bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photosensitive polyrotaxanes: New comb-like polymethacrylamides containing 1,3- diphenyl-2-propen-1-one (chalcone) functions and noncovalently bound cyclodextrin in the side-chains
Authors: Goretzki Christian , Ritter Helmut 
Published: August 2014

AbstractThe synthesis and free radical polymerization of a methacrylamide monomer, 5, bearing non-covalently attached cyclodextrins and the chalcone function with a barrier group, is described. The first step of preparation of the monomer was the condensation of 4-(N-methacryloyl-6-aminohexanoylamino)- acetophenone, 1, with 4-nitrobenzaldehyde. The resulting 1-(N-methacryloyl-6- aminohexanoyl-4-aminophenyl)-3-(4-nitrophenyl)-2-propen-1-one, 2, was reduced with tin(II) chloride dihydrate to the corresponding 1-(N-methacryloyl-6-aminohexanoyl- 4-aminophenyl)-3-(4-aminophenyl)-2-propen-1-one, 3. After this, the aminochalcone was condensed with a barrier group, triphenylacetyl chloride, yielding 1-(N-methacryloyl-6-aminohexanoyl-4-aminophenyl)-3-(N’-triphenylacetyl- 4-aminophenyl)-2-propen-1-one, 4. Monomer 4 was copolymerized with methyl methacrylate to the model polymer poly[4-co-methyl methacrylate], 6, and also complexed with dimethylated β-cyclodextrin to the semi-rotaxane (4 / 2,6-Me2-β- CD) 5, which was copolymerized with methyl methacrylate, yielding a polyrotaxane (5-co-methyl methacrylate) 7, containing a cyclodextrin ring in the side-chain. The semi-rotaxane 5 and both copolymers 6 and 7 were characterized spectroscopically and also by means of differential scanning calorimetry, gel permeation chromatography and thermogravimetrical analysis, and - in the case of 5 - by mass spectrometry. Furthermore, the UV-induced E/Z-isomerization of both polymers 6 and 7 was examined in tetrahydrofuran solution. A retarding effect of the noncovalently attached cyclodextrin was finally detected.
The iniferter technique in radical polymerization under UV and thermal conditions: a comparative study
Authors: Suwier Davy R. , Monteiro Michael J. , Vandervelden Alexander , Koning Cor E. 
Published: August 2014

AbstractUV and thermal polymerisations of styrene were carried out in the presence of conventional ‘iniferters’. The mechanisms of the two methods were investigated and provided new insight into the livingness of the so-called iniferter technique. Chain extension polymerisations were performed using symmetrical iniferters to check the living character of this technique under UV and thermal polymerization conditions. In accordance with the work of Otsu, we have shown that polymerisation under UV irradiation initiated by iniferters proceeds via the classical iniferter living (controlled) mechanism. On the other hand, thermal polymerisations were predominantly controlled by the reversible additionfragmentation chain transfer (RAFT) mechanism.
Supramolecular poly(L-lactide)s containing terpyridine metal complexes
Authors: Heller Marcel , Schubert Ulrich S. 
Published: August 2014

AbstractChiral poly(L-lactide)s end-capped with a novel terpyridine ligand are synthesized by a controlled coordinative polymerization procedure. The resulting well-characterized macroligands can be complexed under phase-transfer conditions with iron(II) ions to form well-defined supramolecular poly(L-lactide) complexes. The outstanding stability of such coordinative polymers enables the full characterization by gel permeation chromatography (GPC) and MALDI-TOF mass spectrometry. In addition, in-line diode array UV-Vis spectroscopy coupled to GPC was carried out to verify the formation of the poly(ester) complexes.
Synthesis and characterization of a polyester/styrene resin obtained by frontal polymerization
Authors: Fiori Stefano , Malucelli Giulio , Mariani Alberto , Ricco Laura , Casazza Elena 
Published: August 2014

AbstractThe frontal polymerization technique has been successfully applied, for the first time, to obtain an unsaturated polyester/styrene resin. The effect of the ratio of the two aforementioned components, as well as of the type and amount of free-radical initiator on both front velocity and maximum temperature reached by the front, has been thoroughly studied. The resulting products have been characterized in terms of their thermal and dynamic-mechanical behaviour. A comparison of such products with the corresponding materials obtained by the classical batch polymerization technique has evidenced that frontal polymerization allows to reach a higher degree of crosslinking with respect to batch copolymerization and hence a better thermal and mechanical behaviour.
Surface-directed phase separation in nanometer polymer films: self-stratification and pattern replication
Authors: Budkowski Andrzej , Bernasik Andrzej , Cyganik Piotr , Rysz Jakub , Brenn Rüdiger 
Published: August 2014

AbstractPhase separation occurs in thin films of polymer blends when molecular mobility is promoted by a temperature above the glass transition but inside the twophase region (temperature quench), or a common solvent added to the polymers (solvent quench). This phenomenon can be altered by a homogeneous surface or pre-patterned substrate, resulting, e.g., in self-stratification or pattern replication, respectively. Such self-organisation processes ordering polymer phases were observed for model polymer blends (deuterated/hydrogenated polystyrene, dPS/hPS, and deuterated/partially brominated PS, dPS/PBrS, both with hPSpolyisoprene diblocks added; dPS/poly(vinylpyridine) and PBrS/PVP) with highresolution ion beam techniques (Nuclear Reaction Analysis, profiling and mapping mode of dynamic Secondary Ion Mass Spectrometry) and Atomic Force Microscopy. The self-stratification process is strongly affected by both the range as well as the strength of the surface/polymer interactions. This is illustrated for the temperature-quenched blends with surface-active copolymer additives tuning the interactions exerted by both external surfaces. The pattern transfer from the substrate to the films is demonstrated for the solvent-quenched blends. Patterndirected composition variations (SIMS maps) coincide with free surface undulations (AFM images). The most effective pattern replication is achieved for the length scale of phase domain morphology comparable with the pattern periodicity and for carefully adjusted polymer/substrate interactions.
Alternating poly(ester amide)s from glutaric anhydride and α,ω-aminoalcohols: synthesis and thermal properties
Authors: Fey Thomas , Keul Helmut , Höcker Hartwig 
Published: August 2014

Abstract Alternating poly(ester amide)s 6a - e were prepared by polycondensation of α-carboxyl-ω-hydroxyamides 3a - e which were obtained by aminolysis of glutaric anhydride (1) and α,ω-aminoalcohols, H2N-(CH2)x-OH (x = 2 - 6) 2a - e. The polycondensation was performed in dimethylformamide solution using a carbodiimide as activating agent, or in bulk with Bu2Sn(OMe)2, Ti(OBu)4 and Sn(octoate)2 as a catalyst. For the polycondensation in bulk, the influence of catalyst and of temperature on the number-average molecular weight was studied. 1H NMR analyses of the poly(ester amide)s clearly show the alternating microstructure. The poly(ester amide)s from glutaric anhydride and the homologous series of α,ω-aminoalcohols are semicrystalline materials; their melting points show the odd/even effect observed for other poly(ester amide)s.
Fine structure formation and physical properties of poly(butylene terephthalate) fibres in high-speed melt spinning
Authors: Sun Hee Lee , Kyoung Hou Kim , Takeshi Kikutani , Hyun Hok Cho 
Published: August 2014

Abstract Poly(butylene terephthalate) (PBT) fibres were obtained by high-speed melt spinning up to a take-up velocity of 8 km/min. Fine structure formation and physical properties of these fibres were investigated. The increase of take-up velocity caused raises in both density and birefringence. In wide-angle X-ray diffraction equatorial profiles, the increase of take-up velocity can be observed in the (010) and (100) reflections of β-crystals; the reflection peaks are the sharpest at a take-up velocity of 6 km/min. The initial modulus of the fibres arises when the fraction of β-crystals is increased, while the tenacity depends more on the fraction of α-crystals, i.e., the total crystallinity. Thermal properties of high-speed spun PBT fibres were measured with differential scanning calorimetry, dynamic mechanical and thermo-mechanical analysis, etc. Endothermic curves become sharper with increasing take-up velocity, and endothermic melting peaks are shifted to higher temperature. Crystal structures are well developed in fibres obtained at higher take-up velocities. The tan δ peaks of PBT fibres tend to shift to higher temperature and the peak intensity is decreased with increasing take-up velocity, i.e., the packing density of PBT fibres is high when the take-up velocity and thus the orientation of amorphous regions is increased. The shrinkage has a tendency to decrease with increasing take-up velocity.
Preparation, characterisation and enantioselective separation properties of a chiral stationary phase based on silica beads coated with a 2-hydroxypropyl-β-cyclodextrin polymer
Authors: Carbonnier Benjamin , Janus Ludovic , Deratani André , Morcellet Michel 
Published: August 2014

Abstract This paper describes the preparation of a chiral stationary phase based on a 2-hydroxypropyl-β-cyclodextrin polymer coated on porous silica. This method requires first the synthesis of a water-soluble cyclodextrin polymer carried out by the polycondensation of 2-hydroxypropyl-β-cyclodextrin with epichlorohydrin under controlled conditions. In the second step, the obtained copolymer was immobilised onto the porous silica surface by physisorption. The macromolecular features of the copolymer were investigated by size exclusion chromatography coupled with a multiple angle laser-light scattering detector. The evolution of the structural parameters of the modified silica beads (specific surface area and pore size distribution) was determined using a nitrogen adsorption method. The enantio-separation capability of the coated silica phase was evaluated for different polycyclic molecules. It was found that the enantioselectivity was strongly influenced by the geometry and shape of the solutes under study and the presence of an acidic modifier in the mobile phase.
Adsorption of monodisperse polybutadienes on carbon black, 2 Bulk adsorption
Authors: Vuillaume Kathy , Haidar Bassel , Vidal Alain 
Published: August 2014

Abstract The adsorption on carbon black (CB) of a series of monodisperse polybutadienes (PBs) with different molecular weights (Mn in the range of 3000 to 120 000) but identical microstructure (1,2-PB content ≈ 80%) was studied in the bulk for different polymer/CB ratios (τ, in the range of 2 to 10 g/g). In this respect we particularly studied the evolution of the amount of polymer, which cannot be extracted from the polymer/filler system upon blending, the so-called bound polymer, and attempted to investigate the conformation of the resulting adsorbed molecules as well as the conditions that control the formation of the polymer/filler network. The conformational transition turned out to depend exclusively on molecular weight, and the networking transition to occur at constant Mn1/2/τ, essentially through an entanglement process of the adsorbed chains.
Glutaraldehyde-crosslinked poly(glycidol-block-ethylene oxide-block-glycidol) networks with temperatureresponsive swelling behaviour
Authors: Christova Darinka , Ivanova Sijka , Trzebicka Barbara , Walach Wojciech , Velichkova Rumiana , Dworak Andrzej 
Published: August 2014

Abstract In order to obtain temperature-responsive hydrogel networks, poly- (glycidol-block-ethylene oxide-block-glycidol) copolymers were chemically crosslinked by using glutaraldehyde and tetraethoxysilane in a sol-gel reaction. The crystallinity of copolymer networks prepared has been estimated by differential scanning calorimetry. Thermo-responsive properties were evaluated by measuring the equilibrium swelling degree for a series of copolymer hydrogels as a function of temperature.
Synthesis and properties of poly(4-vinylpyridine)/ montmorillonite nanocomposites
Authors: Sen Sinan , Nugay Nihan , Nugay Turgut 
Published: August 2014

Abstract 4-Vinylpyridine monomer was mixed with organically modified montmorillonite (MMT) and polymerized in the presence of 2,2’-azoisobutyronitrile as radical initiator. Organophilic montmorillonite was obtained by using a block copolymer of poly(methyl methacrylate) and quaternized poly(4-vinylpyridine) (P4VP) in different compositions. X-ray diffraction (XRD) and thermogravimetric analysis confirmed that the block copolymer is inserted between MMT layers while the interlayer distance is expanded. The P4VP nanocomposites obtained from the block copolymer with the longer P4VP block exhibited no XRD peak, suggesting an exfoliated structure. These composites showed increased storage modulus and thermal stability at a very low loading of 1 - 2 wt.-%, compared to neat P4VP. Scanning electron microscopy and atomic force microscopy analyses were also conducted for selected nanocomposites.
Metallo-celluloses, 1 Synthesis and solution properties of 4-ferrocenylbutylsubstituted cellulose derivatives
Authors: Laube Bettina , Radke Wolfgang , Rehahn Matthias , Wunderlich Winfried 
Published: August 2014

Abstract An efficient method is described for the simultaneous introduction of 4-ferrocenylbutyl and n-hexyl side groups into cellulose. For this purpose, cellulose triacetate is treated in dimethyl sulfoxide/NaOH solution with mixtures of 4-bromobutylferrocene and n-hexyl bromide. An almost quantitative conversion of the cellulose hydroxyl groups was reached when less than one ferrocene substituent was attached to the cellulose repeating units on average. At higher degrees of ferrocene substitution, some of the cellulose hydroxyl groups seem to remain unsubstituted. This conclusion has been drawn on the basis of size exclusion chromatography (SEC) with online light-scattering detector where coil contraction was observed with increasing ferrocene content in the cellulose sample. This finding was further supported by IR spectroscopy, viscometry, and conventional SEC investigations. We assume that steric hindrance of the bulky side groups is responsible for incomplete conversion.
Synthesis and characterization of unsaturated polyester resins cured by frontal polymerization
Authors: Fiori Stefano , Mariani Alberto , Bidali Simone , Malucelli Giulio 
Published: August 2014

Abstract Various crosslinking agents have been used to frontally cure the unsaturated polyester derived by the reaction of maleic anhydride and 1,2-propanediol. The effect of composition of the curing mixture on the front velocity and its maximum temperature, as well as on the thermal properties of the obtained materials, is described.
Nucleation versus melting point depression of the polycaprolactone phase in polypropylene/polycaprolactone blends
Authors: Balsamo Vittoria , Gouveia Laura 
Published: August 2014

AbstractPolypropylene/poly(ε-caprolactone) (PP/PCL) blends were prepared by melt mixing. The thermal behaviour of the blends was investigated using differential scanning calorimetry (DSC) and dynamical rheology in the solid state (RSA). Both non-isothermal and isothermal crystallizations were performed. The Avrami equation was applied to the latter case. DSC and RSA results demonstrated in agreement with morphological observations that PP/PCL blends are immiscible in the whole composition range. PP acts as a nucleating agent for PCL, and when PP forms the disperse phase, it crystallizes in a fractionated fashion. When PCL is the disperse phase, it exhibits an unexpected melting point depression after cooling at 10 °C/min. Such depression was not observed after isothermal crystallizations, indicating that under non-isothermal crystallization kinetic problems show up. Thus, global crystallization is governed by a competition between nucleation and diffusion, which depends on crystallization conditions and composition.
Polymer/organoclay nanocomposites with biodegradable aliphatic polyester and its blends: preparation and characterization
Authors: Lim Sung Taek , Lee Chung Ho , Kim Hee Bong , Choi Hyoung Jin , Jhon Myung Sik 
Published: August 2014

Abstract Synthetic biodegradable aliphatic polyester (BAP) and its blends with polyepichlorohydrin (PECH) were processed with organophilic montmorillonite (OMMT) to make polymer/organoclay nanocomposites via a solvent casting method. Interlayer spacings of each system, measured by X-ray diffraction analysis, suggested that BAP had better affinity to clay than PECH in a competitive intercalation mechanism. The internal structures were visualized using transmission electron microscopy and were discussed in conjunction with the result of other experimental studies, such as thermogravimetric analysis and rheometry. In rheological measurements, the degree of shear-thinning increased drastically with OMMT loading, and both the storage modulus and loss modulus were found to increase with OMMT loading at all frequencies. Throughout this study, we compared the behaviours of polymer/clay nanocomposites in homo and blend systems, and examined the role of various parameters on the material characteristics of polymer/clay nanocomposites.
Scale-free power-law distribution of nonlinear polymers formed in a homeostatic system
Authors: Tobita Hidetaka 
Published: August 2014

Abstract A power-law distribution of molecular weight is found for low-density polyethylene formed in a one-zone autoclave reactor. This reactor could be modelled as a continuously stirred tank reactor (CSTR) operated under homeostatic conditions where the concentration of each component as well as temperature and pressure are kept constant. A simple stochastic model is used to investigate the molecular weight distribution (MWD) formed in free-radical polymerization involving chain transfer to polymer. The MWD profiles are dominated by the Pb value, which represents the probability that the chain end is connected to a backbone chain. By increasing Pb, MWD changes from an exponential to a powerlaw distribution. A scale-free power-law distribution is found for Pb > 0.5. Because the power of the weight fraction distribution, W(M) ~ M -γ, is 1 < γ < 2, the number average molecular weight will reach a stationary-state value but the weightaverage may continue to increase unlimitedly under ideal CSTR conditions.
New materials from degraded styrene-acrylonitrile and ethylene-propylene-diene copolymers
Authors: Vugrinec Jasminka , Kratofil Ljerka , Hrnjak-Murgić Zlata , Jelenčić Jasenka 
Published: August 2014

Abstract Polymer blends of styrene-acrylonitrile (SAN) and ethylene-propylenediene copolymer (EPDM) were prepared by casting films from chloroform solution. Their compositions were 95/5, 90/10 and 80/20, respectively. To simulate ageing, SAN/EPDM blends were degraded at 140°C for several different time intervals and the degree of degradation was followed by IR spectroscopy and by determination of molar masses. To recover thermally degraded SAN/EPDM blends, in situ polymerization by addition of styrene monomer was applied. Characterization of SAN and EPDM, graft copolymer and gel was carried out in order to reveal the polymerization process. Extractions of the polymers were made using solvents in a Soxhlet equipment: SAN in a mixture of acetone/ methanol, EPDM in hexane, graft copolymer in tetrahydrofuran, while the remaining part was considered as gel. Identification of extracted polymers has been conducted by IR spectroscopy. The presence of graft copolymer in the polymerization mixture proved the grafting reaction of polymer radicals. The highest content of graft copolymer was obtained for SAN/EPDM polymer blends that were exposed to thermal treatment for the longest time interval of 90 h.
Novel pattern formation in blends of asymmetric ABC triblock terpolymers
Authors: Abetz Volker , Jiang Shimei , Göpfert Astrid 
Published: August 2014

Abstract A series of polystyrene-block-poly(1,2-butadiene)-block-poly(2-vinylpyridine) (SBV) triblock terpolymers were used to prepare blends with symmetric polystyrene-block-poly(2-vinylpyridine) (SV) and poly(2-vinylpyridine)-block-poly- (cyclohexyl methacrylate) (VC) diblock copolymers. Morphological characterization was carried out by transmission electron microscopy. These triblock terpolymers self-assemble into various core-shell type or lamellar morphologies. In the SBV/SV blends, macrophase separation between the two block copolymers, continuous centrosymmetric lamellae and stacks of non-centrosymmetric lamellae with antiparallel orientation were found. In the blends of SBV/VC, macrophase separation was never observed, what is due to the specific interactions between S and C domains. These systems showed among other morphologies also a cylindrical morphology in which rings surround the cylinders.
Dielectric and hydration properties of segmental polyurethanes
Authors: Raftopoulos Konstantinos , Zegkinoglou Ioannis , Kanapitsas Athanasios , Kripotou Sotiria , Christakis Iraklis , Vassilikou-Dova Aglaia , Pissis Polycarpos , Savelyev Yuri 
Published: August 2014

Abstract Novel polyurethanes (PUs), based on oligo(oxytetramethylene glycol), 4,4’-diphenylmethanediisocyanate and 1,1-dimethylhydrazine as chain extender, were prepared in a two-step process. The ratio prepolymer (PP) to chain extender (CE) was systematically varied in extreme ranges, from 1:1 to 10:1. Dielectric relaxation spectroscopy and thermally stimulated depolarization currents (TSDC) techniques were employed to investigate molecular dynamics and to conclude on microphase separation (MS). In that respect TSDC was proven to be very powerful, in particular as far as the investigation of the interfacial Maxwell-Wagner-Sillars polarization is concerned. Additional information on micromorphology is obtained from water sorption/diffusion measurements. A part of the results suggest that MS improves with increasing the PP:CE ratio. The whole body of results can be explained if, at the same time, it is assumed that a branched structure is developed for samples out of stoichiometry and branching increases with increasing the PP:CE ratio. Preliminary experiments with solutions of the PUs in organic solvents provide support for that assumption.
Some experimental results for the end-linked polydimethylsiloxane network system
Authors: Ladegaard Larsen Anne , Sommer-Larsen Peter , Hassager Ole 
Published: August 2014

Abstract Small-strain equilibrium modulus data of polydimethylsiloxane (PDMS) networks are reviewed. 58 different articles in the literature with values of the modulus of end-linked PDMS networks were found [1-58] including more than 250 values of the small-strain equilibrium modulus as function of variables in the crosslinking system. The dominating variable is shown to be the molecular weight of PDMS as expected, whereas the functionality of the crosslinker methylhydrosiloxane/ dimethylsiloxane copolymer is shown to be less important in good agreement with the phantom model. The data collected was fitted to the phenomenological model of Langley and Graessley including an entanglement contribution. The fitted entanglement plateau (0.16 MPa) is in good agreement with literature values and with the theoretical prediction of the tube model. Experimental data for the Mooney-Rivlin constants was found and it was shown that C2 is constant with increasing functionality. Furthermore it was found that trapped entanglements can be split into two categories, viz. locked entanglements contributing to the C1 term and traditionally trapped entanglements contributing to C2.