bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and investigation of optically active polyesters from α‐ethyl‐α‐phenyl‐β‐propiolactone, 1
Authors: Carrière François J. , Eisenbach Claus D. 
Published: April 2003

Abstractα‐Ethyl‐α‐phenyl‐β‐propiolactone (7) of an optical purity up to 95% was prepared; the resolution of the two optical antipodes was carried out with the optical active precursor ethyl 2‐aminomethyl‐2‐phenylbutyrate (5), and the optical purity was determined by 1H NMR analysis using europium salt shift reagents. The solution and thermal properties of the corresponding polyesters 8, as obtained by anionic ring opening polymerization, were investigated. It was found that the inherent viscosity increased with the optical purity of the lactone. Distinct differences in the melting behaviour were found between the racemic and the optically active polymers; the ideal melting temperature TM0 for the pure enantiomeric polymer was estimated to about 535 K.
Polymères à propriétés pharmacologiques potentiels: greffage par liaison amide et (ou) ester d'un hypoglycémiant
Authors: Friedmann Gilbert , Aichaoui Hocine , Brini Mathilde 
Published: April 2003

AbstractN‐(4‐aminobenzenesulfonyl)‐N′‐butylurea (8) (glibutamide®) and several amino compounds were grafted on water soluble and non‐toxic polymeric backbones, with the intention to study the influence of such a carrier on the hypoglycemic effects of the drug, covalently linked by ester and (or) amide bonds. The spacer by which the drug was fixed to the polymeric carrier contained 1 to 10 atoms. So far, the hypoglycemic effect of only one polymer (13d) was tested. It showed, however, negative results probably due to the amide bond of the drug which is difficult to split off.
Exchange equilibria on anion resins, 2. Effect of chemical structure of functional groups in macroporous polystyrene resins
Authors: Góźdź Antoni S. , Kolarz Bożena N. 
Published: April 2003

AbstractAnion exchange equilibria were studied by the batch technique on macroporous polystyrene resins with the following functional groups: \documentclass{article}\pagestyle{empty}\begin{document}$ - \mathop {\rm N}\limits^ + {\rm H}_{\rm 2} {\rm CH}_{\rm 3} ({\rm M),} - \mathop {\rm N}\limits^ + {\rm H(CH}_{\rm 3} )_2 ({\rm DE),} - \mathop {\rm N}\limits^ + {\rm (CH}_{\rm 3} )_3 ({\rm TM),} - \mathop {\rm N}\limits^ + {\rm H}_{\rm 2} {\rm CH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OH (E),} - \mathop {\rm N}\limits^ + {\rm H}_{\rm 2} {\rm (CH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OH)}_{\rm 2} ({\rm DE),} - \mathop {\rm N}\limits^ + {\rm (CH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OH)}_{\rm 3} ({\rm TE),} - \mathop {\rm N}\limits^ + {\rm CH}_{\rm 3} {\rm (CH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OH)}_{\rm 2} ({\rm MDE), and} - \mathop {\rm N}\limits^ + {\rm (CH}_{\rm 3} {\rm )}_{\rm 2} {\rm CH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OH (DME)}$\end{document}. The selectivity order for these groups in slightly acidic, dilute solutions for the following anion systems: Br−/Cl−, I−/Cl−, and ClO4−/Cl− was found to be TM > DME > MDE > TE > DM > M > DE > E, but it was entirely reversed in the case of F−/Cl− system. These results are discussed in view of some known theories of ion exchange selectivity. It seems that the experimental data can be best explained in terms of the Chu‐Diamond‐Whitney theory which takes into consideration mainly changes of the water structure caused by counter‐ions, co‐ions, and functional groups of the ion exchanger.
Quaternization of poly(acrylonitrile‐co‐2‐methyl‐5‐vinylpyridine) and properties of the products in N,N‐dimethylformamide solution
Authors: Rinaudo Marguerite , Desbrieres Jacques 
Published: April 2003

AbstractThe kinetics of quaternization of poly(acrylonitrile‐co‐2‐methyl‐5‐vinylpyridine) (1) by methyl iodide was investigated. The rate constant k was shown to be independent of the degree of quaternization τ and the second order is valid for the reaction, independent of τ. From the dependence of k on the temperature, the thermodynamic parameters of the reaction were deduced and compared with literature data. Under the conditions to obtain τ = 1 in N‐methylpyrrolidone as solvent, a low charge polyelectrolyte was produced, soluble in DMF without decrease of the average molecular weight. The viscosimetric behaviour of the copolymer in DMF as solvent (in presence or absence of external KI salt) was studied, dependent on the charge density controlled by τ, and the ageing depends on the presence of oxygen, on the basicity of the solvent, on the degree of quaternization, and on the nature and concentration of the external salt. A mechanism is proposed, which implies the oxidation of the I− counterions to IO3−, initiating an intramolecular cyclisation of the nitrile groups.
Polymerisation via macrozwitterions, 2. Ethyl and butyl cyanoacrylates polymerised by pyridine and polyvinylpyridine
Authors: Johnston David Samuel , Pepper David Charles 
Published: April 2003

AbstractAnionic polymerisations of ethyl and butyl cyanoacrylates in THF initiated by pyridine and polyvinylpyridine were studied between 42 and −95°C. The polymers showed the UV absorption of quaternised pyridine, indicating that they had grown as macrozwitterions. Pyridine consumption was very low (few %) and the polymer molecular weights high (3 · 105 – 106) irrespective of reaction conditions. Overall rates increased as reaction temperature was reduced, approaching those found in phosphine‐initiated polymerisations by −78°C. At 20°C the kinetics were complex, e.g. sigmoid conversion curves which reached an internal first order, yet showing apparent 2nd order external order. A qualitative kinetic interpretation is given, postulating absence of intrinsic termination processes, and a complex initiation process involving (exothermic) equilibrium formation of a precursor betaine. Polyvinylpyridine initiates graft copolymers; but only in presence of chain‐terminating agents, e.g. acids, lactones or sultones, can the grafted side chains be kept short, and their number raised towards the potentially complete grafting of all pyridine groups.
On the molecular weight determination by vapour pressure osmometry, 3. Relationship between diffusion coefficient of the solute and non‐colligative behaviour
Authors: Figini R. V. , Marx‐Figini M. 
Published: April 2003

AbstractA recent suggestion by Bersted which takes into account the influence of the diffusion coefficient of the solute on the non‐colligative behaviour in vapour pressure osmometry is studied. Its involvement on the kind of the resulting molecular weight average is derived.
Messungen zum Aggregationsverhalten perfluorierter Alkansäuren
Authors: Hoffmann Heinz , Platz Gerhard , Rehage Heinz , Reizlein Karl , Ulbricht Werner 
Published: April 2003

AbstractWith the use of various techniques an attempt was made to characterize the aggregates that exist in micellar surfactant solutions of salts of the perfluornonanoic acid. The cmc values of the investigated systems were determined by conductivity and surface tension measurements. Conclusions about the shape of the micellar aggregates were drawn from rheologic and electric birefringence measurements. For the lithium, the ammonium and the tetramethylammonium surfactants the existence of normal micelles with spherical shape and with all surfactant ions lying at the micellar surface was found. The perfluornonanoate surfactants with the ammonium counterions that are partially substituted by alkyl groups showed in all investigations a behaviour that was different from the normal case. It was postulated that these solutions contain emulsion‐droplet‐like giant micelles with the surfactant ions and counterions solubilized as ion pairs in the interior of the micelles. Some of these giant micelles do not have spherical shape; these solutions showed electric birefringence. In most cases the giant micelles disappeared at higher temperatures. Only normal small micelles with spherical symmetry could then be detected and the measured values were again in the range for values of normal C8‐perfluordetergents. On the basis of the investigated systems reasons and models for the formation of giant micelles are discussed.
Intrinsic viscosity of polyelectrolytes having hydrophobic side‐residues
Authors: Miyamoto Shigeaki , Ishii Yoshiharu , Ohnuma Hiroshi 
Published: April 2003

AbstractThe intrinsic viscosities [η] of the alternating copolymers from isobutyl vinyl ether and maleic anhydride {p(isoBVE‐co‐MA)}, butyl vinyl ether and maleic anhydride {p(nBVE‐co‐MA)}, ethyl vinyl ether and maleic anhydride {p(EVE‐co‐MA)}, styrene and maleic anhydride {p(St‐co‐MA)}, and indene and maleic anhydride {p(indene‐co‐MA)} were determined and analysed as a function of the molecular weight M and the degree of neutralization β at various NaCl concentrations Cs. The following results were obtained: (1) [η] of the polyelectrolytes having hydrophobic side‐residues and divalent‐like carboxyl residues is very small at low charge density β = ≦ 0,2, increasing steeply with ionization until its maximum in the vicinity of β = 0,5. (2) The longrange interaction parameter Be due to the electrostatic repulsive force and the electrostatic part of the expansion factor α (which is defined by the ratio of [η] to its value at infinite ionic strength) exhibits the same behavior as [η] · (3) α can be expressed in terms of (M/Cs)1/2 in the same manner as for poly(acrylic acid), being different from the results predicted by many authors. The applicability of Fixman's theory in which Be is a linear function of \documentclass{article}\pagestyle{empty}\begin{document}$ 1/\sqrt {C_{\rm s} } $\end{document} was confirmed under consideration of the charge fraction and the bond length.
Synthesis and conformational study of poly(L‐valyl‐L‐valyl‐ϵ‐N‐benzyloxycarbonyl‐L‐lysine) in the solid state and in solution
Authors: D'Alagni Maria , Mignucci Gianfranco 
Published: April 2003

AbstractHigh molecular weight poly(L‐valyl‐L‐valyl‐ϵ‐N‐benzyloxycarbonyl‐L‐lysine) (PVVZL) (7) was obtained by condensation in dimethyl sulfoxide of the L‐valyl‐L‐valyl‐ϵ‐N‐benzyloxycarbonyl‐L‐lysine p‐nitrophenyl ester, synthesized by the DCCStandard abbreviations for amino acid derivatives and peptides are used according to the I.U.P.A.C.‐I.U.B. Commission on Biochemical Nomenclature, Biochemistry 11, 1726 (1972). The abbreviations used are: Boc = tert‐butyloxycarbonyl; Z = benzyloxycarbonyl; OBzl = benzyl ester; H‐Val‐OH = valine; H‐Lys‐OH = lysine; HONp = para‐nitrophenol; DDC = dicyclohexylcarbodiimide; DMSO = dimethyl sulfoxide; TFA = trifluoroacetic acid; TFE = 2,2,2‐trifluoroethanol; CD = circular dichroism; IR = infrared spectra.
method. The conformation of 7 was studied in the solid state and in solution of 2,2,2‐trifluoroethanol, acetonitrile‐trifluoroethanol and dioxane‐trifluoroethanol mixtures by X‐ray diffraction method, CD and IR spectroscopy. The results obtained in the solid state suggest the presence of β‐structure, whereas in trifluoroethanol solution, at least, a mixture of random coil and β conformation, probably occurs. The aging of the solution seems to give rise to a higher content of β‐structure. The addition of acetonitrile and dioxane favours the formation of an increasing amount of β‐structure. Therefore, the conformational behaviour of 7 is similar to that of other sequential polypeptides containing valyl residues, which seem to promote the β‐structure.
Influence of Catalyst and Polymerization Conditions on the Properties of 1,3‐Trimethylene Carbonate and ε‐Caprolactone Copolymers
Authors: Pêgo Ana Paula , Zhong Zhiyuan , Dijkstra Pieter J. , Grijpma Dirk W. , Feijen Jan 
Published: April 2003

AbstractThe influence of the catalyst/initiator system and polymerization conditions on the microstructure and physical properties of copolymers of equimolar amounts of 1,3‐trimethylene carbonate (TMC) and ε‐caprolactone (CL) was studied. Statistical copolymers were prepared in the presence of stannous octoate (SnOct2) in the bulk at 80 °C (14 and 28 d) and 130 °C (1 and 3 d). The copolymerization of TMC and CL initiated by yttrium isopropoxide (Y5(μ‐O)(OiPr)13) was performed in solution at room temperature (5 min) and in the bulk at 80 °C (2 min). Block copolymers, used as reference materials, were also prepared by sequential polymerization of the monomers in solution at room temperature with yttrium isopropoxide. Both SnOct2 and yttrium isopropoxide yielded polymers with shorter average monomer sequence lengths at higher reaction temperatures. For the polymerizations with SnOct2 a similar effect was observed when the reactions were allowed to proceed for longer periods of time. Independent of the catalyst/initiator system, the statistical copolymers prepared in the bulk at 80 or 130 °C were amorphous, with average monomer sequence lengths shorter than 3. The copolymer prepared in solution at room temperature with yttrium isopropoxide was more blocky, with CL sequences long enough to crystallize ($\overline {\rm L} _{{\rm CL}} = 3.93$). The former copolymers are highly flexible but show low tensile strengths, in agreement with their amorphous structure and low glass transition temperature. The latter copolymer is also flexible but much tougher and stiffer, as it is semi‐crystalline. Its properties are characteristic of phase‐separated block copolymers.Expanded regions of carbonyl carbon atoms in 13C NMR (75.5 MHz) spectra of TMC–CL copolymer prepared at 80 °C in the bulk in the presence of yttrium isopropoxide.magnified imageExpanded regions of carbonyl carbon atoms in 13C NMR (75.5 MHz) spectra of TMC–CL copolymer prepared at 80 °C in the bulk in the presence of yttrium isopropoxide.
Emulsion Polymerization of a Sugar Derivative–Kinetic Studies and Properties of the Sugar Latexes
Authors: Koch Ulrich , Yaacoub Emile‐Joseph 
Published: April 2003

AbstractFree‐radical batch‐emulsion polymerization of 3‐O‐methacryloyl‐1,2:5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (3‐MDG) initiated by a water‐soluble initiator (potassium peroxodisulfate, KPS), in the presence of an ionic emulsifier (sodium dodecyl sulfate, SDS), was investigated at 60 °C. The effect of the emulsifier and initiator concentration on the reaction kinetics and on the colloidal and molecular properties of the sugar latexes was studied. It was found that the rate of polymerization over interval II is proportional to the concentration of the initiator and the emulsifier raised to the power of 0.40 and 0.68, respectively. The particle size decreased and the number of particles increased with increasing either SDS or KPS concentration. The average value of the propagation rate constants of polymerization (kp) for 3‐MDG was found to be 257 L · mol−1 · s−1. The weight‐average molecular weights also increased with increasing the emulsifier concentration. The sugar latexes exhibit a high glass transition temperature (Tg) of 167 °C.Effect of SDS concentration on the average number of particles (Np) and the weight‐average molecular weight (Mw).magnified imageEffect of SDS concentration on the average number of particles (Np) and the weight‐average molecular weight (Mw).
Fluorescence of Copoly(ester‐imide)s Containing 2,6‐Naphthoate Units
Authors: Spies Cathrin , Lorenc Aleksandra , Gehrke Rainer , Kricheldorf Hans R. 
Published: April 2003

AbstractThe intrinsic fluorescence of copoly(ester‐imide)s is used to obtain information about the existence of sandwich like arrangement of aromatic units. The copoly(ester‐imide) investigated herein contains tert‐butylhydroquinone, N‐(4‐carboxyphenyl)trimellitimide and 2,6‐naphthoate moieties. Depending on the excitation wavelength, different sandwich like arrangements are observed by the change of the fluorescence. Identification of the different interacting units was performed by comparing the copoly(ester‐imide) fluorescence with the fluorescence of different low molecular weight model substances representing different parts of the polymer chain. Ground‐state stable dimer formation between the imide parts and the naphthoate moieties, as well as mixed ground‐state stable complex formation between these parts was observed. All measurements were performed in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) solutions.Comparison of copoly(ester‐imide) fluorescence with constituent model substances.magnified imageComparison of copoly(ester‐imide) fluorescence with constituent model substances.
Anionic Polymerization of Cyclohexa‐1,3‐diene in Cyclohexane with High Stereoregularity and the Formation of Crystalline Poly(cyclohexa‐1,3‐diene)
Authors: Quirk Roderic P. , You Fengxiang , Zhu Lei , Cheng Stephen Z. D. 
Published: April 2003

AbstractPolymerization of cyclohexa‐1,3‐diene using sec‐BuLi as initiator in cyclohexane produces both soluble (70–90 wt.‐%) and insoluble (10–30 wt.‐%) fractions depending on the temperature. The insoluble poly(cyclohexa‐1,3‐diene) was crystalline as determined by X‐ray diffraction and differential scanning calorimetry analysis (Tm = 178 °C). Both fractions were characterized by size exclusion chromatography and by 1H NMR and 13C NMR spectroscopy. The microstructures of both fractions were determined by high‐resolution 1H NMR and quantitative 13C NMR spectroscopy and compared to those poly(cyclohexa‐1,3‐diene)s prepared in benzene and in cyclohexane with 1,4‐diazobicyclo[2.2.2]octane (DABCO) as additive. The amount of 1,4‐addition of the insoluble fraction in cyclohexane was ≥ 97% and the cis planomer content was higher in cyclohexane than in benzene or in cyclohexane with DABCO as additive.DSC traces for the insoluble PCHD recrystallized from dichloroethane.magnified imageDSC traces for the insoluble PCHD recrystallized from dichloroethane.
Alcoholysis of Methyl Aluminium Biphenoxides: Excellent Initiators for the Ring Opening Polymerisation of ε‐Caprolactone
Authors: Liao Tien‐Chi , Huang Yi‐Lun , Huang Bor‐Hunn , Lin Chu‐Chieh 
Published: April 2003

AbstractSeveral aluminium alkoxides are prepared, and their catalytic activities toward ring‐opening polymerisation of ε‐caprolactone have been investigated. The reaction of [(μ‐EDBP)AlMe]2 (EDBP‐H2: 2,2′‐ethylidenebis(4,6‐di‐tert‐butylphenol)) with 2 molar equiv. of monomethylethylene glycol yields a five‐coordinated dimeric aluminium complex, (1). [(μ‐EDBP)AlMe]2 reacts with 2 molar equiv. of alcohol in toluene at ambient temperature to give a four‐coordinated dimeric aluminium complex, [(EDBP)Al(μ‐OR)]2 (2: R = Me; 3: R = Et; 4: R = 4‐MeOC6H4). However, the reaction of [(μ‐EDBP)AlMe]2 with 2 molar equiv. of benzhydrol in tetrahydrofuran (THF) gives a four‐coordinated monomeric complex, [(EDBP)Al(OCHPh2)(THF)] (5).Molecular structure of 1 as 20% ellipsoids, hydrogen atoms are omitted for clarity.magnified imageMolecular structure of 1 as 20% ellipsoids, hydrogen atoms are omitted for clarity.
Radiation‐induced crosslinking of polypotassium acrylate
Authors: Bashaw R. N. , Harper B. G. 
Published: April 2003

AbstractThe effects of radiation on potassium acrylate and polypotassium acrylate and their aqueous solutions have been studied. In the presence of air and at high and low water concentrations, degradation is the predominant radiation‐induced reaction. Cross‐linking occurs at intermediate concentrations. The degree of crosslinking for a given dose reaches a maximum at a polymer concentration of about 60%. An explanation of these results is presented.
Action des rayons γ du radiocobalt sur les solutions aqueuses de polyoxyethyleneglycol
Authors: Crouzet C. , Marchal J. 
Published: April 2003

AbstractNous avons etudié l'irradiation de solutions aqueuses de polyoxyèthyléneglycol à l'aide des rayons γ issus du radiocobalt. Dans une première série d'expériences les solutions ont été irradiées en présence d'air. Ces resultats montrent l'existence de deux mécanismes opposés dont l'un conduit au pontage du polymere et l'autre à la dégradation.
The infrared spectra of crystalline polysaccharides. VIII. Xylans
Authors: Marchessault R. H. , Liang C. Y. 
Published: April 2003

AbstractOriented films of 4‐O‐methylglucuronoxylan from several sources were prepared by hot stretching acetyl derivatives. The resulting oriented samples could be converted to crystalline xylans without destroying the orientation. Infrared spectra of the oriented samples were recorded using polarized radiation. Band assignments were made on the basis of empirically known group frequencies, the spectra of the deuterated analogs (OH → OD), and comparison with the spectra of small molecule model compounds. The dichroic ratios observed for the carbon hydrogen modes in the polarized spectrum along with the observed 15 A. fiber repeat of crystalline xylan “hydrate” are interpreted in terms of a threefold screw polymer conformation. Finally, by comparison of the polarized spectrum of an oriented hardwood xylan with that derived from a radial section of hardwood it was deduced that the xylan is oriented in the fiber direction in the tree.
Infrared absorption spectra and structure of polyethylene terephthalate
Authors: Tadokoro Hiroyuki , Tatsuka Kiyoaki , Murahashi Shunsuke 
Published: April 2003

AbstractHighly doubly oriented specimens of polyethylene terephthalate were studied by the methods of x‐ray diffraction and of infrared microspectroscopy. The sample for the microspectroscopy was embeded in n‐butyl methacrylate resin and cut perpendicularly to the stretching direction by a microtome. The spectra by the tilting method were also taken for the measurements of the pleochroism of the intense bands. Spectral measurements at various temperatures have been also made to obtain some additional information. It was confirmed that the molecular plane of the polymer (the plane of the benzene ring) is nearly parallel to the rolled plane. The assignments of the main bands are discussed.
Auto‐Organization in Sol‐Gel Type Polycondensation: A Door to the Nanosciences
Authors: Boury Bruno , Corriu Robert 
Published: April 2003

AbstractSilica‐based hybrid organic‐inorganic materials prepared by sol‐gel chemistry exhibit chemical and physical
properties revealing their anisotropic organization. Besides the opportunities that these phenomena open for the preparation of new materials,
they also provide arguments for the chemist looking for better comprehension and control of the solid's organization. © 2003 The
Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 120–132; 2003: Published online in Wiley InterScience
(www.interscience.wiley.com) DOI 10.1002/tcr.10056
Drug‐use initiation and conduct disorder among adolescents in drug treatment
Authors: Hser Yih‐Ing , Grella Christine E. , Collins Cyleste , Teruya Cheryl 
Published: April 2003

ABSTRACTThis study investigated effects of drug‐use initiation and conduct disorder (CD) among 1031 adolescents who participated in the Drug Abuse Treatment Outcomes Studies for Adolescents (DATOS‐A) sponsored by the National Institute on Drug Abuse (NIDA). The mean age of first drug use was 12.7 (s.d.=2.2), 57% met DSM‐III‐R criteria for CD, and earlier initiators were more likely to have CD. About 78% of the adolescents with CD reported that their first CD symptom occurred prior to drug‐use initiation. The proportions of adolescents who had prior treatment were similar (about 28%) across all groups, but earlier initiators reported a greater number of treatment episodes and younger ages at their first treatment. Conduct disordered adolescents revealed greater problems prior to DATOS‐A treatment, but they appeared to be more motivated and ready for treatment. Although adolescents with CD still showed worse outcomes after treatment, the impact of CD appeared to lessen when pretreatment differences were controlled. To a lesser extent, adolescents who began using drugs at earlier ages had greater alcohol and drug use and other problems at intake, but their treatment outcomes appeared to be similar to later initiators. There were few significant interaction effects of initiation and CD. Findings from this study highlight the importance of better understanding the progression of drug use, treatment utilization, and psychiatric comorbidity among adolescents with substance abuse problems.