bluuebunny/crossref_metadata_2025 huggingface dataset:
Insoluble polystyrenes containing amide moieties and N‐alkylated nylon‐66 as phase transfer catalysts
Authors: Kondo Shuji , Inagaki Yasuhito , Yasui Haruhiko , Iwasaki Masaki , Tsuda Kazuichi
Published: April 2003

Insoluble polystrenes containing formamide and acetamide moieties were prepared by free radical terpolymerization of the corresponding vinyl monomers, styrene, and divinylbenzene. These polymers served as phase transfer catalysts for the reaction of n‐octyl bromide with potassium thiocyanate in toluene–water system. The activity of these catalysts was affected by some factors such as stirring speed particle size, and degree of crosslinking. The activity also depended strongly on the structure of active site, copolymer composition, and spacer length which cause the difference in the adsorption of potassium ion and in the microenvironment around the active site. Furthermore, nylon‐66 was found to display the activity for phase transfer reactions, and the activity was remarkably increased by replacing the amide hydrogen with an alkyl group.
Synthesis and characterization of thiocarbonohydrazone‐based epoxy resins
Authors: Thangamathesvaran P. M. , Jain Sampat R.
Published: April 2003

Novel epoxy resins of various thiocarbonohydrazones have been synthesized by reacting the aldehyde or ketone derivatives of thiocarbohydrazide with excess of epichlorohydrin. The resins have been characterized by elemental analyses, epoxy equivalents, 1H‐NMR and IR spectra, thermal analyses, and viscosity measurements. Curing of the resins has been carried out by mixing with thiocarbohydrazide or ethylenediamine and heating at 80°C for 48 h. A comparison of the thermal stability of the cured resin samples has been made.
Immobilization of catalase on membranes of poly(ethylene)‐g‐co‐acrylic acid and poly(tetrafluoroethylene)‐g‐co‐acrylic acid and their application in hydrogen peroxide electrochemical sensors
Authors: Da Silva M. Alves , Gil M. Helena , Piedade A. P. , Redinha J. S. , Brett A. M. Oliveira , Costa J. M. Caridade
Published: April 2003

The immobilization of catalase on grafted membranes of poly(ethylene)‐g‐co‐acrylic acid and poly(tetrafluoroethylene)‐g‐co‐acrylic acid and their application in hydrogen peroxide electrochemical sensors is described. The introduction of carboxylic acid groups onto a hydrophobic support provides a good environment for subsequent enzyme immobilization. This single membrane, hydrogen peroxide sensor showed significant improvement with respect to the double membrane versions. The response is very rapid, the linear range being from 10 μM up to 6 mM, with a detection limit of 4.7 μM, and a lifetime of more than 4 months.
Immobilization of glucose oxidase on nylon membranes and its application in a flow‐through glucose reactor
Authors: Da Silva M. Alves , Gil M. Helena , Redinha J. S. , Brett Ana M. Oliveira , Pereira J. L. Costa
Published: April 2003

The immobilization of glucose oxidase on hydrolyzed nylon‐6,6 was studied. Various spacers were introduced on the support before the coupling of the enzyme. Best results were obtained when the membrane was covered with denatured bovine serum albumin (BSA) before spacer coupling and immobilization of glucose oxidase (GOD). The influence of various factors (pH, ionic strength, etc.) on the activity of the free and immobilized enzyme was investigated. It was found that the behavior of the fixed glucose oxidase and the free enzyme is very similar. The covalently immobilized enzyme had a lifetime of around 2 months (50% of initial activity).
Sulfonation of tert‐alkyl chlorides: Application to the tert‐chloride‐terminated polyisobutylene system
Authors: Storey Robson F. , Lee Youngkwan
Published: April 2003

The direct sulfonation of tert‐chloride‐terminated polyisobutylene was carried out using acetyl sulfate in methylene chloride/hexanes diluent to produce low molecular weight model ionomer systems with narrow molecular weight distribution. The room temperature sulfonation of 2‐chloro‐2,4,4‐trimethylpentane, which serves as a model for the polyisobutylene chain end obtained in the controlled cationic polymerization of isobutylene, was found to be quantitative after 3 h reaction. The two major products, isomeric β,γ‐unsaturated sulfonic acids differing only in the location of the double bond, were the same products obtained from the sulfonation of 2,4,4‐trimethyl‐1‐pentene, which serves as a model for the polyisobutylene chain end after quantitative dehydrochlorination. Near‐monodisperse, tert‐chloride‐terminated, three‐arm star polyisobutylene was synthesized under living cationic polymerization conditions using the tricumychloride/TiCl4/pyridine initiation system in hexanes/methyl chloride consolvents. Sulfonation was carried out directly upon the obtained polymer, and the sulfonated product was purified using ion‐exchange chromatography. Structural elucidation was performed using NMR. Titration and molecular weight characterization revealed that sulfonation produced exactly one sulfonic acid group per polyisobutylene chain end.
Selective vinyl cationic polymerization of monomers with two cationically polymerizable groups. IV. New initiating systems for selective and living polymerization of p‐isopropenylphenyl glycidyl ether
Authors: Hashimoto Tamotsu , Sano Yoshiyuki , Sawamoto Mitsuo , Higashimura Toshinobu , Saito Noriaki , Kanagawa Shuichi
Published: April 2003

A variety of cationic initiators were employed for p‐isopropenylphenyl glycidyl ether (IPGE), an α‐methylstyrene derivative with an epoxy pendant, and optimum initiators and reaction conditions were evaluated in terms of its selective vinyl polymerization and living polymerization. Despite the coexistence of two cationically polymerizable groups in IPGE, binary initiating systems (HI, CF3COOH, or CH3CH(OiBu)‐OCOCH3, each coupled with ZnI2) and sulfonic acids (CF3SO3H and CH3SO3H) selectively polymerized the vinyl group of IPGE in CH2Cl2 at −78°C to produce soluble polymers with epoxy pendant groups in high yield. Metal halides (BF3OEt2 and AlEtCl2) polymerized both the vinyl and epoxy groups of IPGE to give crosslinked insoluble polymers. In contrast, under these conditions, the HI/ZnI2 system also led to a long‐lived polymer, the molecular weight of which increased upon addition of a fresh feed of monomer to a completely polymerized reaction mixture, whereas the use of other initiators resulted in nonliving polymers. At higher temperatures (−40 and −15°C), soluble poly(IPGE) was also obtained with HI/ZnI2, but the polymer yield decreased with raising temperature, because of the occurrence of termination reaction.
Copolymerization behavior of 2‐vinylbenzofuran: Copolymers of ethyl acrylate, n‐butyl acrylate, and methyl methacrylate
Authors: Trumbo D. L.
Published: April 2003

The reactivity of 2‐vinylbenzofuran in copolymerization reactions with n‐butyl acrylate, ethyl acrylate, and methyl methacrylate was investigated. The vinylbenzofuran was found to be a very reactive monomer with the growing chain preferring to react with this monomer no matter what its terminus. Reactivity ratios were calculated using a nonlinear least squares error‐in‐variables method, which gives more reliable values of r1 and r2.
Preparation and properties of polyesters and copolyesters based on 4‐methyl‐2,4‐bis (p‐hydroxyphenyl)‐1‐pentene
Authors: Yang Chin‐Ping , Huang Ching‐Jung
Published: April 2003

4‐Methyl‐2,4‐bis (p‐hydroxyphenyl)‐1‐pentene (MBHPP) was prepared from thermal cracking of bisphenol A (BPA). Unsaturated polyesters were synthesized from the polycondensation of MBHPP with diacid chlorides. Three synthetic routes—solution, interfacial, and melt polycondensation—were employed. MBHPP‐polyesters with higher molecular weights were obtained by the interfacial polycondensation reaction. During the preparation of MBHPP‐polysters, the products usually contain some insoluble gel, which is probably caused by the crosslinking reaction of the vinyl groups of MBHPP in the aqueous NaOH. Thus, a modified interfacial polycondensation method was proposed, in which both of the bisphenol MBHPP and diacid chloride were dissolved in organic phase and then the solution was stirred with an aqueous NaOH solution to promote the polycondensation. This method reduced the time of MBHPP present in the alkali and produced polymers with higher inherent viscosity and lower gel fraction. The effects of some variables, such as the nature of porganic solvents and phase transfer agents and the concentration of reactants, on the modified interfacial polycondensation of MBHPP with the mixture of equal parts of isophthaloyl and terephthaloyl chloride [IPC/TPC (50/50)] were investigated in some detail. Copolyesters of mixed bisphenols of BPA/MBHPP with IPC/TPC (50/50) were also prepared and characterized.
Conformational analysis of poly(2‐hydroxyethyl methacrylate)
Authors: Yoon Jeong Hyeok , Shin Jae Min , Kang Young Kee , Jhon Mu Shik
Published: April 2003

The poly(2‐hydroxyethyl methacrylate) (PHEMA) is a disubstituted vinyl chain in which the substituents CO2CH2CH2OH and CH3 differ in size and shape. In order to verify the various characteristics of the PHEMA chain, the conformational energy calculations for meso and racemic diads, which are the segments consisting of the stereoregular isotactic and syndiotactic chains, respectively, were carried out using ECEPP/2 potential. From these calculations, the averaged geometry and the statistical weights were obtained in a local minima. The characteristic ratio, C∞ = (〈r2〉o/nl2)∞, was determined from the statistical weights and geometries. The calculated C∞ for the isotactic and syndiotactic chain are 10.2 and 2.3, respectively. The characteristic ratio for isotactic chain is larger than that for syndiotactic chain. This shows that the syndiotactic chain is more folded than the isotactic chain is, and that the calculated tendency is in reasonably agreement with the experimental tendency of acrylate polymers.
Preparation and properties of Si‐containing copolymer for near‐UV resist. I. Poly(N‐(4‐hydroxyphenyl) maleimidealt‐p‐trimethylisilylstyrene)
Authors: Chiang Wen‐Yen , Lu Jin‐Yuh
Published: April 2003

A new negative near‐UV photoresist consisting of poly(N‐(4‐hydroxyphenyl) maleimidealt‐p‐trimethylisilylstyrene) (PHMS) and a naphthoquinonediazide ester was developed. PHMS was synthesized by solution free‐radical polymerization of the comonomers with azobisisobutyronitrile (AIBN) in 1,4‐dioxane at 60°C. The preparation of PHMS in terms of reaction time, thermal initiator, and solvent was evaluated; and a series of different molecular weight copolymers were prepared. PHMS was 1: 1 in composition and was predominantly alternating. These copolymers dissolved in a wide range of solvents (including 5% tetramethylammonium hydroxide). The thermal properties of these copolymers were investigated by DSC and TGA. The chain‐stiffening effect of the maleimide group played an important role in effecting high thermal resistance. Near‐UV exposure was carried out using a Canon PLA‐501F contact printer. High resolution negative images were obtained which had resistance to thermal deformation at 330°C and above. The developed patterns exhibited good adhesion to the silicon substrates without the use of an adhesion promoter. The lithographic applications of a bilayer photoresist system in which the prepared resist was used as the top imaging layer were examined. It is supposed that if PHMS was used as a binder for a diazonaphthoquions sulfonate (NDS) photochemically, positive images would be obtained; however, on the contrary, negative images were observed. It is proposed that photocrosslinking occurred in the PHMS main chain.
Laminating resins obtained from 2,2′‐(1,4‐phenylenedivinylene)bispyridine bismaleimides and maleimide‐terminated styrylpyridine prepolymers
Authors: Mikroyannidis John A.
Published: April 2003

A new bismaleimide (2a), biscitraconimide (2b), and bisnadimide (4) were synthesized by reacting 2‐amino‐6‐methylpyridine with an equimolar amount of maleic, citraconic, or nadic anhydride, respectively, and then with a half molar amount of 1,4‐benzenedicarbaldehyde in the presence of acetic anhydride. They, as well as the intermediate amic acids (1a, 1b, and 3) were characterized by IR and 1H‐NMR spectroscopy. The DTA thermograms showed that crosslinking of polymer precursors started at 180–212°C. The crosslinked resins obtained from 2a and 2b were stable up to 300–313°C and afforded anaerobic char yield of 53–60% at 800°C. The cured resin of 4 was less thermostable. In addition, end‐capping of styrylpyridine prepolymers was accomplished by reacting 2,6‐dimethylpyridine (n mol) with 1,4‐benzenedicarbaldehyde (n + 1 mol) in acetic anhydride to yield a formyl‐terminated styrylopyridine prepolymer. The latter reacted with the maleamic acid 1a (2 mol) to afford a series of maleimide‐terminated styrylpyridine prepolymers MTSOs. They showed lower curing temperatures than did the ordinary poly(styrylpyridine). Their cured resins did not lose weight up to 310–344°C both in N2 or air and afforded anaerobic char yield of 66‐72% at 800°C.
Polyisobutylene‐containing block polymers by sequential monomer addition. I. The living carbocationic polymerization of styrene
Authors: Kaszas G. , Puskas J. E. , Kennedy J. P. , Hager W. G.
Published: April 2003

The living carbocationic polymerisation of styrene (St) has been investigated by the 2‐chloro‐2,4,4‐trimethylpentane (TMPCI)/TiCl4 initiating system in the presence of various additives such as electron pair donors (EDs) and the proton trap 2,6‐di‐tert‐butylpyridine (DtBP) by the use of the mixed solvent CH3Cl/methyl‐cyclohexane (MCHx) (40/60 v/v) at −80°C under conventional laboratory conditions. The TMPCl/TiCl4 system in the absence of additives produces ill‐defined bimodal molecular weight distribution (MWD) polymers. Much better defined polystyrenes (PSt) can be obtained in the presence of EDs, such as N,N‐dimethylacetamide (DMA) and hexamethylphosphoramide (HMPA). Monomer depletion should be avoided to prevent intra‐ or intermolecular alkylation yielding indanyl end groups or branched polymers, respectively. In the combined presence of an ED and the proton trap, i.e., DMA + DtBP, the living polymerization of St has been achieved and thus the foundations for the carbocationic synthesis of PSt block polymers by sequential monomer addition have been laid.
Synthesis and double ring‐opening polymerization of cyclic ketals of γ‐methylenelactones
Authors: Bailey William J. , Zheng Zhi‐Feng
Published: April 2003

Several cyclic ketals of γ‐methylenelactones such as 7‐methylene‐1,4,6‐trioxaspiro‐[4,4] nonane (3a), 2‐methyl‐7‐methylene‐1,4,6‐trioxaspiro [4.4] nonane (3b), and 2,7‐dimethylene‐1,4,6‐trioxaspiro [4.4] nonance (3c) were prepared, and polymerized. The results indicated that the former two monomers polymerized with a quantitative double ringopening to form high polymers via a catonic mechanism, but the latter monomer under the same conditions generated a polymer with a network structure.
Kinetics and stereochemical control of propylene polymerization initiated by ethylene bis(4,5,6,7‐tetrahydro‐1‐indenyl) zirconium dichloride/methyl aluminoxane catalyst
Authors: Chien James C. W. , Sugimoto Rynichi
Published: April 2003

The kinetics and sterochemical control of propylene polymerization initiated by rac‐ethylene bis (4,5,6,7‐tetrahydro‐1‐indenyl) zirconium dichloride/methyl aluminoxane (1/MAO) and by rac‐ethylene bis (1‐indenyl) zirconium dichloride/MAO (2/MAO) were investigated. The polymerization activities increase monotonically with temperature corresponding to an overall activation energy of 10.6 kcal mol−1. This is accompanied, however, by reduction of stereochemical control as reflected in the amount of the polypropylene (PP) soluble in low boiling solvent. At a temperature of 30°C and higher, polymerization initiated by 1/MAO produced no PP insoluble in refluxing n‐heptane. Tritium radiolabeling showed that at [Al]/[Zr] ≥ 3500 and 30°C, two‐thirds of 1 becomes catalytically active. There are at least two kinds of active species formed in about equal amounts; one has more stereoselectivity, 10–20 times greater rate constant of propagation, and a factor of 5–15 faster chain transfer to MAO than the second kind of Active species. This is also true at low [Al]/[Zr] of 350, except that the total amount of the two active species corresponds to only 13% of the [1]. Replacement of MAO with trimethyl aluminum resulted in the decrease of stereoselectivity and loss of catalytic activity proportional to the amount of replacement. A comparison was made with the polymers obtained with 2/MAO.
Effects of ultraviolet irradiation on substituted polyacetylenes
Authors: Tsuchihara Kenji , Masuda Toshio , Higashimura Toshinobu
Published: April 2003

Effects of UV irradiation on various substituted polyacetylenes were examined. Upon irradiation in air, main‐chain scission and crosslinking occurred with a wide range of probabilities dependent on the nature of substituents. For example, poly(2‐alkyne)s rapidly degraded to low molecular weights, whereas polymers from aromatic monosubstituted acetylenes [e.g., poly(o‐CF3‐phenylacetylene)] were quite stable. Several other polyacetylenes [e.g., poly(1‐Me3Si‐1‐propyne)] showed intermediate degradability. Polymer degradation was minimal in vaccum. The polymers irradiated in air contained CO and OH groups, and dissolved in polar solvents which are nonsolvents for the initial polymers. These results indicate that oxidation causes degradation. Only poly(1‐chloro‐1‐alkyne)s of the polyacetylenes studied, formed gels upon UV irradiation. The amount of the gel was larger, when the polymer was irradiated in vacuum than in air. Further, the longer the alkyl pendant in the polymer, the higher the gel fraction. Differences between photo‐and thermal degradations are discussed.
13C‐NMR studies of compositional and configurational sequence distribution in acrylonitrile–ethyl methacrylate copolymers
Authors: Kapur G. S. , Brar A. S.
Published: April 2003

Acrylonitrile–ethyl methacrylate (A/E) copolymers of different monomer concentrations were prepared in bulk by free radical initiation. Copolymer composition was determined by nitrogen analysis and the comonomer reactivity ratios were determined by the method of Kelen‐Tüdos. 13C‐NMR spectra of several acrylonitrile/ethyl methacrylate copolymers are discussed in terms of their triad monomer sequence and cotacticity. Terminal and penultimate reactivity ratios have been calculated using the observed monomer triad sequence distribution determined from 13C‐NMR spectroscopy for individual samples. Triad sequence distribution was used to calculate dyad concentrations, probability parameters, number average sequence lengths, and the comonomer mole fractions in the copolymers. The configurational sequence distributions in terms of all the 10 A‐centered and 10 E‐centered triad cotactic sequences have been determined and found to be in excellent agreement with those obtained using various cotactic probability parameters.
Studies of particle formation in styrene emulsion polymerizations using 9‐vinyl anthracene as a probe molecule
Authors: Pearson L. T. , Louis Pierre E. J. , Gilbert Robert G. , Napper Donald H.
Published: April 2003

The effects of 9‐vinyl anthracene (VAn) on solution and emulsion polymerization of styrene are examined, to gain information about the mechanism of particle formation in emulsion polymerizations. Styrene solution polymerization in ethyl benzene is found to be inhibited by small amounts of VAn. In an emulsion system, the effects of VAn are found to depend on surfactant concentration [S]. With [S] = 0, addition of VAn engenders some inhibition and very little change in the steady‐state polymerization rate. As [S] is increased from zero to above the critical micelle concentration (cmc), a slight increases in the induction period and an increasing retardation (reduction in the steady‐state rate) are observed. Below the cmc, VAn has no significant effect on the particle number, but above the cmc it considerably increases the latter with concomitant appearance of very small (5–15 nm radius) particles. The data strongly support the supposition that the coagulative/homogeneous nucleation mechanism dominates particle formation for [S] below the cmc. Above the cmc, the data are compatible with both the micellar entry and coagulative/homogeneous mechanisms.
Investigations of the chemical structure of sulfonated amino‐formaldehyde resins. V. 13C‐NMR analysis of sulfonated urea–melamine–formaldehyde resins
Authors: Pasch Harald , Hovakeemian George , Lahalih Shawqui
Published: April 2003

13C‐NMR spectroscopy was used to characterize the chemical structure of sulfonated urea–melamine–formaldehyde resins, prepared by a three‐step procedure (addition, sulfonation, condensation). Each of the three reaction steps was investigated separately and the average number of functional groups, obtained after each step, was determined quantitatively. The effect of the reactant ratios on the chemical structure was studied.
Polyanhydrides. IV. Unsaturated and crosslinked polyanhydrides
Authors: Domb Abraham J. , Mathiowitz Edith , Ron Eyal , Giannos Steven , Langer Robert
Published: April 2003

Unsaturated polyanhydrides of the structure [(COCHCHCOO)x(CORCOO)y]n, were synthesized. The polymers were prepared by either melt or solution polycondensation. Weight average molecular weights of up to 30,000 were obtained. The double bonds remain intact throughout the polymerization process and were available for a secondary reaction to form a crosslinked matrix. Poly(fumaric acid) is crystalline and insoluble in common organic solvents. Copolymers of fumaric acid with aliphatic diacids are less crystalline and soluble in chlorinated hydrocarbons. These copolymers displayed nearly constant degradation rates and drug release rates under physiological conditions. The time for complete degradation of 14 × 1.5 mm discs of poly(fumaric anhydride) and poly(sebacic anhydride) occurred in 2 and 15 days, respectively, while their copolymers degraded within this range. Further crosslinking of the polyanhydrids is demonstrated.
Spin trapping of propagating radicals derived from dialkyl fumarates
Authors: Yamada Bunichiro , Yoshikawa Eilchiro , Otsu Takayuki
Published: April 2003

Propagating radicals of dialkyl fumarates (DRFs) and deuterated fumarate were trapped by admitting a 2‐methyl‐2‐introsopropane (BNO) solution to the polymerization mixture containing the active radicals or by the polymerizations initiated with di‐t‐butyl hyponitrite in the presence of BNO. Although ESR spectra of the propagating radicals were appreciably changed with the size of the ester alkyl groups, all the nitroxyl radicals resulting from the spin trapping exhibited similar six‐line spectra. The hyperfine splitting constant for the α‐hydrogen of the radical moiety showed a slight dependence on the chain length, and the bulkiness of the ester alkyl group did not affect splitting of the spectra. These findings indicate that a substituted methylene radical is produced by addition of the primary radical to DRF followed by propagation throughout the polymerization and that poly(DRF) radical does not encounter severe hindrance in the reaction with BNO.
Monomer‐isomerization polymerization. XXVI. Formation of polyallylcyclohexane from propenylcyclohexane through monomer‐isomerization polymerization with Ziegler–Natta catalysts
Authors: Endo Kiyoshi , Otsu Takayuki
Published: April 2003

Monomer‐isomerization polymerization of propenycyclohexane (PCH) with TiCl3 and R3‐xAICIx (R = C2H5 or i‐C4H9, x = 1–3) catalysts was studied. It was found that PCH underwent monomer‐isomerization polymerization to give a high molecular weight polymer consisting of an allylcyclohexane (ACH) repeat unit. Among the alkyaluminum cocatalysts examined, (C2H5)3Al was the most effective cocatalyst for the monomer‐isomerization polymerization of PCH, and a maximum for the polymerization was observed at a molar ratio of Al/Ti of about 2.0. The addition of isomerization catalysts such as nickel acetylacetonate [Ni(acac)2] to the TiCl3–(C2H5)3Al catalyst accelerated the monomer‐isomerization polymerization of PCH and gave a maximum for the polymerization at a Ni/Ti molar ratio of 0.5. PCH also undergoes monomer‐isomerization copolymerization with 2‐butene (2B).
Interfacial electrostatic potential of polyions as probed by acid‐base indicator dyes covalently attached to the main chain
Authors: Morishima Yotaro , Higuchi Yuji , Kamachi Mikiharu
Published: April 2003

Polyanions with various charge densities with a solvatochromic acid‐base indicator dye attached to the main chain were prepared by the terpolymerization of acrylic acid, acrylamide, and a small mole fraction of 1‐(2‐methacryloyloxyethyl)‐4‐(2‐(4‐hydroxyphenyl)ethenyl)pyridinium bromide. The apparent pK value for the polymer‐bound indicator dye (pKabs) was determined by the spectroscopic pH titration. The interfacial electrostatic potential (ψ) was calculated from pKobs. Dielectric contribution to the acid‐base equilibrium was taken into account for the calculation. The electrostatic potentials thus obtained were compared with those calculated from the nonlinearized Poisson‐Boltzmann equation for a cylinder model. The indicator dye moieties are suggested to be reporting the mean field potential at a distance of about 10 Å from the axis of the polyion cylinder. The observed values as a function of the charge density were also discussed in connection with Manning's theory.
The effect of sodium methacrylate on the soapless emulsion copolymerization of methyl methacrylate and n‐butyl acrylate
Authors: Pan Ting‐Chung , Kuo Jen‐Feng , Chen Chuh‐Yung
Published: April 2003

The soapless emulsion polymerization of methyl methacrylate (MMA) and n‐butyl acrylate (BA) containing various concentrations of sodium methacrylate (NaMA) or methacrylic acid (MMA) is studied. The hydrosoluble yields in final latexes are not larger than 1.3–5%, depending on the concentration of NaMA used. Below 25% conversion, the change of conversion with reaction time follows the square rule and the particle size is proportional to the 2/3 power of time. Above 25% conversion, serious gel effect occurs, and the conversion follows the seventh power on time and the growth of particle diameter obeys the 2.5 power on time. The multiple glass transition (Tg) occur below 20% conversion, where monomer droplets exist. NaMA added induces more Tgs. The effect of molecular weight of the copolymers obtained on Tg (even the molecular weight distributions were shown to be shouldertype bimodal) is estimated to be insignificant. Thus, the heterogeneity of copolymer compositions for multiple Tgs is ascribed to be caused from neither the molecular weight heterogeneity nor the shifts in compositions due to the difference of the monomer reactivity ratios. Referring to the results mentioned, we assume the sublayer surrounding the particle, rich with SO4− and COO− groups, and the concentration gradients of monomers in particles to illustrate particle morphology. In addition, the relatively hydrophilic sublayer is proposed to be closely relative with the occurrence of the composition heterogeneity in particles.
Nitro‐ and fluoropolyformals. II. Novel polyformals from α, ω‐fluoro‐ and nitrodiols
Authors: Adolph Horst G. , Nock Lori A. , Goldwasser Judah M. , Farncomb Robert E.
Published: April 2003

The scope of polyformal formation from nitro‐ and fluorodiols has been explored further with a series of α, ω‐diols. Polymers with M̄ns of 2000–4000 were generally obtained but M̄ns approaching 10,000 are possible in some cases. Effects of monomer structure and reaction parameters on polymer molecular weight are described. The polymers were characterized by GPC, 1H‐NMR, and DSC analysis.
Synthesis and characterization of novel aromatic polyamides from 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylpyrrole and aromatic diacid chlorides
Authors: Jeong Hwa‐Jin , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

A new polymer‐forming monomer, 3,4‐bis(4‐aminophenyl)‐2,5‐diphenylpyrrole, was synthesized in three steps starting from 4′‐nitrodeoxybenzoin. Tetraphenylpyrrole‐containing aromatic polyamides and copolyamides were prepared from the diamine with various aromatic diacid chlorides and from a mixture of the diamine and 4,4′‐oxydianiline with terephthaloyl chloride, respectively. The resultant polymers had inherent viscosities in the 0.3–1.8 dL/g range and were generally soluble in various organic solvents including N,N‐dimethylacetamide and m‐cresol. They have glass transition temperatures in the range of 306–333°C and showed no weight loss below 380°C in both air and nitrogen atmospheres.
Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. V. Preparation and properties of polytitanosiloxanes from silicic acid and bis(2,4‐pentanedionato)titanium diisopropoxide
Authors: Gunji Takahiro , Nagao Yukinori , Misono Takahisa , Abe Yoshimoto
Published: April 2003

Preparation and properties of polytitanosiloxanes (PTS) as a preceramic polymer for SiO2‐TiO2 fibers were investigated. The PTS was prepared by the reaction of bis(2,4‐pentanedionato) titanium diisopropoxide (PTP) with silicic acid (SA), extracted with tetrahydrofuran from an aqueous solution, in methanol. They were soluble in methanol, ethanol, and THF. The molecular weight (Mn) was 1500–4200 depending on the reaction molar ratio (SA/PTP). A Concentrated methanol solution of PTS showed an appreciable stability to self‐condensation and good spinnability. Dry spinning of the solution provided golden yellow precursor fibers which can be subjected to thermal‐treatment to give ceramic fibers. The PTS is considered to be a copolymer formed by the condensation of oligomeric silicic acid with PTP consisting of SiOTi and SiOSi linkages in the molecular main chain with the ligand and hydroxy groups as pendants.
Synthesis of aromatic polyethers by Scholl reaction. II. On the polymerizability of 4,4′‐bis(phenoxy)diphenyl sulfones and of 4,4′‐bis(phenythiol)diphenyl sulfone
Authors: Percec Virgil , Wang James H. , Oishi Yoshi
Published: April 2003

4,4′‐Bis(phenoxy)diphenyl sulfone (1), 4,4′‐bis(phenylthio)diphenyl sulfone (2), and 1 substituted with various electron‐donating groups in the phenoxy units were synthesized and polymerized under oxidative reaction conditions. The presence of methyl, tert‐butyl, and methoxy groups as substituents on the phenoxy groups of 1 increases both the yield and the solubility of the resulting polymers. The structure‐reactivity relationship of the monomers and of the growing species were discussed based on a radical‐cation mechanism of polymerization. Monomers of high nucleophilicity and resonance stabilized radical‐cation growing species are crucial to achieve polymers of high molecular weight. The structure of the polymers and in several cases of their chain ends were determined by 1H‐NMR spectroscopy. The mechanism of termination and the side reactions occuring during this polymerization process were discussed based on the structure of the resulting polymers.
Synthesis and characterization of side‐chain liquid crystalline polysiloxanes containing 4‐alkanyloxyphenyl trans‐4‐alkylcyclohexanoate side groups
Authors: Hsu Chain S. , Lu Yong H.
Published: April 2003

The synthesis and characterization of nine polysiloxanes containing 4‐alkanyloxyphenyl trans‐4‐alkylcyclohexane side groups are described. Six monomers which contain a pentenyloxy of a hexenyloxy flexible spacer display a nematic mesophase, while the other three monomers which contain an undecenyloxy flexible spacer display nematic, smetic A and smectic E mesophases. All synthesized polymers present two smectic mesophases except one containing 4‐hexanyloxyphenyl trans‐4‐n‐butylcyclohexanoate side groups presents one smectic mesophase and one containing 4‐undecanyloxyphenyl trans‐4‐n‐pentylcyclohexanoate side groups presents three smectic mesophases. Trans‐cis isomerization of mesogens and side chain crystallization did not occur for any of the synthesized polymers.
Kinetics and mechanism of emulsion polymerization initiated by oil‐soluble initiators. II. Kinetic behavior of styrene emulsion polymerization initiated by 2,2′‐azoisobutyronitrile
Authors: Nomura M. , Yamada A. , Fujita S. , Sugimoto A. , Ikoma J. , Fujita K.
Published: April 2003

In order to clarify the general kinetic behavior of emulsion polymerization initiated by oilsoluble initiators, the emulsion polymerization of styrene initiated by 2,2′‐azoisobutyronitrile was as a typical example, investigated thoroughly. The variations of the polymerization rate and the number of polymer particles produced with changes in emulsifier (sodium lauryl sulfate), initiator, and monomer concentrations initially charged and the reaction temperature were determined. It is shown from these experimental results that the kinetic behavior of this emulsion polymerization system is quite similar to that of styrene emulsion polymerization initiated by the water‐soluble initiator, potassium persulfate despite the difference in the principal loci of radical production in both systems.
Preparation and properties of aromatic polymides from 2,2′‐bibenzoic acid and aromatic diamines
Authors: Liou Guey‐Sheng , Oishi Yoshiyuki , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

Aromatic polyamides having inherent viscosities up to 1.8 dL/g were synthesized either by the direct polycondensation of 2,2′‐bibenzoic acid with various aromatic diamines or by the low temperature solution polycondensation of 2,2′‐bibenzoyl chloride with aromatic diamines. All the aromatic polyamides were amorphous and soluble in a variety of organic solvents including N,N‐dimethylacetamide (DMAc), N‐methyl‐2‐pyrrolidone, dimethyl sulfoxide, m‐cresol, and pyridine. Transparent and flexible films of these polymers could be cast from the DMAc solutions. These aromatic polymides had glass transition temperatures in the range of 226‐306deg;C and began to lose weight around 350°C in air.
Elementary reaction and anionic polymerization of isopropenly t‐butyl ketone
Authors: Ito Hiroshi , Renaldo Alfred F.
Published: April 2003

Isopropenyl t‐butyl ketone (IPTBK) does not undergo radical homopolymerization and its anionic polymerization is a slow equilibrium process with a low ceiling temperature, which is due to its limited conjugation imposed by steric hindrance. Equimolar reactions of IPTBK with several anionic initiators were carried out, products isolated and identified by 1H‐and 13C‐NMR, and product distributions determined by GC. While n‐butyllithium and phenyllithium preferentially produce allyl alcohols, Grignard reagents predominantly undergo β‐addition to produce mono‐adducts, and a significant amount of dimers. t‐Butyllithium and t‐butylmagnesium chloride provide the cleanest β‐addition with minimal dimer formation and no carbonyl addition. However, Grignard reagent do not yield a polymer. The 1:1 reaction mixture of IPTBK with t‐butyllithium is very stable at 0°C, providing a methyl‐terminated mono‐adduct quantitatively when quenched with methyl iodide after 29 h. Addition of a second IPTBK to the mono‐adduct anion appears to be affected by the low ceiling temperature. Although t‐butyllithium can efficiently reduce as well as add to di‐t‐butyl ketone, such reactions are minor in the presence of IPTBK. Anionic polymerization of IPTBK with t‐butyllithium was carried out under several conditions. The 1:1 model reactions and the lack of acidic hydrogens in its structure suggest that anionic polymerization of IPTBK with t‐butyllithium may be “living.” The molecular weight distribution of the polymers ranged from 1.1 to 1.6 with the number‐average molecular weight varying from 2,800 to 233,500. Group transfer polymerization of IPTBK produced only a six‐membered lactone.
Synthesis, characterization, and fire retardancy of ferrocene containing polyphosphate esters
Authors: Kishore K. , Kannan P. , Iyanar K.
Published: April 2003

Polyphosphate esters containing ferrocene structures were synthesized from 1,1′‐bis (p‐hydroxyphenylamido) ferrocene and 1,1′‐bis (p‐hydroxyphenoxycarbonyl) ferrocene with aryl phosphorodichloridates by interfacial polycondensation using a phase transfer catalyst. The polymers were characterized by infrared, 1H‐, 13C‐, and 31‐NMR spectroscopy. The molecular weights were determined by end group analysis using 31P‐NMR spectral data. The thermal stability and fire retardancy were respectively determined by thermogravimetry and limiting oxygen index (LOI) measurements. The polyamide‐phosphate esters showed better thermal stability and higher LOI values than the polyester‐phosphate esters.
Synthesis of poly(arylene ether)s based on 9,9‐bis(3,5‐diphenyl‐4‐hydroxyphenyl)fluorene
Authors: Wang Z. Y. , Hay A. S.
Published: April 2003

The synthesis of a novel bisphenol, 9,9‐bis(3,5‐diphenyl‐4‐hydroxyphenyl)fluorene, in high yield by the transalkylation of 9,9‐bis(4‐hydroxyphenyl)fluorene is described. Three poly(arylene ether)s based on this hindered phenol were prepared with molecular weights (Mn) ranging from 34 800 to 51 300 and inherent viscosities ranging from 0.27 to 0.43 dL/g. The polymers have Tg's of 236–262°C and did not lose weight below 350°C, with 10% weight loss recorded above 550°C. They are readily soluble in chlorinated solvents such as methylene chloride, chloroform, and 1,2‐dichloroethane at room temperature. Attempts to synthesize an analogous monomer, bis (3,5‐diphenyl‐4‐hydroxyphenyl)diphenylmethane, are described.
The copolymerization behavior of acrylate dimers: Copolymers of methyl, ethyl, and n‐butyl acrylate dimers
Authors: Trumbo D. L. , Zander R. A.
Published: April 2003

Dimers of methyl, ethyl, and n‐butyl acrylate were synthesized in good yield through the use of a phosphine catalyst. The dimers synthesized in this manner have one double bond. The activity of this double bond was investigated in copolymerization reactions with styrene. The methyl acrylate dimer proved to have a slightly more favorable reactivity ratio than either the ethyl or n‐butyl acrylate dimers.
Intramolecular cyclization of pendant phenylethynyl groups as a route to solvent resistance in polyphenylquinoxalines
Authors: Lindley Patricia M. , Reinhardt Bruce A.
Published: April 2003

Biphenyl‐based bisbenzil monomers which contain pendant phenylethynyl groups in the 2,2′‐positions were condensed with 3,3′‐diaminobenzidine to make polyphenylquinoxalines (PPQs) of high molecular weight. Thermal cure of these polymers at 193°C caused an intramolecular cyclization (IMC) of the phenylethynyl groups to give the rigid 9‐phenyldibenzanthracene system in the backbone of the polymer. The initial, uncured polymers formed though films which were soluble in m‐cresol and chlorinated solvents, but after thermal cure the films became insoluble in all common organic solvents and acids while maintaining their toughness. DSC scans of the cured materials showed small residual exotherms indicating that after vitrification even the intramolecular rotation required for the IMC reaction became restricted.
Epoxy modified polyurethane rigid foams
Authors: Lee Yng‐Long , Ku Wen‐Hsiung , Tsou Jenq‐Der , Wel Kuo‐Tung , Sung Po‐Hou
Published: April 2003

Rigid IPN foams were prepared by sequential polymerization of polyurethane and epoxy systems. Significantly higher compressive modulus and strength were observed with the IPN foams in comparison to the corresponding polyurethane rigid foams. The IPN foams show one glass transition temperature. The single Tg indicates the very small domain size in the PU‐epoxy IPN's.
Effect of alkyl substituents on initiator activity in cationic polymerization of styrene with p‐methoxybenzyldialkylsulfonium salts as initiators
Authors: Kikkawa Atsushi , Takata Toshikazu , Endo Takeshi
Published: April 2003

The effect of alkyl substituents on cationic polymerization of styrene with p‐methoxybenzyldialkysulfonium salts was studied. p‐Methoxybenzyl tetramethylene (1), dimethyl (2), diethyl (3), dibuty (4), and diisopropylsulfonium salts (5) were synthesized by the reaction of p‐methoxybenzyl bromide with the corresponding sulfides, followed by exchange of the counter anion Br− with SbF−6. These sulfonium salts served as potent cationic thermal initiators of which activity was estimated by the bulk and solution polymerizations of styrene. The bulk polymerizations with 1–4 (0.1 mol %) for 30 min gradually proceeded at 30–50°C, but the exothermic polymerization occurred vigorously at 40–60°C. The Polymerization with 5 took place exothermically even at room temperature. Temperature‐conversion curves of the polymerizations for 30 and 5 min revealed that the activity of the sulfonium salts was in the following order: 5 > 4 > 3 > 2 ≈ 1. This order was explained by the order of the bulkiness of the alkyl substituents on the sulfur atom. Number‐average molecular weight (M̄n) of polystyrene obtained by the polymerization undergoing no exothermic process was in a range of 6600–16000, which depended on the structure of the alkyl substituents: the more bulky the substituent was, the higher M̄n was.
Hydrosilylation of m‐TMI: New siloxane based aliphatic polyisocynates
Authors: Zhou Guangbin , Smid Johannes
Published: April 2003

Well‐characterized polyfunctional aliphatic isocyanates were obtained in high purity and quantitative yield by the hydrosilylation of m‐isopropenyl‐α,α‐dimethylbenzyl isocyanate (m‐TMI) with cyclic and acyclic hydrogementhylsiloxance. The products were characterized by 1H‐ and 13C‐NMR, IR, and GPC, and all result exclusively from ß‐addition to m‐TMI. Polymers with SiH Groups are also effective hydrosilylating agents of m‐TMI. The isocyanato siloxanes can be used as precursors for star and network polymers as well as other poly‐functional reagents, and examples of reactions with methoxy polyethylene glycol and with amine‐containing compounds are discussed.
Nitro‐ and fluoropolyformals. III. Copolyformals from mixtures of fluoro‐ and nitro‐α,ω‐diols
Authors: Nock Lori A. , Goldwasser Judah M. , Adolph Horst G.
Published: April 2003

Polyformals of fluoro‐, nitramine‐, and C‐nitrodiols show widely differing properties with respect to glass transition temperature, melting transition, and solubility. Polymers with desirable combinations of these properties, e.g., low Tg, high nitro content, and good solubility in polar solvents, were expected to result from acid‐promoted copolycondensation of appropriate mixtures of diols with formaldehyde. A series of such condensations were carried out and the polymers obtained from binary mixtures of fluoro‐ and nitrodiols, different nitrodiols, and fluoro‐ or nitrodiols and carboranediols, were characterized by GPC, 1H‐NMR, and DSC analysis.
Synthesis and properties of aliphatic‐aromatic poly(amide‐imide)s from sulfonyldianilines and N,N′‐bis(ω‐carboxyalkyl)pyromellitimides
Authors: Yang Chin‐Ping , Lin Jiun‐Hung , Hsiao Sheng‐Huei
Published: April 2003

Seven imide‐containing dicarboxylic acids IIa‐g were synthesized from pyromellitic dianhydride and amino acids of the formula HOOC—(CH2)m—NH2, with m—1,2,3,4,5,10,11. These diacids were condensed directly with 3,3′‐ or 4,4′‐sulfonyldianiline using triphenyl phosphite in N‐methyl‐2‐pyrrolidone (NMP)‐pyridine solution containing calcium chloride and lithium chloride. The resulting poly(amide‐imide)s have moderate to high inherent viscosities ranging from 0.47 to 2.02 dL/g in dimethylacetamide. These polymers showed excellent solubility in polar solvents such as NMP, and most of them could be cast into transparent and tough films. Glass transition temperatures (Tgs) of these poly(amide‐imide)s were recorded in the range 116–258°C and increased with decreasing number of methylene groups in the repeated unit. The polymers with longer aliphatic chains (e.g., m = 10 and 11) exhibited higher crystallinity, higher initial decomposition temperature, and lower solubility in polar solvents.
Catalytic epoxidation of styrene–butadiene triblock copolymer with hydrogen peroxide
Authors: Jian Xigao , Hay Allan S.
Published: April 2003

Styrene‐butadiene‐styrene linear block copolymer (SBS) can be epoxidized with hydrogen peroxide in the presence of methyltrioctylammonium tetrakis (diperoxotungsto) phosphate(3‐) as the catalyst in a biphasic system. The effects of reaction time, temperature, solvent, the ratio of the organic phase to the aqueous phase, the concentration of the catalyst, hydrogen peroxide and polymer, respectively, are studied on the conversion of double bonds to oxirane groups. 1H‐NMR analysis confirms the absence of ring opening side reaction in this epoxidation reaction system up to at least 70% conversion of the double bonds. When the conversion of double bonds is over about 70% the resultant polymer is insoluble in chloroform even at reflux but soluble in polar solvents such as DMSO when heated. Toluene is a better solvent for the reaction than dichloroethane. The reaction rate constants are measured at four temperatures and the activation energy for the reaction with toluene as solvent is determined as 49.9 kJ/mol.
Preparation and thermal properties of polyquinazolones: Effect of the chemical structure of bisbenzoxazinones on the thermal properties
Authors: Kubota Shigeru
Published: April 2003

Four kinds of polyquinazolones were synthesized from 4,4′‐diaminodiphenylether and bisbenzoxazinones having different central aromatic nuclei (benzene, biphenyl, benzophenone, diphenylmethane). All the polymers were prepared by solution polycondensation at 190°C at a concentration of 15% solid in m‐cresol, and were obtained with intrinsic viscosities in the range of 0.3–0.8 dL/g in 97–98% yield. Their thermal properties were studied by using dynamic thermogravimetry and isothermal weight loss. All the polymers were found to produce high char yields (55–75%) in nitrogen. Oxidative thermal stability of the polymers was dependent on the chemical structure of bisbenzoxazinone and was governed by the stability of the bonds in the quinazolone units. The following order of oxidative thermal stability of the quinazolone units was determined from this study: diphenylmethane < benzophenone < biphenyl < benzene.
Syndiospecific polymerization of styrene. II. Monocyclopentadienyltributoxy titanium/methylaluminoxane catalyst
Authors: Chien James C. W. , Salajka Zdenek
Published: April 2003

Syndiospecific polymerization of styrene was catalyzed by monocyclopentadienyltributoxy titanium/methylaluminoxane [CpTi (OBu)3/MAO]. The atactic and syndiotactic polystyrenes were separated by extracting the former with refluxing 2‐butanone. The activity and syndiospecificity of the catalyst were affected by changes in catalyst concentration and composition, polymerization temperature, and monomer concentration. Extremely high activity of 5 × 107 g PS (mol Ti mol S h)−1 with 99% yield of the syndiotactic product were achieved. The concentration of active species, [C*], has been determined by radiolabeling. The amount of the syndiospecific and nonspecific catalytic species, [C] and [C] respectively, correspond to 79 and 13% of the CpTi(OBu)3. The rate constants of propagation for C and C at 45°C are 10.8 and 2.0 (M s)−1, respectively, the corresponding rate constants for chain transfer to MAO are 6.2 × 10−4 and 4.3 × 10−4s−1. There was no deactivation of the catalytic species during a batch polymerization. The rate constant of chain transfer with monomer is 6.7 × 10−2 (M s)−1; the spontaneous β‐hydride transfer rate constant is 4.7 × 10−2 s−1. The polymerization activity and stereospecificity of the catalyst are highest at 45°C, both decreasing with either higher or lower temperature. The stereoregular polymer have broad MW distributions, M̄w/M̄n = 2.8–5.7, and up to three crystalline modifications. The Tm of the s‐PS polymerized at 0–90°C decreased from 261.8 to 241°C indicating thermally activated monomer insertion errors. The styrene polymerization behaviors were essentially insensitive to the dielectric constant of the medium.