bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnesium chloride supported high‐mileage catalysts for olefin polymerization. XVII. Effect of lewis base on propylene polymerization
Authors: Chien James C. W. , Hu Youliang 
Published: April 2003

AbstractA systematic study has been made on the functions of external Lewis base (Be, methyl‐p‐toluate, MPT) and internal Lewis base (Bi, ethyl benzoate, EB) for the CW‐catalyst system MgCI2/EB/PC/AlEt3/TiCl4–AlEt3/MPT (PC, p‐cresol). Bi is a nonstereoselective modifier. It increases the active site concentrations and rate constants of propagation, kp, of both the isospecific and nonspecific sites, and thus the productivities of the stereoregular and irregular polypropylenes by five‐ to tenfold. It seems that Bi complexes with the MgCl2 support to lower the electronegativity of the surface Mg atoms. It also acts to lower the rate constant of chain transfer to aluminum alkyl, k, by two‐ to fourfold. The action of Be is highly stereospecific. The isotacticity index of polypropylene is ≫ 95% in the presence of Be but ≪ 68% without it. Addition of Be decreases nonspecific [Ti*]a by about (11 ± 2)‐fold; there is only about a twofold reduction of the isospecific [Ti*]i. It decreases kp,a about three times but has no effect on kp,i, so that the latter is (21 ± 4) times the former. Be decreases k for transfer with aluminum alkyl much more than it does to k; but it does not affect the rates of chain transfer with monomer and by β‐hydride elimination or the rate of catalyst deactivation. The number of active sites without Be is [Ti*]i = 15% and [Ti*]a = 55% for a total of 70%. In the presence of Be they are both about 6%. Optimum performance in propylene polymerizations requires both Bi and Be in the case of the CW‐catalyst.
Study on functionalization of metal surfaces. III. Photopolymerization of monomer films on metal surfaces
Authors: Mori Kunio , Watanabe Akira , Muroi Aikou , Nakamura Yoshiro 
Published: April 2003

AbstractThe three kinds of monomer films on metal surfaces were deposited by adsorption from a solution of 6‐polymerizable substituents‐1,3,5‐triazine‐2,4‐dithiol monosodium salts (RTDN); the polymerizable substituents such as cis‐9‐octadecenylamino, di(cis‐9‐octadecenyl)amino, and p‐vinylbenzyl(cis‐9‐octadecenyl)amino groups were selected in view of the polymerization activity of unsaturated groups in the substituents and the packing degree of monomer molecules. The monomer films were estimated to consist of mainly 6‐substituents‐1,3,5,‐triazine‐2,4‐dithione (3H, 5H) and to be multimolecular layers that are considerably cross‐packed and ordered. The monomer films on metal surfaces were polymerizable under a UV light irradiation in air atmosphere to give polymer films. In the photopolymerization, azobis(isobutyronitrile) (AIBN) was very effective for increasing the monomer conversion and the polymerization rate. The optimum concentration of AIBN in monomer films was very small, about 0.025 mol %. The monomer conversion was influenced by the kind of monomers, namely, the polymerization activity and the packing degree. The effect of the packing degree was especially remarkable. The monomer conversion decreased with an increase in the thickness of monomer films. This is because the polymerization was initiated by oxygen and AIBN, which were diffused into the inner of monomer films. The possibility of polymerization of the unsaturated groups and the thione groups in monomer molecules under UV light irradiation is discussed.
Electroconductivity study of active centers of polar vinyl monomers in the anionic polymerization
Authors: Dotcheva D. , Tsvetanov Ch. , Lochmann L. 
Published: April 2003

AbstractIon equilibria in THF solutions of organolithium compounds are studied at −30°C. The extremely low values of the dissociation constants (from 10−11 to 10−13M) and the formation of ion triples of the types A−, B+, A− prove that active centers exist in THF mainly as contact ion pairs with very small interionic distance (∼ 2.5 Å) and tend to form higher associates. A comparison is made between the physicochemical characteristics of active centers of vinyl nitriles, ketones, and esters. A planar structure is proposed for the anion of methyl methacrylate. The results indicate that the intramolecular chelate complexation between the polar group and the counterion of the active center decreases in the order . A greater participation of ion triples in the propagation reaction is proposed.
Synthesis of block cotelomers involving a perfluorinated chain and a hydrophilic chain. III. Synthesis and use of fluorinated telogens with a trichloromethyl end group
Authors: Boutevin B. , Pietrasanta Y. , Youssef B. 
Published: April 2003

AbstractThe addition by redox catalysis (CuCl or FeCl3 with benzoin) of CCl4 and CCl3CF2CCl3 on pentafluorostyrene and on fluorinated allyl ether, C6F13C2H4OCH2CHCH2 was performed. The monoaddition compounds were mainly obtained with satisfactory yields and characterized by NMR (13C, 1H, and 19F). These compounds were then used as telogens in telomerization by redox catalysis of acrylamide, methyl methacrylate, and acrylic acid and in radical‐initiated telomerization of N‐vinyl‐pyrrolidone. The chain lengths of the hydrocarbonated sequences were determined from fluorine elemental analysis. A critical investigation of correlations between DPn and concentrations of products involved was made.
Radical ring‐opening polymerization behavior of vinylcyclopropane derivatives bearing an ester group
Authors: Endo Takeshi , Watanabe Makoto , Suga Katsufumi , Yokozawa Tsutomu 
Published: April 2003

AbstractEthyl 2‐vinylcyclopropanecarboxylate derivatives (VCP) that underwent radical ring‐opening polymerization were prepared from the corresponding diene and diazoacetate in the presence of copper‐Schiff base complex as a catalyst. The polymerization behavior of the obtained monomers was investigated, and the reaction of VCP with thiophenol was also carried out as a model reaction of their polymerization.
Study of photopolymers. XXX. Syntheses of new di(meth) acrylate oligomers by addition reactions of epoxy compounds with active esters
Authors: Nishikubo Tadatomi , Takehara Eiji , Saita Seiji , Matsumura Takahisa 
Published: April 2003

AbstractSome dimethacrylate oligomers were synthesized by new addition reactions of 2,2‐(4‐hydroxyphenyl)propane diglycidyl ether (BPGE) or glycidyl methacrylate (GMA) with phenyl methacrylates such as phenyl methacrylate (PMA), 4‐nitrophenyl methacrylate (NPMA), 2,4‐dichlorophenyl methacrylate (DCPMA), 4‐methoxyphenyl methacrylate (MPMA), and (4‐cinnamoyloxy)phenyl methacrylate (CIPMA) using tetrabutylammonium bromide as a catalyst at 120°C. The other new dimethacrylate or diacrylate oligomers were also prepared by the addition reactions of GMA or glycidyl acrylate with active esters such as di(S‐phenyl)thioisophthalate (PTIP), di(4‐nitrophenyl)isophthalate (NPIP), di(4‐nitrophenyl)adipate (NPAD), and di(4‐nitrophenyl)sebacate (NPSB) under similar reaction conditions. Furthermore, the rates of photochemical reaction of the obtained dimethacrylate oligomers were measured with 3 mol % of various photosensitizers such as benzoin iso‐propyl ether (BIPE), 2‐ethylanthraquinone (EAQ), and benzophenone (BP). The rate of photochemical reaction of BPGE‐DCPMA oligomer was higher than those of BPGE‐PMA, BPGE‐NPMA, and BPGE‐MPMA oligomers using BIPE as a photosensitizer. However, the photochemical reactivity of the unsensitized BPGE‐CIPMA was almost the same as that of the sensitized BPGE‐DCPMA. On the other hand, when EAQ was used as a photosensitizer, GMA‐PTIP oligomer showed much higher reactivity than GMA‐NPAD, GMA‐NPSB, and GMA‐NPIP oligomers. Also it was shown that the activity of EAQ as a sensitizer was higher than BIPE and BP in the photochemical reaction of BPGE‐DCPMA oligomer.
Photosensitive poly(methacrylates) having styrylpyridinium and styrylquinolinium groups
Authors: Ichimura Kunihiro , Oohara Noboru 
Published: April 2003

AbstractThree methods to introduce photodimerizable styrylpyridinium or styrylquinolinium groups to methacrylate polymers are described. Among these, copolymerization of methacrylate monomers with methacrylated styrylpyridine or styrylquinoline offered the most convenient procedure to prepare photosensitive polymers because of the excellent solubility of the polymers having the photofunctional groups in high content. Subsequent treatment with p‐toluenesulfonic acid to quaternize the pyridine or quinoline moiety made the polymer highly photosensitive. The polymers having a styrylquinolinium group were found to be sensitive to 488 nm light of an Ar laser, and the sensitivity was about 3 mJ/cm2 when the content of the photosensitive group was 15 mol %.
Ring‐opening polymerization of 2,3,5,6‐tetrasubstituted‐3,4‐dihydro‐2H‐pyrans and their copolymerization behaviors. Syntheses of alternating head‐to‐head vinyl copolymers and their properties
Authors: Lee Ju‐Yeon , Cho Iwhan 
Published: April 2003

Abstract2‐Methoxy‐6‐ethoxy‐5‐cyano‐3,4‐dihydro‐2H‐pyran (1a), 2‐isobutoxy‐6ethoxy‐5‐cyano‐3,4‐dihydro‐2H‐pyran (1b), and 2,6‐diethoxy‐3‐methyl‐5‐cyano‐3,4‐dihydro‐2H‐pyran (1c) were prepared by (4 + 2) cycloaddition reaction of ethyl α‐cyanoacrylate with the corresponding vinyl ethers. Compounds 1a‐c were ring‐open polymerized by cationic catalyst to obtain alternating head‐to‐head (HH) copolymers. For comparison, head‐to‐tail (HT) copolymer 3a was also prepared by free radical copolymerization of the mixture of the corresponding monomers. The H–H copolymer exhibited minor differences in its 1H‐NMR and IR spectra, but in the 13C‐NMR spectrum significant differences were shown between the HH and HT copolymers. Glass transition temperature (Tg) of HH copolymer was higher than that of the corresponding HT copolymer, but thermal decomposition temperature of the HH copolymer was lower than that of the HT copolymer. Compounds 1a and 1b copolymerized well with styrene by cationic catalyst, but compound 1c failed to copolmerize with styrene. All of the H‐H and H‐T copolymers were soluble in common solvents and the inherent viscosities were in the range 0.2–0.5 g/dL.
Melting points of homogeneous random copolymers of ethylene and 1‐alkenes
Authors: Clas S.‐D. , McFaddin D. C. , Russell K. E. , Scammell‐Bullock M. V. , Peat I. R. 
Published: April 2003

AbstractMelting points of copolymers of ethylene and 1‐alkenes ranging from 1‐butene to 1‐octadecene have been determined. The copolymers were prepared by means of a homogeneous Et3Al2Cl3/VOCl3 initiating system so that in individual samples, comonomer contents do not vary with molecular weight. Evidence is presented for a random distribution of comonomer units in the copolymers. Melting points determined by differential scanning calorimetry are essentially independent of branch length at low comonomer contents. At higher comonomer contents (5–9 mol% 1‐alkene), melting points decrease in the order 1‐butene > 1‐octene > 1‐octadecene copolymers. The weight fraction of ethylene sequences drops to less than 60% in copolymers with 1‐octadecene of high comonomer content and this results in a reduction in the crystallite thicknesses attained by these copolymers.
Polystyrenes with structurally different oligosiloxanes as p‐substituents for oxygen permeable membrane materials
Authors: Kawakami Yuhsuke , Kamiya Hiroki , Toda Hiroshi , Yamashita Yuya 
Published: April 2003

AbstractPolystyrenes with structurally different oligosiloxanes as p‐substituents were synthesized and the selective oxygen permeation through the polymer film was studied. It was found that the structure of the p‐oligosiloxane substituents had great effects not only on the glass transition temperature of the polymer but also on the oxygen permeation behavior through the polymer film. Trimethylsiloxyl groups, especially, were shown to play an essential role in enhancing the permeability.
Synthesis of polyurethanes containing nucleic acid base derivatives as grafted pendants and their precursor amino functionalized polyurethane
Authors: Lu C. X. , Yang Yang , Xiao Chaodong , Ji Aixue 
Published: April 2003

AbstractA new route to polyurethanes containing nucleic acid base derivatives as grafted pendants have been established. The method is based on the grafting of 2‐(thymin‐1‐yl)propionic acid (TPA) or 2‐(adenin‐9‐yl)propionic acid (APA) onto amino functionalized polyurethane, poly[2‐amino‐2‐methyl‐1,3‐propylene methylene bis(4‐phenyl carbamate)] (PU‐NH2, IX) at the primary amino group by the N‐hydroxy compound of active ester technique. Two novel polymer models of polynucleic acid—poly[2‐(2′‐(thymin‐1′‐yl) propionamido)‐2‐methyl‐1,3‐propylene methylene bis(4‐phenylcarbamate)] (PU–NHT, X) and poly[2‐(2′‐(adenin‐9′‐yl)propionamido)‐2‐methyl‐1,3‐propylene methylene bis(4‐phenylcarbamate)] (PU–NHA‐40, XI)—were obtained. The amino functional polyurethane was prepared by the following three step reactions; (1) Selective N‐protection of N‐benzyloxycarbonyloxy‐5‐norbornene‐2,3‐dicarbonimide (CbzONB) with 2‐amino‐2‐methyl‐1,3‐propanediol gave the N‐protecting diol monomer 2‐benzyloxycarbonylamino‐2‐methyl‐1,3‐propanediol (CbzAMP); (2) N‐Protecting polurethane poly(2‐benzyloxycarbonylamino‐2‐methyl‐methyl‐1,3) propylene methylene bis(4‐phenylcarbamate) (PU–NHCbz, VIII) was obtained by the polyaddition of 4,4′‐diphenyl‐methane diisocyanate (MDI) with CbzAMP. (3) Deprotection of PU–NHCbz produced amino polyurethane PU‐NH2. Prior to polymer synthesis, the amidation of APA with 3‐aminoheptane or diethylamine were carried out as a model reaction study and the related monomer model compounds were prepared by the same methods.
Synthesis and characterization of photosensitive polyimides
Authors: Crivello J. V. , Lee J. L. , Conlon D. A. 
Published: April 2003

AbstractAll aromatic polyimides bearing diarylsulfide linkages in the main chain were prepared either by condensation of a sulfur containing dianhydride with an aromatic diamine or the condensation of a sulfur containing aromatic diamine with a dianhydride. Phenylation with diphenyl iodonium salts was then used to convert the diarylsulfide groups to triarylsulfonium salts. The resulting photosensitive polyimides were shown to undergo main chain cleavage during photolysis using UV irradiation. These new polyimides are candidates for positive working, high temperature photoresist materials.
New approach to the measurement of polymer photooxidation
Authors: Bigger S. W. , Delatycki O. 
Published: April 2003

AbstractIn an attempt to eradicate many of the problems associated with outdoor and accelerated testing of polymeric formulations, an apparatus was constructed for the sensitive measurement of oxygen uptake into a polymer during its incipient stages of photooxidation. The photooxidation curves of certain HDPE and LDPE formulations demonstrate a first order asymptotic approach to a limiting value which corresponds to the initial number of reactive centers that are available in the material for oxygen attack. An equation for oxygen uptake as a function of time is derived which incorporates the asymptotic value together with a constant whose value reflects the rate at which the asymptote is approached. These parameters are used to calculate the value of the initial quantum yield for oxygen uptake, a quantity which is indicative of the relative photostability of a given formulation. The kinetics parameters obtained from analyses of certain photooxidative curves confirm that the initial rate of photooxidation is proportional to the concentration of polymer hydroperoxide species which are present in the material as a result of oxidation during processing. The removal of these by thermal treatment of the material in an inert atmosphere results in the appearance of an induction period in the photooxidative profile. The experimental results suggest that this method of determining and interpreting photooxidative curves has certain potential for assessing the relative photostabilities of polymeric formulations.
Polymerization of 1,3,5‐trithiane in the solid state initiated by UV‐irradiation. II. Investigation of the initiation process
Authors: Andrzejewska Ewa , Żuk Aleksander , Krzyminiewski Ryszard , Pietrzak Jerzy 
Published: April 2003

AbstractThe influence of the irradiation and polymerization atmosphere on polymer yield was observed. It was shown that in the initiation process oxygen presence is necessary. ESR studies of UV‐and γ‐irradiated 1,3,5‐trithiane were done. The influence of the irradiation atmosphere on generated radicals and the influence of UV‐action on radicals formed by γ‐irradiation was also investigated. The possible initiation mechanism of cationic polymerization of 1,3,5‐trithiane is discussed. A comparison of the 1,3,5‐trithiane is polymerizations initiated chemically and by UV‐ or γ‐irradiation is also given.
Polyarylates. IV. Synthesis of block copolymers via two‐step interfacial polycondensation
Authors: Tsai Hong‐Bing , Lee Yu‐Der 
Published: April 2003

AbstractA new method for preparing block copolyarylates via two‐step interfacial polycondensation is proposed. First, oligomers with acid chloride end groups were obtained from interfacial polycondensation with a mole ratio of bisphenol A to diacid chloride(s) less than I. In the second step, two reaction systems containing various oligomers were mixed thoroughly and more bisphenolate was charged into this mixture. The synthesis of the block copolyarylates was justified from the viewpoint of statistics, and of differences in molecular weight between oligomers and block copolymers. These block copolyarylates could be differentiated from polyarylates through crystal‐line behavior and solubility in m‐cresol analyses.
The synthesis, characterization, and weathering behavior of polycarbonates derived from 3,3′‐dihydroxydiphenyl ether
Authors: Factor A. , Lynch J. C. , Greenberg F. H. 
Published: April 2003

AbstractPrevious studies of the photodegradation of bisphenol A polycarbonate (BPA PC) indicate that both alkyl side chain and ring oxidation play significant roles. In order to determine the relative importance of these two pathways in the photoyellowing that accompanies photodegradation, side chain free polycarbonates based on 3,3′‐dihydroxydiphenyl ether were synthesized and tested. Both accelerated weathering experiments using a QUV test apparatus and outdoor weathering indicated that these polymers photoyellowed faster than BPA PC. This suggests that ring oxidation is an important source of photoyellowing of aromatic polycarbonates.
Studies of poly(ortho‐acylstyrenes). I. Syntheses and characterization
Authors: Weir N. A. , Whiting K. , Arct J. 
Published: April 2003

AbstractThe syntheses of a number of o‐acylstyrenes (o‐acetyl through o‐hexanoyl) have been described. Polymerizations were carried out radically at 80°C under high vacuum. While all polymerizations conform to the usual free radical kinetic scheme, rates are sensitive to the nature of the acyl substituent, and this has been ascribed to steric effects, the bulky substituents adjacent to the propagating radicals inhibiting the approach of monomer. Molecular weight and polydispersity data indicate that both combination and disproportionation occur during terminations. UV spectra consist of two absorptions associated with n → π* and π → π* transitions. 13C‐NMR spectra have been analyzed and assignments made on the basis of spectral editing. The considerable variation of glass transition temperatures has been accounted for in terms of a combination of steric and dipolar interactions.
Effect of molar mass ratio of monomers on the mass distribution of chain lengths and compositions in copolymers: Extension of the stockmayer theory
Authors: Tacx J. C. J. F. , Linssen H. N. , German A. L. 
Published: April 2003

AbstractIn statistical copolymers, there exists a distribution according to molar mass as well as according to chemical composition. Stockmayer derived distribution functions, describing the relative weight of a particular molar mass and composition interval, assuming equal molar masses of the monomer units. In this article we present an extension of the distribution functions, suited for those cases where the aforementioned assumption is not valid. The final mathematical results is a product of the original Stockmayer distribution function and a correction function, due to the unequality of molar masses. It appears the correction function is dependent on the average composition, the composition deviation, and the ratio of molar masses of the monomers. Furthermore, a three‐dimensional representation of distributions has been developed to get insight in the shape of the distributions.
13C‐NMR spectra of cis‐polymyrcene and cis‐polyfarnesene
Authors: Newmark Richard A. , Majumdar Ramendra N. 
Published: April 2003

AbstractHomopolymers of myrcene and farnesene were prepared anionically in pure cyclohexane. The microstructure, determined from an analysis of the 13C‐NMR spectrum and spin‐lattice relaxation times, indicates the polymers are at least 85% cis‐1,4, 10% cis‐3,4, and under 3% trans‐1,4.
Synthesis and characterization of aromatic polyimide and polyamide‐imide from 2,5‐bis(4‐isocyanatophenyl)‐3,4‐diphenylthiophene and aromatic tetra‐ and tricarboxylic acids
Authors: Kakimoto Masa‐Aki , Akiyama Reiko , Negi Yuvraj Singh , Imai Yoshio 
Published: April 2003

AbstractSoluble polyimide having an inherent viscosity up to 1.4 dL/g was synthesized by the high‐temperature solution polycondensation of 2,5‐bis(4‐isocyanatophenyl)‐3,4‐diphenylthiophene with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride. The polycondensation of the tetraphenylthiophene diisocyanate with trimellitic anhydride afforded polyamide‐imide with an inherent viscosity up to 0.9 dL/g. These polymers showed limited solubility in organic solvents and had glass transition temperatures around 320°C.
Polymerization of optically active β‐substituted β‐propiolactones. IV. β‐1,1‐dichloroalkyl β‐propiolactones polymerized with aluminum triisopropoxide
Authors: Voyer Richard , Prud'Homme Robert E. , Jéarôme Robert , Teyssiéa Philippe 
Published: April 2003

AbstractThe polymerization of three optically active β‐1,1‐dichloroalkyl β‐propiolactones has been investigated in toluene, at 55°C, using aluminum triisopropoxide (Al(OiPr)3) as initiator in a range of monomer/initiator molar ratios smaller than 150. β‐1,1‐dichloroethyl β‐propiolactone polymerizes according to a living mechanism. However, the ability to polymerize decreases with an increase in the length of the alkyl substituent. For instance, β‐1,1‐dichloro‐n‐propyl β‐propiolactone is obtained only in low yields, whereas β‐1,1‐dichloro‐n‐butyl β‐propiolactone does not polymerize at all. Actually, each of the lactones investigated reacts with Al(OiPr)3 in an initiation step that obeys a coordination‐insertion mechanism. However, the size of the chloroalkyl substituent has a critical effect on the propagation: when the alkyl group contains more than two methylene units, the insertion of a second monomer becomes exceedingly slow.
Preparation and properties of polyamides from 4‐phenoxy‐ and 4‐phenylthio‐m‐phenylenediamine and both aromatic and aliphatic diacids
Authors: Kakimoto Masa‐Aki , Yoneyama Masaru , Imai Yoshio 
Published: April 2003

AbstractNew soluble aramids having pendant phenoxy and phenylthio groups were prepared in high molecular weights by the polycondensation of aromatic diacids with 4‐phenoxy‐m‐phenylenediamine and 4‐phenylthio‐m‐phenylenediamine, respectively. Glass transition temperatures (Tg) of these aramids were in the range 195–255°C, where Tgs of phenoxy pendant aramids were higher than those of phenylthio substituted aramids. These properties were compared with those of the parent aramids derived from m‐phenylenediamine and aromatic diacids. Aromatic‐aliphatic polyamides were also prepared by the reaction of these three diamines with aliphatic diacids having 4–10 methylene groups and were characterized in detail.