bluuebunny/crossref_metadata_2025 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

A 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

The 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

Ion 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

The 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

Ethyl 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

Some 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

Three 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

2‐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

Melting 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

Polystyrenes 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

A 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

All 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

In 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

The 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

A 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

Previous 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

The 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

In 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

Homopolymers 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

Soluble 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

The 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

New 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.
Microanalysis of polymers using a windowless energy‐dispersive X‐ray detector
Authors: Hayat Umar , Bartlett Philip N. , Dodd George H. , Lewis Michael H.
Published: April 2003

The surface compositions of various polymeric films, grown electrochemically on platinum foils, have been investigated by energy‐dispersive x‐ray analysis in conjunction with scanning electron microscopy (SEM/EDS). Comparison of the relative area ratios of peaks for the C and N Kemission lines show that the EDS may be used to study the surface composition of polymers. The evidence presented strongly suggests that there is limited structural degradation and the elemental composition is not changed under the electron beam at relatively low accelerating voltages. This technique statistically samples the repeat units of the polymer. For samples grown in both aqueous and nonaqueous solutions. SEM/EDS provides evidence for extensive contamination with oxygen.
Cationic copolymerization of 3‐methyltetrahydrofuran and 3,3‐dimethyloxetane: Structural study of the copolymers
Authors: Guzmáan J. , García M. , Riande E.
Published: April 2003

The bulk cationic copolymerization of 3‐methyltetrahydrofuran and 3,3‐dimethyloxetane was studied at 0°C using acetylhexafluoroantimonate as initiator. Values of the composition of the copolymers and the dyad and triad probabilities were obtained by 1H‐ and 13C‐NMR spectroscopy. A kinetic scheme was proposed for this copolymerization and the values of the reactivity ratios were directly determined from the dyad probabilities. The experimental values of the triad probabilities were found to be in good agreement with those calculated from the reactivity ratios.
Synthesis of intramolecularly cyclized poly(phenylene sulfide)s of the thianthrene‐type
Authors: Bizzarri P. Costa , Casa C. Della , Fiorini M. , Porzio W.
Published: April 2003

Oligomers containing thianthrene units in the chain are synthesized by AlCl3‐catalyzed reaction of diphenylsulfide, thianthrene, poly(p‐phenylene sulfide), and poly(m‐phenylene disulfide) with sulfur at 80°C. The products are compared with that obtained by the reaction of diphenylsulfide with AlCl3 at 225°C. IR spectra and elemental analyses are consistent with cyclic chain structures and show a higher cyclization for CHCl3‐insoluble fractions. X‐ray diffraction analysis indicates the same structure for the samples obtained with the different methods of synthesis. A possible structural model is tentatively proposed.
Polymer complexes stabilized through hydrogen bonds. Influence of “structure defects” on complex formation: Viscometry and fluorescence polarization measurements
Authors: Iliopoulos I. , Halary J. L. , Audebert R.
Published: April 2003

The structure of polymer complexes stabilized through hydrogen bonds can be much influenced by the presence of nonactive groups (structure defects) on the polymer chains. In this paper two very simple homopolymer/copolymer systems are studied: the homopolymer is a polybase, polyoxyethylene (PEO) or polyvinylpyrrolidone (PVP), and the copolymer a partially neutralized poly(acrylic acid) (PAA). The acrylate groups on PAA chain behave as structure defects. Viscometry provides information about macroscopic structure of polymer complex in solution while fluorescence polarization is especially adapted for the study of the local mobility of polymer chains. Two kinds of structure are found: the first one is compact and implies a low viscosity of the mixture, eventually precipitation occurs, the second one is a highly branched structure, close to a gel, which leads to a very high increase in viscosity. For instance, the viscosity of the mixture may be several hundred times higher than the sum of the viscosities of the two individual polymer solutions. Such mixtures are especially adapted to be used like thickening agents.
Electro‐initiated polymerization of acrylonitrile in aqueous acetic acid containing Mn(OAc)2·4H2O and CNCH2COOH
Authors: Balasubramanian T. R. , Mahadevan V.
Published: April 2003

The electro‐initiated polymerization of acrylonitrile initiated by the anodic oxidation of an aqueous acid solution (80% HOAc + 20% H2O) containing Mn(OAc)2 · 4H2O/CNCH2COOH has been investigated in the 30–40°C temperature range. The kinetics and mechanism of the process has been investigated as a function of variables and a suitable mechanism proposed. From the experimental observations the rate of polymerization is seen to be proportional to [An]1.5I0.5[Mn+2]0.5 and [CAA]0.5. The rate of polymerization gradually decreases at a higher applied current. The rate was independent of [CAA]0.5. The rate of polymerization gradually decreases at a higher applied current. The rate was independent of CAA at high concentration. The average degrees of polymerization (Pn) increases with increasing AN and decreasing [CAA], [Mn+2] and applied current, I. The initiation is due to the anodic oxidation of Mn+2–CNCH2COOH complex. Both the initiation of polymerization by the primary radical, viz., CNCḢCOOH as well as the oxidation of the primary radical at the electrode are equally significant reactions and neither can be neglected in comparison with the other. Predominant mutual termination accounts for all the observed data.
Backbone‐assisted reactions of polymers. VII. Kinetics of isomerization of poly[(chloromethyl)thiirane] in the absence of solvent
Authors: Zussman Melvin P. , Tirrell David A.
Published: April 2003

The kinetics of the repeating unit isomerization of poly[(chloromethyl)thiirane] have been determined at four temperatures in the absence of solvent. The reaction can be treated as a reversible first‐order process with rate constants and activation energies similar to those observed in analogous reactions of β‐chlorosulfides of low molecular weight. These observations are consistent with a mechanistic scheme that involves rate determining cyclization to a thiiranium ion intermediate, followed by rapid ring opening by chloride ion attack.
Studies on diacetylenic vinyl compounds. II. Copolymerization of phenyl‐4′‐vinylphenylbutadiyne with styrene and methyl methacrylate
Authors: Castillóan Felipe F. , Navarro Rosa E. , Ogawa Takeshi
Published: April 2003

The copolymerizations of phenyl‐4′‐vinylphenylbutadiyne (PVPB) with styrene and methyl methacrylate were carried out under various conditions. PVPB was more readily incorporated in copolymerization than the comonomers, but the diacetylenic group of PVPB interacted with the propagating radical, decreasing the polymerization rate and the molecular weight of copolymer. When the polymerization system became very viscous, crosslinking took place giving light green luminescent gels. The thermal behaviors of copolymers were also studied.
The introduction of hydroxyl functionality into polymers: The synthesis, polymerization, and hydrolysis of vinylbenzyl acetate
Authors: Beihoffer T. W. , Glass J. E.
Published: April 2003

Vinylbenzyl acetate was synthesized in yields greater than 80% via the reaction of vinylbenzyl chloride with potassium acetate. Radical copolymerization of the monomer with styrene and methylmethacrylate were studied at 60°C. Reactivity ratios determined from FT‐IR analysis of low conversion copolymerizations with styrene (M1) were r1 = 0.78 ± 0.07 and r2 = 1.33 ± 0.13. Polymers and copolymers of vinylbenzyl acetate were found to completely hydrolyze in dioxane/water/base solution to yield hydroxymethyl functionality. Size exclusion chromatography studies indicated that the hydrolysis proceeded without crosslinking. This procedure is a useful method for the introduction of hydroxyl functionality on polymers and avoids crosslinking problems common in previously reported methods.
Comparative study of the absolute reactivity of vinyl monomers: Kinetics of polymerization of vinyl monomers initiated by Mn3+–thiodiglycolic acid redox system
Authors: Balakrishnan T. , Subbu S.
Published: April 2003

The kinetics and mechanism of polymerization of methacrylic acid (MAA) and ethyl acrylate (EA) initiated by the redox system, Mn3+–thiodiglycolic acid (TDGA) were investigated in the 15–35°C temperature range. The polymerization kinetics of both the monomers followed the same mechanism, viz., initiation by primary radical and termination by Mn3+–thiodiglycolic acid complex. The rate coefficients ki/k0 and kp/kt were related to the monomer reactivity and polymer radical reactivity, respectively. It was observed that both monomer reactivity and polymer radical reactivity followed the same order, viz., EA > MAA. The polymer radical reactivity varied inversely with the Q values of the monomers.
Synthesis and characterization of polystyrene–poly(ethylene oxide)–heparin block copolymers
Authors: Vulić I. , Okano T. , Kim S. W. , Feijen J.
Published: April 2003

A procedure for the preparation of new block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic spacer‐block of poly(ethylene oxide) and a bioactive block of heparin was investigated. Polystyrene with one amino group per chain was synthesized by free radical oligomerization of styrene in dimethylformamide, using 2‐aminoethanethiol as a chain transfer agent. This amino group was used in the coupling reaction with amino‐telechelic poly(ethylene oxide) to produce an AB type diblock copolymer with one amino group per polystyrene (PSt)–poly(ethylene oxide) (PEO) chain. The amino‐semitelechelic oligo‐styrene was converted into the isocyanate‐semitelechelic oligo‐styrene using toluene 2,4‐diisocyanate and subsequent coupling with H2N–PEO–NH2 afforded AB type block copolymers with terminal amino groups. The coupling of PSt–PEO–NH2 with heparin was performed in a DMF–H2O mixture, first by activating the heparin carboxylic groups with EDC at pH 5.1–5.2 and subsequently reacting the activated carboxylic groups with the amino groups of the PSt–PEO–NH2 at pH 7.5. Depending on the molecular weights of the diblock copolymer used 25–29% w/w heparin was incorporated. These polymers will be further evaluated for their blood‐compatibility.
Synthesis and electrical properties of substituted paracyclophane polymers
Authors: Longone Daniel T. , Glans Jeffrey H.
Published: April 2003

We report the synthesis of three new substituted [6.2]paracyclophane‐1,5‐dienes and their conversion to medium molecular weight polymers by an intra/intermolecular cyclopolymerization. These materials can be oxidatively “doped” by exposure to iodine vapor to give semiconductor properties.
Highly active supported catalysts for olefin polymerization. Supports from a grignard reagent for preparation of highly active catalysts
Authors: Yano Takefumi , Inoue Tokuji , Ikai Shigeru , Shimizu Michimasa , Kai Yoshiyuki , Tamura Masanori
Published: April 2003

Supports were obtained by the interaction of C4H9MgCl with the reaction mixture of AlCl3 and CH3Si(OC2H5)3 or Si(OC2H5)4 (Mg/Al/Si = 2/1/1). With the combination of Al(C2H5)3 and methyl‐p‐toluate, immobilized titanium catalysts prepared by the treatment of the supports with TiCl4 and ethylbenzoate showed extraordinary high activity and stereoregularity in the polymerization of propylene.1 By the study of the reaction of AlCl3 with CH3Si(OC2H5)3, the elemental analysis and powder x‐ray diffractometric measurements of the supports, it was found that the supports comprised of Cl, Mg, Al, and Si atoms, OC2H5 groups, C4H9 groups, and ethers, and that they were amorphous solids to the extent that the x‐ray diffraction peak assigned to the 003 plane in MgCl2 crystals completely disappeared.
Crosslinking of epoxy resins at interfaces. IV. Anhydride‐cured resins at carbon and graphite surfaces
Authors: Garton Andrew , Stevenson William T. K.
Published: April 2003

Dispersions of carbon blacks and chopped carbon fibers in epoxy resins may be characterized by infrared internal reflection spectroscopy (IR–IRS). The high surface areas of the carbons (often ≥ 100 m2/g) ensure a high degree of interfacial contact between the carbon surface and the polymer. The crosslinking kinetics and final crosslinked state of an anhydride‐cured epoxy resin are shown to be affected strongly by the carbons through adsorption of the tertiary amine catalyst at oxidation sites on the carbon surface. Oxidative treatments of the carbons (nitric acid oxidation, air oxidation) increase the effect on the crosslinking chemistry. Carbon dioxide treatment of the carbons, which produces a basic surface, reduces the effect on the crosslinking. The effects on the crosslinking kinetics were confirmed by differential scanning calorimetry (DSC). The relevance of these results to the characterization of the interphase in carbon fiber/epoxy composites is discussed.
Functional polymers. XLVII. Synthesis of various derivatives of ω‐alkenoates
Authors: Purgett Mark D. , Xie Shishan , Bansleben Donald A. , Vogl Otto
Published: April 2003

A number of derivatives of ω‐alkenoates were synthesized in preparation for the synthesis of functional polymers based on α‐olefins. For the preparation of most of the methyl esters, the regular esterification of ω‐alkenoic acids, specifically 10‐undecenoic acid with methanol and sulfuric acid as the catalyst, was most effective. For the preparation of thetert‐butyl‐ and 2‐ethylhexyl esters of 10‐undecenoic acid, the acid chloride route was found to be most convenient, whereas for the preparation of the corresponding esters of 5‐hexenoic acid, our method of choice was the synthesis via the imidazolyl derivative of the acid. 2,2,2‐Trifluoroethyl 10‐undecenoate and the 2,2‐dimethyloxazolidine derivative of 10‐undecenoic acid were prepared from the acid and 2,2,2‐trifluoroethanol or 2‐amino‐2‐methyl‐propanol withp‐toluene sulfonic acid as the catalyst. Esters of phenol, 2,6‐dimethylphenol, and 2,6‐diphenylphenol were synthesized from 3‐butenoic and 10‐undecenoic acid with trifluoroacetic anhydride.
Synthesis of aromatic polyethers by Scholl reaction. I. Poly(1,1′‐dinaphthyl ether phenyl sulfone)s and poly(1,1′‐dinaphthyl ether phenyl ketone)s
Authors: Percec Virgil , Nava Hildeberto
Published: April 2003

A novel synthetic method for the preparation of high molecular weight aromatic polyethers is presented. It consists in the Scholl reaction of di(1‐naphthyl) ethers of aromatic derivatives exhibiting lower nucleophilicity and higher oxidation potential than the 1‐naphthoxy groups. The examples described in this paper refer to the synthesis of aromatic polyether sulfones and aromatic polyether ketones by the polymerization of 4,4′‐di(1‐naphthoxy)diphenyl sulfone and respectively 4,4′‐di(1‐naphthoxy)benzophenone. Both polymerization reactions are performed at room temperature in nitrobenzene, using anhydrous FeCl3 as catalyst, and apparently follow a “reactive intermediate polycondensation” polymerization mechanism.
Liquid crystal polymers. IX. Copolyesters of trans‐4,4′‐stilbenedicarboxylic acid, 1,4‐butanediol, and aromatic dicarboxylic acids
Authors: Jackson W. J. , Morris J. C.
Published: April 2003

Copolyesters of trans‐4,4‐stilbenedicarboxylic acid (SDA), terephthalic acid, and 1,4‐butanediol exhibit thermotropic liquid crystallinity if at least 40 mol % SDA is present (acids total 100 mol %); SDA/2,6‐naphthalenedicarboxylic acid/1,4‐butanediol copolyesters are liquid crystalline if at least 30 mol % SDA is present. The effects of SDA content on the thermal, rheological, plastic, and fiber properties of the copolyesters were determined. The SDA component increases the relaxation times of the polymers and enables injection‐molded plastics and melt‐spun fibers to have significantly increased tensile strength and stiffness.
Participation of water in conformational change of isotactic poly(2‐hydroxyethyl methacrylate) as studied by viscometry in various electrolytic solutions
Authors: Kim Whan Gun , Jhon Mu Shik
Published: April 2003

Conformational properties of isotactic poly(2‐hydroxyethyl methacrylate) (PHEMA) have been studied by viscometry in various electrolytic solutions. The intrinsic viscosity of isotactic PHEMA at 0.01M salt solution increases with decreasing the B coefficient in Jones—Dole's equation. In respective to water structures, a polymer chain is more expanded in the salt solution including water structure breaker ions. As the concentration of ions increases, the interactions between polymer segments and ions make a major contribution to conformational changes of isotactic PHEMA. Depending on the kind of ions, a salting‐in or out effect is observed at higher concentrations than 0.1M salt solution. We observed that the denaturing effects of various anions in isotactic PHEMA salt solutions are as follows; SO42‐ < F− < I− NO3− < SCN‐. This order is similar to the Hofmeister series. To investigate the influences of denaturing agents on solvent structures, we also compared the guanidine hydrochloride effect with the tetrabutylammonium chloride effect in isotactic PHEMA solution.
Synthesis of polyphthalocyanines by an oxidoreduction reaction initiated by the benzhydrol functional group. I. Model study
Authors: Pascal Thierry , Malinge Jean , Sillion Bernard , Claudy Pierre , Letoffe Jean‐Marie
Published: April 2003

A novel route for the thermal conversion of bis(phthalonitrile)monomers into metal‐free phthalocyanine network polymers was investigated on the basis of a model study on the tetramerization reaction of 4‐benzoylphthalonitrile and benzhydrol derivatives into metal‐free phthalocyanine compounds. This procedure of conversion of phthalonitrile derivatives involved an oxidoreduction reaction initiated by the alcohol functional group of benzhydrol coreactant. The influence of molar ratio of phthalonitrile and benzhydrol functional groups, chemical environment of the benzhydrol reducing group has been studied by microcalorimetry and electronic spectroscopy. It was observed that the theoretical 4 : 1 phthalonitrile: benzhydrol molar ratio is respected and the reductive capacity of the benzhydrol group is increased by the electron withdrawing effect of its substituants.
Monte Carlo estimation of kinetic parameters in polymerization reactions
Authors: Duever T. A. , O'Driscoll K. F. , Reilly Park M.
Published: April 2003

A general method for estimating kinetic parameters in polymerization reactions using Monte Carlo simulation to represent the models of the reactions is developed. From a statistical point of view, the procedure is a Bayesian one in which a posterior probability density surface (PPDS) is calculated for points on a grid in the parameter space. A smoothing function is fitted to the PPDS, then a posterior probability region, which is similar to a confidence region, is calculated for the parameters. An application to a relatively trivial example, the Mayo–Lewis copolymerization model is shown in detail. Many other potential applications are suggested.
Syntheses and characterization of poly(benzimidazolyl) thiaxanthones
Authors: Reddy T. Ashok , Srinivasan M.
Published: April 2003

Novel polybenzimidazoles containing thiaxanthone heterocyclic units were synthesised from 2,7‐thiaxanthonedicarboxylic acid‐5,5′‐dioxide and 2,8‐thiaxanthonedicarboxylic acid‐5,5′‐dioxide and two aromatic tetramine hydrochlorides by PPA solution polycondensation in 60–70% yield. Two model compounds, 2,7‐bis(2‐benzimidazolyl)thiaxanthone‐5,5′‐dioxide and 2,8‐bis(2‐benzimidazolyl)thiaxanthone‐5,5′‐dioxide, were prepared and characterized by spectral methods. The polybenzimidazoles have inherent viscosities in the range 1.13–1.50 dL/g and decomposition temperatures of 495–560°C. The effect of thiaxanthone units on polymer properties are discussed.
Polymérisation radicalaire du pentadiène‐1,3. II. Microstructure des résidus pentadiéniques dans les homo‐ et copolymères des cis et trans pentadiènes‐1,3 avec l'acrylonitrile
Authors: Petit A. , Cung M. T. , Neel J.
Published: April 2003

The microstructure of diene units was investigated in radical homopolymers of the cis and trans isomers of 1,3‐pentadiene and copolymers with acrylonitrile, synthetized in bulk and emulsion. Experiments were carried out by infrared spectroscopy, 100 MHz 1H‐NMR, and 25 MHz 13C‐NMR studies. No difference between the bulk and emulsion samples was noted. The microstructure of poly(1,3‐pentadiene) is practically independent of the cis or trans configuration of the diene monomer and is as follows: 56–59% trans‐1,4, 15–17% cis‐1,4, 16–20% trans‐1,2 7–10% cis‐1,2 and 0% 3,4. On the other hand, up to about 30% of incorporated acrylonitrile (10% in the feed), the microstructure of the pentadiene fraction in the copolymers is not affected. This finding suggests that the penultimate unit has very little influence on the polymerization process involving the terminal pentadienly unit. Beyond 10% of acrylonitrile in the feed, the proportions of the structural units were linearly dependent upon the acrylonitrile content: trans‐1,4 content increased whereas the amounts of cis‐1,4 trans‐1,2 and cis‐1,2 decreased (except the cis‐1,2 fraction, constant in the copolymers from the cis‐diene). These results are discussed on the assumption that the microstructure of pentadiene residues is strongly associated with the acrylonitrile comonomer in the feed.
Emulsion polymerization: On the characterization of the particle size distribution
Authors: Chen Show‐An , Wu Kuo‐Wei
Published: April 2003

In emulsion polymerization, the polymer particles generated exhibit a size distribution. Broadness of the distribution is usually characterized by the uniformity (Dp), a ratio of weight to number average particle sizes, and is found to decrease with reaction time despite the fact that the particle volume distribution is usually broadened. Based on the mathematical model proposed by Lichti, Gilbert, and Napper, detailed analysis using the method of moment shows that standard deviation of the particle volume distribution increases with time, while that of the particle diameter distribution decreases with time. Dp's of both volume and diameter distributions all show decreasing with reaction time. These results are in agreement with those found experimentally. The present analysis indicates that, in the characterization of the broadness of the PSD in the emulsion polymerization, one has to be aware of the difference in meanings among these parameters related to the broadness of the PSD.
Bismaleimides chain‐extended by imidized benzophenone tetracarboxylic dianhydride and their polymerization to high temperature matrix resins
Authors: Melissaris Anastasios P. , Mikroyannidis John A.
Published: April 2003

Heat‐resistant polymers were obtained by thermal polymerization of several bismaleimides or their substituted derivatives. The chain of the polymer precursors was extended by incorporation of imidized benzophenone tetracarboxylic dianhydride between the maleimide rings in order to impart a degree of flexibility in the polymers. The bismaleimides and their corresponding tetraamic acids were characterized by infrared (IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy. The differential thermal analysis (DTA) thermograms of the monomers showed exotherms at 200–340°C attributed to the thermally induced polymerization reactions. The influence of different substituents in the maleic double bond on the curing temperature was investigated. The thermal stability of the cured resins was evaluated by thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). They were stable up to 367–433°C both in nitrogen and air atmosphere and afforded 57–68% char yield at 800°C under anaerobic conditions. The structure of the aromatic and aliphatic diamines utilized for imidization was correlated with the thermal stability of the cured resins. The bismaleimide derived from p‐phenylenediamine gave the most heat‐resistant resin because of its higher rigidity.