bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterisation of poly(arylene sulfides), 9. Optimisation of the solvent composition for solution polymerisation of copper(I) 4‐bromobenzenethiolate at atmospheric pressure and structural investigations of low molar mass poly(1,4‐phenylene sulfide)
Authors: Lovell Peter A. , Still Richard H. 
Published: April 2003

AbstractSolution polymerisation of copper(I) 4‐bromobenzenethiolate (CBT) was effected at atmospheric pressure using a range of quinoline/pyridine solvent mixtures. Yields of poly(1,4‐phenylene sulfide) (PPS) were evaluated and PPS fractionated into toluene soluble (TS) and 1‐chloronaphthalene soluble (CNS) material. The fractions were characterised by end‐group analysis, viscometry and differential scanning calorimetry. The yield of CNS PPS is optimum for solvent mixtures comprising 70–80 vol.‐% quinoline, whereas the molar mass of this fraction is at a maximum for 95 vol.‐% quinoline. Results are discussed in terms of the effects of reaction temperature, complexing of CBT by quinoline and pyridine, and copper(I) bromide‐catalysed debromination. A low molar mass TS PPS fraction prepared in pyridine was subjected to detailed structural analysis by IR, 1H NMR and Raman spectroscopy. Evidence is presented to show that this material contains disulfide linkages and that thiol end‐groupings are absent. These results are discussed relative to possible structures for poly(arylene sulfides). The relevance of this observation to high molar mass samples of PPS and their chain extension and degradative behaviour is also discussed.
Polymérisation de thiirannes différemment substitués à l'aide du système chiral ZnEt2/(S)‐dihydroxy‐2,2′ binaphtyl‐1,1′, 1. Stéréoélectivité de la polymérisation
Authors: Sepulchre Maurice 
Published: April 2003

AbstractDifferently substituted thiiranes were polymerized using an atropoisomeric chiral initiator: ZnEt2/(S)‐2,2′‐dihydroxy‐1,1′‐binaphthyl (DHBN) (mole ratio 1/1). It was observed that high stereoelectivities are obtained with monomers bearing small alkyl substituents and that the resolution efficiency of the initiator decreases as the bulkiness of the substituent increases. From the comparison of the results obtained with another initiator system, ZnEt2/(R)‐3,3‐dimethyl‐1,2‐butanediol (DMBD) (mole ratio 1/1), the use of ZnEt2/(S)‐DHBN could be shown to be more suitable for the polymerization of thiiranes with linear alkyl substituents. Contrary to the case of polymerization initiated by the system ZnEt2/(R)‐DMBD, the polymerization reaction of thiiranes with ZnEt2/(S)‐DHBN was usually accompanied by the production of the corresponding olefins in various amounts.
Studies in electroactive polymers, 2. Soluble polyacetylene: A new synthetic route
Authors: Stowell Jonathan A. , Amass Allan J. , Beevers Martin S. , Farren Trevor R. 
Published: April 2003

AbstractPolyacetylene‐block‐polystyrene was synthesized via an anionic‐to‐metathesis catalysis. The polymers obtained were characterized by UV/visible spectroscopy, IR spectroscopy and gel permeation chromatography.
Quantitative evaluation of soluble polymeric photosensitizers, 4. Trans‐cis isomerization of stilbene photosensitized by polymerbound o‐ and p‐benzyloxybenzaldehyde
Authors: Martinez‐Utrilla Roberto , Catalina Fernando , Sastre Roberto 
Published: April 2003

AbstractThe grafting of o‐ and p‐benzyloxybenzaldehyde onto linear chloromethylated polystyrene is described. The resulting soluble polymeric photosensitizers and their model compounds, o‐ and p‐(p‐isopropylbenzyloxy)benzaldehyde, were tested as triplet energy donors against trans‐stilbene in benzene solution. Irradiation of the ortho‐compounds gives rise to a transformation which has been tentatively attributed to an intramolecular photocyclization. Stern‐Volmer constants for the photostable para‐compounds were determined. Results for both types of compounds show that the sensitizer efficiency diminishes when it is bound to the polymer.
Viscosity behaviour of macro‐ring polystyrene in solution
Authors: Qian Renyuan , Cao Ti 
Published: April 2003

AbstractA simple treatment for the intrinsic viscosity data of a flexible macro‐ring polymer in solution is proposed. The viscosity behaviour of dilute solutions of a macro‐ring with molar mass M is considered to be equal to that of a linear chain with molar mass λT·M, where the factor λT is found to be close to 0,5. Thus the ratio of the intrinsic viscosity of the macro‐ring polymer and that of the corresponding (same molar mass) linear chain polymer gr ≡ [η]r/[η]l = λ with α = exponent of Mark‐Houwink equation gives the correct excluded volume effect on the value of gr as verified by the dilute solution viscosity behaviour of a macro‐ring polystyrene sample of weight‐average molecular weight Mw = 2,72·105 and theta‐ and thermodynamically good solvents.
Photo‐oxydation de polyéther‐bloc‐polyamides, 3. Propriétés des hydroperoxydes dans les homopolym`res de polyéthers correspondants
Authors: Gauvin Pascal , Lemaire Jacques , Sallet Daniel 
Published: April 2003

AbstractThe photooxidation of poly(tetramethylene glycol) (PTMG), poly(propylene glycol) (PPG) and poly(ethylene glycol) (PEG) was studied at 60°C applying wavelengths longer than 300 nm. Hydroperoxy groups were found to accumulate in high photostationary concentration in PTMG and were decomposed essentially into formate groups. Hydroperoxides were observed in low photostationary concentration in PEG and PPG. Decomposition of the PPG hydroperoxides into formate groups showed that hydroperoxidation occurs, surprisingly, at the secondary carbon atom of the propylene glycol monomeric unit, rather than at the tertiary carbon. These results account for the large variation in the properties of hydroperoxides observed throughout the photooxidation of polyether‐block‐polyamides of various composition.
Polymerization of N‐phenylmaleimide with organozinc compounds as initiators
Authors: Hagiwara Tokio , Sato Junji , Hamana Hiroshi , Narita Tadashi 
Published: April 2003

AbstractThe polymerization of N‐phenylmaleimide (N‐PMI) was carried out with organozinc compounds as initiators. Within the initiators examined [Zn(OCH3)2·(C2H5ZnOCH3)6] gave the highest yield of poly(N‐PMI). The polymer yield increased rapidly at the early stage of the polymerization reaction. The poly(N‐PMI) produced shows a unimodal molecular weight distribution in the high‐molecular‐weight region and two components in the oligomeric region in GPC. 1H NMR and 13C NMR spectra suggest an addition polymerization without any remarkable side reactions. The results of the copolymerization with styrene and of the polymerization in nitrobenzene suggest an ionic polymerization mechanism.
Poly(α‐amino acid)‐immobilized polymer adsorbents for optical resolution, 2. Effect of crosslinking degree of the support resin on the resolution efficiency
Authors: Kiniwa Hideaki , Doi Yuka , Nishikaji Takashi , Ogata Naoya 
Published: April 2003

AbstractPolymer adsorbents for chromatographic optical resolution were synthesized by grafting poly(N5‐benzyl‐L‐glutamine‐co‐γ‐benzyl L‐glutamyl) onto cross‐linked polystyrene beads. The effects of the crosslinking degree (1,5%, 9%, 30%) and the porosity of the polystyrene matrix on the resolution efficiency of the adsorbent were investigated. Similar resolution efficiencies were observed on 1,5% cross‐linked gel (non‐porous) and 9% cross‐linked porous adsorbents, while a decline in the efficiency was observed on 30% cross‐linked porous adsorbent. Studies of transmission electron micrographs of these adsorbent clearly showed the effect of degree of crosslinking on the distribution manner of the incorporated poly(α‐amino acid). At a degree of 30%, clustered incorporation occurs mainly on the pore surface and not within the cross‐linked polymer matrix. Such incorporation manners are also suggested by the swelling properties of the adsorbents. Pore volumes, pore radii, and specific surface areas of the adsorbents were also measured. It was observed that uniform incorporation of poly(α‐amino acid) derives a higher resolution efficiency of the adsorbent.
Poly(α‐amino acid)‐immobilized polymer adsorbents for optical resolution, 3. A total chromatographic optical resolution on poly(N5‐benzyl‐L‐glutamine)‐immobilized resin
Authors: Kiniwa Hideaki , Doi Yuka , Nishikaji Takashi , Ogata Naoya 
Published: April 2003

AbstractA 9% cross‐linked porous polystyrene resin (10–15 μm) incorporating poly(γ‐methyl L‐glutamate) (PMLG) was synthesized, and the grafted PMLG was then converted into poly(N5‐benzyl‐L‐glutamine) (PBLGN). In this newly developed procedure, almost quantitative conversion of PMLG to PBLGN is achieved. The obtained adsorbent for liquid chromatography demonstrated a total optical resolution of (RS)‐5‐isopropylhydantion. Experimental evidence demonstrated that the degree of polymerization (DP) of the incorporated poly(α‐amino acid) is a critical variable. At DP = 2, no resolution was accomplished, whereas At DP = 14 or 36, base line resolutions were achieved. Other fundamental factors, such as the concentration of the immobilized PBLGN, the column temperature and the eluent composition, which affect the resolution efficiency, were also evaluated.
Polylactones, 11. Cationic copolymerization of glycolide with L,L‐dilactide
Authors: Kricheldorf Hans R. , Kreiser Ingrid 
Published: April 2003

AbstractCopolymerizations of glycolide with L,L‐dilactide were conducted in chloroform, 1,2‐dichloroethane and nitrobenzene. Chlorosulfonic acid, triflic acid, boron trifluoride, triethyloxonium tetrafluoroborate, but mainly methyl triflate, were used as initiators. 50°C was found to be an optimum reaction temperature, because higher temperatures resulted in dark coloured products of low viscosities. The composition of the copolyesters was determined by 1H NMR spectroscopy and the sequences by 13C NMR spectroscopy. Dyad splitting of the carbonyl signals allowed an accurate calculation of average block lengths. Under all circumstances glycolide showed a higher rate of incorporation, and truely random sequences were never obtained. However, the relative reactivities of both monomers largely depend on the nature of the initiator. The best results with regard to random sequences were obtained in 1,2‐dichloroethane with methyl triflate (rG = 10,5 and rL = 0,9) and with triflic acid (rG = 14,0 and rL = 0,5). DSC measurements revealed that most samples possess crystalline domains of polyglycolide blocks. Nonetheless, many samples are soluble in hexafluoro‐2‐propanol and the amorphous samples also in dichloromethane or chloroform.
Effect of ionenes on structure and catalytic activity of cobaltphthalocyanine, 1. Visible light spectroscopic investigations
Authors: van Welzen Joke , van Herk Alex M. , German Anton L. 
Published: April 2003

AbstractThe structural behaviour of cobalt(II)phthalocyanine‐tetrasodium sulfonate (CoPc(NaSO3)4) (1), a catalyst used in thiol oxidation, was investigated in the presence of ionenes (poly‐quaternary ammonium salts), (2) using visible light spectroscopy. It was observed that ionenes, which have been shown to promote the catalytic activity, strongly enhance the aggregation of the cobalt complex. No cobalt site isolation occurred up to N+/Co = 105. Furthermore, a stoichiometric CoPc(NaSO3)4/ionene complex appeared to be formed with an N+/Co‐ratio of 4:1. This ratio was found to hold for ionenes with M̄n varying from 6 100 to 22 000 and charge densities from 0,8 to 1,5. As the charge density was increased, the observed CoPc(NaSO3)4 spectrum was more affected. Experiments with oxygen in alkaline solution revealed that the complex was resistant toward oxygen adduct formation in the presence of ionenes. This phenomenon is discussed in relation to the catalytic activity of the system.
Metathesis polymerization of exo,exo‐, endo, exo‐ and endo, endo‐5,6‐dimethylbicyclo[2.2.1]hept‐2‐enes; microstructure of the polymers and their hydrogenated products
Authors: Greene Ruth M. E. , Ivin Kenneth J. , McCann G. Malachy , Rooney John J. 
Published: April 2003

AbstractPolymers of exo,exo‐, endo,exo, and endo,endo‐5,6‐dimethylbicyclo[2.2.1]hept‐2‐ene monomers were prepared using a selection of eight metathesis catalysts and their structures examined by 13C NMR spectroscopy. Tacticities could be determined for the polymers of the endo, endo and endo,exo monomers and for all three hydrogenated polymers. RuCl3 gave hightrans atactic polymers while ReCl5 gave high‐cis syndiotactic polymers, but WCl6/Bu4Sn gave a high‐cis atactic polymer of the endo,endo monomer. The endo,exo monomer was unusual in giving polymers of relatively low cis content (fraction of cis double bonds σc ≤ 0,3), and with strong exo,endo (XN) bias except in the case of RuCl3. The parallel with the head, tail (HT) biased polymers of 1‐methylbicyclo[2.2.1]hept‐2‐ene is noted. Polymers of the exo,exo and endo,endo monomers have a blocky cis/trans double bond distribution at moderate cis content. The results are discussed in terms of a mechanism involving propagation by metal‐carbene, metal‐carbene‐olefin and metallacyclobutane complexes.
Compositional analysis of styrene‐acrylic acid copolymers by 1H NMR
Authors: Koźluk Tomasz , Spychaj Tadeusz , Hamielec Archie 
Published: April 2003

Abstract1H NMR analysis of low molecular weight styrene‐acrylic acid (St/AA) copolymers is described. Three approaches to copolymer composition determination were evaluated and these include: (i) use of the signal for the carboxylic acid protons of the original copolymers, (ii) formation of the ammonium salt of the copolymers and then use of the signal for the ammonium protons, (iii) exchange of the ammonium protons with deuterium (…COONH4 + 4D2O → … COOND4 + 4DOH) and use of the signal for the proton on DOH to estimate the number of acid groups in the original copolymer sample.
X‐ray investigations of liquid crystalline homo‐ and copolysiloxanes with paired mesogens
Authors: Diele Siegmar , Oelsner Steffi , Kuschel Frank , Hisgen Bernd , Ringsdorf Helmut , Zentel Rudolf 
Published: April 2003

AbstractX‐ray scattering experiments on oriented polysiloxanes with paired mesogens and different distances between these swallow‐tailed side groups show a remarkable dependence of the smectic monolayer thickness on the degree of dilution, whereas the interplanar distance of the side groups remain nearly constant. Due to the dominating interaction of the mesogenic moieties, the flexible main chain is forced to take part in the layer formation. A packing model is proposed to explain the results of the X‐ray studies. For polymers with five or more dimethylsiloxane copolymer segments, a diffuse scattering appears in the smectic as well as in the isotropic phase. This scattering is independent of the orientation of the samples. It is probably caused by the main chain and has also been observed for the unsubstituted poly(hydrogenmethylsiloxane).
Studies in ring‐opening polymerization. The kinetics of the reactions between tungsten hexachloride and cyclopentene: A study of the metathesis initiation reaction
Authors: Amass Allan J. , Lotfipour Mahmoud , Zurimendi Jon A. , Tighe Brian J. , Thompson Cheryl 
Published: April 2003

AbstractThe complex series of reactions that takes place between WCl6 and cyclopentene was studied spectroscopically. The products of reaction remain soluble when chlorobenzene is used as solvent. A number of intermediates was observed and the kinetics of formation and removal of these was studied in detail. A complex series of reactions was postulated to account for these changes and the significance of each reaction to the overall scheme was determined by computer simulation of the changes that occur. One of the products has particular significance in the scheme of reactions since it is believed that this species is eventually responsible for the monometallic initiation of the polymerization of cyclopentene. The reaction was also studied gas chromatographically when it was shown that the reaction is accompanied by the formation of a complex mixture of products. One of these products was shown to have the mass spectrum that would be expected of 3‐chlorocyclopentene and a reaction scheme that would account for its formation is postulated. The reactions involved in the generation of centres active towards the formation of polypentenamer were considered for both monometallic and bimetallic (WCl6/AlR3) catalyst.
On the polymerization of 2‐isopropenylnaphthalene, 8. Reactivity and structure of the living species at different temperatures
Authors: Rhein Thomas , Boileau Sylvie , Schulz Rolf C. 
Published: April 2003

AbstractESR spectroscopic analyses of the deep‐green solutions of living poly(2‐isopropenylnaphthalene) [poly(2‐IPN)] in THF at −80°C provided no evidence of the presence of radical anions as long as butyllithium (BuLi) was used as initiator. In contrast to this finding, radicals could indeed be detected if the polymerization was performed with metallic potassium in THF. These radicals were found to be only stable at low temperatures. UV/VIS spectra of solutions of 2‐IPN in THF or toluene and of catalytic quantities of BuLi were recorded at temperatures between −45 and +20°C. On heating to >0°C, the colour of the deep‐green solution changes irreversibly to reddish‐brown, and this colour change is associated with a spontaneous deactivation of the living poly(2‐IPN). End‐capping reactions with anthracene derivatives and the block copolymerization with hexamethylcyclotrisiloxane gave a first idea of the reactivity and structure of the species present in the reddish‐brown solution. A suggestion is made for the deactivation mechanism.
The use of pressure dilatometry for studying phase separation in polymer mixtures
Authors: Walsh David J. , Zoller Paul 
Published: April 2003

AbstractIt has been shown that it is possible to use pressure dilatometry (also known as pressure‐volume‐temperature (PVT) techniques) to follow the phase separation of a polymer blend. PVT data have been obtained for polyether sulfone, poly(ethylene oxide) and blends of the two over a range of compositions. For the pure polymers one can observe the glass transition and melting transitions, respectively. In the case of the blends the volume expansion accompanying phase separation on heating can be seen along with the different thermal expansion coefficients of the generated two phase structures. One can also observe the effect of pressure in elevating the temperature of phase separation.
Exoemission of polymers induced by deformation and fracture: High density polyethylene
Authors: Fuhrmann Jürgen , Scherer Günter H. , Nick Leo 
Published: April 2003

AbstractThe deformation‐induced exoemission of high density polyethylene stressed uniaxially is a true, intrinsic polymer property, i.e., not resulting from other experimental parameters, e.g., atmospheric gases, adsorbed layers, surface charges, and other extrinsic influences. The processes which originate tribostimulated exoemission are irreversible and depend strongly on the deformation ratio. The occurrence of exoemission is correlated with molecular fracture processes. The energy distribution of the emitted negatively charged particles exhibits a narrow maximum in the range of 5 to 15 eV (8·10−19to 24·10−19J).
Quaternization of poly(N‐tert‐butyliminoethylene)
Authors: Goethals Eric J. , Vandevelde Marleen , Dierick Anneke , Rigole Wilfried 
Published: April 2003

AbstractPoly(N‐tert‐butyliminoethylene) was quaternized with several agents. Only the very reactive methyl trifluoromethanesulfonate allowed to attain relatively high quaternization degrees after short reaction times. The maximum degree of quaternization was 0,44. This was attributed to the complete lack of reactivity of amino functions which have a quaternized neighbour. By means of 1H NMR spectroscopy it was possible to measure the fractions of the different triads and . Analysis, by means of Monte Carlo calculations, of the relative amount of these triads as a function of the degree of quaternization lead to the conclusion that the reactivity of the first, second and third nitrogen next to an ammonium function is 0,0,20 and 0,57, respectively, the reactivity of a nitrogen in an ammonium‐free chain being 1. This shows that the electrostatic deactivation exerts its action to at least nine atoms away from the charged atom. The quaternized polymer is unstable even at room temperature. After a few days the formation of isobutene is observed.
Kinetische analyse der copolymerisationsgeschwindigkeit von N‐vinyl‐2‐pyrrolidon mit styrol und methylmethacrylat
Authors: Braun Dietrich , Czerwinski Wojciech K. 
Published: April 2003

AbstractThe polymerization rate of two binary monomer systems styrene (St)/N‐vinyl‐2‐pyrrolidone (NVP) and NVP/methyl methacrylate (MMA) was investigated dilatometrically in bulk at 60°C with AIBN as initiator. While the copolymerization rate of the system St/NVP can be satisfactorily described by means of the classical reaction model, this is not the case for the system NVP/MMA. This deviation from the classical model can be explained by a charge‐transfer interaction between NVP and MMA which was measured by means of 1H and 13C NMR spectroscopy.
Préparation et caractérisation des poly(o‐chlorométhylstyrène), poly(m‐chlorométhylstyrène) et poly(p‐chlorométhylstyrène). Etudes des résonances magnétiques nucléaires 1H NMR et 13C NMR. Application à l'étude d'une résine de type merrifield
Authors: Monthéard Jean‐Pierre , Camps Marcel , Boinon Bernard , Tabet Driss Ainad , Pham Quang Tho 
Published: April 2003

AbstractOrtho‐, méta‐ and para‐chloromethylstyrene were polymerized and their 1H NMR and 13C NMR spectra were studied. The knowledge of the chemical shifts, especially those in 13C NMR, allows the analysis of poly(o‐‐chloromethylstyrene‐co‐m‐‐chloromethylstyrene) and of a Merrifield‐type resin which was prepared by a terpolymerization reaction of styrene, chloromethylstyrene and divinylbenzene.
Polylactones 12. Cationic polymerization of 2,2‐dimethyltrimethylene carbonate
Authors: Kricheldorf Hans R. , Dunsing Ruth , Albet Angels Serra i 
Published: April 2003

AbstractThe polymerization of 2,2‐dimethyltrimethylene carbonate (1) was initiated with borontrifluoride etherate, trifluoromethanesulfonic acid (triflic acid), methyl triflate and ethyl fluorosulfate. The reaction was studied at 20, 50, 80 and 120°C in 1,2‐dichloroethane and nitrobenzene. Methyl triflate and triflic acid turned out to be the most reactive initiators. Yet, due to “black biting” degradation, yields > 80% were never obtained. With BF3 etherate yields up to 98% and molecular weights (M̄n) up to 5200 g/mol were found. From 1H NMR and IR spectra it can be deduced that methyl triflate alkylates the exocyclic oxygen (carbonyl group) and the resulting carbenium ion reacts with its counterion by ring‐opening of the alkyl‐oxygen bond. The oligomers and polymers formed in this way initially possess methyl (or ethyl) carbonate groups at one end and triflate groups at the other end of the chain. Elemental analyses and IR spectra prove that no carbon dioxide is lost in the course of the cationic polymerization. DSC measurements showed that crystallinity and melting points of poly(1) largely depend on the polymerization conditions in contrast to the glass transition temperature.
Réactivité du groupement N‐(époxy‐2,3 propyl)‐N‐méthylamino vis‐à‐vis d'amines aromatiques à l'état fondu. Etude des mécanismes et des chemins réactionnels
Authors: Grenier‐Loustalot Marie‐Florence , Orozco Laurence , Grenier Philippe 
Published: April 2003

AbstractMechanism and kinetics of the reactions of N‐(2,3‐epoxypropyl)‐N‐methylaniline (1) with aniline or 4,4′‐sulfonyldianiline (3) were investigated using high performance liquid chromatography and 13C FT NMR under different conditions (110–172°C). Comparison of 1 with its derivatives shows that the activity of the 2,3‐epoxypropyl group in such epoxides depends on the structure and the substituents at the benzene ring; etherification may occur already before the secondary amine is consumed.