/methanol with different DBSA contents
Authors: Chen Chia-Fu , Dai Chi-an , Chiu Wen-Yen
Published: August 2014

In this work, poly(3-ethylenedioxythiophene) (PEDOT) was synthesized on glass by spin coating for 10 seconds at 500 rpm and polymerization was carried out in an oven at 110°C for 10 min. Methanol and water mixture were used as the solvent and dodecylbenzene sulfonic acid (DBSA) as the surfactant. The conductivities of films were measured and their relationship with different solvent or various surfactant contents were discussed. The morphology of films was observed by SEM, and PEDOT synthesized in methanol-rich solvents or with less DBSA content had more smooth surfaces, showed lower degradation temperature (by TGA). Also, PEDOT synthesized in methanol-rich solvents or with less DBSA were doped better, as observed by UV-Vis spectra.
Polymerization of n-butyl methylacrylate using bis(β- ketoamino)nickel(II)/MAO catalytic systems
Authors: He Xiaohui , Chen Yiwang , Liu Yongming , Chen Muqing , Yu Shuxian , Hong Sanguo , Wu Qing
Published: August 2014

The polymerizations of n-butyl methylacrylate (nBMA) were carried out using bis(β-ketoamino)nickel(II) complexes (Ni[CH3C(O)CHC(NR)CH3]2: R = phenyl, 1; R = naphthyl, 2) in combination with methylaluminoxane (MAO) in toluene. The effect of parameters such as polymerization temperature, Al/Ni molar ratios, polymerization time, and monomer concentration, on catalytic polymerization activity and polymer molecular weights, were examined in detail. Both of the nickel(II) catalytic systems exhibited moderate activity, and produced P(nBMA) with high molecular weight and relatively broad molecular weight distribution (Mw/Mn=2.0~3.0. The obtained polymer has been characterized by means of FTIR, 1H NMR, 13C NMR, DSC, and WAXD technique and was confirmed to be syndio-rich stereospecific P(nBMA).
Water dispersible carbon black prepared through ultrasonically assisted radical polymerization
Authors: Huang Jianfeng , Li Qiuying , Bao Yubin , Wu Chifei
Published: August 2014

To improve the dispersion stability of carbon black (CB) in aqueous media, an anion vinyl monomer, namely potassium 4-vinylbenzoate (K-4VBA) was polymerized and coated on to the CB particles through ultrasonically assisted radical polymerization. FT-IR was used to detect the presence of poly(K-4VBA) on the CB surface. The TGA results indicated that the polyelectrolyte contents of the CB particles could reach 77.5% in weight. The TEM studies revealed that the surface morphologies for the coated polyelectrolyte. Combined aqueous electrophoresis and DLS studies confirmed that these polyelectrolyte modified CB particles had pH-dependent colloid stabilities, as expected. The modified particles were colloidal stable at high or neutral pH, but became aggregated at low pH.
Quantum-mechanical simulation of the structure and stability of starch – metal cation complexes
Authors: Ciesielski Wojciech
Published: August 2014

Molecular mechanics computations and simulations involving the Mopac assisted SCF LCAO MO ZINDO1 method were performed for complexes of ɑ-Dglucose with Co(II), Cu(II), Fe(III), Mn(II) and Ni(II) acetates, chlorides and nitrates. The computations resulted in the following findings: Usually the saccharide ligand completely repulsed water molecules from the inner coordination sphere of the central metal atoms. The complexes with Fe(III) acetate and chloride and nitrates of Co(II) and Cu(II) constituted random exceptions having some water molecules in that sphere. The oxygen atom of the 3-hydroxyl group in ɑ-D-glucose (the O3 atom) was the preferred coordination site. The stability of complexes declined as the primary saccharide chain composed of one ɑ-D-glucose was extended by subsequently 1→4 bound ɑ-D-glucose mers. Also such chains coordinated to the central atoms through the O3 oxygen atom. Analysis of the increment of increase in the heat formation with each subsequent ɑ-D-glucose mer in the saccharide chain might suggest that such chain forms chelates with the central metal atom. With CuCl2 first and third ɑ-D-glucose mers were involved in the chelate formation, whereas in case of CoCl2 the first and fourth D-glucose mers were involved.
Synthesis and characterization of novel optically active poly(ester-imide-imine)s
Authors: Hajipour Abdol Reza , Roosta Parniyan , Zahmatkesh Saeed , Ruoho Arnold E.
Published: August 2014

N,N´-(3,3´,4,4´-Benzophenonetetracarboxylic)-3,3´,4,4´-diimido-di-Lamino acids (1a-1d) and N,N´-pyromelliticdiimido-di-L-amino acids (2a-2d) are prepared from the reaction of 3,3´,4,4´-benzenetetracarboxylic-3,3´,4,4´- dianhydride or pyromellitic dianhydride with the corresponding L-amino acids in a solution of glacial acetic acid/pyridine (3:2) at refluxing temperature. 4-(4-((4- Hydroxyphenylimino)methyl)benzylidene amino) phenol (3) is prepared from 4- amino phenol and terephthaldialdehyde in refluxing ethanol. Interfacial polycondensation method was used to prepare the corresponding polymers (PEII1-8) in two immiscible solvents (water/dichloromethane). The resulting poly(esterimide- imine)s (PEIIs) having good inherent viscosities (0.13-1.25 dl g-1), optical activity and thermal stabilities is obtained in high yields.
Synthesis of monodisperse poly(styrene-co-divinyl benzene) microspheres by precipitation polymerization in acetonitrile and n-butanol mixture
Authors: Hongyan Jiang , Hou Chen , Ying Liang , Yuhong Xuan , Mingliang Wang
Published: August 2014

Narrow disperse poly(styrene-co-divinylbenzene) microspheres were prepared by precipitation polymerization using acetonitrile/n-butanol mixture as the reaction medium and 2,2’-azobis(2-methylpropionitrile) (AIBN) as initiator. The resulting particles have smooth surfaces due to the absence of any additional stabilizer. Effects of the reaction parameters such as n-butanol fraction in the reaction medium, monomer and initiator concentration, and divinylbenzene content were investigated. It was found that the particle size increased with an increasing concentration of monomer and initiator, while the uniformity was kept constant. The number-average particle diameter ranged from 2.36 to 1.63 μm and decreased with an increasing divinylbenzene concentration. In addition, the uniformity was enhanced as the concentration of divinylbenzene increased. On the basis of the DSC and TGA data, the microspheres prepared by the precipitation polymerization possessed a highly crosslinked structure and the thermal stability improved with the DVB concentration.
Physical and mechanical properties of sulfonated aromatic copolyimide membranes
Authors: Rabiee Ahmad , Mehdipour-Ataei Shahram
Published: August 2014

Physical and mechanical properties of four series of chemically and thermally stable sulfonated copolyimides as ion-conducting ionomers for application in fuel cell membrane, depending on chemical structure of diamine monomers were studied. The physical and mechanical properties of solid polymer membranes including thermal stability, mechanical strength, water uptake, stability in water, crystallinity and morphology were evaluated. All the polymers were thermally stable. The XRD analysis and SEM micrograph revealed that the polymers were almost amorphous and hydrophobic-hydrophilic phase separation in polyimide did not occur. Use of flexible monomers such as 4,4'-oxydianiline (ODA) and 4,4'-(4-aminophenoxy) diphenylsulfone (APDS) in the hydrophobic sequences increased the plastic behavior compared to rigid polymers prepared from 4,4'-(5- amino-1-naphthoxy) diphenylsulfone (ANDS) and m-phenylenediamine (m-PDA). It was concluded that the properties of polymeric films were strictly dependent on chemical composition of monomers and molecular weight of copolymers.
Dissolution of microcrystalline cellulose and its graft copolymer in ionic liquid of 1-allyl-3-ethylimidazolium chloride
Authors: Guo Liying , Shi Tiejun , Li Zhong
Published: August 2014

The ionic liquid of 1-allyl-3-ethylimidazolium chloride ([AEIM]Cl) was synthesized and its chemical structure was confirmed. Dissolution of microcrystalline cellulose (MCC) in [AEIM]Cl by microwave heating method was researched. Acrylamide (AM) was grafted onto the dissolved MCC with initiator in [AEIM]Cl and aqueous medium respectively. The effect of temperature, initiator and its dosages on monomer conversion and grafting efficiency was studied. The results showed that [AEIM]Cl was a good solvent for MCC and dissolution rate was the highest (28.8%) when the MCC pretreated with 15% NaOH under the high pressure. Graft copolymer prepared by AM and MCC in [AEIM]Cl had higher monomer conversion and grafting efficiency than in aqueous medium. The best condition for preparing graft copolymer was that potassium persulfate was used as initiator with the dosage of 1g/L under the temperature of 45 °C-50 °C. Spectra of FT-IR had proved that AM was grafted onto MCC. The thermal stability of MCC improved after grafting, and the crystal form was destroyed thoroughly.
Controllable fabrication of poly(vinyl pyrrolidone) (PVP) nanofibers by wheel-spinning technique
Authors: Chang Guo-Qing , Chen Zhen
Published: August 2014

A simple and facile approach to fabricate PVP fibers by wheel-spinning technique was investigated. Poly(vinyl pyrrolidone) sol (PVP, Mw =1,300,000, 6-14 w% in ethanol) was used as the candidate polymeric material. It was demonstrated by a rotating wheel with the speeds of 18.84, 15.70 and 12.56 m/s, respectively, PVP fibers can be drawn with diameters ranging from under 200 to over 2 μm and controlled by changing the rotating speed and sol concentration. The morphologies of the wheel-spinning fibers were observed by electronic scanning microscopy (SEM). The nanofibers obtained by this technique are long, straight and smooth, and the fabricated apparatus is simple.
An investigation on modelling and measurements of transient elongational rheology of polymer melts by SER testing platform
Authors: Rajabian Mahmoud , Naderi Ghassem , Piroozfar Hamid , Beheshty Mohammad H. , Samadfam Mohammad
Published: August 2014

Transient elongational rheology of PP is investigated experimentally. A specifically designed fixture consisting of two drums mounted on a TA Instruments ARES rotational rheometer was used to measure the transient uniaxial extensional viscosity of two commercial grades polypropylene in the molten state. The Hencky strain was varied from 0.003 to 2 s-1 and the temperature was fixed at 180 oC. The measurements show that the steady state elongational viscosity was reached at the measured Hencky strains for polypropylene. Eslami and Grmela have recently introduced a reptation diffusion term arising from the intermolecular chain forces into the rigid FENE-P dumbbells model. The same approach has been used in this study to interpret the transient rheological data in both shear-free and simple shear flows.
Preparation and characterization of poly(styrenemethacrylic acid)/MCM-41 core/shell nanocomposite microspheres
Authors: Zhao Yansheng , Ma Xingji , Liu Yongmei , Yuan Guangwei , Guo Meijuan , Chen Kai , Shen Yinghua
Published: August 2014

In acidic media, poly(styrene-methacrylic acid)/MCM-41 [P(St- MAA)/MCM-41] core/shell microspheres were synthesized using monodisperse P(St-MAA) particles contained in soap-free emulsion and cetyltrimethylammonium bromide as co-templates by adsorption self-assembly method. The effects of P(St- MAA) composition on shell structure of the core/shell microspheres were investigated. The morphology and composition of P(St-MAA)/MCM-41 microspheres were characterized by TEM, XRD and FTIR. The results show that the ordering degree of MCM-41 shells increased as the molar ratio of MAA to St increased. When n(MAA)/n(St) is 0.2, the average diameter and the shell thickness of nanocomposite microspheres are about 170 nm and 20 nm, respectively.
Materials for intraocular lenses (IOLs): Review of developments to achieve biocompatibility
Authors: Tripti D. , Haldar R.S. , Geetha S. , Niyogi U.K. , Khandal R.K.
Published: August 2014

It is true that the developments in material sciences along with the improvements in various aspects of technology involved in transforming materials into products, over the years, have been responsible for making many of the impossible-looking devices possible. It is also a fact that the demand for a new, improved and better material has never ended; in fact it has been increasing to a greater degree and with bigger dimensions than ever before, especially in recent times. As a matter of fact, for certain advanced applications, the need for efforts to have new materials can never be over emphasized; for example, in the area of biomedical devices such as intraocular lens (IOL). The advances in the field of bio-medical applications require the materials of high quality meeting stringent norms of performance. For implants such as the ones like IOL used for correction of vision of the eyes, besides the quality and performance of materials, biocompatibility is an issue of major concern. The material scientists have been working on the development of materials for IOLs targeting the needs arising out of the developing countries. The challenges include not only to bring down the cost of the materials used for IOLs but also to increase the biocompatibility of IOLs. For making the development process easy and bringing the state-of-the- art of knowledge to those looking for new materials, it is thought necessary to review various facets of IOLs in the present paper. Not only the aspects related to the recent developments in biomedical devices of eye care but also related to the properties of available materials vis a vis the deficiencies in properties of existing materials have been covered in this review. The aim has been to bring out the gap areas at various levels of process of product chain starting from the monomer to polymer, blank to IOL, insertion of IOL into eyes to life cycle of IOLs, mainly to provide certain possible and feasible leads to meet the challenges of making new and more biocompatible materials.
Effect of different amine modified clays on the compatibility and clay dispersion of polypropylene nanocomposites
Authors: Sánchez-Valdes S. , Méndez-Nonell J. , Ramos de Valle L. F. , Lozano-Ramírez T. , Ramírez-Vargas E. , López-Quintanilla M. L. , Gutiérrez-Rodríguez J. M.
Published: August 2014

The compatibilization effects provided by different amines in the synthesis of polypropylene/amine modified montmorillonite clay nanocomposites (PP/ A-MMT) were studied. Nanocomposites were prepared by melt processing using a twin-screw extruder, by compounding maleic anhydride grafted polypropylene (PPgMA) with MMT modified with three different amines: ethanolamine (EA), hexamethylenediamine (DA6) and 1,12-diaminododecane (DA12) to form amine modified montmorillonite "A-MMT". FTIR characterization confirmed the formation of characteristic amide linkages and X-ray confirmed the intercalation of PPgMA between the silicate layers. X-ray, scanning electron microscopy with transmission modulus (STEM), thermogravimetric analysis (TGA), rheological properties plus mechanical properties were used to characterize those nanocomposites. X-ray diffraction patterns of the composites using A-MMT showed 001 basal spacing enlargement with good clay exfoliation-intercalation compared with the natural MMT (Na-MMT). The DA12 modified MMT showed the greatest increase in basal spacing. TGA revealed that the decomposition of the composite took place at a slightly higher temperature than that of neat PP. Nanocomposites using EA or DA6 modified MMT showed a decrease in viscosity whereas those using DA12 showed an increase in viscosity. Nanocomposites using the DA12 modified MMT showed the most substantial improvement in terms of both mechanical properties and clay exfoliation. It appears that the longer the amine chain the higher the separation of the clay platelets and the higher the interactions between the clay and the polymer matrix.
Gate location optimization scheme for plastic injection molding
Authors: Zhai Ming , Lam Yeecheong , Au Chikit
Published: August 2014

Gate location of injection molding is vital to achieve high quality plastic part. The determination of gate location is an important issue in mold design. A computationally efficient scheme based on flow path is proposed to locate the optimum gate for achieving balanced flow. The range of filling time is employed as objective function. Comparisons were made between the flow path search scheme and the existing adjacent node evaluation scheme, and between the objective function of the range of filling time and the existing standard deviation of filling time. The two examples investigated indicated that the search routine based on the concept of flow path is more efficient computationally and the range of filling time is a better objective function to reflect the uniformity of fill.
A new salt-resistant superabsorbent hydrogel based on kappa-carrageenan
Authors: Hosseinzadeh Hossein
Published: August 2014

In this work, a novel biopolymer-based superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of 2-hydroxyethyl acrylate (HEA) onto kappa-carrageenan, using potassium persulfate (KPS) as a free radical initiator in the presence of methylene bisacrylamide (MBA) as a crosslinker. The chemical structure of the hydrogels was confirmed by FTIR spectroscopy. The morphology of the samples was examined by scanning electron microscopy (SEM). The certain variables of the graft copolymerization (i.e. the monomer, the initiator, the polysaccharide, and the crosslinker concentration) were systematically optimized to achieve a hydrogel with maximum swelling capacity. The swelling ratio in various salt solutions was also investigated in detail. Since this hydrogel exhibited a very high absorptivity in saline, it may be referred to as low salt sensitive superabsorbent. The swelling of superabsorbing hydrogels was also measured in solutions with pH ranging from 1 to 13.
Synthesis and characterization of a solvent-based acrylate pressure adhesive for transdermal drug delivery
Authors: Sun Fang , Zhu Guoqiang. , Li Shunlai , Du Hongguang
Published: August 2014

The present investigation was directed towards the synthesis of a copolymer of vinyl acetate, butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid and acrylamide to be exploited as a pressure sensitive adhesive (PSA) in transdermal drug delivery systems. The experimental methodology involved the optimization of reaction conditions for the polymer synthesis. The optimal synthesis conditions of PSA were determined as that polymerization reaction of PSA in ethyl acetate with BPO of 0.5% w/w of reactants at 75 oC throughout the whole process with polymerization reaction time of eight hours. The copolymer was then characterized by FTIR, 1H-NMR, 13C-NMR and DSC. The PSA was also evaluated for residual monomer content, viscosity, tack, peel adhesion and drug release behavior. The synthesized PSA’s tack is 21#; peel adhesion is 1.39 N/mm. And the residual monomers content in the copolymer after polymerizing for eight hours are VAc 2.98%, BA 0.004%. The PSA also exhibited excellent drug release behavior. Membranes containing oxybutynin were capable of releasing in zero order fashion. It was found that the release velocity depended on the concentration of modified monomer. Drug release from those membranes could be easily tailored by changing the content of the modified monomers. It was found suitable for use in transdermals and could be further exploited either as an adhesive or as a system component in the area of transdermal drug delivery.
Prediction of the polarity parameter π for the radical derived from monomer
Authors: Yu Xinliang , Yu Wenhao , Yi Bing , Wang Xueye
Published: August 2014

An artificial neural network (ANN) model was successfully developed for the modelling and prediction of the polarity parameter π used in the revised patterns scheme for the prediction of monomers reactivity ratios in radical polymerizations. Four quantum chemical descriptors based on density functional theory (DFT) calculations were used to develop the ANN model. The optimal condition of the neural network was obtained by adjusting various parameters by trial-and-error. Simulated with the final optimum BP neural network 4-4-1, the results show that the predicted parameter π values are in good agreement with the experimental ones, with the root mean square (rms) errors being 0.053 (R=0.960) for the training set and 0.070 (R=0.942) for the test set. The ANN model has better statistic quality than the MLR model, which indicates there are nonlinear relationships between these quantum chemical descriptors and the parameter π.
Elaboration of stimuli responsive core-shell magnetic latexes from oil in water ferrofluid emulsion
Authors: Pibre Guillaume , Hakenholz Luc , Braconnot Sebastian , Mouaziz Hanna , Elaissari Abdelhamid
Published: August 2014

This manuscript describes the elaboration of temperature sensitive highly magnetic latex particles. The particle core is crosslinked polymer matrix containing iron oxide nanoparticles. The shell is a combination of highly crosslinked hydrophobic polymer and crosslinked stimuli responsive hydrophilic polymer. The polymerization was performed in two steps: the elaboration of seed magnetic latex particles for oil in water magnetic emulsion and (ii) the functionalization of the obtained magnetic latexes via seed polymerization in the presence of water soluble reactants. The obtained final core-shell latexes exhibit the following properties: The iron oxide content is above 50 wt.%. The size distribution is governed by the size distribution of the used oil in water magnetic emulsion. The thermal sensitivity of the shell is due to the presence of poly(N-isopropylacrylamide). The cationic character of the outer layer shell is due to the use of cationic initiator and amino containing monomer.
New optically active poly(amide-imide)s from N,N΄- (bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracrboxylic)-bis-L-valine diacid and aromatic diamines: synthesis and properties
Authors: Faghihi Khalil , Shabanian Meisam , Hajibeygi Mohsen
Published: August 2014

New optically active aromatic poly(amide-imide)s (PAIs) were prepared from newly synthesized N,N΄-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracrboxylic)-bis-Lvaline diacid (4) via polycondensation with various aromatic diamines. The diacid (4) was synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene- 2,3,5,6-tetracarboxylic dianhydride (1) with L-valine (2) in acetic acid. All polymers were obtained in quantitative (high) yields with inherent viscosities of 0.24-0.36 dL/g. All of these polymers were highly organosoluble in solvents like N-methyl-2- pyrrolidone (NMP), dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc) and dimethylsulfoxide (DMSO) at room temperature and were fully characterized by means of NMR spectroscopy, FTIR spectroscopy, elemental analyses, inherent viscosity, solubility test, specific rotation and thermal properties of the poly(amideimide) s were investigated using TGA/DTG.
Modification of styrene polymer by attaching suitable groups as side chain
Authors: Mahkam Mehrdad , Massoumi Bakhshali , Mirfatahi Hossien
Published: August 2014

Chemical modification of inexpensive commercial polymers, such as styrene, is a safe methodology to obtain new copolymers. The 4-chloromethyl styrene (CMS) was copolymerized with styrene (in various mole ratios) by free radical polymerization method at 70 ºC using α,α-azobis(isobutyronitrile) (AIBN) as an initiator. The azide ion was covalently attached to the obtained copolymers with replacement of all the chlorine atoms in CMS units. The 1,3-dipolar click cycloaddition reaction between azido polymers and dimethyl acetylene dicarboxylate (DMAD) yielded polymers with 1,2,3-triazoles in side chain. The polymers, obtained in quantitative yields, were characterized by FT-IR and 1H NMR spectroscopy; thermogravimetric analysis (TGA) and GPC studies. The thermogravimetric analysis (TGA) indicated that the thermal stability of copolymers increases with incorporation of 1,2,3-triazole groups in side chains of copolymers.
Synthesis and characterization of novel fluorinated polybenzoxazoles derived from 2,5-difluoroterephthalic acid
Authors: Huang Xiao-Song , Qing Feng-Ling
Published: August 2014

A new serious of fluorinated polybenzoxazoles (PBOs) were prepared from 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane together with 2,5- difluoroterephthalic acid (DFTA) and terephthalic acid by the one-pot polycondensation in polyphosphoric acid. The resulting PBOs showed good solubility in many common organic solvents and the thermal stability of PBOs was improved by the introduction of DFTA monomer.
Fabrication and investigation of core-sheath polymer/ polyaniline composite nanofibers
Authors: Huang Huimin , Li Zhenyu , Wang Wei , Yang Fan , Li Shangyu , Wang Ce
Published: August 2014

Three types of coaxial polymer/polyaniline (PANi) fibers were prepared by in situ polymerization of aniline on the electrospun poly(methyl methacrylate) (PMMA), polystyrene (PS) and polyacrylonitrile (PAN) fibers, respectively. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) were applied to characterize the morphologies of these core-sheath structures. Under identical polymerization conditions, a thicker layer of PANi was deposited on the hydrophilic PAN fibers than those on the other two hydrophobic polymer core fibers. The results revealed that the nature of the polymer cores could influence the formation of the coaxial fibers, which may provide a deeper insight into the formation of core-sheath nanostructures.
Flame retardance and thermal properties of a novel phosphorus-containing unsaturated polyester resin/SiO2 hybrid nanocomposite
Authors: Zhang Chen , Liu Shu Mei , Huang Jun Yi , Zhao Jian Qing
Published: August 2014

A novel phosphorus-containing unsaturated polyester resin/SiO2 hybrid nanocomposite was prepared from the in-situ curing of unsaturated polyester resin (UP) and triethoxysilane (DI) which was synthesized from the nucleophilic addition reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) and 3- (trieoxysilyl) isocyanate(icteos). The formation of unsaturated polyester resin/SiO2 hybrid nanocomposite (UP-DI) was confirmed by infrared spectra (FTIR) and scanning electron microscopy (SEM). With the increase of DI contents, the limiting oxygen index (LOI) value of the cured UP-DIs was raised from 19 to 29, suggesting a significant improvement in flame retardance. The improved flame retardance could also be revealed by the variations of weight and morphology of char residues. Thermogravimetric analysis (TGA) both in air and in nitrogen was used to estimate mechanism of thermal degradation and activation energy (Ea) of different degree of conversion (α) was calculated by Ozawa’s method. The UP-DI containing 10%DI (UP-DI10) had higher Eathan the pure UP as α>5% because the degradation mechanism was altered by the incorporation of DI.
The reflection of the texture of swollen polymer matrix on the release of incorporated substance
Authors: Pavli Matej , Kristl Julijana , Dolenc Andrej , Zvonar Alenka , Vrečer Franc , Kosel Franc , Baumgartner Saša
Published: August 2014

Our aim was to investigate the texture of hydrated biopolymer matrices that are now being considered in the design of pharmaceutical controlled-release dosage forms, in order to determine their influence on the release of an active compound. Prolonged release of pentoxifylline, a highly soluble drug, is needed for once-daily administration to achieve its therapeutic effect. For this purpose, pentoxifylline was incorporated in a polymer matrix made of a combination of xanthan and locust bean gum (XLBG), both of which are of biotechnological origin. Different methods were used to investigate the interplay of the XLBG gel structure characteristics in the absence and presence of 200 mM CaCl2 on pentoxifylline release: drug-release studies, determination of swelling, erosion, and viscoelasticity of the gel, as well as its texture analysis and microscopic imaging. From the results obtained, the following conclusions can be drawn: the pentoxifylline release from XLBG matrices in water was prolonged for 24 h whereas from the control lactose formulation was completed within 30 min. The presence of Ca2+ ions in water resulted in faster pentoxifylline release, in spite of less swelling and erosion. However, the rheology, texture analysis and scanning electron microscopy revealed that in the presence of the Ca2+ ions the gel layer of the XLBG was more cohesive and thinner, as the attraction for water molecules was lower due to the condensation of counter-ions on the xanthan carboxylic-moieties, and consequently greater interpolymer interactions. Therefore, relatively larger amounts of free water molecules were available within the XLBG hydrogel in the presence of Ca2+, allowing faster drug dissolution and diffusion. Here, the presence of Ca2+ ions had a completely opposite effect on XLBG gel structure and drug release in comparison with other more investigated matrix polymers like alginate or non-ionic cellulose ethers. A firm matrix structure that is accompanied by low swelling and erosion cannot guarantee a more prolonged drug release.
A simple procedure to tailor the compositional gradient of copolymeric materials
Authors: Reinecke Helmut , Aguilar María Rosa , Güven Güldem , Piskin Erhan , Gallardo Alberto
Published: August 2014

Copolymeric structures with compositional gradient were produced by “in situ” radical polymerization -in water and with redox initiation- of acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) in the presence of an inhibitor (hydroquinone). The inhibitor has a key role in controlling the mixing of precursor solutions because it produces a retardation of the polymerization. Raman spectral analysis confirmed the changes in the composition along the long axis of the produced cylindrical materials. Compression tests were also performed, exhibiting the gradient and reference material’s unique properties, which were well correlated to the compositional pattern.
A novel shape memory polymer based on conetworks
Authors: Li Zonghui , Pan Yi , Zhang Peng , Zheng Zhaohui , Ding Xiaobin , Peng Yuxing
Published: August 2014

A novel shape memory polymer based on conetworks (CNs) was synthesized. These conetworks consisting of poly(methyl methacrylate) and poly (ethylene glycol) diacrylates showed excellent shape-memory properties with a recovery ratio of nearly 100%. Moreover, different shape memory effects were discovered in different mediums due to their amphiphilic properties. In addition, a large storage modulus ratio above and below the glass transition temperature(Eratio), which probably means excellent shape memory effect, were obtained due to the designed CN structure whether crystallization existed or not. It is quite different from the traditional methods to achieve large Eratio values. The versatility of shapememory conetworks potentially provides us a new route to prepare shape memory materials.
Surface-initiated atom-transfer radical polymerization from polyethersulfone membranes and their use in antifouling
Authors: Li Liang , Yan Guoping , Wu Jiangyu , Yu Xianghua , Guo Qingzhong
Published: August 2014

A simple one-step method for the chloromethylation of polyethersulfone (PES) under mild conditions provided surface benzyl chloride groups as the active initiators for the surface-initiated atom-transfer radical polymerization (ATRP) to tailor the functionality of the PES membrane. Functional hydrophilic polymer brushes of poly(ethylene glycol)monomethacrylate (PEGMA) and sodium 4- styrenesulfonate (NaStS), as well as their block copolymer brushes, were prepared via surface initiated ATRP from the chloromethylated PES surfaces. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize the surface-modified membranes. The PEGMA-grafted PES membranes showed great protein resistance to protein adsorption compared to the pristine PES surface.
Morphology of inorganic–organic systems consisting of polyhedral oligomeric silsesquioxanes (POSS) and polyamide 6
Authors: Alongi Jenny , Monticelli Orietta , Russo Saverio , Galy Jocelyne , Gérard Jean-François
Published: August 2014

Preparation of inorganic-organic hybrids made of polyhedral oligomeric silsesquioxanes (POSS) and polyamide 6 (PA6) has been attempted either by melt mixing of the two components or by in-situ polymerization of -caprolactam (CL) in presence of POSS. The samples have been characterized by wide angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM) techniques. Specific processing conditions (namely, high T in presence of different shear stresses) have been tested. Two different approaches for melt mixing have been used and the morphology of the corresponding systems compared. The melt-mixed pairs prepared in the microcompounder revealed a coarse phase separation, while those made in a simple mixer did not show any perceivable POSS segregation phenomenon, as evidenced by both WAXD data and SEM investigation. Similarly, the in-situ polymerization of CL in presence of POSS did not result in any POSS self-aggregation in the polyamide matrix, achieving a very fine Si dispersion of nanometric dimensions.
Self-assembly in the solutions of poly(methyl methacrylates) end-capped with fluorophenyl groups
Authors: Gasilova Ekaterina R. , Zakharova Olga G. , Zaitsev Sergey D. , Semchikov Yury D.
Published: August 2014

Self-assembly of poly(methyl methacrylates) end-capped with -Ge(C6F5)3 groups (PMMA-F) has been studied in a selective solvent (acetone) by means of photon correlation spectroscopy and static light scattering. PMMA-F’s of different molecular weights (MW), were obtained by radical polymerization in the presence of a chain transfer agent, HGe(C6F5)3. At MW>130 000 conformational and hydrodynamic properties of PMMA-F’s is shown to be the same as of PMMA. At MW less than130 000 an aggregation starts: additional fraction of large scatterers appears in PCS. Large aggregates of Rh=200 - 300 nm are likely to be formed by bridged micellar clusters. Presence of large aggregates indicates a super strong segregation limit predicted in the work of Semenov et al.
Synthesis of poly(butadiene)-poly(ε-caprolactone) multiblocks based on hydroxyl telechelic poly(butadiene): composition and kinetic study
Authors: Lemoine Michael , Brachais Claire-Hélène , Boni Gilles , Couvercelle Jean-Pierre
Published: August 2014

Thermoplastic block copolymers based on poly(butadiene) and poly(ε- caprolactone) were synthesised from the ring opening polymerization of ε- caprolactone onto a polybutadiene macroinitiator. The lithium alkoxide macroinitiator results from BuLi addition on hydroxy telechelic polybutadiene (HTPB R45®) chain ends. The reaction is fast (about 5 min) and quantitative, leading to well defined copolymers with PCL/PBHT ratio varying from 45/55 and 18/82. Average molar masses range from 10 000g/mol to 26 000g/mol with PDI about 1.6. 1H NRM was used to follow the polymerization kinetic and 13CNMR was used to determine the chemical link between the blocks.
Crystallization and rheological behavior of POSS filled polypropylene
Authors: Zhou Zhiyong , Ouyang Chunfa , Zhang Yong , Zhang Yinxi , Yin Nianwei
Published: August 2014

Octaaminophenyl polyhedral oligomeric silsesquioxane (OapPOSS) was prepared as nanofillers and filled to isotactic polypropylene (PP). Maleic anhydridegrafted PP (MAPP) was selected as compatibilizer. The morphology, crystallization, melting behavior and rheologcial behavior of PP/OapPOSS composites with or without MAPP were studied by scanning electron microscopy, differential scanning calorimetry, polarized optical microscope, oscillatory and capillary rheological analysis. The results showed that the morphology, crystallization and rheological behavior of the composites were strongly influenced by the existence of MAPP. MAPP improves the compatibility between PP and OapPOSS because of the reaction of OapPOSS with MAPP. The OapPOSS retards the crystallization of PP while promoting it when MAPP is added. MAPP could decrease the viscosity of PP/OapPOSS probably due to the weaker particleparticle interaction and interface slipping.
The influence of polymerization temperature on structure and properties of polyaniline
Authors: Yılmaz Faris , Küçükyavuz Zuhal
Published: August 2014

The influence of polymerization temperature (from -25 to +25 oC) on molecular weight, crystallinity, electrical conductivity, thermal and morphological properties of polyaniline has been investigated. Aniline was oxidized in an aqueous medium with ammonium persulfate and 1.0 M hydrochloric acid. The reaction mixture freezes below -10 oC and hence lithium chloride was used in sufficient amount to prevent freezing. As the reaction temperature decreases, both the molecular weight of polyaniline and its crystallinity increase. Thermal studies show a common three step decomposition pattern irrespective of the temperature used during synthesis. The morphology of polyaniline changes from granular (reaction in liquid medium) to tubular (polymerization in the frozen state). Thermal analysis indicated that the polyaniline stability increased with decreasing synthesis temperatures. Electrical conductivity of polyaniline was found to be independent of the polymerization temperature and, consequently, of the molecular weight.
Homo- and copolymers of 3-tosyloxymethyl-3-methyl oxetane (TMMO) as precursors to energetic azido polymers
Authors: Barbieri Ugo , Keicher Thomas , Polacco Giovanni
Published: August 2014

Poly(3-azidomethyl-3-methyloxetane) and its copolymers with 3,3- bis(azidomethyl)oxetane were synthesized by cationic polymerization from 3- tosyloxymethyl-3-methyl oxetane and 3,3-bis(bromomethyl)oxetane, using a polyol as initiator and boron trifluoride complex as catalyst, followed by azidation. The final objective is the synthesis of an energetic binder to be used for rocket propellants and therefore the effects of different initiator/catalyst systems on important properties, like, i.e., the molecular weight distribution and the functionality of the polymer, were investigated. It was found that, even though both the operating conditions and the catalytic system were chosen in order to grant the living character of the polymerization, the latter seems to be prevalently driven by an “active chain end” mechanism. In particular, this may lead to the undesired formation of a small quantity of oligomers and to the presence of non-hydroxylic chain-end functionalities. Nevertheless, the average number of OH groups can be strictly controlled when boron trifluoride tetrahydrofuranate is used as catalyst.
Characterization of thin films of regioregular poly(alkylthiophene)s bearing optically active substituents
Authors: Angiolini Luigi , Brazzi Alice , Grenci Valeria , Salatelli Elisabetta , Catellani Marinella , Luzzati Silvia
Published: August 2014

The spectroscopic behavior of thin films of regioregular poly(alkylthiophene)s bearing an optically active alkyl group has been investigated in the solid state under different sample preparation procedures. The experimental results are interpreted in terms of influence of the side-chain substituents on the extent of planarity of the polymeric chains and the formation of optically active chiral aggregates.
Study of the compounding process parameters for morphology control of LDPE/layered silicate nanocomposites
Authors: Coiai Serena , Scatto Marco , Bertoldo Monica , Conzatti Lucia , Andreotti Leonardo , Sterner Marion , Passaglia Elisa , Costa Giovanna , Ciardelli Francesco
Published: August 2014

A careful insight into melt compounding procedure is proposed in order to achieve a better understanding and control of the dispersion and orientation mechanisms of organo-clay platelets into LDPE nanocomposites. The method involved is the preparation of a maleic anhydride grafted polyethylene masterbatch containing 10 wt% organo-clay via twin-screw extrusion. A substantial nanodispersion and orientation of clay platelets was obtained as observed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Moreover, the nanocomposites prepared by diluting the master-batch through the blend mixing with additional LDPE preserved or improved the exfoliation and lamellae orientation. Finally, the thermo-gravimetric analysis (TGA) showed a significant improvement of the thermal stability while both differential scanning calorimetry (DSC) and XRD evidenced a slight increase of the LDPE crystallinity degree with respect to neat polymer matrices thus suggesting the occurrence of orientation also for the polymer.
Frontal polymerization as a convenient technique for the consolidation of tuff
Authors: Mariani Alberto , Bidali Simone , Cappelletti Piergiulio , Caria Giuseppe , Colella Abner , Brunetti Antonio , Alzari Valeria
Published: August 2014

Frontal Polymerization was successfully exploited as an innovative technique for the consolidation of Neapolitan Yellow Tuff, the main volcaniclastic rock of Campania region (Italy). The protocol used and the full characterization in terms of mechanical properties of the resulting consolidated stone are presented here and discussed together with the data obtained by X-ray tomography as a non destructive analytical technique for determining the internal map of the consolidated material. The proposed treatment definitely succeeded from the technical point of view resulting in an enhancement of mechanical properties.