bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel cationically polymerizable propenyl and vinyl ethers derived from renewable sources
Authors: Crivello J. V. , Bratslavsky S. A. 
Published: April 2003

AbstractThe preparation of several novel mono‐ and dipropenyl and divinyl ethers derived from renewable starting materials is described using simple, straightforward synthetic methods. Utilizing real‐time infrared spectroscopy, the reactivity of the monomers in photoinitiated cationic polymerization was studied employing diaryliodonium and triarylsulfonium salts as photoinitiators. The monomers were shown to undergo very rapid cationic photopolymerization. © 1994 John Wiley & Sons, Inc.
A facile synthesis of aliphatic polybenzoxazoles from a bis(o‐aminophenol) or its hydrochloride and aliphatic dinitriles
Authors: Itoya Kazuo , Sawada Hidetsugu , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractA facile one‐step method for the synthesis of aliphatic polybenzoxazoles has been developed. Thus, a series of aliphatic polybenzoxazoles having inherent viscosities of 0.2–0.7 dL/g in concentrated sulfuric acid were successfully synthesized by the melt polycondensation of alipatic dinitriles with 4,4′‐diamino‐3,3′‐dihydroxybiphenyl (AHB) or its hydrochloride (AHB–HCl) with the elimination of ammonia or ammonium chloride, respectively. Monomer AHB–HCl was more reactive than the parent AHB, thereby affording higher molecular weight polybenzoxazoles in a shorter reaction time. The aliphatic polybenzoxazoles having 6–10 methylene units were highly crystalline with melting temperatures in the range of 187–308°C, which were stable up to 400°C in a melt state in nitrogen. © 1994 John Wiley & Sons, Inc.
Initiation of cationic polymerization of n‐butyl vinyl ether by stable cation radicals of substituted phenothiazines
Authors: Morishima Yotaro , Nomura Shigeki , Kamachi Mikiharu 
Published: April 2003

Abstract3,7‐Diethyl‐ 10‐phenylphenothiazine (DEPPT), a phenothiazine derivative whose 3,7‐ and 10‐positions are blocked, was synthesized. Potentiostatic electrolysis of DEPPT in acetonitrile (ACN) in the presence of 0.1M of LiClO4 at 0.7 V (vs. Ag/Ag/Cl) yielded the stable cation radical of DEPPT (DEPPT+·) which was characterized by cyclic voltammetry, UV‐visible spectroscopy, and ESR spectrometry. Stable cation radicals of 10‐phenylphenothiazine and 3,7‐diethyl‐10‐methylphenothiazine were also prepared. The cationic polymerization of n‐butyl vinyl ether was initiated by these cation radicals, including DEPPT·+. The electron transfer mechanism for the initiation step, which we proposed previously, was supported by the fact that DEPPT·+ was capable of initiating the polymerization; dimerization of DEPPT·+ by releasing protons is precluded because 3,7‐ and 10‐positions are all blocked. © 1994 John Wiley & Sons, Inc.
Amphiphilic networks. VII. Synthesis and characterization of pH‐sensitive poly(sulfoethyl methacrylate)‐1‐polyisobutylene networks
Authors: Keszler Balazs , Kennedy Joseph P. 
Published: April 2003

AbstractA series of environmentally sensitive amphiphilic networks consisting of 2‐sulfoethyl methacrylate (SEMA) chains linked by methacrylate‐ditelechelic polyisobutylene (MA–PIB–MA) chains have been prepared and characterized. Network composition was determined after sequential solvent extraction by elemental analysis. These networks are two‐phase microheterogeneous systems containing hydrophobic rubbery PIB domains (Tg ∼ −60°C) and hydrophilic poly(2‐sulfoethyl methacrylate) domains (Tg ∼ −15°C). They exhibit large contact‐angle hysteresis in water which is due to surface segmental mobility and microheterogeneity. By increasing the SEMA content of the networks the contact‐angle hysteresis increases. This phenomenon is due to an increase in the advancing contact angle most likely caused by the migration of the nonpolar PIB domains toward the surface and concomitant decrease of the receding contact angle. These amphiphilic networks exhibit non‐Fickian swelling in n‐heptane, as well as in water, and show pH‐sensitive swelling in aqueous media. They rapidly and reversibly swell and deswell in response to increasing or decreasing the pH of the media (cycling between pH = 2 and 12). © 1994 John Wiley & Sons, Inc.
The structures of low molecular weight glycerin propoxylates: An experimental, semi‐empirical, and Monte Carlo study
Authors: Cooper Charles F. , Polley Charles W. 
Published: April 2003

AbstractA simple Monte Carlo model has been developed for calculating the structural features and properties of low molecular weight triols produced by the base‐catalyzed propoxylation of glycerin. The model computes the probability of a reaction to a specific oligomer from the local site reactivities of model compounds with an adjustment for the molecular weight of the reacting oligomer. The resulting product array is then used to calculate typical polymer properties such as average molecular weight, polydispersity, and average chain length. Trial rate constants were estimated from the activation energies of MNDO‐PM3 semi‐empirical molecular orbital theory. For the compounds used to model the oligomer chain end groups, the activation enthalpies were found to be within the ranges reported for experimental values. Although the predicted enthalpies of activation were significantly higher for the alkoxylation directly at glycerin, this was found to be attributable to intramolecular hydrogen bonding in the reactants that was disrupted in the transition states. Although the hydrogen bonding energies were higher than what are normally considered typical, comparison tests showed that the calculated energies agreed well with experimental values of alkoxide anion–alcohol systems. The PM3 rate constants, when used to calculate Monte Carlo probabilities, predicted the isomer distribution of the four isomeric monopropoxylates with a error of 4%. Optimization of the model reduced this to 0.5%. However, to accurately predict the oligomer distribution of higher molecular weight adducts and other properties, the correction term (M0/Mi)b had to be included, where M0/Mi is the ratio of the molecular weight of glycerin to the molecular weight of the oligomer undergoing alkoxylation, and b is assigned the value 0.7. Although b is empirical, it is consistent with a simple molecular mechanics (MM2) conformational study of the relative availability of the reactive end groups. When the final model was used to simulate the propoxylation of glycerin for a variety of PO/glycerin ratios, it was found to accurately reproduce properties such as primary hydroxyl content, polydispersity, oligomer distribution, and change in the monopropoxylate isomer ratio as a function of bulk PO/glycerin ratio. © 1995 John Wiley & Sons, Inc.
Molecular structure of polymerization product containing phenyl‐ and diphenylsiloxy units
Authors: Hayashida Shoichi , Imamura Saburo 
Published: April 2003

AbstractThe molecular structure of the hydrolyzate, and of the prepolymers and polymerization products of phenyltrichlorosilane and diphenyldichlorosilane are investigated.29Si‐NMR measurements reveal the kinds of component units and their ratio in each synthesis step. The molecular structure of the prepolymer chain end and the polymerization product are also discussed in relation to the change in the NMR spectra. © 1995 John Wiley & Sons, Inc.
Chemical reactions between immiscible polymers in the melt: Transesterification of poly(ethylene‐co‐methyl acrylate) with mono‐hydroxylated polystyrenes
Authors: Hu Guo‐Hua , Lambla Morand 
Published: April 2003

AbstractThis article presents a unique example dealing with how chemical reactions between immiscible polymers in the melt behave differently than they would do in solution. Specifically, a model reaction was chosen: the transesterification between poly(ethylene‐co‐methyl acrylate) (EMA) and polystyrene mono‐hydroxylated at the chain end (PSOH). It was carried out in the melt in a batch mixer. The overall rate of this reaction has a similar dependence of temperature, composition of reactants, and the nature and concentration of catalyst as in solution. The reactivity of PSOH decreases drastically with increasing molecular weight, and it becomes very weak when the molecular weight exceeds 8000 g/mol. As opposed to a reaction in solution or in a homogeneous melt, mechanical mixing increases the reaction rate since it generates interfacial area and reduces the diffusion length. The EMA‐g‐PS graft copolymer formed at the interfaces reduces the interfacial tension, and increases the miscibility of the reaction mixture. However, its occupation of the interfaces reduces contact between the reactive moieties, thus decreasing the overall reactivity. More importantly and much to our surprise, adding 1 to 2 wt % of an inert solvent increased greatly the overall reaction rate. While an increased interfacial mixing and diffusion by the presence of minor amounts of solvent are thought to be the major factors contributing to the drastic increase in reactivity, numerous questions still remain. Nevertheless, this study clearly showed that as opposed to a reaction in solution, mechanical mixing and the presence of minor amounts of solvent are two additional and critical means to control chemical reactions between immiscible polymer melts. © 1995 John Wiley & Sons, Inc.
Photochemistry of amphiphilic copolymers: Fluorescence spectra of copolymers of 1‐(2‐naphthyl)ethyl methacrylate and sodium 2‐acrylamido‐2‐methylpropanesulfonate in solution
Authors: Itoh Yoshihiro , Yamashita Osamu , Hachimori Akira , Kojima Masanobu , Suzuki Satoshi 
Published: April 2003

AbstractAmphiphilic copolymers containing 1‐(2‐naphthyl)ethyl ester groups were prepared and their fluorescence properties were examined. The fluorescnce spectra of the copolymers with a higher naphthyl content showed predominantly a broad monomer emission with λmax at 340 nm in methanol, whereas a structured emission with λmax at 344 and 362 nm was observed in aqueous solution. The former spectra changed rapidly to the latter ones upon UV irradiation. Photolysis of the copolymers and the monomeric model compound in methanol gave 2‐vinylnaphthalene, whose fluorescence agreed with those of copolymers in water, together with methyl ether, alkylnaphthalenes, and other products. These results indicate that the copolymers hold vinylnaphthalene‐like traps, which may emit preferentially in water because of efficient sensitization. © 1995 John Wiley & Sons, Inc.
Microgel formation in the free radical crosslinking polymerization of ethylene glycol dimethacrylate (EGDMA). II. Simulation
Authors: Chiu Y. Y. , Lee L. James 
Published: April 2003

AbstractThe simulation of free radical crosslinking polymerizations of multifunctional monomer by a percolation model was performed on a two‐dimensional lattice with periodical boundaries. The model was formulated in such a way that a variety of monomers, translational diffusion of monomer and polymer molecules, segmental diffusion of polymer, shielding effects, microgel formation, and unequal reactivities of vinylene bonds can be considered. Simulation results of the 2‐D model agreed well with those of a 3‐D model. The percolation model was able to qualitatively verify several experimental results. © 1995 John Wiley & Sons, Inc.
Dispersion copolymerization of styrene and divinylbenzene: Synthesis of monodisperse, uniformly crosslinked particles
Authors: Thomson B. , Rudin A. , Lajoie G. 
Published: April 2003

AbstractMonodisperse, crosslinked polystyrene latexes were prepared by the dispersion technique. Some general observations regarding the effect of initial reagent concentrations on final particle size and size distribution are offered, in addition to a detailed discussion concerning the problems encountered with the use of the crosslinker divinylbenzene (DVB) in latex preparation. Particles synthesized in very polar media were found to reach their growth plateau sooner than those made in less polar surroundings. This trend was proposed to be the result of more effective nucleation in polar environments, which increases available surface area, thereby allowing the rapid replacement of monomer consumed within the particle phase during the polymerization. Attempts to favorably influence the growth rate and size distribution of particles during the reaction were unsuccessful, underlining the importance of the nucleation period in defining particle size characteristics. Up to 1% DVB was successfully incorporated in the synthesis of coagulum‐free, monodisperse, 5 μm beads, by controlling the entry of the crosslinker into the particle phase during the major particle growth period. Latex stability is proposed to be largely dependent on the mobility of the adsorbed steric stabilizer. © 1995 John Wiley & Sons, Inc.
LC‐Polyimides. XIX. Chiral and thermotropic poly(esterimide)s based on N‐(4′‐caboxyphenyl)trimellitimide and novel chiral spacers
Authors: Kricheldorf Hans R. , Berghahn Matthias 
Published: April 2003

AbstractStarting from commercial S‐ or R‐3‐bromo‐2‐methylpropanol, several new spacer diols were prepared. These spacers were polycondensed with the acid chloride of N‐(4′‐carboxyphenyl)trimellitimide. The resulting poly(ester‐imide)s were characterized by elemental analyses, viscosity measurements, 1H‐NMR spectroscopy, DSC‐ and WAXD‐measurements and optical microscopy. The poly(ester‐imide)s derived from chiral, aliphatic spacers form layer structures in the solid state, but no liquid crystalline phase. With nonsymmetrical, nonchiral semialiphatic spacers, poly(ester‐imide)s were obtained, which form a smectic E or H phase in the solid state, a smectic‐A or ‐C phase in the melt, and a nematic phase, when the spacer possesses an odd number of CH2 groups. The polycondensation of a chiral semialiphatic spacer yielded thermotropic poly(ester‐imide)s with either S‐ or R‐configuration. WAXD patterns measured with synchrotron radiation at various temperatures proved that a layer structure exists in the solid state (smectic‐E* or H*) and a chiral smectic‐A* or ‐C* phase plus a cholesteric phase in the melt. A 1 : 1 blend of the S‐ and R‐polyesters was also studied, but did not show unusual features. © 1995 John Wiley & Sons, Inc.
Solid‐state polymerization of diacetylene: 1,11,13,23‐tetracosatetrayne
Authors: Nezu S. , Lando J. B. 
Published: April 2003

AbstractThe solid‐state polymerization of a diacetylene, 1,11,13,23‐tetracosatetrayne, was studied using x‐ray powder diffraction and electron diffraction. It is shown that the material exhibits polymorphism. Thermochromic transitions, which are generally observed for diacetylenes, are related to the particular crystalline phase using x‐ray powder diffraction. The unit cell dimensions and space group of one polymorph were determined by electron diffraction analysis: a = 20.83 Å, b = 4.84 Å, c = 10.08 Å, β = 92.4°, space group: P21/n. © 1995 John Wiley & Sons, Inc.
Synthesis and radical polymerization of α‐ethyl β‐hexafluoroisopropyl itaconate
Authors: Sato Tsuneyuki , Hirose Yuichiro , Seno Makiko , Tanaka Hitoshi 
Published: April 2003

AbstractThe synthesis of α‐ethyl β‐hexafluoroisopropyl itaconate (EFiPI) was performed. The polymerization of EFiPI initiated with dimethyl 2,2′‐azobisisobutyrate (MAIB) was investigated kinetically in benzene. The polymerization rate (Rp) was expressed by Rp = k[MAIB]0.5[EFiPI]2.0 at 50°C. The overall activation energy of the polymerization was calculated to be a low value of 57.38 kJ/mol. Rate constants of propagation (kp) and termination (kt) were estimated under different polymerization conditions, using the ESR‐determined concentrations of the propagating polymer radical. The increase in kp value (3.3‐6.0 L/mol s) and the decrease in kt value (0.94‐3.7 × 105 L/mol s) with monomer concentration are mainly responsible for the high dependence of Rp on the monomer concentration. Activation energies of initiation (Ei), propagation (Ep), and termination (Et) were also determined: Ei = 130.7 kJ/mol, Ep = 18.0 kJ/mol, Et = 57.4 kJ/mol. The large apparent activation energy of termination is a main origin of low overall activation energy of the polymerization. Thermal behavior of the resulting poly(EFiPI) was investigated by differential scanning calorimetry (DSC) and dynamic thermogravimetry (TG). Copolymerization of EFiPI (M1) with St (M2) was also examined at 50°C in benzene. The following copolymerization parameters were obtained according to the curve‐fitting method: r1 = 0.05, r2 = 0.46, Q = 0.46, e = +1.14. Using these results, the rate constants of cross propagations in the copolymerization were estimated. © 1995 John Wiley & Sons, Inc.
Preparation and properties of novel soluble poly(aryl ether)s bearing covalently bound tetrapyrazinoporphyrazine units
Authors: Yang Haixin , Sargent Jonathan R. , Hay Allan S. 
Published: April 2003

AbstractThermooxidatively stable amorphous poly(dicyanopyrazine ether)s with high glass transition temperatures are synthesized and converted into poly(aryl ether)s bearing covalently bound zinc(II) 2,3,9,10,16,17,23,24‐octaphenyltetrapyrazinoporphyrazine units. They are soluble in common organic solvents and can be cast into strong and flexible films. The maximum absorption wavelength of the poly(aryl ether)s bearing zinc (II) 2,3,9,10,16,17,23,24‐octaphenyltetrapyrazinoporphyrazine units in chloroform is 654 nm. © 1995 John Wiley & Sons, Inc.
Soluble polymer‐supported catalysts containing pendant quaternary onium salts for the addition reaction of oxiranes with carbon dioxide
Authors: Nishikubo Tadatomi , Kameyama Atsushi , Yamashita Jun , Fukumitsu Takahiro , Maejima Chika , Tomoi Masao 
Published: April 2003

AbstractThe addition reaction of oxiranes (15a‐d) with carbon dioxide (CO2) was carried out using 1 mol % of soluble polymer‐supported quaternary onium salts as catalysts under atmospheric pressure. The reaction of 15a‐d with CO2 proceeded very smoothly to give the corresponding five‐membered cyclic carbonates (16a‐d) in high yields at 90‐100°C. The catalytic activity of the soluble polymer‐supported quaternary onium salts was strongly affected by the following factors: kind of reaction solvent, degree of introduction of the pendant onium salt residues in the polymer chain, and type of alkyl group on the onium salts due to the balance between lipophilicity and steric hindrance of the onium salt residue. Furthermore, these soluble polymer‐supported quaternary onium salts were found ordinarily to have higher catalytic activity than low molecular weight quaternary onium salts under the same reaction conditions. It was also found that the rate of reaction was proportional both to catalyst concentration and to oxirane concentration. © 1995 John Wiley & Sons, Inc.
Alternating copolymers consisting of arylalkyl methacrylates. I. Fluorescence properties of poly(arylalkyl methacrylate‐alt‐styrene) in organic solution
Authors: Itoh Yoshihiro , Inoue Masamitsu , Takahashi Tomoko , Hachimori Akira , Suzuki Satoshi 
Published: April 2003

AbstractAlternating and random copolymers of 9‐phenanthrylmethyl methacrylate or 2‐(9‐carbazolyl)ethyl methacrylate with styrene were synthesized and their fluorescence properties were examined. There was no noticeable difference in the spectral features of the alternating and random copolymers in tetrahydrofuran (THF), demonstrating that this type of polymers have no quenching sites in the polymer chains. The fluorescence quenching studies indicated that the alternating copolymers permitted singlet‐state energy migration as efficiently as the corresponding random copolymers but less efficiently than the random copolymers with higher chromophore contents. These results strongly suggest that to be chromophores close to each other is most important for facilitation of an intramolecular energy migration. © 1995 John Wiley & Sons, Inc.
Growth of poly(methyl methacrylate) particles in three‐component cationic microemulsions
Authors: Gan L. M. , Lee K. C. , Chew C. H. , Tok E. S. , Ng S. C. 
Published: April 2003

AbstractPolymerization of methyl methacrylate (MMA) has been studied in ternary microemulsions which were stabilized by tetradecyltrimethylammonium bromide (TTAB) or stearyltrimethylammonium chloride (STAC). The sizes of MMA‐swollen polymer particles (Rh) increased continuously during polymerization. This is in contrast to that of the styrene system, where Rh increased very rapidly to a maximum and then decreased continuously towards a constant value. The continuous growth of PMMA particles at 60°C are discussed. The stability of PMMA latexes increased with increasing the hydrophobic chain length of the cationic surfactant used. Traces of the coagulations of PMMA particles in the TTAB system can be seen from TEM. © 1995 John Wiley & Sons, Inc.
Study of the reaction between 1,5‐naphtalene diisocyanate and polycaprolactone in different solvents
Authors: Lesar Meta , Žigon Majda , Malavašič Tatjana 
Published: April 2003

AbstractThe reaction between polycaprolactone and 1,5‐naphtalene diisocyanate has been investigated in solvents with different dielectric constants and hydrogen bonding powers (toluene, ethyl acetate, ethyl methyl ketone), and in the same solvents with the addition of a catalytic amount of dimethyl sulfoxide (DMSO). The reaction was considered to proceed over two steps, the reaction of the first NCO group being faster. The course of the reaction was measured by titration of the unreacted NCO groups, 1H‐ and 13C‐NMR spectroscopy, and size exclusion chromatography. By titration only the overall reaction order and reaction rate constants could be determined. DMSO accelerated the reaction in all three solvents, which was explained by the stabilization of the activation complex by DMSO. Both steps of the reaction could be specified by NMR spectroscopy. The ratio between the reaction rate constants for the first and the second step decreased with the increased hydrogen bonding strength of the solvent and with DMSO. By SEC only the reaction of the first NCO group could be determined due to the low resolution for higher molar mass reaction products with a broad distribution. The values obtained for the first step reaction rate constants were in good agreement with NMR values. © 1995 John Wiley & Sons, Inc.
Solvation effect in thermal decomposition of 2,2′‐azoisobutyronitrile on the N,N‐dimethylformamide/methyl methacrylate system
Authors: Szafko J. , Feist W. 
Published: April 2003

AbstractThe thermal decomposition rate constant of AIBN (𝓀d) in N,N‐dimethylformamide (DMF)/methyl methacrylate (MM) mixtures of various compositions at 60°C is studied. The 𝓀d value is 6.45 × 10−4min−1 for pure DMF and 7.20 × 10−1 min−1 for pure methyl methacrylate. The 𝓀d values of DMF/MM mixtures were found to be dependent on the mixture composition. This dependence is not a linear function of the monomer mole fraction, but has a minimum at ca. 20 30 mol% of MM. The relationship between the AIBN decomposition rate constant and the monomer mole fraction was interpreted on the basis of solvation of the initiator molecules. © 1995 John Wiley & Sons, Inc.