bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymers having stable radicals. II. Synthesis of nitroxyl polymers from 4‐methacryloyl derivatives of 1‐hydroxy‐2,2,6,6‐tetramethylpiperidine
Authors: Kurosaki Toshikazu , Takahashi Osamu , Okawara Makoto
Published: April 2003

Polymers having stable pendant . radicals were synthesized through their precursor polymers by oxidizing them in air or by H2O2–Na2WO4. Hydrochlorides and sulfates of 4‐methacryloylamino‐ and 4‐methacryloyloxy‐1‐hydroxy‐2,2,6,6‐tetramethylpiperidines were synthesized as precursor monomers and polymerized by using α,α′‐azobisisobutyronitrile under appropriate conditions to precursor polymers of high molecular weight: poly‐4‐methacryloylamino‐/oxy‐1‐hydroxy‐2,2,6,6‐tetramethylpiperidinehydrochlorides and sulfates. The precursor polymers were converted to polymers having nitroxyl stable radicals, i.e., poly‐4‐methacryloylamino‐/oxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyls, by oxidation in air or with H2O2–Na2WO4 without any main‐chain scission. The structure of the resultant stable radical polymers was determined by infrared, ultraviolet, and ESR spectroscopy. Based on the results of spectroscopic analysis and Kjeldahl analysis, the transformation from precursors to nitroxyl stable radical polymers was found to be quantitative. Investigations on the applicability of polymeric nitroxyl radicals to oxidation‐reduction reactions were attempted by means of polarography; the reduction half‐wave potential was found to be −1.16 V for the mercury pool.
Wetting properties of bis(trifluoromethyl)carbinyl acrylate polymers
Authors: Roitman James N. , Pittman Allen G.
Published: April 2003

A series of bis(trifluoromethyl)carbinyl acrylate monomers [Y‐C(CF3)2 OCOCHCH2] in which Y is CH3, CH3CH2, CH3CH2CH2, CH3CH2CH2CH2, C6H5, H, F, CF3, N3, CN, and CH3OCH2CH2O, was prepared. Polymers were easily prepared from all of these monomers except where Y = CN, wherein a variety of initiation methods failed to produce high molecular polymer. Wettabilities of the polymer films were examined by means of contact angle measurements by using n‐alkane test liquids and water. Values of the dispersion force contribution (γsd) and the polar force contribution (γsp) to the solid surface energy were calculated by employing both geometric and harmonic mean approximations. Values of γsd calculated by either method agreed well with γc (critical surface tension) values determined graphically from contact angle data employing n‐alkane test liquids, confirming the suggestion that γc is an approximate measure of the dispersion force contribution to solid surface energy. Values of γsd ranged from 15 dyne/cm (Y = F or CF3) to 25 dyne/cm (Y = C6H5). Values of the polar force contribution to solid surface energy (γsp) varied from 0.6 dyne/cm (Y = CH3CH2CH2CH2) to 3.4 dyne/cm (Y = CH3OCH2CH2O) when calculated by the geometric mean equation. The values of γsp obtained from the harmonic mean equation followed the same trend upon varying substituents, but were larger in value, ranging from 2.9 dyne/cm (Y = CH3CH2CH2CH2) to 7.5 dyne/cm (Y γ CH3OCH2CH2O).
Synthesis and copolymerizations of 3,3‐difluorocyclobutene‐1‐carbonitrile
Authors: Hall H. K. , Okamoto Y.
Published: April 2003

3,3‐Difluorocyclobutene‐1‐carbonitrile (DFCB) was synthesized via cycloaddition of 1‐chloro‐2,2‐difluoroethylene and acrylonitrile, followed by dehydrochlorination with 1,4‐diazabicyclo[2.2.2]octane in tetrahydrofuran. Unlike cyclobutene‐1‐carbonitrile, this monomer did not homopolymerize either under radical or anionic conditions. As an electron‐poor monomer it copolymerized in the presence of free radicals with electronrich monomers such as styrene in good yield. It also copolymerized with electron‐poor monomers such as acrylonitrile, although in lower yields. The extent of incorporation of DFCB in the copolymers also depended on the electronic characteristics of the comonomers: high incorporation occurred with electron‐rich monomers, low incorporation with electron‐poor monomers. One extremely electron‐poor monomer, trimethyl ethylenetricarboxylate, did not copolymerize with DFCB.
Intersequence cyclization in copolymers of N‐vinyl carbamates
Authors: Guilbault L. J. , Harwood H. James
Published: April 2003

Monomer reactivity ratios determined for the copolymerization of tert‐butyl N‐vinylcarbamate (rA = 0.55 ± 0.05) with phenyl N‐vinylcarbamate (rB = 2.08 ± 0.15) indicate that the monomer units are distributed randomly along the polymer chains. The following sequence of reactions was used to cause intersequence cyclization between tert‐butyl N‐vinylcarbamate and phenyl N‐vinylcarbamate units in the copolymers. The extent of cyclization obtained was in accord with that expected for random copolymers.
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Solid‐state reactions of vinylpyridine coordination complexes. II
Authors: Agnew N. H. , Brown M. E.
Published: April 2003

Crystals of the trans‐octahedral complex Co(4‐Vpy)4(NCS)2 on being heated below the melting point decompose with liberation of 4‐vinylpyridine (Vpy) and concurrent polymerization of the free monomer. The two reactions have been followed by differential scanning calorimetry, thermogravimetry, and optical microscopy. Polymerization is inhibited by inclusion of hydroquinone during recrystallization of the complex. This has allowed the kinetic analysis of the decomposition and polymerization to be simplified. Isothermal mass‐loss determinations under reduced pressure (10−2 torr), at various temperatures in the range 120–160°C, on hydroquinone‐inhibited crystals corresponded to the loss of up to three molecules of vinylpyridine per molecule of starting complex. With uninhibited crystals over the same temperature range the total number of ligands lost was approximately two with a marked decrease near 175°C owing to rapid polymerization. Isothermal decomposition curves for inhibited and uninhibited crystals approximated to the Avrami‐Erofeev equation. Values of n varied with temperature. Activation energies for decomposition and polymerization for both types of crystal were estimated from Arrhenius plots.
Heterogeneous reactions of singlet molecular oxygen with solid polymers
Authors: Breck A. K. , Taylor C. L. , Russell K. E. , Wan J. K. S.
Published: April 2003

The effect of gas‐phase singlet molecular oxygen (1ΔO2) upon several solid polymers was investigated by using electron paramagnetic resonance, infrared spectroscopy, and chemical detection techniques. The study was performed by use of 1ΔO2 produced by microwave discharge. The application of this method to polymer studies was closely examined. The saturated‐chain polymers polystyrene, polyurethane, and polyethylene were found to be inert within the experimental conditions to reaction with 1ΔO2, while the unsaturated polymers cis‐polybutadiene, trans‐polybutadiene, and trans‐polyisoprene were found to react quite readily in an apparently surface or near‐surface limited reaction to produce hydroperoxide and/or peroxide groups. The introduction by homogeneous mixing of some known metal‐chelate 1ΔO2 quenchers into the polymer trans‐polyisoprene appeared to significantly decrease the rate of oxidation observed.
Effects of structure on properties of some new aromatic‐aliphatic polybenzimidazoles
Authors: Tsur Yoel , Levine Harold H. , Levy Moshe
Published: April 2003

Polybenzimidazoles were prepared in poly(phosphoric acid) from isophthalic, m‐ and p‐phenylene diacetic, succinic, adipic, suberic, and sebacic acids and 3,3′‐diaminobenzidine, 3,3′,4,4′‐tetraaminodiphenyl ether and 3,3′,4,4′‐tetraaminodiphenylmethane. The thermal, mechanical, and bonding properties were studied. A 3:1 copolymer of isophthalic and m‐phenylenediacetic acid with 3,3′‐diaminobenzidine showed the best results as far as isothermal oxidation resistance and thermal and processing characteristics.
Effect of temperature on the radiation‐induced polymerization of ethylene in various media
Authors: Wada Takeshi , Watanabe Terutaka , Takehisa Masaaki , Machi Sueo
Published: April 2003

The effects of temperature on the radiation‐induced polymerization of ethylene in bulk and in the presence of ethyl alcohol, n‐butyl alcohol, tert‐butyl alcohol, cyclohexane, 2,2,4‐trimethylpentane, and 2,2,5‐trimethylhexane were studied. The changes of the amounts of polymerized monomer with the reaction temperature were different from each other in these reaction systems, especially in the range lower than 60–80°C. At temperatures lower than 60–80°C, as the reaction temperature increases, the amount of polymerized monomer decreased in bulk and in the presence of tert‐butyl alcohol. The amount was almost constant in the presence of ethyl alcohol and 2,2,4‐trimethylpentane, and it increased in the presence of n‐butyl alcohol, cyclohexane, and 2,2,5‐trimethylhexane. However, in the temperature range higher than 60–80°C, the amount of polymerized monomer increased with increasing temperature in every reaction system except for bulk polymerization. The molecular weight of polymer decreased with increasing temperature in every reaction system except at temperatures lower than 25°C. The molecular weight of polymer formed in bulk, in tert‐butyl alcohol, and also in 2,2,4‐trimethylpentane were relatively higher than that in other reaction systems. A bimodal molecular weight distribution was observed for the polymer formed in bulk and in tert‐butyl alcohol at 40–60°C. These results are discussed in connection with the heterogeneity of the reaction system. The differences due to temperature in each reaction system are explained as due to the difference in affinity of the reaction system for the propagating chain and in the facility of chain transfer to the medium.
Electron spin resonance studies on radiation graft copolymerization. I. Grafting initiated by alkyl radicals trapped in irradiated polyethylene
Authors: Seguchi Tadao , Tamura Naoyuki
Published: April 2003

The behavior of trapped radicals in polyethylene which is irradiated in air at room temperature, under grafting of methylmechacrylate or butadiene has been studied by electron spin resonance. Part of the alkyl radicals are converted to allyl radicals by reaction with double bonds and the others disappear by recombination under vacuum. The active species of grafting are alkyl radicals when the vapor pressure of monomers is relatively high, while at low pressure allyl radicals also play a role as well as alkyl radicals. In the grafting at 20°C, the grafting yields depend mainly on the decay rate of alkyl radicals which come out of the crystalline regions of polyethylene. The decay rate of alkyl radicals and the rate of grafting at the initial stage increase with decreasing crystallite size of polyethylene.
Dilatometric constant for polymerization of α‐methylstyrene
Authors: Lowry George G. , Petiet John
Published: April 2003

By measurement of the specific volume of solutions of poly‐α‐methylstyrene in α‐methylstyrene monomer at 25°C, the dilatometric constant was found to be KD = (0.002007 ± 0.000030)%−1. Estimation of the temperature dependence resulted in the equation (KD)t = 1.81 × 10−3 + 7.82 + 10−6 t, where t denotes temperature in °C.
A basis for the determination of branching in polymers by use of gel‐permeation chromatography
Authors: Ambler M. R. , Mate R. D. , Purdon J. R.
Published: April 2003

The technique for determining branching in polymers by using a combination of GPC and intrinsic viscosity data has been extended beyond current methods. Equations used in these analyses are presented. The derivations are based upon the assumption that branching is present only when there is a measurable reduction in the intrinsic viscosity. Techniques for calculating the functionality of the star branch point in starbranched polymers are given. Three random‐branching parameters are calculated from a knowledge of the average branching density, \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \lambda $\end{document}: (a) the lowest molecular weight branched polymer that can be measured, M̄*; (b) the average molecular weight between branch points, M̄bp; (c) the weight percentage of polymer that is branched. The applicability of this technique is demonstrated by using an analysis of published data on characterized fractions of a randomly branched polystyrene.
Experimental branching results for diene polymers by use of gel‐permeation chromatography
Authors: Ambler M. R. , Mate R. D. , Purdon J. R.
Published: April 2003

Branching analyses in styrene–butadiene rubbers and polybutadiene rubbers have revealed large differences in branching between rubbers polymerized in different ways. The functionalities of several star‐branched solution‐polymerized styrene–butadiene rubbers were calculated and compared to their expected structures. Emulsion‐polymerized polybutadiene rubber and a series of solution‐polymerized polybutadienes made with different catalysts had different degrees of random branching, and evidence is presented indicating that the different available catalyst systems provide some latitude in making rubbers of different branching contents. Random branching analyses on a series of emulsion‐polymerized styrene–butadiene rubbers revealed the dependency of branching on molecular weight and molecular weight distribution. The influence of polymerization temperature on the branching of emulsion‐polymerized styrene–butadiene rubber was also studied.
Polymeric nitrile–palladium chloride complexes and their reaction with olefins
Authors: Kraus M. , Tomanová D.
Published: April 2003

Polymers containing cyano groups connected to the polymeric chain by means of at least one methylene group adsorb palladium dichloride reversibly from its slightly acidic solutions and form surface complexes of the probable structure (CH2CN)2PdCl2. These complexes can adsorb gaseous olefins; ethylene is consumed continuously, but adsorption of propylene and 1‐butene reaches saturation. Additional ethylene can be added to the propylene or 1‐butene adsorbate. Hydrolysis of the surface olefinic complexes yields aldehydes, the ethylene complex giving acetaldehyde and butanal, the mixed ethylene–1‐butene complex giving acetaldehyde, butanal and hexanal.
Carbon‐13 NMR spectroscopy of acrylic monomer and Lewis acid complexes
Authors: Furukawa Junji , Kobayashi Eiichi , Nagata Shiro , Moritani Tōhei
Published: April 2003

13C NMR spectra of acrylic monomers complexed with a Lewis acid were measured and their electronic structures discussed in relation to their alternating copolymerizability. The β‐carbon of acrylonitrile and methacrylonitrile showed a downfield shift due to the complex formation with the Lewis acid, while the α‐carbon showed an upfield shift and the nitrile carbon showed no significant shift. The degree of shift of olefinic carbons decreased in the following order: AlCl3 > EtAlCl2 > Et1.5AlCl1.5 > Et2AlCl > SnCl4, EtOAlCl2 > Et(EtO)AlCl, which seems to run parallel to the Lewis acidity and acid strength. On the other hand, the chemical shift of olefinic carbons of methyl acrylate, methyl methacrylate, and olefinic diesters was influenced little by complex formation with Lewis acids, whereas the carbonyl and alkoxyl carbons were deshielded significantly by the complex formation. These results are discussed in terms of electron distribution on the carbons and an alternating polymerization mechanism.
A new single‐step process for polybenzimidazole synthesis
Authors: Hedberg F. L. , Marvel C. S.
Published: April 2003

Aromatic benzimidazole polymers have been prepared by reaction of the corresponding tetraamine and diester in refluxing sulfolane or phenyl sulfone. The convenience of using these sulfone solvents together with the good yields, high viscosities and absence of crosslinking make this procedure an attractive new route to this class of polymers. The preparation by this procedure of poly[2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole], poly‐[2,2′‐(p‐phenylene)‐5,5′‐bibenzimidazole], poly[2,2′‐(m‐phenylene)‐5,5′‐di(benzimidazole) ether], and poly[2,2′‐(m‐phenylene)‐5,5′‐di(benzimidazole) ketone] is described.
Photoisomerization of 1,2‐diphenylcyclopropane sensitized by polypeptides containing naphthalene groups in their side chain
Authors: Ueno Akihiko , Toda Fujio , Iwakura Yoshio
Published: April 2003

Poly(γ‐1‐naphthylmethyl L‐ and DL‐glutamate) (PNLG and PNDLG) and copolypeptides of γ‐1‐naphthylmethyl L‐glutamate and γ‐benzyl‐L‐glutamate were used as sensitizers for isomerization of trans‐1,2‐diphenylcyclopropane. Quantum yields relative to that of 1‐methylnaphthalene were measured in dichloroethane (DCE) and dichloroacetic acid (DCA). The relative quantum yield in DCE was smaller than unity for PNLG, but greater than unity for PNDLG and copolypeptides. The result is discussed in terms of increased effective collisional radius and energy trapping by excimer formation. The relative quantum yields in DCA were close to unity except for the copolypeptides of higher γ‐benzyl L‐glutamate content. This suggests that the naphthalene groups act in the same manner as their monomeric counterparts in the random conformation and that the greater proportion of γ‐benzyl L‐glutamate in the copolypeptides lowers the quantum efficiency because trans‐1,2‐diphenylcyclopropane must penetrate through the polymeric medium in order to encounter the excited naphthalene.
Functional monomers and polymers. XIX. Copolymerization of vinyl monomers containing nucleic acid bases
Authors: Takemoto K. , Akashi M. , Inaki Y.
Published: April 2003

Taking into account the specific base–base interaction existing between nucleic acid molecules, we studied the free‐radical copolymerization of N‐β‐methacryloyloxyethyl derivative of uracil with that of adenine at 60°C in various solvents. N‐β‐Methacryloyloxyethyltheophylline as well as methyl methacrylate were used also as comonomers. From the data on the rates in different comonomer feed ratios and the r1 and r2 values obtained, copolymerizability was discussed in some detail. The results suggest that the interaction between uracil and adenine bases plays a role in the copolymerization behavior.
Radiation‐induced emulsion copolymerization of tetrafluoroethylene with propylene. IV. Effects of emulsifier concentration and dose rate
Authors: Matsuda Osamu , Okamoto Jiro , Suzuki Nobutake , Ito Masayuki , Danno Akibumi
Published: April 2003

Radiation‐induced emulsion copolymerization of tetrafluoroethylene with propylene was carried out by batch operation with an initial molar ratio of tetrafluoroethylene to propylene of 3.0 in the emulsifier concentration range of 0.1 to 3.0% and in the dose rate range of 2 × 104 to 2 × 105 R/hr. The effects of emulsifier concentration and dose rate on the polymerization rate and the number‐average degree of polymerization are discussed in comparison with the Smith‐Ewart theory. The polymerization rate is proportional to the 0.26 power of emulsifier concentration and to the 0.7 power of dose rate. The degree of polymerization is independent of the emulsifier concentration and the dose rate above the critical micelle concentration (CMC) of the emulsifier. These results are not in agreement with the Smith‐Ewart theory. It is explained that the termination reaction is a degradative chain transfer of propagating radicals to propylene. On the other hand, the copolymerization in emulsion occurs either below the CMC or in the absence of emulsifier. Under these conditions, however, it is impossible to obtain a copolymer of high molecular weight at a high rate of polymerization because of the presence of a small number of polymer particles formed and the short interval of chain growth in the polymer particle.
Spectrophotometric investigation of the mechanism of polymerization of isobutylene with vanadium tetrachloride and visible light
Authors: Toman L. , Marek M. , Jokl J.
Published: April 2003

The spectra of n‐heptane solution of VCl4, isobutylene, and their mixture at temperatures ranging from +25 to −80°C in the range of wavelengths from 200 to 2000 nm were investigated. In the region of wavelengths of visible light (400–700 nm) in which the absorption of isobutylene alone and of VCl4 (concentration lower than 2.2 × 10−4 mole/l.) is practically zero, their mixtures exhibit an absorption which depends on the concentration of both components and on temperature. A colored complex of VCl4 and isobutylene is thus obtained, the concentration of which increases with decreasing temperature and is in equilibrium with that of the starting components. The polymerization of isobutylene under the experimental conditions investigated here probably is initiated with the isobutylene–VCl4 complex after its excitation with light or heat. At low temperatures (t < −20°C), when the polymerization of isobutylene with VCl4 virtually does not take place at all in the dark, only excitation with light is operative in the initiation, while at higher temperatures (t > +10°C) thermal excitation plays the predominant role.
Electron spin resonance studies on radiation graft copolymerization in polyethylene. II. Grafting initiated by allyl radicals trapped in irradiated polyethylene
Authors: Seguchi Tadao , Tamura Naoyuki
Published: April 2003

The regions trapping allyl radicals in irradiated polyethylene and the reactivity of the radicals with various monomers have been studied by electron spin resonance. Most of the allyl radicals are trapped in defects or surfaces of the crystallite, and only 10% of the radicals are trapped inside the crystallites. Since the reactivity of the allyl radicals depends on whether they come in contact with reactive monomers, the rate of reaction is related to the concentration of the monomers. When grafting reactions are initiated by allyl radicals, the rate of initiation is rapid and the rate of termination at the initial stage is also very fast. Consequently the yield of grafting increases at the initial stage but soon levels off, which is in contrast to the grafting behavior with alkyl radicals.
Coordination polymers from polycondensates and metal oxides. II. Effect of water molecules on the reactions of polyesters with Mgo and Zno
Authors: Vancsó‐Szmercsányi I. , Szilágyi Á.
Published: April 2003

Polyester molecules containing free carboxyl end‐groups react with MgO and ZnO as polydendate ligands to form donor–acceptor complexes, followed by the increase in molecular weight of the original polyester. The role of water in these coordination reactions was studied. It was demonstrated that the water can catalyze the reactions by promoting an ionization effect. In some case it can coordinate to the metal compound and effectively compete with the other ligands present.
Influence of conformational changes of co(III)–poly‐N‐vinyl‐2‐methylimidazole complexes on electron‐transfer reactions of the complexes
Authors: Tsuchida Eishun , Shigehara Kiyotaka , Kurimura Yoshimi
Published: April 2003

In order to study the effect of conformational changes in electron‐transfer reactions of Co(III)–polymer complexes, cis‐[Co(III)(en)2LCl]Cl2, where the ligand L is PVI(poly‐N‐vinyl‐2‐methylimidazole) or NEI (N‐ethylimidazole), was prepared. Electrontransfer reactions with ferrous sulfate or FeEDTA2− were examined mainly with respect to the effects of the degree of coordination, ionic strength, composition of reaction solvent, in relation to the conformational changes. In the reduction by FeEDTA2−, an increase in the degree of coordination of Co(III)–PVI brought about an extreme increase in its reactivity, while it was almost unity in the reduction by ferrous sulfate. With an increase in the ionic strength, the reactivity decreased due to the electrostatic shielding in the reduction by FeEDTA2−. It was noticed that the reaction of Co(III)–PVI was much more enthalpically disadvantageous due to the shrinkage of the polymer chain than that of Co(III)–NEI, when neutral salts were added. In an aqueous alcoholic solvent, an increase in the alcohol concentration accelerated the reaction with FeEDTA2−, and especially in the reaction of Co(III)‐PVI, the maximum and minimum points of the reactivity were observed. On increasing the reaction temperature, the maximum and minimum points shifted to lower alcohol concentration. These phenomena are discussed in regard to the conformational changes of Co(III)–PVI.
Radiation‐induced emulsion polymerization of ethylene. VI. Continuous flow system
Authors: Senrui Shiro , Kodama Atsuro , Takehisa Masaaki
Published: April 2003

The radiation‐induced emulsion polymerization of ethylene in a continuous flow system was carried out at 100°C by using FC‐143 and potassium myristate. The polymer concentration in the latex during the course of the polymerization oscillated several times and then approached a steady‐state value in a few hours in the case of short residence time. The rate of polymerization was almost constant within the residence time range of 0.2–0.9 hr. This is explained by the kinetics assuming the same mechanism previously proposed in the batch system, that is, the number of polymer particles in this range is considered to be constant. Gel formation was observed at longer reaction times in spite of the continuous supply of myristate micelles, possibly because large polymer particles are produced in this stage. The concentration of carbonyl group in the polymer produced by chain transfer to absorbed myristate ion changes in the same way as the polymer concentration with reaction time. The methyl group in the polymer is produced mainly by chain transfer to the polymer, and the concentration is nearly constant during the polymerization except in the initial stage. The rate constants for the continuous polymerization were very different from the batch polymerization previously studied, despite their similarities in nature. The mass transfer rate of the emulsifier from the micelles to the polymer particles requires future study.
Modification of PVC. XXVI. Syntheses and photocrosslinking of polysulfide pendant poly(vinyl chloride)
Authors: Mori Kunio , Harada Hitoshi , Nakamura Yoshiro
Published: April 2003

Poly(vinyl chloride) pendant with polysulfide (PS–PVC) having various degrees of substitution, various S substituents, and various numbers of atoms in the sulfur chain has been synthesized by the reaction of poly(vinyl chloride) with a thiol, sulfur, and triethylamine in dimethylformamide at 30°C for 0.4–5 hr. The photocrosslinking reaction has been investigated under ultraviolet irradiation at 250–450 mμ. The photocrosslinking reaction of PS–PVC is influenced by the degree of substitution, the nature of the S substituent, and the number of atoms in the sulfur chain. The degree of photocrosslinking r increased in the order, n‐C4H9 < n‐C8H17 < C6H5CH2 < i‐C3H7 < t‐C4H9. On the photocrosslinking of PS–PVC having two different S substituents, r increases in the similar order for aliphatic substituents and in the order NO2C6H4 < ClC6H4 < C6H5CH2 < CH3C6H4 < t‐C4H9C6H4 < C6H5 for the aromatic substituents. Further, r increases markedly with the increase of sulfur chain number for all PS–PVC. The chemical structure of the crosslinks and the crosslinking mechanism are discussed on the basis of the results.
Photochromic behavior of copolymers of indolinospirobenzopyrane methacrylic derivatives
Authors: Verborgt J. , Smets G.
Published: April 2003

Three photochromic 3,3‐dimethyl‐6′‐nitroindolinospirobenzopyran methacrylic derivatives have been synthesized, namely, 1‐methyl 8′‐methacryloxymethyl (A), 1‐(β‐methacrylamidoethyl) (B), and 1‐(β‐methacryloxyethyl) (C). They have been copolymerized with methyl, isobutyl, and n‐propyl methacrylates. The photochromic behavior of these copolymers in the solid state has been compared to that of the homologous isobutyric compounds dissolved in corresponding polymeric matrices. The kinetics of decoloration were resolved in three simultaneous first‐order reactions with rate constants k1, k2, and k3. The influence of the polarity of the polymeric matrix and of the photochrome incorporation has been examined. The rates of decoloration of the copolymers with isobutyl and n‐propyl methacrylate are very sensitive to the glass transition temperature Tg; the activation energy of decoloration increases markedly above Tg, from 19.8 to 36.5 kcal; below Tg the entropy of activation is strongly negative (around ‐20 e.u.), above Tg strongly positive. These effects are interpreted on the basis of an increasing chain segment mobility above Tg.
Inorganic coordination polymers. XVI. Zinc(II) phosphinate polymers containing polyphenylene and poly(phenylene oxide) side groups
Authors: Nannelli Piero , Gillman H. D. , Monsimer Harold G. , Advani Shyam B.
Published: April 2003

The synthesis and characterization of a series of new phosphinic acids and the zinc polymers prepared from them are reported. These compositions are characterized by the presence of short polyphenylene and poly(phenylene oxide) chains as side groups. Some of the zinc derivatives were found to be tractable polymers with good thermal stability.
Photopolymerizations initiated by oxime derivatives
Authors: Il Hong Sung , Kurosaki Toshikazu , Okawara Makoto
Published: April 2003

A number of ester, urethane, and carbonate derivatives of biacetyl monooxime, dimethylglyoxime, and ketone oxime, were synthesized and their photolyses studied by means of ultraviolet spectroscopy. Most of the oxime derivatives photolyzed easily upon UV irradiation. Among them, however, only the free radicals formed by photolysis from the ester and carbonate of biacetyl monooxime could effectively initiate the polymerization of a vinyl monomer such as methyl methacrylate. Based on the results obtained from the monomeric reactions, syntheses of grafting polymers were made. Graft polymers were obtained by using a copolymer of methyl methacrylate and methacrylic acid–biacetyl monooxime ester (copolymer I) and that of methyl methacrylate and vinyl benzioc acid–biacetyl monooxime ester (copolymer II) in good yield and without the formation of homopolymer. It was also found that when copolymer I was employed as a grafting polymer, a considerable amount of main‐chain scission was seen, but no chain degradation was noted in the case of copolymer II. Photocrosslinking was attempted by using these copolymers in the presence of divinyl benzene. It was confirmed that copolymer II was photocrosslinkable, whereas copolymer I underwent photodegradation.
Aspects of the synthesis and the properties of linear poly‐2,5‐dimethylbenzylenes
Authors: Peppas Nikolaos A. , Valkanas George N.
Published: April 2003

Polydimethylbenzylenes, \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} [C_6 H_2 (CH_3 )_2 CH_2 \rlap{--} ]_n$\end{document}, have been obtained by polycondensation of the monochloromethyl, acetoxymethyl, and methoxymethyl derivatives of p‐xylene, via an acid‐catalyzed reaction in anhydrous acetic acid and in 1‐nitropropane. In the highly ionizing solvent acetic acid, because of ionic depolymerization, chain growth takes the form of an equilibrating polycondensation, of a maximum number‐average molecular weight of 2200. In the noninteracting solvent 1‐nitropropane, the molecular weight distribution is more random, and soluble polymers of number‐average molecular weight up to 3900 are formed. The polycondensation reaction in 1‐nitropropane is also initiated by perchlorate salts, in support of the suggestion of a “hot carbonium ion” propagation mechanism. The results are explained by a cataionic polycondensation reaction, yielding crystalline “living polymers” of high structural purity.
Low‐angle x‐ray estimation of macromolecular parameters of the scattering particles in Agave sisalana
Authors: Ratho T. , Patel A. , Singhal O. P.
Published: April 2003

Various macromolecular parameters of Agave sisalana (sisal) fiber were investigated by the low‐angle x‐ray scattering method. The well known Kratky camera of the latest design was utilized for the experimental measurements. The sample studied was a densely packed colloidal system belonging to a general micelle system, and the theories of Kratky and Kratky and Porod were utilized to estimate the parameters. Pore analysis of the substance yields a value for the specific inner surface of the dispersed phase of 0.406 × 10−1 m2/cm3; the transversal length is the same as the length of inhomogeneity, 107.31 Å, and the length of coherence is 342.21 Å. The air fraction of the scattering particles was found to be 0.01%.
Further studies on the ultraviolet graft copolymerization of maleimide by vapor‐phase method
Authors: Hayakawa Kiyoshi , Kawase Kaoru , Yamakita Hiromi
Published: April 2003

Graft copolymerization of maleimide onto polyethylene and ethyl cellulose films by using its sublimation vapor was carried out under ultraviolet irradiation in the presence or absence of air; the effect of air or additives on the grafting reaction and on the nature of the grafted films was investigated. The extent of grafting gradually approached a fixed value, in spite of the continuous ultraviolet irradiation. Air retarded the grafting reaction but did not suppress the reaction nor alter the final extent of grafting. Benzoquinone showed no inhibiting effect on the grafting. The grafted polymaleimide was found to be amorphous, even though ultraviolet irradiation produces a highly crystalline homopolymer in the solid phase as well as in the liquid phase. The results were discussed in comparison with those of the vapor‐phase grafting under γ‐ray irradiation; the reaction is attributed to the vapor–crystal equilibrium of monomer and to the formation of short‐chain crosslinks.
Block polymers from isocyanate‐terminated intermediates. II. Preparation of butadiene–ϵ‐caprolactam and styrene–ϵ‐caprolactam block polymers
Authors: Hergenrother William L. , Ambrose Richard J.
Published: April 2003

Polystyrene–nylon 6 and polybutadiene–nylon 6 block copolymers have been prepared from isocyanate‐terminated prepolymers. From extraction and fractionation data the products obtained were found to be mixtures of both homopolymers and pure block copolymer. The polybutadiene–nylon 6 copolymers are extremely pliable at ambient temperatures even at high ϵ‐caprolactam contents (70–80 wt‐%). This is true even though these copolymers show a crystalline melting point at 213°C similar to poly‐ϵ‐caprolactam. Presumably this unusual behavior occurs because of the nature of the synthesis which renders the butadiene portion of these copolymers the continuous phase. Plasticity measurements indicate that pliability is dependent on the molecular weight of the block poly‐ϵ‐caprolactam.
Luminescence from thermally oxidized model amides in relation to nylon 66 degradation
Authors: Allen N. S. , McKellar J. F. , Phillips G. O.
Published: April 2003

Fluorescence and phosphorescence are observed following the mild thermal oxidation of two model compounds for nylon 66. Both emissions are remarkably similar in structure and in wavelength location to the corresponding emissions normally observed from the commercial polymer. Although the fluorescence could not be characterized, the phosphorescence exhibits several features which are clearly consistent with that of a nπ* carbonyl emission. The role of carbonyl groups in the thermal and photochemical oxidation of nylon 66 is discussed.
Influence of the low molecular weight amides on the dynamic behavior of polymers
Authors: Kotlik P. , Heidingsfeld V. , Zelinger J.
Published: April 2003

Dependence of the dynamic shear modulus G′ and mechanical damping tan δ was measured for mixtures of low molecular amides with VC/VAc copolymer and polystyrene, respectively. A new secondary relaxation was found, which in some cases depends on content of moisture. The effect of molecular structure and concentration of amide is shown.
Effect of photochemical oxidation on polypropylene phosphorescence
Authors: Allen N. S. , McKellar J. F. , Phillips G. O. , Wood D. G. M.
Published: April 2003

Phosphorescence from polyolefins was studied from the aspects of excitation and emission wavelength and lifetime. Effects of photochemical oxidation on polypropylene phosphorescence are discussed in contrast to the effects of thermal oxidation.
Polymerization of coordinated monomers. VI. Molecular complex formation of methyl methacrylate coordinated to stannic chloride with styrene or toluene
Authors: Hirai Hidefumi , Komiyama Makoto
Published: April 2003

The equilibrium constants for the complex formation between stannic chloride and methyl methacrylate were determined in n‐hexane–toluene solution at 0, −20, and −30°C by using the absorption band at 350 nm. Continuous variation plots at −20°C in n‐hexane based on the 1H‐chemical shifts definitely show a 1:1 interaction between the coordinated methyl methacrylate and styrene or toluene. The magnitudes of the shifts for the four groups of protons in methyl methacrylate are found to be in a specific ratio in common with the 1:2 complex–styrene or ‐toluene system. The equilibrium constants for the ternary molecular complex formation between the 1:2 complex and styrene or toluene were determined in n‐hexane in the temperature range −50 to +20°C by use of the chemical shifts. The concentrations of the complex species in the alternating copolymerization solutions were estimated by use of the equilibrium constants. There is a linear relationship between the enthalpy and the entropy changes for the ternary molecular complex formation, which is governed by the enthalpy factor. The specificity of the interactions indicates a specific time‐averaged orientation of benzene ring to the coordinated methyl methacrylate. The effects of the coordination of methyl methacrylate to stannic chloride were discussed on the basis of results of 13C‐NMR spectroscopy.
Kinetic approach to radiation–induced grafting in the polyethylene–styrene system
Authors: Imai Masahiko , Shimizu Harumichi
Published: April 2003

To investigate the mechanism of radiation‐induced grafting in this system, the increase of monomer concentration in the polyethylene film in styrene vapor was evaluated by measuring the weight increase and formulated to be V([M∞] − [M]). The decay of radical concentration was also measured by ESR and the rate constant of the decay was determined. The alkyl type radical was affected only a little by styrene, while the allyl type radical was much affected by styrene. A new computer investigation method was proposed to clarify the reaction mechanism. The data obtained were substituted into differential equations and used to calculate the pattern of increase of the degree of grafting for the preirradiation method with reaction in the vapor phase. Results of these calculations suggest that only allyl type radicals induce grafting reactions and that the grafting reaction seldom occurs in the region of grafted polystyrene.
Photo‐induced cellulose radicals capable of initiating graft copolymerization
Authors: Kubota Hitoshi , Ogiwara Yoshitaka , Matsuzaki Kei
Published: April 2003

The decay behavior of cellulose radicals produced by photo‐irradiation at room temperature and the characteristics of photo‐irradiated cellulose samples to initiate graft copolymerization of methyl methacrylate (MMA) were investigated. ESR spectra of such untreated, swollen, oximated, and ferric ion‐sensitized samples irradiated at room temperature were constructed mainly of a single absorption line with a line width of 20 to 22 gauss and a g value of 2.003, and it is surely conceivable that the radicals showing a singlet spectrum should agree with those of alkoxy end produced at either the C1 or C4 position of the glucose unit by the scission of glucosidic bonds. The decay of radicals was accelerated by contact of various solvents with the samples, the activity decreasing in the order, water ≈ methanol ≫ acetone > dioxane. On the other hand, the decay of radicals by vinyl monomers became smaller in the order, methacrylic acid > MMA ≈ styrene. Graft copolymerization of MMA by a photo‐irradiated sample was effectively initiated with the use of a certain amount of water or methanol, but not with acetone and dioxane. As no initiation can occur with the unirradiated sample, it is concluded that the initiation of graft copolymerization on the photo‐irradiated sample is attributable to cellulose radicals showing a singlet spectrum which are formed in photo‐irradiation at room temperature.
Mechanism of vinyl chloride polymerization
Authors: (Rogozinski) M. Ravey , Waterman J. A. , Shorr L. M. , Kramer M.
Published: April 2003

An overall mechanistic scheme for the suspension polymerization of vinyl chloride is presented. The process can be resolved into five discrete stages, each of which presents a unique environment for the interaction of the systems parameters. It is shown that the surface area of the polymer formed during the reaction is not a major factor in autoacceleration and that the increase of kinetic chain length with conversion is due to a radical dilution effect. The latter is a direct result of the difference in rates between polymerization and radical formation, the former being greater. The increase of the initial polymerization rate and the reduction of autoacceleration brought about by chain transfer agents can be explained by the lower diffusion rate and greater bulkiness of the chain transfer agent radical relative to that of the monomer radical. The chaintransfer agent CBr4 is preferentially absorbed by PVC from solution in vinyl chloride. With lauryl peroxide as initiator it is shown that the “hot spot” is the result of a build‐up of initiator in the monomer caused by its exclusion from the polymer phase. Vinyl chloride was found to dissolve 0.03% PVC at ambient temperature and to have no effect on the decomposition rate of lauryl peroxide.
Synthesis and polymerization of 1,5‐dioxo‐1‐methyl‐4‐azaphosphepane
Authors: Shalaby S. W. , Sifniades S. , Klein K. P. , Sheehan D.
Published: April 2003

1,5‐Dioxo‐1‐methyl‐4‐azaphosphepane was synthesized and polymeized in the presence of water, stannic chloride, or phosphoric acid. Polymers obtained by using these catalysts were shown to have lower molecular weights than nylon 6 samples prepared under identical reaction conditions. Thermal and other physical properties of the phosphorus‐containing polyamide are reported and compared with those of nylon 6.
Preparation and properties of n6‐tricarbonylchromium‐complexed arylenesiloxane polymers
Authors: Pittman Charles U. , Patterson William J. , McManus Samuel P.
Published: April 2003

Polytetramethyl‐p‐silphenylenesiloxane (I) and polymethylphenylsiloxane (II) were prepared and subsequently reacted with hexacarbonylchromium to generate their n6‐Cr(CO)3 complexed analogs, III and IV, respectively. During the complexation reaction, completing decomposition to chromium salts took place. Furthermore a competing chain scission reaction took place resulting in lower molecular weights for the complexed polymers. Heating III and IV resulted in carbon monoxide evolution and the presence of n6‐Cr(CO)3 moieties lowered the thermal stability of the polymers.
Polymerization of diallyl phthalate and gelation of poly(diallyl phthalate) by copolymerization with styrene
Authors: Ito Koichi , Murase Yasuo , Yamashita Yuya
Published: April 2003

In the polymerization of diallyl phthalate in bulk at 60°C with azobisisobutyronitrile, extensive branching of the polymers obtained before gelation was ascertained from the enhanced broadening of the molecular weight distribution, coupled with the decrease of the residual unsaturation. Copolymerization of poly(diallyl phthalate) and styrene in bulk at 80°C with benzoyl peroxide was studied in detail with regard to the gel formation. The gel time increased with increasing fraction of styrene in feed. Both the gel yield and the conversion of styrene incorporated into the gel increased steadily with polymerization time, even after the total conversion of styrene exceeded 95%. The polystyrene recovered by saponification of the gel was found to carry hydroxyl groups, which should come from the copolymerized diallyl phthalate units. It was concluded that styrene behaved as a diluent in the early stage, and that the crosslinking after gelation of the system proceeded mainly through polymer–polymer reactions involving the occluded polystyryl radicals and poly(diallyl phthalate).
Fluorocarbon polymers with alternating oxyalkylene and oxysilylene units
Authors: Tanquary A. Charles , Burks Robert E. , Jackson M. Virginia
Published: April 2003

Linear polymers were prepared by the condensation of bis(dimethylamino)dimethylsilane and 1,4‐bis(dimethylaminodimethylsily)benzene with fluorocarbon diols. 1,5‐Dihydroxy‐3‐methyl‐1,1,5,5‐tetrakis(trifluoromethyl)‐2‐pentene, the cis addition product of hexafluoroacetone and isobutylene, with the silylbenzene monomer gave a polymer that cured at room temperature to a rubber exhibiting a glass transition temperature of 0°C, low swelling in hydrocarbons, and excellent resistance to hydrolytic, oxidative, and thermal degradation, retaining its flexibility after exposure to air for 3 hr at 305°C. The polymers obtained by condensing 1,5‐dihydroxy‐1,1,5,5‐tetrakis(trifluoromethyl)‐2‐pentene, the trans addition product of hexafluoroacetone and propylene, with the silylbenzene and the silane monomers had glass transition temperatures of −12 and −50°C respectively, and greater resistance to swelling in hydrocarbons.
Highly branched acrylamide graft copolymer
Authors: Kim Oh‐Kil , Griffith James R.
Published: April 2003

Acrylamide graft copolymerization onto poly(3‐O‐methacryloyl D‐glucose) (PMG) as a backbone was performed by the ceric ion method. The number of polyacrylamide (PAM) chains grafted was dependent upon the concentration ratio of the redox catalyst system at constant acid concentration and increased in proportion to the ceric ion concentration. A maximum number of grafts obtained, for example, was 29 onto PMG (DP = 244) under the conditions [Ce4+]/[PMG] = 1/5, [H+] = 1.0 × 10−2 mole/l. In other words, the graft frequency was 12 per 100 monomer units of PMG. Such a high frequency of the grafts was, however, greatly decreased when the acid concentration was increased. Characteristics of the highly branched structure were revealed by the relationship between intrinsic viscosity and graft frequency, which showed a downward curvature with the increasing graft frequency. Influences of acid and ceric ion concentrations on the copolymerization were kinetically evaluated. The rate of polymerization was found to be first‐order with respect to ceric ion and proportional to the square of the reciprocal acid concentration. The result suggests that the graft frequency is dependent upon the rate of polymerization.
Copolymerization behavior of vinylimidazolium salts
Authors: Salamone J. C. , Taylor P. , Snider B. , Israel S. C.
Published: April 2003

Copolymerization studies of cationic monomers have been reported in the literature to yield wide variations in reactivity ratios and Q–e values, depending on the comonomer and the nature of the solvent. In this work are presented the copolymerization characteristics of a variety of vinylimidazolium salts in both water and ethanol solution. From these studies, the effect of solvent polarity, of substitution at the imidazolium 2‐position, of the type of counterion, and of the hydrophilic–hydrophobic character of the monomeric salts could be ascertained. The results of the study are consistent with other related investigations, in that solvent polarity and comonomer both strongly affected copolymerization.
Solid‐state ultraviolet irradiation of some maleimides and bismaleimides
Authors: Boens N. , De Schryver F. C. , Smets G.
Published: April 2003

The solid‐state photoreactivity of a series of maleimides and bismaleimides is studied Various crystalline maleimides are found to dimerize on irradiation by ultraviolet light Based on this discovery, the photopolymerizability of the related bismaleimides in the crystalline state is examined. As a result it is found that some N,N,‐alkylenebismaleimides polymerize into highly crystalline polymers. The polymers do not melt below their decomposition temperature (>300°C) and are practically insoluble in all solvents. The obtained irradiation products are different from the reaction products of the solution‐phase photochemistry. Closely related bismaleimides, such as members of a homologous series, show substantial differences in their solid‐state photochemical behavior; on excitation they either lead to polymers or are not reactive. This indicates that the solid‐state photoreactivity of maleimides and bismaleimides is controlled by the geometry of their crystal structure.