bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring the chemical heterogeneity of metallocenecatalysed copolymers of ethylene and higher 1-olefins using CRYSTAF and SEC-FTIR
Authors: Graef Sven M. , Brüll Robert , Pasch Harald , Wahner Udo M.
Published: August 2014

Copolymers of ethylene with 1-decene, 1-tetradecene and 1-octadecene were prepared using the catalyst system racEt[Ind]2ZrCl2/MAO and were analysed with regard to chemical heterogeneity using crystallisation analysis fractionation (CRYSTAF), differential scanning calorimetry (DSC) and size exclusion chromatography coupled to FTIR (SEC-FTIR). The melting and crystallisation temperatures from DSC decrease linearly with increasing amount of comonomer, independently of the nature thereof. The decrease in crystallisation temperature from CRYSTAF of copolymers with higher 1-olefin content indicates a small dependence on the length of the side chain. The chemical heterogeneity of the copolymers as analysed by DSC and CRYSTAF broadens with increasing comonomer concentration.
Effect of SBS compatibilizer on the interphase boundary of polymer blends of polystyrene and natural rubber
Authors: Boyanova Mileta , Mina Mohammed Forhad , Calleja Francisco José Baltá , Fakirov Stoyko
Published: August 2014

Microhardness (H) has been used to quantitatively characterize the quality of the interphase boundary of blends of atactic polystyrene (PS) with natural rubber (NR) and the compatibilizer styrene-butadiene-styrene (SBS) block copolymer. Qualitative conclusions are drawn for the same purpose from scanning electron microscopy (SEM) observations on surface indentation. Cast films of neat PS and the blends PS/NR, PS/SBS and PS/NR/SBS were prepared from a common solvent (toluene). While neat PS shows a constant H = 175 MPa, the PS/SBS blend exhibits a gradual decrease starting from H = 130 - 140 MPa at a distance of about 100 μm from the phase boundary up to the final value of 25 MPa. For the PS/NR blend this decrease starts at about 50 μm, reaching the same final value. Owing to the elastic recovery, no indentations on the NR or SBS particles surface can be detected as confirmed by SEM. The compatibilized blend PS/NR/SBS is characterized by the thinnest phase boundary (about 25 μm) and a final H value of 75 MPa which demonstrates that the compatibilizer SBS is distributed just on the phase boundary between PS and NR. Results confirm previous findings in incompatible blends of poly(methyl methacrylate)/NR, highlighting that microindentation is a sensitive tool for studying the breadth and quality of the interphase boundary in compatibilized or non-compatibilized polymer blends and other non-homogeneous materials. This technique allows, in addition, the localization of the compatibilizer in the polymer blends.
Organisation and melting of solution grown truncated lozenge polyethylene single crystals
Authors: Tian Mingwen , Loos Joachim
Published: August 2014

Morphological features and the melting behaviour of truncated lozenge crystals have been studied. For the crystals investigated, the heights of the (110) and the (200) sectors were measured to be 14.5 and 12.7 nm, respectively, using atomic force microscopy (AFM) in contact and non-contact mode. Moreover, melting temperatures of 123°C for the (110) sector and of 120°C for the (200) sector have been measured using real-time AFM during annealing experiments. Applying atomic force acoustic microscopy and the n-alkane decoration technique, no difference in the surface fold organisation of (110) and (200) sectors could be detected. For similar stem lengths, variations in stem tilt angle within the sectors might cause the thickness difference observed. However, a very high tilt angle difference above 20° is required. More likely, a shorter stem length within the (200) sector may cause its lower melting temperature.
Effect of polymerization sequence on the electrochemical properties of polypyrrole / poly(3-methylthiophene) bilayers
Authors: Ayoub Samira , Dias Bruna L. , Mascaro Lucia H. , Micaroni Liliana , Gazotti Wilson A.
Published: August 2014

The electrochemical and photoelectrochemical characteristics of conducting polymer bilayers composed by polypyrrole, PPy, and poly(3-methylthiophene), PMeT, are described. The bilayers were produced by galvanostatic deposition of the polymers using different charge densities. Scanning electron micrographs indicate that the sequence of polymerization affects the surface morphology of the bilayers and, while PMeT polymerizes into the pores of the PPy film, a PPy film is formed over the PMeT film. Cyclic voltammetry of the bilayers shows the peaks corresponding to PPy and PMeT, regardless of the sequence of deposition; however, the potentials of redox processes are slightly shifted. The sequence of polymer deposition also affects the photoelectrochemical properties of the bilayers. The results show that, for a bilayer with PMeT as inner polymer and PPy as outer polymer, an enhanced photocurrent can be obtained by controlling polymer film thickness.
Frontal atom transfer radical polymerization of tri(ethylene glycol) dimethacrylate
Authors: Bidali Simone , Fiori Stefano , Malucelli Giulio , Mariani Alberto
Published: August 2014

The first frontal atom transfer radical polymerization (FATRP) has been successfully carried out using tri(ethylene glycol) dimethacrylate as a monomer. The effect of the catalyst/initiator ratio has been investigated and related to the front velocity and its maximum temperature. By comparing this new approach with classical radical polymerization routes and with conventional frontal polymerization, it was found that the so-obtained polymer is characterized by higher conversion, shorter reaction times, higher degradation temperature, and does not contain entrapped bubbles.
Synthesis and characterisation of propene / higher 1-olefin copolymers with the catalyst system (CH3)2Si(2-methylbenz[e]indenyl)2ZrCl2/MAO
Authors: Brüll Robert , Luruli Nyambeni , Pasch Harald , Raubenheimer Helgard G. , Sadiku E. Rotimi , Sanderson Ron , Reenen Albert J. van , Wahner Udo M.
Published: August 2014

The melting and crystallization behaviour of random copolymers of propene with 1-butene, 1-pentene and 1-hexene synthesized with the catalyst system (CH3)2Si(2-methylbenz[e]indenyl)2ZrCl2/methylaluminoxane (MAO) were investigated by differential scanning calorimetry and crystallization analysis fractionation (CRYSTAF). The melting and crystallization temperatures decreased linearly with increasing comonomer content. The depressions of the melting and crystallization temperatures are strongly dependent on the nature of the monomer and are more pronounced for copolymers of propene with 1-hexene than with 1-butene. In comparison to 1-hexene and 1-butene, the incorporation of 1-pentene leads to an intermediate behaviour. This is in contrast to the behaviour of copolymers of propene with longer chain 1-olefins, where the melting and crystallization temperatures are independent of the comonomer type. The depressant effects of the amount of comonomer incorporated on the melting and the crystallization temperatures are equal.
End-group interchain exchange reaction in polymer blends: evolution of the block weight distribution
Authors: Kudryavtsev Yaroslav V. , Govorun Elena N.
Published: August 2014

The kinetics of interchain exchange reactions proceeding via end-group mechanism in homogeneous polymer blends is studied theoretically. A set of kinetic equations describing the evolution of the block weight distribution is derived. It is demonstrated that the process may be divided into a fast and a slow stage. The fast stage is characterized by alteration in the fractions of end sequences of different type. At the same time most of the homopolymer chains transform into copolymer with block weight distribution close to the Flory distribution. In the course of the subsequent slow stage, the distribution shape is preserved, with average block lengths gradually decreasing to the values typical of the completely random copolymer. The copolymer composition is found to change mostly in the course of the fast stage of the process. The possibilities of using kinetic data for the discrimination between end-group and direct interchange mechanisms are discussed.
Functional segmented polymer networks based on polytetrahydrofuran and poly(vinylbenzyl chloride)
Authors: Jonckheere Laura , Goethals Eric J. , Du Prez Filip E.
Published: August 2014

Functional segmented polymer networks (FSPNs) were synthesised via free radical initiated copolymerisation of polytetrahydrofuran (PTHF) bis-macromonomers with vinylbenzyl chloride (VBCl). The purpose of this work was to create FSPNs, providing supports with a functional group that can be substituted and may serve to immobilise other reagents such as catalysts. After the preparation and detailed characterisation of several PTHF bis-macromonomers, FSPNs were prepared with varying molecular weight of the PTHF chain and varying PTHF/ PVBCl ratio. Measurements of the soluble fraction and elemental analyses demonstrated that FSPNs with a wide composition range could be prepared. From dynamic-mechanical and thermal analyses, it could be concluded that most FSPNs showed some degree of compatibility and complete absence of crystallinity. The mechanical properties of the FSPNs are directly related to their composition. The degree of substitution of all networks is close to quantitative.
Synthesis and characterization of 4-chloromethylstyrene polymers containing bulky organosilicon groups
Authors: Safa Kazem Dindar , Babazadeh Mirzaagha
Published: August 2014

The homopolymer of 4-chloromethylstyrene and its copolymers with styrene (in 1:3 and 1:1 mole ratio) were synthesized by bulk and solution freeradical polymerisations, respectively, at 70±1°C using α,α'-azoisobutyronitrile as an initiator. Highly sterically hindered tris(trimethylsilyl)methyl (Tsi) substituents were then covalently linked to the obtained homopolymer and copolymers. The polymers were characterized by IR, 1H NMR and 13C NMR, differential scanning calorimetry (DSC) and gel permeation chromatography. DSC showed that incorporation of Tsi substituents in the side chains of homopolymer and copolymers increases the rigidity of the polymers and, subsequently, their glass transition temperature.
Conformational properties of dendritic polymers with variable branching functionality in their generational shells
Authors: Roovers Jacques
Published: August 2014

The shrinkage factors, g, of long-chain dendritic polymers with different branching functionalities in their generational shells are derived in the Gaussian approximation. The equations for generations zero (star) to 3 are given explicitly in a form that can be extrapolated easily to higher generation number. Examples of the evolution of the shrinkage factors with branching functionality are given. The form factors, P(x), of the same dendritic polymers are also derived. The equations can be extrapolated to higher generation number and easily incorporated into a simple calculation program. Comparisons are made with regular stars with the same number of arms as the peripheral subchains in the dendrimers. It is found that 3rd generation dendritic polymers with low branch functionality (= 3) are less sphere-like than the star with 24 arms, but the 3rd generation dendrimer with functionality 5 is more sphere-like than the star with 108 arms.
Synthesis and characterization of a pressure-sensitive adhesive based on an isobutyl acrylate / 2-ethylhexyl acrylate copolymer
Authors: López Betty L. , Murillo Edwin , Hess Michael
Published: August 2014

A removable pressure-sensitive adhesive was obtained by free-radical emulsion polymerization. The product is a low-viscosity copolymer from different polar and apolar acrylic monomers consisting of microspheres of about 1 μm diameter. 2-Ethylhexyl acrylate and isobutyl acrylate were used as non-polar constituents while acrylic acid and acrylamide provided the more polar constituents to regulate the cohesive force of the adhesive. The amounts of initiator, water and emulsifier (nonylphenol) were varied to obtain the best adhesive properties at the given copolymer composition. The resulting adhesive showed the desired balance of low tack and good adhesive strength in combination with a wide variety of substrates, which made it useful as a removable adhesive for many applications. The product was characterised by viscometry, measurements of tack and peel strength, FTIR, DSC, and microscopy.
Electrorheology of conducting polyaniline composite particles
Authors: Choi Hyoung Jin , Cho Min Sung , Lee Young Hoon , Cho Yun Hyang , Jhon Myung S.
Published: August 2014

Three different kinds of particles of semiconductive polyaniline (PANI), spherical poly(methyl methacrylate) with a PANI shell (PAPMMA), and conductive PANI encapsulated by insulating melamine-formaldehyde resin (MCPA) were synthesized and adopted as a dispersed phase for electrorheological (ER) fluids. ER fluids are suspensions of polarizable particles dispersed in non-conducting liquids. The rheological characteristics of ER fluids rapidly change in the presence of an applied electric field, which can be controlled by both the applied electric field strength and particle concentration with a fast response time on the order of milliseconds. MCPA-based ER fluids show the largest stress enhancement by an applied electric field compared with both PANI- and PAPMMA-based ER fluids, demonstrating that the conductive core with an insulating shell system is a better ER material than homogeneous, semiconductive materials or surface-semiconductive materials with insulating cores.
Pre-treatment of CaCO3 nanofiller by irradiation in the presence of vinyl monomers for the preparation of poly(vinyl acetate) composites
Authors: Leskovac Mirela , Kovačević Vera , Lučić Blagojević Sanja , Vrsaljko Domagoj , Volovšek Vesna
Published: August 2014

Poly(vinyl acetate) (PVAc) composites were prepared by different approaches, namely (i) by mechanical mixing of untreated CaCO3 and PVAc, (ii) by mechanical mixing of CaCO3 pre-treated by irradiation polymerization in the presence of vinyl acetate, and (iii) by in situ emulsion polymerization of VAc in the presence of untreated CaCO3 nanofiller. The effects of nanoparticle pre-treatment and different approaches of preparation were correlated with changes in morphology and mechanical properties of PVAc composites using scanning electron microscopy and tensile tests. Untreated CaCO3 nanoparticles in the composite prepared by mechanical mixing provided strong interactions with the PVAc matrix. On the other hand, CaCO3 pre-treated nanoparticles decreased the interfacial interactions. For composites prepared by in situ polymerization a better dispersion of encapsulated nanoparticles was achieved and, as a result, a significant improvement of composite strength was observed. Interfacial interactions in nanocomposites can be changed by filler pre-treatment or by a suitable way of nanocomposite preparation.
Distribution of clay particles in the spherulitic texture of poly(L-lactide)/organo-modified montmorillonite hybrids
Authors: Ninomiya Naoya , Nam Pham Hoai , Fujimori Atsuhiro , Masuko Toru
Published: August 2014

The distribution of clay particles in the spherulitic texture of poly(Llactide)/ clay hybrids crystallized isothermally at 140°C has been investigated by use of energy-dispersive X-ray microanalysis. After crystallization of the hybrids, the clay particles were found to distribute with almost constant concentration along the radial direction of the spherulites, i.e., they are still kept in stacked state inside the spherulites without any segregation during crystallization. The concentration distribution of the clay particles showed that these particles were incorporated into the spherulitic texture of the crystallized hybrids.
Interaction between sodium polystyrenesulfonate and Triton X-100 in aqueous solution
Authors: Salem Jamil K. J. , Melad Omar , Baraka Rajai
Published: August 2014

The interaction between sodium polystyrenesulfonate (PSS) and Triton X-100 (α-(4-octylpenyl)-poly(oxyethylene), TX-100) has been investigated by viscosity and conductivity measurements. The results show that the reduced viscosity of PSS increases with increasing PSS concentration at low constant TX-100 concentrations (0.006 - 0.029 g/ml). On the other hand, at higher constant TX-100 concentrations, 0.048 and 0.062 g/ml, the reduced viscosity decreases with increasing PSS concentration. The behaviour of conductivity of PSS in pure water is quite different from that in the presence of TX-100.
Application of dynamic mechanical analysis techniques to bismuth telluride based thermoelectric materials
Authors: Brostow Witold , Menard Kevin P. , White John B.
Published: August 2014

Dynamic mechanical analysis (DMA) techniques are commonly applied to characterize polymer-based materials - but little if at all to characterize semiconductor thermoelectric (TE) materials. TE materials may be coupled with polymeric materials in advanced thermoelectric devices, and the knowledge of TE material properties will be useful in the choice of materials for future applications. We have obtained DMA results for both n-type and p-type bismuth telluride based TE materials. We find that tan δ values, indicative of viscoelastic energy dissipation modes, approach the values for glassy or semi-crystalline polymers, and are larger by more than a whole order of magnitude than the tan δ of structural metals. DMA thermal scans show clear hysteresis-type effects and a correlation with differential scanning calorimetry thermal transitions. DMA properties as a function of frequency are briefly discussed. Our results show that DMA techniques are useful in the evaluation of thermophysical and thermomechanical properties of these TE materials and of assembled coolers. The viscoelastic effects we report may provide a damping mechanism for severe stresses inherent to service conditions of the TE coolers.
Small-angle neutron scattering study of shear-induced phase separation in aqueous poly(N-isopropylacrylamide) solutions
Authors: Stieger Markus , Lindner Peter , Richtering Walter
Published: August 2014

The influence of shear flow on the structure of concentrated aqueous poly(N-isopropylacrylamide) solutions near the lower critical solution temperature was investigated by means of small-angle neutron scattering. Two samples, both in the semi-dilute regime above the overlap concentration, were studied. The scattering curve of the less concentrated sample was not influenced by shear flow, although high shear rates were reached. The more concentrated 4 wt.-% sample, however, displayed shear-induced demixing under strong shear flow conditions. Experiments at different shear stresses indicated the existence of a threshold shear stress and the phase separation process became faster with increasing stress. The two-dimensional scattering patterns remained isotropic even during the phase separation process and the correlation length as obtained from an Ornstein- Zernike plot increased. The influence of shear flow on the phase separation process is thus similar to a temperature increase. The results are in excellent agreement with data from recent rheo-optical experiments where shear-induced phase separation was also observed for the concentrated solution at high shear rates. Apparently, strong shear flow exerts an effect analogous to a temperature increase.
Formation of superlattices in blends of 3-miktoarm star terpolymers with diblock copolymers
Authors: Abetz Volker , Jiang Shimei
Published: August 2014

In this contribution we report on the morphological structures formed in blends of microphase-separated 3-miktoarm star terpolymers of polystyrene-armpolybutadiene- arm-poly(2-vinylpyridine) (SBV*) and polystyrene-block-polybutadiene (SB), polystyrene-block-poly(2-vinylpyridine) (SV), poly(2-vinylpyridine)- block-poly(cyclohexyl methacrylate) (VC) diblock copolymers. The morphologies are characterized by transmission electron microscopy. Blends with similar morphologies as known from linear triblock terpolymers are found, like core-shell structures based on cylinders or gyroids. Other blends show very distorted morphologies, or morphologies similar to the ones found for pure 3-miktoarm star terpolymers. While attractive interactions between blocks of the two species enhance the formation of common superlattices, blends with too large diblock copolymers tend to macrophase-separate.
Molar mass characterization of hydrophilic copolymers, 1 Size exclusion chromatography of neutral and anionic (meth)acrylate copolymers
Authors: Adler Martina , Pasch Harald , Meier Christian , Senger Raimund , Koban Hans-Günter , Augenstein Michael , Reinhold Günter
Published: August 2014

A robust and reproducible method for the molar mass analysis of neutral and anionic copolymers based on methacrylic acid and different (meth)acrylates has been developed. Size exclusion chromatography (SEC) using a novel polyester- based packing as the stationary phase and dimethylacetamide (DMAC) as the mobile phase yields highly accurate results for copolymers with a methacrylic acid content up to 50 wt.-%. To suppress the different polar and ionic interactions between the sample molecules, the stationary phase and the eluent, DMAC was modified with LiBr and acetic acid. Calibrating the SEC system with poly(methyl methacrylate) of narrow polydispersity, molar masses were obtained that are in good agreement with data obtained by SEC-MALLS (multi-angle laser light scattering) and SEC measurements of methylated samples. The reproducibility and the robustness of the novel method were proven by running similar samples in three different laboratories and for an extended period of two weeks.
Studies on flocculation of clay suspension by polyacrylamide
Authors: Prabhu T. Niranjana , Rao Y. Jagannadha , Prashantha K.
Published: August 2014

The flocculation of dilute pottery clay suspension using polyacrylamide (PAM) was investigated. Different molecular weight PAMs were synthesized by free-radical polymerization initiated with the persulfate-bisulfate redox pair. The synthesized polyelectrolytes (PAM1, PAM2 and PAM3, from low to high molecular weight) and a commercial one (C-492) were used for flocculation studies. The flocculating performance of polyelectrolytes was measured on 3% w/v pottery clay suspension using settling tests and turbidity measurements. PAM2 at pH 5.0 showed the maximum settling rate, which is nearly three times that of C-492, and it also showed a better turbidity reduction. Molecular weight is the key factor in influencing settling and turbidity reduction. In the present study, increasing molecular weight enhanced settling rate and turbidity reduction to a certain level beyond which there is a decrease, suggesting an optimum molecular weight for the given application. PAM2, a medium molecular weight polyelectrolyte (2.0·105 g/mol) has shown better performance than PAM1 (1.3·105 g/mol), PAM3 (6.0·105 g/mol) and the commercial polyelectrolyte C-492 (molecular weight of order 106).
AB Block-copolymers poly(oxyethylene)-blockpoly( dicyclohexyl itaconate): temperature dependence of the morphology
Authors: Aleksieva Krasimira , Ancev Ane , Koseva Slobodanka , Cvetkovska Maja , Nedkov Emanuel
Published: August 2014

The paper deals with AB block-copolymers poly(oxyethylene)-blockpoly( dicyclohexyl itaconate) (POE/PDCHI) containing 2000 and 5000 g/mol of the flexible POE. The study aims at revealing the thermal effect on the copolymer morphology in the 20 - 200°C range. Optical microscopy investigations were performed. The results confirm our previous X-ray studies. A liquid crystalline state is observed in the 90 - 180°C range. It is characterized by birefringence and is determined by the chair-chair conformation, a dominating structure of the cyclohexyl rings. A condis-crystal state is observed at cooling in the interval 90°C to room temperature. It is characterised by a variety of cyclohexyl conformations and, therefore, by a lack of birefringence. The PEO component in the copolymer starts crystallising into small local spherulites at about room temperature. The results obtained allow the conclusion that the presence of PDCHI is a determining factor for the mesomorphic state of the copolymers discussed.
Synthesis and characterization of 1,4-diazophenylenebridged Cu-phthalocyanine polymer
Authors: Alkan Cemil , Aras Leyla , Gündüz Güngör
Published: August 2014

A novel type of phthalocyanine polymer, 1,4-diazophenylene-bridged Cuphthalocyanine, was prepared from the diazonium salt of diaminobenzene and Cu(II) 1,8,15,22-tetraaminophthalocyanine. The polymer is partially soluble in tetrahydrofuran, dichloromethane, and dimethylformamide. Characterization of the polymer was performed by IR and UV-visible spectroscopy, X-ray diffraction, ash analysis, viscometry, differential scanning calorimetry and thermogravimetric analysis. The molecular weight of the soluble part of the polymer was determined by ebullioscopy. Electrical conductivity of the polymer and its doped samples were determined by the 4-probe technique. It was found that the electrical conductivity increased up to 10-4 S/cm after doping. The redox behaviour of the polymer was investigated utilizing cyclic voltammetry.
Thermal stability of side-chain polymer liquid crystals
Authors: Mano João F.
Published: August 2014

Five simple-comb polymer liquid crystals - four polyacrylates and one polysiloxane - were studied using thermogravimetric analysis. A simple kinetic model was used to access the activation energy of the weight loss events. For the polyacrylates one main degradation process was observed with activation energy around 165 kJ/mol, probably involving intramolecular transfer, which would include a coupled weight loss mechanism of both polymeric backbone and mesogenic side-groups. For the studied polysiloxane, two overlapped mechanisms are observed that suggest separate mechanisms for the degradation of side-groups and main chain.
Poling of β-poly(vinylidene fluoride): dielectric and IR spectroscopy studies
Authors: Sencadas Victor , Costa Carlos M. , Moreira Victor , Monteiro Jorge , Mendiratta Sushil K. , Mano João F. , Lanceros-Méndez Senentxu
Published: August 2014

β-Poly(vinylidene fluoride) (β-PVDF) exhibits ferroelectric properties due to the special arrangement of the chain units in the crystalline phase. The piezoelectric properties of the material can be optimised by poling the original stretched film. The main effect of the poling process is the alignment of the randomly organised dipolar moments against the applied field. In this work, poled and non-poled β- PVDF from the same batch are characterised by dielectric spectroscopy. The origin of the electrical and mechanical response of poled and non-poled β-PVDF were further explored by far IR spectroscopy and discussed on a molecular level. The main effect of the poling process on the dielectric response of the material is a small increase of the dielectric constant due to the preferential alignment of the main dipolar contribution and a slight decrease of the dielectric loss, due to the more organized amorphous structure. The conductivity is strongly increased by poling, especially the high-temperature conductivity, ascribed mainly to hopping conductivity due to free charges induced during poling. FTIR experiments indicate that the origin of these effects and also of the variations in the thermo-mechanical response of the material can be found in the reorientation of the crystalline dipoles along the poling field, together with a partial reduction of the amount of α phase and an increase of the amount of β phase. The α to β transformation, mainly due to the stretching process, seems to be optimized by the poling process.
Synthesis and characterization of highly branched polymethacrylates via self-condensing oxyanionic copolymerization
Authors: Jia Zhifeng , Huang Wei , Yan Deyue
Published: August 2014

Highly branched polymethacrylates were successfully synthesized by the self-condensing vinyl copolymerization of 2-dimethylaminoethyl methacrylate (DMAEMA) and methacrylic inimer containing a vinyl group and an oxyanionic active site, which was formed via the in situ reaction of 2-hydroxyethyl methacrylate (HEMA) with potassium hydride. Depending on the comonomer ratio, γ = [DMAEMA]0/[HEMA]0, branched poly(DMAEMA)s with number-average molecular weights between 4800 and 22 000 and degree of branching between 0.09 and 0.38 were obtained, as evidenced by gel permeation chromatography and NMR analysis. Thermally reversible phase transitions were observed for the branched poly(DMAEMA)s produced at higher comonomer ratio (γ ≥ 5). Quaternization of the branched poly(DMAEMA)s with methyl iodide led to cationic polyelectrolytes with branched structure.
Atom transfer radical polymerization of styrene initiated by the novel initiator 2-bromo-2-nitropropane
Authors: Wang Gang , Zhu Xiulin , Zhengping Cheng , Zhu Jian
Published: August 2014

Heterogeneous atom transfer radical polymerization (ATRP) of styrene initiated by 2-bromo-2-nitropropane in bulk was carried out with CuCl/2,2′-bipyridine as the catalyst. The kinetics was first order in monomer and the numberaverage molecular weight of the polymer increased linearly with monomer conversion, indicating the ‘living’/controlled nature of the polymerization. However, the number-average molecular weight was usually higher than the theoretical one. The nitro group might react with the Cu complex, resulting in insufficient initiation. The amount of catalyst has no effect on the controllability of this catalyst system for the ATRP of styrene. The presence of a halide end group in the obtained polymer was confirmed by both 1H NMR and chain-extension reaction.
SEC/MALDI-TOF Mass spectrometry study of hydroxy-, carboxy- and methyl ester-terminated aliphatic polyesters
Authors: Salhi Slim , Tessier Martine , Blais Jean-Claude , Gharbi Rachid El , Fradet Alain
Published: August 2014

Poly(ethylene adipate) (PEA) and poly(ethylene dodecanedioate) (PED) with dicarboxy-, dihydroxy-, dimethyl ester- and hydroxy-carboxy end-groups were synthesized and characterized by 13C NMR and MALDI-TOF MS. Size-exclusion chromatography (SEC) fractions of these polyesters were analyzed by MALDI-TOF MS and used as standards to obtain SEC calibration curves leading to the absolute molar masses of the unfractionated polyesters. PEA and PED calibration curves were different from each other, but the same calibration curve was obtained for each type of polyester, irrespective of the nature of end-groups, showing the predominant role of the nature of repeating units on the hydrodynamic volume of oligoesters. The study also shows that the conventional SEC calibration method using polystyrene standards leads to a significant overestimation of polyester average molar masses.
‘Surfactant-free’ stable nanoparticles from biodegradable and amphiphilic poly(ε-caprolactone)-grafted dextran copolymers
Authors: Ydens Isabelle , Degée Philippe , Nouvel Cécile , Dellacherie Edith , Six Jean-Luc , Dubois Philippe
Published: August 2014

A variety of poly(ε-caprolactone)-grafted dextran copolymers were synthesized with a controlled architecture through a three-step procedure: partial protection of the dextran hydroxyl groups by silylation, ring-opening polymerization of ε-caprolactone initiated from remaining free hydroxyl groups on partially silylated dextran, and silyl ether deprotection under mild conditions. The potential of these amphiphilic grafted copolymers as surfactants was investigated by water/toluene interfacial tension measurements. Since each copolymer showed noticeable surfactant properties, their ability to form ‘surfactant-free’ nanoparticles was evaluated using the nanoprecipitation method. It was found that remarkably stable core (polyester) - shell (polysaccharide) nanoparticles with a mean diameter around 200 nm were formed.
The effect of curing on sorption and diffusion of a brake fluid in EPDM elastomer
Authors: Farahani Tahereh Darestani , Bakhshandeh Gholam Reza
Published: August 2014

The effect of a poly(ether glycol) brake fluid on cured EPDM (ethylenepropylene- diene monomer) elastomer based on 5-ethylidene-2-norborene has been studied. Different amounts of dicumyl peroxide (DCP) curing agent were used and the effect of ageing in a brake fluid (at 100°C for 70 h) on technical properties of EPDM have been investigated. By increasing the amount of DCP, significant changes were not observed. Tensile strength and modulus increased but elongation at break and abrasion loss decreased due to oxidative degradation and crosslinking. Hardness was constant due to the replacement of plasticizer with brake oil.
Synthesis of fructooligosaccharide-based plastic films starting from inulin
Authors: Grandtner Gerlinde , Joly Nicolas , Cavrot Jean-Paul , Granet Robert , Bandur Geza , Rusnac Lucian , Martin Patrick , Krausz Pierre
Published: August 2014

In this preliminary study, inulin, a fructooligosaccharide extracted from chicory roots, was converted into plastic films by acylation in homogeneous medium and under conventional heating, using methacryloyl and lauroyl chlorides as acylating reagents and N,N-dimethyl-4-aminopyridine as basic catalyst. Products were analyzed by FT-IR and 1H NMR spectroscopies to confirm their structures. A preliminary study of their thermal properties was also achieved.
Molar mass characterization of hydrophilic copolymers, 2 Size exclusion chromatography of cationic (meth)acrylate copolymers
Authors: Adler Martina , Pasch Harald , Meier Christian , Senger Raimund , Koban Hans-Günter , Augenstein Michael , Reinhold Günter
Published: August 2014

A robust and reproducible method for the molar mass analysis of cationic copolymers based on dimethylaminoethyl methacrylate or trimethylammonioethyl methacrylate and different (meth)acrylates has been developed. Size exclusion chromatography (SEC) using a novel polyester-based packing as the stationary phase and dimethylacetamide (DMAC) as the mobile phase yields highly accurate results for copolymers with an amino comonomer content up to 50 wt.-%. To suppress the different polar and ionic interactions between sample molecules, stationary phase and eluent, DMAC was modified with LiBr and tris(hydroxymethylamino) methane (TRIS). Calibrating the SEC system with poly(methyl methacrylate) of narrow polydispersity, molar masses were obtained that are in good agreement with viscosity data. Reproducibility and robustness of the novel method were proven by running samples for an extended period of two weeks.
Calorimetric investigation of the phase behaviour of the binary system 7-mPEG 5000-succinyloxymethyloxycarbonyl- Paclitaxel (PP7)/water
Authors: Sohn Jung-Sun , Choi Soo-Kyung , Jo Byung-Wook , Schwark Kirsten , Hess Michael
Published: August 2014

Paclitaxel is an antineoplastic agent derived from the bark of the Pacific Yew Tree (Taxus brevifolia). Oral administration of the pure drug is problematic as it has a poor absorption due to its poor solubility in aqueous media. A specific water-soluble prodrug - PP7 - has been introduced by coupling the drug with a water-soluble polymer. For any kind of medical application and administration, knowledge of the binary isobaric phase-diagram is important since it gives information about solubility, phase transitions and the corresponding compositions. The system PP7 + H2O was studied calorimetrically from -20°C and shows the typical behaviour of an eutectic system. The properties of the phase diagram are discussed in view of other solution properties of the system presented earlier.
Preparation of fluorescent polymer particles by emulsion polymerization
Authors: Gu Shunchao , Anzai Naoto , Nagao Daisuke , Kobayashi Yoshio , Konno Mikio
Published: August 2014

Core-shell type fluorescent polymer particles were produced in multi-step emulsion polymerization. Cross-linking was introduced to the shell to suppress leakage of fluorescent dyes contained in the core particles. First, fluorescent polymer particles were synthesized by emulsion copolymerization of styrene (St) and butyl acrylate (BA) with an anionic surfactant (SE1025A) initiated by ammonium persulfate (APS) in the presence of pyrene. The concentrations of St, BA, SE1025A and APS were 550, 89, 8.2 and 5 mol/m3 water, respectively. Then the fluorescent particles were covered with cross-linked polymer by emulsion copolymerization of St, BA and divinylbenzene (DVB) with SE1025A emulsifier. In the polymerization, a mixture of St, BA, SE1025A and DVB was added dropwise to the reaction system. The average size of cross-linked fluorescent particles ranged from 50 to 70 nm. The fluorescence intensity of the particles prepared in a pyrene concentration range of 8 - 20 mol/m3 water increased linearly with pyrene concentration. Fluorescence intensities of the particles prepared with and without DVB were also measured. The cross-linked polymer formed by DVB addition drastically suppressed the intensity drop caused by dye leakage almost to one-third of the intensity drop measured for particles prepared without DVB addition.
Microwave-assisted synthesis of channel-containing polymeric materials
Authors: Klink Michael , Kolb Ute , Ritter Helmut
Published: August 2014

Iron shows fast heat development under microwave (MW) irradiation. This property was used to start polymerization reactions on the surface of iron fibres. MW irradiation of metal fibres, which are located in a monomer solution consisting of methyl methacrylate, ethylene glycol dimethacrylate, N,N’-azoisobutyronitrile and toluene led to the formation of polymer on the metal fibre surface. After dissolving the covered iron component in hydrochloric acid, a channelcontaining polymeric material was obtained. Scanning electron microscopy showed a smooth material with rough inner channels. These internal surface structures were caused by the rough surface of the metal fibres.
Microwave-assisted nitroxide-mediated polymerization of alkyl acrylates
Authors: Leenen Mark , Wiesbrock Frank , Hoogenboom Richard , Schubert Ulrich S.
Published: August 2014

Nitroxide-mediated polymerizations of methyl and tert-butyl acrylate were performed in a single-mode microwave reactor at 120°C. The polymerizations could be carried out in a controlled way in concentrated solution (approx. 50 wt.-% of monomer) up to monomer conversions of around 90%. Monomer conversion followed first-order kinetics in the case of tert-butyl acrylate. For methyl acrylate, it seems that the kinetics obeyed the persistent radical effect. The polymers obtained from this controlled radical polymerization technique exhibited narrow molecular weight distributions (indicated by polydispersity indices below 1.3).
Drug-loaded ultrafine poly(vinyl alcohol) fibre mats prepared by electrospinning
Authors: Zhang Chunxue , Yuan Xiaoyan , Wu Lili , Sheng Jing
Published: August 2014

Submicron poly(vinyl alcohol) (PVA) fibre mats embedded with Aspirin and bovine serum albumin (BSA) were prepared by electrospinning of their aqueous solutions. Fibre morphology was investigated by scanning electron microscopy. The composition of the fibre mats was characterized by Fourier transform IR spectroscopy and X-ray photoelectron spectroscopy. The in vitro drug release was investigated by immersing the fibre mats in phosphate buffer solution at 37°C. Results indicated that the morphology of fibre mats was influenced by the amount of drug, and more beaded and irregularly shaped fibres were found with increasing drug amounts. There were drug molecules distributed on the surface of the PVA fibres. Studies of in vitro drug release showed that both Aspirin and BSA were released more quickly from PVA fibre mats than from PVA films because of the large surface area and high porosity of the fibre mats.
A highly efficient, solvent-free and energy-effective method of cellulose acetylation
Authors: Memmi Abdelmajid , Granet Robert , Champavier Yves , Krausz Pierre
Published: August 2014

Acetylation of cellulose by acetic anhydride was found to be catalysed quantitatively by iodine under solvent-free conditions at room temperature. Cellulose acetates were characterised by 1H NMR spectroscopy.
Poly(L,L-lactide) and poly(L,L-lactide-co-glycolide) microparticles by dialysis
Authors: Gadzinowski Mariusz , Sosnowski Stanislaw , Slomkowski Stanislaw
Published: August 2014

Formation of poly(L,L-lactide) (PLLA) and poly(D,L-lactide-co-glycolide) (PLGA) microparticles by dialysis from 1,4-dioxane, tetrahydrofuran (THF), acetonitrile, dimethyl sulfoxide (DMSO), and dimethylformamide (DMF) against water has been investigated. In some instances microparticles were obtained from a mixture of the above-mentioned polyesters and PLLA-block-polyglycidol-blockpoly( ethylene oxide) triblock copolymer containing a hydrophobic PLLA block as well as hydrophilic polyglycidol and poly(ethylene oxide) blocks, the former with functional -OH groups. The effects of the nature of polyester, solvent and concentration of triblock copolymer on particles morphology, size, size distribution, and degree of crystallinity have been determined. Dialysis of PLGA yielded particles in the form of microspheres regardless of the solvent. Diameters of these particles were in the range of 0.36 - 1.77 μm and particles’ diameter polydispersity (Dw̅/Dn̅ ) varied from 1.37 to 2.04, depending on the solvent. In the case of PLLA, microspheres were obtained only by dialysis from 1,4-dioxane solutions. Dialysis of PLLA solutions in THF, acetonitrile and DMF yielded particles in the form of microcrystals. In the case of dialysis of PLLA solutions in DMSO, the product was in form of crystalline flakes of c. 1 μm thickness. Microspheres composed of PLGA were amorphous. The degree of crystallinity of microparticles from PLLA was in the range of 39% - 72%.
Tuning morphologies of thermoset / thermoplastic blends Part 1: Kinetic modelling of epoxy-amine reactions using amine mixtures
Authors: Lahlali Nadir , Dupuy Jérôme , Dumon Michel
Published: August 2014

Different epoxy amine networks based on a mixture of diamine hardeners have been studied and their kinetic behaviour was modelled in order to understand the global and particular behaviour of each diamine in such blends. 4,4’-Diaminodiphenylsulfone (DDS) and 4,4’-methylenebis-(3-chloro-2,6- diethylaniline) (MCDEA) were used for this study by varying the DDS molar ratio from 0% to 50%. The determined kinetic model allowed us to calculate the composition for each diamine of the reactive epoxy-amine system in the whole range of epoxy conversions. Then the influence of 10% thermoplastic additive was checked and it was found to be negligible in the kinetic behaviour.
Tuning morphologies of thermoset / thermoplastic blends Part 2: Phase separation of poly(vinyl methyl ether), PVME, using amine mixtures as thermoset hardeners
Authors: Lahlali Nadir , Dupuy Jérôme , Dumon Michel
Published: August 2014

Part 2 of the study investigates morphologies of epoxy thermoset / thermoplastic blends obtained with formulations of the thermoset hardeners. The thermosetting matrices are composed of one epoxy resin crosslinked by a mixture of two aromatic diamine hardeners, namely MCDEA+DDS or MDEA+DDS (DDS is 4,4’-diaminodiphenylsulfone, MCDEA is 4,4’-methylenebis-(3-chloro-2,6- diethylaniline), MDEA is 4,4’-methylenebis-(2,6-diethylaniline). The blends are made at a fixed concentration of thermoplastic (poly(vinyl methyl ether), PVME, 10wt%) whereas three different cure temperatures are chosen and the matrix composition is varied by the ratio of DDS. DDS is a PVME-insoluble diamine whereas MDEA or MCDEA are PVME-soluble diamines.

The domain size of the PVME nodules is tuned from a few micrometers down to sub micron sizes, typically between 50 and 80 nm. We attempt to explain this evolution thanks to the difference in the reactivity of the amines with the epoxy oligomer coupled to the difference in miscibility of each amine towards PVME. The kinetic study developed in Part 1 of this work is used to calculate the concentrations of each amine along the reaction time and their rate of incorporation in the polymer network. The latter parameter is shown to be the limiting factor for obtaining a nano phase separation.
Phase Behavior of Weakly-segregated Multiblock Copolymers with Two-scale Periodic Architecture
Authors: Kuchanov Semion , Pichugin Vladimir , Brinke Gerrit ten
Published: August 2014

The phase behavior of a melt of periodic two-scale multiblock copolymers has been theoretically studied in the framework of the Weak-Segregation Limit theory. The effect of the structural symmetry of the macromolecules on the vertex functions of the Landau free energy expansion is considered in detail. The existence of a thermodynamically stable mesophase with a two length-scale space periodicity has been revealed for a melt of monodisperse periodic heteropolymers.
First GPC results of terpyridine based chain extended supramolecular polymers: comparison with viscosity and analytical ultracentrifugation
Authors: Meier Michael A. R. , Hofmeier Harald , Abeln Caroline H. , Tziatzios Christos , Rasa Mircea , Schubert Dieter , Schubert Ulrich S.
Published: August 2014

The molecular weight of an extended metallo-supramolecular polymer, based on a α,ω-bis-terpyridine-poly(ethylene glycol) polymer linked via ruthenium(II) ions, was determined by gel permeation chromatography, viscosimetry as well as analytical ultracentrifugation. An optimized GPC method was applied for the first time to this kind of chain extended supramolecular polymers and the obtained results showed a good agreement with viscosimetry and analytical ultracentrifugation. A chain extended polymer with an average molecular weight of around 140 000 was found. These results clearly demonstrate that well-soluble high-molecular-weight metal-containing coordination polymers that are based on well-defined telechelics can be synthesized and fully characterized.
Thiodiethylene glycol based polyesters: synthesis and thermal characterization
Authors: Lotti N. , Finelli L. , Messori M. , Munari A.
Published: August 2014

Poly(thiodiethylene terephthalate) (PSDET), poly(thiodiethylene adipate) (PSDEA), poly(diethylene terephthalate) (PDET) and poly(diethylene adipate) (PDEA) for comparison were synthesized and characterized in terms of chemical structure and molecular weight. The thermal behavior was examined by thermo gravimetric analysis and differential scanning calorimetry. All the polymers showed a good thermal stability, even though lower for the sulfur-containing polyesters. At room temperature they appeared as semicrystalline materials, except PDEA, which was an oil; the effect of substitution of ether oxygen atoms with sulfur ones was a lowering in the Tg value, an increment of melting temperature and an increase of crystallization rate. The results were explained as due to the presence of flexible C-S-C bonds in the polymeric chain.
Study on synthesis and characterization of novel optically active poly(amide-imide)s based on bis(p-aminobezoic acid)-N-trimellitylimido-S-valine via direct polycondensation
Authors: Mallakpour Shadpour , Kolahdoozan Majid
Published: August 2014

N-Trimellitylimido-S-valine (3) was prepared by reaction of trimellitic anhydride (1) with S-valine (2) in acetic acid solution at refluxing temperature. This diacid was reacted with thionyl chloride and N-trimellitylimido-S-valine diacid chloride (4) was obtained in quantitative yield. The reaction of this diacid chloride with p-aminobenzoic acid was carried out in dry tetrahydrofurane and bis(paminobenzoic acid)-N-trimellitylimido-S-valine (5) was obtained as a novel optically active amide-imide diacid monomer in high yield. The direct poly condensation of amide-imide diacid monomer with aromatic diamins such as 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, benzidine, 4,4'-diaminodiphenyl methane, 1,4- phenylene diamine and 2,5-diamino toluene was carried out in tosyl chloride/ pyridine/dimethylformamide system. The resulting novel optically active poly(amide-imide)s (PAIs) with inherent viscosities ranging from 0.24-0.76 dLg-1, were obtained in good yield. All of these polymers were fully characterized with FTIR spectroscopy and specific rotation. Some elemental analysis, thermal properties and 1H-NMR of these new optically active PAIs are also reported.