bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and properties of liquid crystalline polyurethanes
Authors: Penczek Piotr , Frisch Kurt C. , Szczepaniak Barbara , Rudnik Ewa 
Published: April 2003

AbstractLiquid crystalline polyurethanes were prepared from 4,4′‐bis(2‐hydroxyethoxy)biphenyl (BHBP) and 2,4‐tolylene diisocyanate (TDI). The effect of partial replacement of BHBP by 25–75 mol % poly(oxytetramethylene) diol (PTMO, Mn = 250) on the liquid crystalline properties was studied. The BHBP/TDI/PTMO polyurethanes were obtained by one‐ and two‐step polyaddition. The polyurethanes were investigated by DSC, polarizing microscopy, x‐ray, and IR spectroscopy. The molecular weight distribution was determined by GPC. The morphology of the polymers was investigated by the SALS method. Thermogravimetric investigations of the polyurethanes were also performed. All polyurethanes containing BHBP units have liquid crystalline properties. Partial replacement of BHBP by PTMO‐250 considerably changes the phase transition temperatures and the range of mesophase occurrence. More homogeneous polyurethanes were obtained, if the two‐step polyaddition method was applied. The polyaddition method affects the phase transition temperatures. © 1993 John Wiley & Sons, Inc.
Enzymatic polyesterification in organic media. Enzyme‐catalyzed synthesis of linear polyesters. I. Condensation polymerization of linear hydroxyesters. II. Ring‐opening polymerization of ϵ‐caprolactone
Authors: Knani Dafna , Gutman Arie L. , Kohn David H. 
Published: April 2003

AbstractWith the object to synthesize polyesters by enzymatic catalysis in organic media, two directions have been investigated: (1) the condensation polymerization of linear ω‐hydroxyesters and (2) the ring‐opening polymerization of lactones. The commercially‐available crude porcine pancreatic lipase (PPL), suspended in organic solvents, was the preferred enzyme for the reactions. In order to determine the optimal conditions for the condensation polymerization, the bifunctional methyl 6‐hydroxyhexanoate was used as a model compound to study the influence of the following parameters: type of the enzymecatalyst, kind of solvent, concentration, temperature, duration, size of the reaction mixture, and stirring. Film‐forming polyesters with a degree of polymerization (DP) up to about 100 were obtained from linear aliphatic hydroxyesters in n‐hexane at reflux temperature (69°C). Yet concurrently with the intermolecular condensation polymerization, macrolactones were also formed by intramolecular reaction. Two aromatic hydroxyesters did not react under these conditions. For the ring‐opening polymerization of lactones the reaction of ϵ‐caprolactone with methanol as the preferred nucleophile, was studied. Polyesters with a DP of up to 35 were obtained in n‐hexane at temperatures between 25 and 40°C. The degrees of polymerization of the polyesters were determined by comparative analyses of the end groups in the 1H‐NMR spectra and by determination of molecular weights either by vapor phase osmometry, gel permeation chromatography, or intrinsic viscosity. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of poly(2,6‐diarylphenylene oxide)s
Authors: Yang Hu , Hay Allan S. 
Published: April 2003

AbstractThe oxidative polymerization of 2,6‐diphenylphenol that contains substituents (fluoro, chloro, bromo, iodo, cyano, t‐butyl, phenoxy, methoxy, phthalimidyl) in the para‐positions of the pendant phenyl groups is described. The melting points of the monomers, with some exceptions, correlate with the glass transition temperatures and the melting points of the corresponding polymers. Random copolymers of some of these phenols with 2,6‐diphenylphenol have also been prepared and characterized. © 1993 John Wiley & Sons, Inc.
Direct polyesterification by use of phosphorus oxychloride and LiCl in pyridine
Authors: Higashi Fukuji , Kobayashi Akira , Shimazaki Hisashi 
Published: April 2003

AbstractThe reaction of the N‐phosphonium salt of pyridine derived from phosphorus oxychloride in pyridine was successfully used for the preparation of aromatic polyesters with high molecular weight when carried out in the presence of lithium chloride. In the copolycondensations of isophthalic and terephthalic acid with diphenols, the mode of reaction with the diacids was expected to produce several types of the diacid activated intermediates, which might control the sequences of the diacids in the copolymers. The possible variation of the sequences was studied in terms of the mode and copolymer properties such as glass transition temperatures and liquid crystalline transition temperatures. Competitive model reactions were carried out to discuss these relationships. © 1993 John Wiley & Sons, Inc.
Oxidation of polyethylene surface by glow discharge and subsequent graft copolymerization of acrylic acid
Authors: Wang Chee‐Chan , Hsiue Ging‐Ho 
Published: April 2003

AbstractPlasma‐induced graft copolymerization of acrylic acid, which was incorporated into PE films, was investigated here. The influence of plasma conditions such as plasma treatment gases, power, pressure, time, monomer concentration, and graft copolymerization time on polymerization yield was determined. The samples were characterized by ESCA, IR, and water contact angle. A respective chemical shift of the C1s signal of Ar or O2 plasmatreated and untreated PE films was revealed by ESCA, in which the presence of the grafted PAAc was also verified. An increase in polymerization yield with plasma treatment duration and power was found. That the grafted copolymerization was limited to a very thin surface region was revealed by optical microscopy on the cross section of the grafted film. © 1993 John Wiley & Sons, Inc.
The mechanism of butadiene polymerization with the catalytic system NdCl3 · 3TBP(1C4H9)2AIH
Authors: Sabirov Z. M. , Minchenkova N. Kh. , Urazbaev V. N. , Monakov Yu. B. 
Published: April 2003

AbstractThe polymerization of butadiene with the catalytic system NdCl3 · 3TBP‐(1C4H9)2AlH (TBP‐tributyl phosphate) was studied. With regard to the anti‐syn‐isomerization of both free‐ and monomer‐complexed active centers, the kinetic scheme of the propagation reaction was shown to afford adequate descriptions of the experimental dependence of the polymer microstructure on the monomer concentration. Following the results of the quantum‐chemical calculations, it was assumed that the free molecules (1C4H9)2AlH coordinated competitively with the monomer molecules on the active centers in solution, which finally led to lower reactivity of the active centers. © 1993 John Wiley & Sons, Inc.
Synthesis of fusible and soluble conducting polyfluorene derivatives and their characteristics
Authors: Fukuda Masahiko , Sawada Keiji , Yoshino Katsumi 
Published: April 2003

AbstractConducting polyfluorene derivatives with alkyl chains—poly(9‐alkylfluorene)s and poly‐(9,9‐dialkylfluorene)s—have been synthesized by chemical polymerization utilizing FeCl3 as an oxidizing agent. The polymers obtained are found to be soluble in conventional organic solvents such as chloroform and have been characterized by 1H‐ and 13C‐NMR. The results indicate that the fluorene moeities are mainly linked in the 2,7′‐fashion to yield the straight chain polymer. The degree of polymerization is estimated (by gel permeation chromatography) to be of the order of 10. The polymers are found to be fusible and the thermal properties of the polymers have been characterized by differential scanning calorimetry. The glass transition temperature is found to decrease with an increase of the alkyl chain length. © 1993 John Wiley & Sons, Inc.
Star‐shaped polymers by living cationic polymerization. VII. Amphiphilic graft polymers of vinyl ethers with hydroxyl groups: Synthesis and host–guest interaction
Authors: Kanaoka Shokyoku , Sueoka Masanori , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractAmphiphilic graft polymers of vinyl ethers (VEs) (6) where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(alkyl vinyl ether) segment were prepared on the basis of living cationic polymerization, and their properties and functions were compared with the corresponding amphiphilic star‐shaped polymers. In toluene at −15°C, the HI/ZnI2‐initiated living block polymer 2 of an ester‐containing VE (CH2CHOCH2CH2OCOCH3) and isobutyl VE (IBVE) was terminated with the diethyl 2‐(vinyloxy)ethylmalonate anion [3; ΦC(COOEt)2CH2CH2OCH  CH2] (2/3 = 1/2 mole ratio) to give a macromonomer (4), H[CH2CH(OCH2CH2OCOCH3)] m‐[CH2CH(OiBu)]nC(COOEt)2CH2CH2OCH  CH2 (m = 5, n = 15; M̄n = 2600, M̄w/M̄n = 1.13, 1.10 vinyl groups/chain). Subsequently, 4 was homopolymerized with HI/ZnI2 in toluene at −15°C. In 3 h, 85% of 4 was consumed and a graft polymer (5) was obtained [M̄w = 15000, DPn (for 4) = 6]. The apparent M̄w (10,900) of 5 by size‐exclusion chromatography (SEC) is smaller than that by light scattering as well as that (18,300) by SEC of the corresponding linear polymer with the almost same molecular weight, indicating the formation of a multi‐branched structure. Hydrolysis of the pendant esters in 5 gave the amphiphilic graft polymer 6 where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(IBVE) segment. The graft polymer 6 was found to interact specifically with small organic molecules (guests) with polar functional groups, and 6 differed in solubility and host‐guest interaction from the corresponding star‐shaped polymer. © 1993 John Wiley & Sons, Inc.
Polyelectrolyte titration using fluorescent indicator. I. Direct titration of anionic and cationic polyelectrolytes with 10−4N standard solutions
Authors: Tanaka Hiroo , Sakamoto Yumi 
Published: April 2003

AbstractThe polyelectrolyte titration, which was originally called colloid titration, is based on the stoichiometric reaction between positively charged colloidal particles and negatively charged ones. In the conventional method, the metachromatic color change of the indicator, toluidine blue, from blue to red‐purple has been applied for the determination of the end point in the titration. 2.5 × 10−3N potassium polyvinylsulfonate (KPVS) is usually used as the standard titrant. In this work, fluorescent indicators such as 6‐(p‐toluidino)‐2‐naphthalene sulfonate (TNS), acridine orange, etc., have been introduced. The fluorescence intensity was measured using the spectrophotometer equipped with magnetic stirrer and connected with a vinyl tube attached to the hand piston burette. For example, TNS is practically nonfluorescent, but it exhibits strong fluorescence when it is bound to a cationic polyelectrolyte (CP). The fluorescence of the TNS–CP complex is diminished by titration with KPVS standard solution since TNS is liberated from the complex by substitution with KPVS. After the equivalent point, the fluorescence intensity becomes constant and the end point can thus be detected by that point. It has been elucidated that the very dilute standard solution like 1 × 10−4N can be used because the sensitivity of fluorescence detection is extremely high. © 1993 John Wiley & Sons, Inc.
Polyelectrolyte titration using fluorescent indicator. II. Analysis of cationic starches and flocculants
Authors: Tanaka Hiroo , Sakamoto Yumi 
Published: April 2003

AbstractIn the conventional polyelectrolyte titration, toluidine blue (TB) has been used exclusively as an indicator. This is a very convenient method for analyses of polyelectrolytes with fairly high charge density, but it is very difficult, or impossible, to analyze samples with low charge density such as commercial cationic starches because of the unclear color change of TB at the end point. Also analyses of polyelectrolytes with ultrahigh molecular weights over 107 (such as common flocculants) are often accompanied by serious errors. Usually, the concentration of standard titrant is around 0.2 × 10−3 N. On the other hand, the standard titrant with very dilute concentration such as 1 × 10−4 N can be used in the polyelectrolyte titration using a fluorescent indicator because the sensitivity of fluorescence detection is extremely high. It has been elucidated that this method can be employed for accurate analyses of cationic starches, cationic and anionic flocculants, and also for determination of sulfonic and carboxyl groups contained in the same molecule by the titration at pH 2.8 and 9.5, respectively. © 1993 John Wiley & Sons, Inc.
Confirmation of the presence of imine bonds in thermally cured polyimides
Authors: Saini Ajay K. , Carlin Clifford M. , Patterson Howard H. 
Published: April 2003

AbstractModel compounds for imines formed during the thermal curing of short chain polyimides have been synthesized and characterized. These compounds have imine bonds (CN) formed by the nucleophilic attack of primary amines on imide carbonyls. The CN stretching mode appears at 1649–1664 cm−1 in the Raman and infrared spectra of these compounds and the band assigned to the carbonyl mode in an imide ring with an imine bond appears near 1740 cm−1. These compounds have been prepared and characterized to verify the conclusions of a previously reported study in which bands observed in thermally cured short chain polyimides at 1656 and 1742 cm−1 were assigned as the CN and associated CO modes, respectively. It has also been confirmed that the CN stretching mode in the imide model compounds is inherently IR weak and can only be seen if the concentration of imine species is high. © 1993 John Wiley & Sons, Inc.
Functionalization of polypropylene by hydroboration
Authors: Chung T. C. , Rhubright D. 
Published: April 2003

AbstractThis article relates to functionalized polypropylene with high molecular weight and high crystallinity. The chemistry involves the hydroboration of poly(propylene‐co‐1,4‐hexadiene) with borane reagents, such as diborane and 9‐BBN. In turn, the borane‐containing polymers are very versatile and can be easily converted to various functionalized polymers under mild reaction conditions. Despite the heterogeneous reaction conditions, both hydroboration and interconversion reactions were very effective using appropriate solvents. Apparently, the double bonds in the side chains are located in the amorphous phase and are ready for reaction with reagents. Overall, this functionalization process preserves the molecular weight and most of the crystallinity of poly(propylene‐co‐1,4‐hexadiene). © 1993 John Wiley & Sons, Inc.
Studies on bulk polymerization of methyl methacrylate. I. Thermal polymerization
Authors: Clouet G. , Chaumont P. , Corpart P. 
Published: April 2003

AbstractThe thermal bulk polymerization of methyl methacrylate (MMA) in a wide range of temperatures has been studied using a dilatometric reactor. It is shown that, irrespective of the care taken to purify the MMA, the evolution of the time‐conversion curve can be explained only if we account for the presence of an impurity associated with the monomer acting as a free radical initiator. The activation energy for the decomposition of this impurity has been estimated as 98 kJ/mol. Having accounted for this impurity, the activation energy for the real thermal polymerization of the MMA has been estimated to be 75 kJ/mol. © 1993 John Wiley & Sons, Inc.
Ring dehydration mechanisms and kinetics of polyamic acid models in solution and in the solid state
Authors: Grenier‐Loustalot Marie‐Florence , Gillard Marguerite , Joubert Frédréric , Grenier Philippe 
Published: April 2003

AbstractWe have synthesized and studied the ring dehydration mechanisms and kinetics of polyamic acid models in solution and in the solid state using13C‐NMR (solid and liquid), HPLC, FTIR, and x‐ray diffraction. Results obtained in solution show the role of temperature, catalysts, and the basicity of the amine in ring dehydration mechanisms and kinetics, as well as conformation and intramolecular bonds in the amic acid bond in the solid state. © 1993 John Wiley & Sons, Inc.
Polymer‐supported lewis acid catalysts. VII. Polystyrene‐bonded Ti(IV) chloride catalysts
Authors: Ran Ruicheng , Fu Diankui , Shen Ji , Wang Qingyang 
Published: April 2003

AbstractA polystyrene‐bonded Ti(IV) chloride catalyst was synthesized by the reaction of a polystyryl lithium (catalystI, PS—TiCl2) or a polystyryl magnesium (catalystII, PS‐TiCl3) combined with titanium tetrachloride. The catalyst produced is a polymeric organometallic compound containing 0.479 mmol Ti/g catalyst, 0.986 mmol Cl/g catalyst (catalystI) and 0.281 mmol Ti/g catalyst, 0.766 mmol Cl/g catalyst (catalystII), depending on the method of synthesis. Both catalysts showed very good stability and good catalytic activity in such organic reactions as esterification, acetalation, and ketal formation. They can be reused many times without losing its catalytic activity. © 1993 John Wiley & Sons, Inc.
Functionalization and crosslinking reactions of ethyl‐α‐hydroxymethylacrylate
Authors: Avci Duygu , Küsefoğlu Selim H. 
Published: April 2003

AbstractEthyl‐α‐hydroxymethylacrylate (EHMA) was esterified with hexanoyl chloride in 80% yield. The homopolymer of the hexanoate ester was found to be a glassy thermoplastic and soluble polymer. Copolymerization of the hexanoate ester with EHMA in varying ratios gave polymers that were thermoplastic and more soluble as a result of internal lubrication of the long alkyl pendant groups. Copolymers with styrene were synthesized with relatively high conversion. Reaction of EHMA with adipoyl chloride gave a bis‐ester which served as crosslinking agent when copolymerized with different monomers including EHMA itself. In a separate synthesis EHMA was reacted with toluenediisocyanate (TDI). In the absence of catalyst a monourethane was formed. This monomer still contains one isocyanate function and is capable of further reactions subsequent to double bond addition polymerization. This reaction was also carried out on poly‐EHMA, with or without catalyst. The products were the mono and the crosslinked bisurethanes as expected. Thus, acyl chlorides and isocyanates were found to be excellent reagents for derivatization of EHMA. © 1993 John Wiley & Sons, Inc.
Microstructural analysis of methacrylonitrile‐styrene copolymers to obtain reactivity ratios
Authors: Hill David J. T. , Dong Limin , O'Donnell James H. 
Published: April 2003

AbstractThe copolymerization of methacrylonitrile (M) and Styrene (S) at 60°C in bulk has been studied at low conversion by the use of 1H‐ and 13C‐NMR to examine the copolymer microstructure for copolymer composition and sequence distribution. The penultimate model was found to provide the best description of the polymerization with rMM = 0.220, rSM = 0.519, rSS = 0.241, rMS = 0.570. These results have been compared with those found for the corresponding acrylonitrile‐styrene copolymerization. © 1993 John Wiley & Sons, Inc.
Polymeric aluminoxanes: A possible cocatalytic support material for Ziegler–Natta‐type metallocene catalysts
Authors: Janiak Christoph , Rieger Bernhard , Voelkel Rüdiger , Braun Hans‐Georg 
Published: April 2003

AbstractThe reaction of methylaluminoxane (MAO) with 1,6‐hexanediol or 1,10‐decanediol leads to white powdery materials which were studied by 13C and 27Al MAS NMR, scanning electron microscopy (SEM), and whose surface area and porosity was determined according to the BET method. The hydrolysis of trimethylaluminum with hydrogel was carried out and the product was investigated by SEM. © 1993 John Wiley & Sons, Inc.
Polymerization of mono‐substituted acetylenes with a liquid crystalline moiety by Ziegler–Natta and metathesis catalysts
Authors: Oh Se‐Young , Ezaki Ryuichi , Akagi Kazuo , Shirakawa Hideki 
Published: April 2003

AbstractPolymerization of five monomers, 1‐[p‐(trans‐4′‐alkylcyclohexyl)phenoxy]alkyne (i.e., PCH001A, where PCH, 0, 01 and A represent phenylcyclohexyl mesogenic moiety, number of carbon in an alkyl group attached to cyclohexyl group, ether linkage + number of methylenic units in the spacer between phenoxy and acetylenic groups, and terminal acetylene, respectively) were carried out using Ziegler‐Natta and metathesis catalysts. All polymers were soluble in organic solvents such as benzene, chloroform, and THF. A liquid crystalline phase was observed in the polymers of PCH303A and PCH503A through the polarized optical microscope and DSC measurements. Polymerization of PCH003A by the Fe(acac)3‐AlEt3 catalyst yielded a high‐molecular‐weight polymer with Mw = ca. 3 × 106. © 1993 John Wiley & Sons, Inc.
Polymeric phosphonium salts as a novel class of cationic biocides. V. Synthesis and antibacterial activity of polyesters releasing phosphonium biocides
Authors: Kanazawa Akihiko , Ikeda Tomiki , Endo Takeshi 
Published: April 2003

AbstractPolyesters were prepared which retained phosphonium biocides as counter ions of sodium sulfonate moieties incorporated into the polymers, and surface antibacterial activity of the polyester films against Staphylococcus aureus and Escherichia coli was explored. These films exhibited a high surface antibacterial activity against S. aureus and E. coli, particularly against S. aureus, and the activity was affected by the structure and the compositional ratio of the phosphonium salts. Amount of the released phosphonium salts was very small, so that liberation of the phosphonium biocides can be expected to occur over a long period. Morphological changes of the cells of S. aureus and E. coli in contact with the polyester films were evaluated by scanning electron microscopy. It was found that the surface antibacterial activity of the polyester films was rather bacteriostatic than bactericidal as evidenced by no morphological changes of the bacterial cells in contact with the phosphonium biocides © 1993 John Wiley & Sons, Inc.
Revisiting the design of experiments for copolymer reactivity ratio estimation
Authors: Burke A. L. , Duever T. A. , Penlidis A. 
Published: April 2003

AbstractTidwell and Mortimer used the D‐optimal criterion to design terminal model reactivity ratio estimation experiments. In this paper, two problems are investigated which were not addressed by Tidwell and Mortimer. The first problem is the design of reactivity ratio estimation experiments subject to composition constraints. It is shown that all the key information contained in the D‐optimal criterion can be summarized in two equations: one which is a function of r̂1, and one which in a function of r̂2. These two equations can be used to design reactivity ratio estimation experiments under composition constraints which are within 3 mol % of the D‐optimal feed compositions. The second problem is the design of penultimate reactivity ratio estimation experiments. The D‐optimal criterion for the penultimate model was derived and optimized for two existing systems as well as a large number of hypothetical systems. The D‐optimal criterion for the penultimate model was found to be much more complicated than the terminal model criterion. For this reason, the optimal penultimate reactivity ratio estimation experiments can not be approximated by simple equations. Anyone interested in designing such experiments must derive and optimize the D‐optimal criterion. © 1993 John Wiley & Sons, Inc.
Organized‐polymerization in micelle formed by diblock macromonomers
Authors: Ishizu Koji , Yukimasa Shinichi , Saito Reiko 
Published: April 2003

AbstractVinylbenzyl‐terminated poly[styrene(S)‐b‐isoprene(I)] AB type diblock macromonomers were prepared by the direct coupling of corresponding living diblock anions with a large excess of p‐chloromethylstyrene (CMS). The end group functionality of these diblock macromonomers was close to unity. Diblock macromonomers showed a narrow polydispersity (M̄w/M̄n = 1.04–1.09). Free radical polymerizations were carried out in micelle formed by diblock macromonomers. We also studied the formation of (AB)n type star block copolymers by means of micro‐gelation between diblock macromonomer and ethylene glycol dimethacrylate as a linking agent. © 1993 John Wiley & Sons, Inc.