bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copolymerization of 2,2‐dimethyltrimethylene carbonate with 2‐allyloxymethyl‐2‐ethyltrimethylene carbonate and with ε‐caprolactone using initiators on the basis of Li, Al, Zn and Sn
Authors: Kühling Steffen , Keul Helmut , Höcker Hartwig 
Published: April 2003

AbstractThe homopolymerization of 2,2‐dimethyltrimethylene carbonate (1), 2‐allyloxymethyl‐2‐ethyl‐trimethylene carbonate (2) and ε‐caprolactone (3) with sec‐butyllithium (sec‐BuLi), tri‐sec‐butoxyaluminium (Al(O‐secBu)3), diethylzinc (ZnEt2) and dibutyldimethoxytin ((Bu)2Sn(OMe)2) in toluene at 80°C results in a reaction product consisting of a high‐mole‐cular‐weight polymer and a homologous series of oligomers. The weight ratio polymer/oligomers, under standardized conditions, depends on the type of initiator. The sequence of monomeric units in the copolymers is statistical, for all initiators used. For sec‐BuLi and Bu2Sn(OMe)2 the distribution arises both from random addition of the monomers to the active chain end and from transesterification, while with Al(O‐secBu)3 and ZnEt2 the addition of the monomers is non‐selective.For poly[(2,2‐dimethyltrimethylene carbonate)‐stat‐(2‐allyloxymethyl‐2‐ethyltrimethylene carbonate)] the carbonyl region of the 13C NMR spectrum is suitable for diad analysis, for poly[(2,2‐dimethyltrimethylene carbonate)‐stat‐(ε‐caprolactone)] the methyleneoxy region is most indicative. The assigment of the diads was made on the basis of model compounds.
Photoreactive chiral liquid‐crystalline side‐group copolymers containing azobenzene mesogens
Authors: Ringsdorf Helmut , Urban Claus , Knoll Wolfgang , Sawodny Michael 
Published: April 2003

AbstractA series of liquid‐crystalline copolymers 1 with a chiral azobenzene moiety as photoreactive mesogenic unit was prepared. The polymers were fractionated and the mesophase behaviour of the high‐ and low‐molecular weight fractions was examined. The copolymers display smectic A and cholesteric phases. For the cholesteric phases the pitch of the helix was determined, which ranges from 3 to 20 μm. Stable monolayers at the air‐water interface were obtained from two monomers and one of the homopolymers. Multilayer assemblies of the azobenzene‐containing polymers can be used to study photo‐induced order/disorder transitions.
Functional polysiloxanes with benzophenone side‐groups: a photochemical application as radical polymerization macroinitiators
Authors: Pouliquen Lydie , Coqueret Xavier , Lablache‐Combier Alain , Loucheux Claude 
Published: April 2003

AbstractFunctional siloxane copolymers containing one or more ester groups derived from 2‐benzoyl‐benzoic acid (2‐BBA), 4‐dimethylaminobenzoic acid (4‐DMABA) or acrylic acid, were synthetized. These polymers were employed to prepare novel photo‐initiating systems based on the phenone/tertiary amine photogeneration of radicals. The influence of nature and relative amount of functional pendant units on the overall efficiency of the system mixed with an acrylate‐based composition was examined by quantitative IR spectroscopy. By comparing the different polymeric systems to the low‐molecular‐weight analogues, one observes a neat polymer effect inducing a greater initiation efficiency, especially when a polysiloxane containing only 2‐BBA ester groups is associated to free 4‐DMABA esters in the photosensitive composition.
Etude des propriétés microlithographiques d'une résine siliciée renfermant en mélange le poly(p‐triméthylsiloxystyrène) et le sel (C6H5)3SAsF6
Authors: Bonfils Frédéric , Giral Louis , Montginoul Claude , Sagnes René , Schué François 
Published: April 2003

AbstractThe study of a photoresist containing poly(p‐trimethylsiloxystyrene) (1, poly[1‐(4‐trimethyl‐siloxyphenyl)ethylene]) mixed with (C6H5)3SAsF6, which could be employed in a bilevel pattern‐transfer process, is reported. The onium salt undergoes efficient photolysis under UV radiation, to generate strong acids, responsible of the cleayage of the silicon‐containing side groups. The first results obtained show that this kind of resist could be used in microlithography, because it displays a very good sensitivity to deep UV and an excellent resistance to oxygen plasma. The syntheses of the compounds and substances used in this work are described.
Synthesis, polymerization, copolymerization, and transition‐metal coordination of 4‐(2,2′:6′,2″‐terpyridin‐4′‐yl)styrene and its polymers and copolymers
Authors: Hanabusa Kenji , Nakamura Atsushi , Koyama Toshiki , Shirai Hirofusa 
Published: April 2003

AbstractHomopolymer 5 from 4‐(2,2′:6′,2″‐terpyridin‐4′‐yl)styrene (4) and copolymers 6–8 from 4 and styrene, vinyl acetate, or acrylic acid were prepared by radical‐initiated polymerization with 2,2′‐azoisobutyronitrile. These polymers containing pendent 2,2′:6′,2″‐terpyridinyl ligands readily formed monotridentate complexes with FeCl2, NiCl2, and CuCl2. By reaction of copolymer 6 with 4′‐(p‐tolyl)‐2,2′:6′,2″‐terpyridyliron(III) trichloride or 4′‐(p‐tolyl‐2,2′:6′,2″‐terpyridylruthenium(III)) trichloride in the presence of ammonium hexafluorophosphate yielded polymer‐metal complexes 11a, 11b containing the corresponding bistridentate complexes. A cyclic voltammogram of 11a containing a bis(2,2′:6′,2″‐terpyridyl)iron(II) complex showed characteristic Fe2+/Fe3+ redox couples at + 1,12 V vs. saturated calomel electrode, which was also observed as a reversible color change between purple and colorless.
Block copolymers of narrow molecular‐weight distribution with a side‐chain liquid‐crystalline polymeric block as one component
Authors: Kodaira Toshiyuki , Mori Kazumi 
Published: April 2003

AbstractSyntheses of block copolymers have been undertaken by photo‐polymerization of 6‐{4‐[4‐(butoxyphenoxy)carbonyl]phenoxy}hexyl methacrylate (1) using the living propagating chain end of poly(methyl methacrylate) as an initiating species. The latter was derived from photo‐polymerization of methyl methacrylate (MMA) in the presence of methyl(5,10,15,20‐tetraphenylporphinato)aluminium. The polymerization of 1 proceeded from the propagating end of poly(MMA) with high blocking efficiency to produce poly(MMA)‐block‐poly(1) with narrow molecular‐weight distribution. The length of the block chain could be controlled by varying the amounts of monomers. An endothermic peak of the block copolymer with higher mass of liquid‐crystalline chain was observed at almost the same temperature region as that of poly(1) on differential scanning calorimetric analyses, which suggests that the former has a structure with microphase separation.
Thermodynamics of norbornene, of its polymerization process and of polynorbornene from 0 to 400 K at standard pressure
Authors: Lebedev Boris , Smirnova Natal'ya , Kiparisova Yelena , Makovetsky Kirill 
Published: April 2003

AbstractThermodynamic properties of norborneneSystem: name: bicyclo[2.2.1]hept‐2‐ene.
and polynorbornene, viz. isobaric heat capacity of the monomer and polymer between 10 and 330–400 K, parameters of physical transitions of the monomer and polymer, and energy of combustion for the polymer were studied by means of precise adiabatic and isothermal calorimetry. From the experimental data, the thermodynamic functions H°(T)–H°(0), S°(T) and G°(T)–H°(0) in the range of 0 to 330–400 K as well as enthalpies of combustion and thermochemical quantities of formation ΔH, and ΔS for polynorbornene were calculated. The results were used to calculate enthalpies, entropies and Gibbs functions of bulk polymerization for norbornene between 0 and 330 K and to evaluate the ceiling temperature of polymerization.
Effects of procatalyst composition on the stereospecificity of a Ziegler‐Natta catalyst system
Authors: Chadwick John C. , Miedema Arjen , Ruisch Bart J. , Sudmeijer Olof 
Published: April 2003

AbstractIn propylene polymerization with MgCl2/TiCl4/phthalate ester catalysts, using 2,2,6,6‐tetramethylpiperidine as external donor, it has been found that the fraction of atactic polymer formed increased with decreasing ester content in the catalyst. At the same time, however, the stereoregularity of the isotactic polymer fraction, as measured by 13C NMR, increased. Polymerization in the absence of the external donor led to lower polymer yield and a lower stereoregularity of the isotactic fraction. The results indicate that the external donor is actively involved in the generation of isospecific sites, particularly in catalysts having relatively low ester contents.
Gas permeation through two side‐chain liquid‐crystalline polyacrylate‐based membranes containing 4‐methoxyphenyl 4‐hexyloxybenzoate or 4‐cyanophenyl 4‐hexyloxybenzoate mesogenic side groups
Authors: Chen Deng‐Shan , Hsiue Ging‐Ho , Hsu Chain‐Shu 
Published: April 2003

AbstractTwo kinds of side‐chain liquid‐crystalline (LC) polymers with different side‐chain mesogenic end groups were synthesized. The laminated membrane was prepared by sandwiching the side‐chain LC polymer between two porous polypropene (Celgard) films. Permeation properties for O2, N2, CO2 and CH4 through the laminated side‐chain LC polymer‐based membranes were measured using a gas‐chromatographic method at several temperatures corresponding to the stability range of the different phases of the side‐chain LC polymers. The gas permeation behaviour depends strongly on the state of the side‐chain LC polymer. The activation energy for permeation depends on the state, too. The plot of separation factor P/P versus P exhibits an unusual behaviour. P/P increases with P when the temperature rises and the phase of the side‐chain LC Polymer changes from the glassy state to the liquid‐crystalline state. The magnitude of gas permeability coefficients for the laminated membranes is rather low compared to those of some common polymers. The low gas permeability seems to originate from the low gas solubility rather than from the low gas diffusivity in the laminated side‐chain LC polymer membrane.
Arylpropenoates as photoactive units in photocontrollable polymers
Authors: Proctor Andrew D. , Gilbert Andrew , Mitchell Geoffrey R. 
Published: April 2003

AbstractThe synthesis of photochemical properties of a range of arylpropenoates are described and their suitability as photoactive units for the reversible manipulation of polymer properties assessed. The Z and E isomers of the 1‐naphthyl‐, 1‐(4‐methoxynaphthyl)‐ and 9‐phenanthryl‐ derivatives have sufficiently different absorption characteristics to allow their selective exciation to give photostationary states having high concentrations of each isomer. Incorporation of the photoactive units into methacrylate based polymers changes the photostationary state concentrations of the Z and E isomers but the effect on the 1‐(4‐methoxynaphthyl)‐derivative is small and here the photointerconversion is not accompanied by fatigue. The 9‐anthryl derivative undergoes facile (4π + 4π) photodimerization and this may have potential as a reversible crosslinking mechanism.
Synthesis and photosensitized homo‐ and block copolymerization of a bisphenol‐A derivative of dibenz[b, f]azepine
Authors: Alimoglu Ali K. , Bamford Clement H. , Ledwith Anthony , Yagci Yusuf 
Published: April 2003

AbstractA bisphenol‐A derivative of dibenz[b,f]azepine (DBA‐Bisphenol‐DBA) was synthesized and characterized. Sensitized photopolymerization of the DBA‐Bisphenol‐DBA was studied in detail. The usefulness of N‐acyldibenz[b,f]azepine groupings in promoting photochemically induced linking of the related molecules is further demonstrated by block copolymerization of DBA‐Bisphenol‐DBA and polystyrene having terminal dibenz[b,f]azepine substituents. Those reactions arise through benzophenone‐sensitized photocyclodimerization of the central double bond of the dibenz[b,f]azepine moieties.
Reactivity of individual stereoisomers based on 4‐(3‐buten‐1‐ynyl)‐1,2,5‐trimethyl‐4‐piperidinol in radical polymerization
Authors: Aliev Nysanly U. , Kurmanaliev Oraz Sh. , Shaikhutdinov Erengaip M. , Kudaibergenov Sarkyt E. , Bekturov Esen A. 
Published: April 2003

AbstractThe radical polymerization of individual stereoisomers of 4‐(3‐buten‐1‐ynyl)‐1,2,5‐trimethyl‐4‐piperidinol (1) was investigated. The reaction order with respect to the monomer and the initiator, and also the kinetic and energetic parameters of the polymerization reaction were determined. The values of constants of polymerization of the stereoisomers were found with the help of the “rotating sector” method. It was established that the spatial orientation of the reactive centres with respect to the six‐membered heterocycle influences the reactivity of the monomers and leads to a change of the polymerization rate of the stereoisomers by a factor of about 1,5 to 3. To ascertain the influence of the spatial structure on the reactivity of the stereoisomers, quantum chemical calculations for model structures were performed. By means of IR and Raman spectroscopy it was established that the polymerization of 1 occurs via the double bond of the 3‐buten‐1‐ynyl groups.
Reactivity in radical and anionic copolymerizations of 4‐(trimethylsilyl)styrene. Synthesis of soluble poly{(1,4‐divinylbenzene)‐co‐[4‐(trimethylsilyl)styrene]}
Authors: Nagasaki Yukio , Han Sang Bong , Kato Masao , Tsuruta Teiji 
Published: April 2003

AbstractRadical copolymerization of 4‐(trimethylsilyl)styrene (TMSS) with styrene were carried out to estimate the reactivity of TMSS. The monomer reactivity ratios r1 and r2 in the radical copolymerization of TMSS (M1) with styrene (M2) were evaluated as 0,28 and 0,48, respectively. The value r1 · r2 (= 0,13) being smaller than unity indicates that the trimethylsilyl group at para position behaves as an electron‐withdrawing substituent. Reactions of lithium diethylamide with TMSS in the presence of diethylamine, gave the 1:1 addition product 1‐[2‐(N,N‐diethylamino)‐ethyl]‐4‐(trimethylsilyl)benzene. Kinetic analysis showed that the second‐order rate constant (k) for this addition reaction is 34,4 · 10−4 dm3 · mol−1 · s−1, which is by a factor of 2 larger than that for the reaction with styrene (k = 16,0 · 10−4 dm3 · mol−1 · s−1). The fact is also compatible with the above consideration for the r1 · r2 values. Lithium diisopropylamide initiated anionic copolymerizations of TMSS with 1,4‐divinylbenzene (DVB) were also examined. The polymerizations proceed smoothly without any gel formation and the resulting copolymers are soluble in various common solvents such as benszene, tetrahydrofuran, chloroform, etc. Thus, novel organosilicon‐containing polymers having appropriate amounts of reactive pendent vinyl groups are easily synthesized.
MgCl2‐supported Ziegler‐Natta catalysts: A structural investigation by X‐ray diffraction and Fourier‐transform IR spectroscopy on the chemical activation process through MgCl2‐ethanol adducts
Authors: Di Noto Vito , Zannetti Roberto , Vivani Maria , Marega Carla , Marigo Antonio , Bresadola Silvano 
Published: April 2003

AbstractBy X‐ray diffraction on polycrystalline powders and Fourier‐transform IR spectroscopy, some adducts MgCl2(C2H5OH)x were studied, having different composition in the range from x = 0 (α‐MgCl2) to x = 6. For 2 < x ≤ 6, the structure of such adducts shows prevalently ionic MgCl bonds. For x ≤ 2, covalent bonds are observed among chlorine and magnesium atoms, which give rise to chain compounds through chlorine bridges among the Mg‐atoms. The obtained structural data are also discussed in terms of the synthesis of some MgCl2‐based supports which are very active in the Ziegler‐Natta process of olefin polymerization, after a treatment with titanium halides and a successive addition of a cocatalyst and of other suitable donors.
Polymerization of olefins with the catalyst system (RCp)TiCl3 (R = H, CH3)/SiO2‐common alkylaluminium activated with a suitable Lewis acid
Authors: Soga Kazuo , Lee Dong Hee 
Published: April 2003

AbstractThe silica‐supported catalyst (RCp)TiCl3 (R = H, CH3; Cp = cyclopentadienyl) was prepared by reaction of (RCp)TiCl3 with silica gel. The resulting catalyst combined with common alkylaluminium as cocatalyst does not show any activity for olefin polymerization. However, the catalyst system is easily activated by adding a strong Lewis acid like (C6H5)3C·B(C6F5)4. Polymerization of propene and ethylene‐propene copolymerization with this catalyst system gives atactic polypropene with frequent chemical inversion and a random copolymer whose structure is very similar to that produced with a homogeneous vanadium catalyst system, respectively.
1H NMR study of the kinetics of metathesis polymerization of 5‐ and 5,6‐methoxycarbonyl derivatives of bicyclo[2.2.1]‐hept‐2‐ene, initiated by
Authors: Ivin Kenneth J. , Kress Jacky , Osborn John A. 
Published: April 2003

AbstractThe ring‐opening metathesis polymerization of 5‐endo‐methoxycarbonyl (1), 5‐exo‐methoxy‐carbonyl (2), 5,6‐endo,endo‐bis(methoxycarbonyl) (3), 5,6‐exo,exo‐bis(methoxycarbonyl) (4) and 5,6‐endo,exo‐bis(methoxycarbonyl) (5) derivatives of norbornene, initiated by the tungsten cyclopentylidene complex , have been followed by 1H NMR in situ at 290 – 320 K. The initial metal‐carbene adduct P1 is usually distinguishable from the subsequent adducts Pn(n > 1). Initiation is generally faster than or as fast as propagation. The propagation rate constants for the monosubstituted derivatives 1 and 2 are two to four times greater than those for the 5,6‐disubstituted derivatives 3–5. Arrhenius parameters were determined for the propagation reactions of 1 and 3.
Preparation of polyaniline by oxidation of aniline using H2O2 in the presence of an iron(II) catalyst
Authors: Moon Doo Kyung , Osakada Kohtaro , Maruyama Tsukasa , Yamamoto Takakazu 
Published: April 2003

AbstractOxidative polymerization of aniline using the H2O2‐FeSO4 system gave polyaniline under mild conditions. The prepared powdery emeraldine base, a form of polyaniline, is blue black and shows high solubility in organic solvents (e.g., ca. 200 mg/mL in N‐methylpyrrolidone). The number‐average molecular weight (Mn) of the polymer obtained was 1,3–1,7 · 104 (via gel permeation chromatography vs. polystyrene) and Mw/Mn = 1,6–2,2. Poly(2‐ethylaniline) and poly‐(2‐propylaniline) with high molecular weights were also synthesized by this procedure in high yield.
Thermotropic liquid‐crystalline aromatic‐aliphatic polyimides, 1. Novel poly(imide‐carbonate)s containing pyromellitimide ring
Authors: Sato Moriyuki , Hirata Tomohiro , Mukaida Ken‐ichi 
Published: April 2003

AbstractSemi‐rigid poly(imide‐carbonate)s with high inherent viscosities were synthesized in high yields by melt polycondensation of the monomer, N,N′‐bis(6‐hydroxyhexyl)pyromellitdiimide and/or 6,6′‐(4,4′‐biphenylylenedioxy)dihexanol with alkylene bis(phenyl carbonate)s (m = 6, 8, 10 and 12). The monomer was prepared by deacetylation of an intermediate diacetylated compound derived from the condensation of pyromellitic dianhydride with 6‐aminohexanol followed by cyclization with acetic anhydride. The resulting polymers were characterized by FTIR and 13C NMR measurements and elemental analyses. The thermal and mesomorphic properties were evaluated by polarizing microscope observation, DSC measurements and powder X‐ray analyses. The polymers showed very good solubilities in organic solvents such as chloroform and 1,4‐dioxane. Flexible and tough films were cast from the chloroform solutions. All the polymers have low glass transition temperatures below room temperature which decreased with increase of the aliphatic spacer lengths. Most of the polymers display no thermotropic liquid‐crystalline properties, but only the biphenyl unit‐rich copolymer exhibits a nematic melt. It is suggested that the mesogenic character of the pyromellitimide ring is very low.
Propene polymerization with δ‐TiCl3/AlCl(C2H5)2 and δ‐TiCl3/Al(C2H5)3 catalyst systems, 1. Effect of external donors
Authors: Coutinho Fernanda , de Santa Maria Luiz Claudio 
Published: April 2003

AbstractThe effect of ethyl benzoate (EB), diisobutyl phthalate (DIBP), dibutyl ether (DBE) and triethoxy(phenyl)silane (EPS) as third components on the propene polymerization with the catalyst systems δ‐TiCl3/AlCl(C2H5)2 and δ‐TiCl3/Al(C2H5)3 was investigated. The influence of external donors on the isotacticity, catalyst activity and average molecular weight (Mv) was tested. If external donors are employed, Mv decreases, the insoluble fraction in boiling isooctane increases and the catalyst activity is strongly influenced by the mole ratio external donor/TiCl3. The results indicate that all external donors employed have the same qualitative effect on catalytic active centers.
End‐functionalized polymers of p‐alkoxystyrenes by living cationic polymerization, 2.p‐tert‐butoxystyrene
Authors: Shohi Hajime , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractA series of end‐functionalized polymers of p‐tert‐butoxystyrene (tBOS), with an acetoxy, an ethyl malonate, or a methacryloxy group, were synthesized by living cationic polymerization with the use of hydrogen iodide/zinc iodide (HI/ZnI2) as initiating system: XCH2CH2OCH(CH3)‐(tBOS)nOCH3 (4) [X:(C2H5OCO)2CH (4a); CH3COO (4b)]; H(tBOS)nOCH2CH2Z (8) [Z: OCOC(CH3)CH2 (8a), OCOCH3 (8b)]. For the synthesis of these polymers, the following two methods were employed: (i) living polymerization of tBOS initiated with a functional vinyl ether‐hydrogen iodide adduct 2 [XCH2CH2OCH(CH3)I] in conjunction with ZnI2 to give “αend”‐functional polymers 4 and (ii) quenching the HI/ZnI2‐initiated living poly(tBOS) with a functional alcohol 7[HOCH2CH2Z] to give “ωend”‐functional polymers 8. All these polymers were shown to possess controlled molecular weights (number‐average degree of polymerization DPn=[tBOS]0/[initiator]0), narrow molecular weight distributions (Mw/Mn < 1,1), and end‐functionalities close to one. The end groups of the polymers 4a and 4b were converted into carboxy (5a) and hydroxy (5b) functions.
A novel synthetic route to rigid‐rod polyimides
Authors: Helmer‐Metzmann Freddy , Rehahn Matthias , Schmitz Ludwig , Ballauff Matthias , Wegner Gerhard 
Published: April 2003

AbstractA new synthetic approach to soluble, rigid‐rod, aromatic polymides is described. The polycondensation is done by a Pd‐catalyzed aryl‐aryl coupling of N,N′‐bis(4‐bromo‐2,5‐didodecyl‐phenyl)‐1,2:4,5‐pyromellitic diimide (2) and 2,5‐didodecyl‐1,4‐benzenediboronic acid (3). Here, the imide structure is already preformed in monomer 2. A structurally identical polymer is synthesized by the classical procedure condensing 1,2:4,5‐pyromellitic dianhydride (PMDA) (4) and 4,4″‐diamino‐2,5,2′,5′,2″,5″‐hexadodecyl‐p‐terphenyl (5). Both polymers are characterized in detail by 1H and 13C NMR spectroscopy, membrane osmometry and size exclusion chromatography. The average degree of polycondensation is of the order of 15. The thermal behaviour of the polymers is studied by differential scanning calorimetry and thermogravimetrical analysis.
1H NMR investigation of some aromatic copolyester
Authors: Abis Luigi , Po' Riccardo , Spera Silvia , Bachilega Giancarlo , Occhiello Ernesto , Garbassi Fabio 
Published: April 2003

AbstractThe microstructure of aromatic copolyesters prepared by bulk polymerization was investigated by means of 1H NMR spectroscopy. The aromatic region of the spectra appears to be sensitive to the sequence distribution of aromatic rings. Line shape simulation and resolution enhancement of the time domain spectra with a Gaussian window function allow a quantitative evaluation of the relative intensities. Sequence distribution in terms of triads and diads formed by aromatic rings was then derived and compared with the one calculated on the basis of a random distribution. The results show that the distribution, as expected for this class of copolymers, is random.