bluuebunny/crossref_metadata_2025 huggingface dataset:
Photochemical reactions of high polymers. XIV. Syntheses and photochemical reactions of copolymers bearing O‐acyloxime groups
Authors: Tsunooka Masahiro , Kotera Kohei , Tanaka Makoto
Published: April 2003

Copolymers bearing pendant O‐acyloxime groups were synthesized by two methods: copolymerizations of oxime acrylate (methyl β‐naphthyl ketone oxime acrylate or benzophenone oxime acrylate) and styrene, condensation of acrylic acid—styrene copolymer with oximes (benzophenone oxime, p‐nitrobenzophenone oxime, methyl β‐naphthyl ketone oxime, benzalacetone oxime or 9‐fluorenone oxime). The photochemical behavior of the O‐acyloxime copolymers changed markedly with the irradiation conditions: irradiation of benzene solutions led to degradation in air and crosslinking under nitrogen, while irradiation of solid films in air resulted in simultaneous degradation and crosslinking. Photolysis of methyl β‐naphthyl ketone oxime acetate, a model for the O‐acyloxime copolymer, in benzene solution under nitrogen resulted in scission of the NO bond. The same reaction was observed in the irradiation of the O‐acyloxime copolymers. It is suggested that formation of free radicals on the polymer chains via scission of the NO bond is followed by decarboxylation. In the absence of oxygen, crosslinking of the polymer by recombination of the free radicals competes with degradation via β‐scission. In the presence of oxygen, autoxidative degradation predominates.
Evidence of crosslinking and chain scission in the degradation of poly(tert‐butyl crotonate) by γ‐irradiation
Authors: O'Donnell J. H. , Rahman N. P. , Winzor D. J.
Published: April 2003

The effect of γ‐irradiation on poly(tert‐butyl crotonate) has been investigated by velocity sedimentation and solubility studies. Evidence of significant crosslinking as well as of chain scission has been obtained, the estimates of G(X) and G(S) being 0.66 and 0.59, respectively.
Reactivity of fluorostyrenes in cationic polymerization
Authors: Laval F. , Marechal E.
Published: April 2003

Reactivity ratios relative for cationic copolymerization of three fluorostyrenes and styrene were studied. The values of r1 and r2 for various experimental conditions were determined. The influence of the nature of the solvent and of the polymerization temperature were studied in particular. Relative activation entropies and enthalpies were determined, and an isokinetic relationship was found for 2‐, 3‐, and 4‐fluorostyrenes. There is a fairly linear correlation between the C8 chemical shift and the values of 1/r2. All the experimental reactivities were correlated with the quantum chemistry parameters. From this correlation, interaction with C8 and also with C7 and F, was found to be possible, depending on the nature of the monomer.
Conformation of syndiotactic poly(styrenesulfonic acid)
Authors: Aylward N. N.
Published: April 2003

A conformational energy map for syndiotactic PSSA indicates that a planar trans sequence of chemical repeat units with a side‐chain orientation of χ ≃ 10° is favored over helix or glide‐plane sequences. As the electrostatic potential of this planar sequence is greater than for the (0°,−120°) or (0°, −80°) sequences it is especially favored under conditions of high ionic strength. Only a very small energy is needed to cause rotational transitions from a planar trans sequence, so that many different sequences exist at any one time in solution. Sequences such as (0°,−20°) are calculated to be hypochromic with respect to the other probable sequences, and this seems consistent with some experimental evidence on the apparent hypochromicity of the band near 261.5 nm under conditions of high ionic strength.
Hydrothermal contraction–dilation of polymer networks by reversible complexation with a complementary macromolecule
Authors: Osada Yoshihito
Published: April 2003

A mechanochemical system which works by complexation between a poly(methacrylic acid) (PMAA) network and poly(ethylene glycol) (PEG) was studied. A PMAA membrane swollen with an aqueous PEG solution, to which a load 100 times the weight of the membrane was attached, contracts by over 90% of its length when heated from 10°C to 60°C. The work per contraction was 5 × 10−3 cal/g of membrane. The temperature at which the mechanochemical system undergoes a specified contraction can be regulated by the PEG concentration of the swelling fluid. The sign of the temperature coefficient of the membrane dimension can be reversed by addition of a small amount of ethanol to the swelling solution of PEG. A simple method for calculating the stability constant and thermodynamic parameters for the complexation is outlined.
Synthesis of hydroxyl‐containing polyamides by ring‐opening polyaddition of 4,4′‐disubstituted bis(4‐butanolide) with aliphatic diamines
Authors: Ueda Mitsuru , Yabuuchi Masahiko , Imai Yoshio
Published: April 2003

Hydroxyl‐containing polyamides have been prepared by the ring‐opening polyaddition of 4,4′‐oxydi‐p‐phenylenebis(4‐butanolide) with aliphatic diamines in alcoholic solvents at 65–80°C. These polymers having inherent viscosities ranging from 0.1 to 0.5 were soluble in a variety of solvents including dimethylformamide, formic acid, and m‐cresol. Transparent and flexible films cast from these solutions were highly hygroscopic. All the polymers had low softing temperatures in the range of 115–130°C, and began to decompose at around 250°C, both in air and under nitrogen.
Selective dimerization of styrene to 1,3‐diphenyl‐1‐butene by acetyl perchlorate
Authors: Higashimura Toshinobu , Nishii Hideo
Published: April 2003

The linear unsaturated dimer of styrene, 1,3‐diphenyl‐1‐butene, was obtained exclusively in the oligomerization of styrene by acetyl perchlorate in various solvents. In benzene, the linear dimer was produced in more than 90% yield at 50°C. In n‐hexane and cyclohexane, the yield of the linear dimer was lower. The yield of the linear dimer was strongly dependent on the nature of solvent. When an increasing amount of 1,2‐dichloroethane was added to benzene, the yield of the linear dimer gradually decreased. On the other hand, when a small amount of 1,2‐dichloroethane was added to n‐hexane or cyclohexane, the yield of the linear dimer increased. The yield of the linear dimer was almost independent of the reaction temperature and the initiator concentration. For comparison, the dimerization of α‐methylstyrene was carried out, and the effects of the initiator and the solvent on the structure of dimers were investigated. On the basis of these results, the mechanism of the dimerization of styrene initiated by acetyl perchlorate is discussed.
Some aspects on the polymerization of N‐vinylpyrrolidone in the presence of poly(methacrylic acid) templates
Authors: Bartels T. , Tan Y. Y. , Challa G.
Published: April 2003

N‐Vinylpyrrolidone (NVP) was polymerized in dimethylformamide (DMF) at 60°C in the presence of poly(methacrylic acids) (PMAA) of different tacticities and molecular weights. The rate enhancement, which was ascribed to chain growth of the poly(vinylpyrrolidone) (PVP) radical along the polyacid template, became more pronounced with increasing chain length and syndiotacticity of the PMAA template. The results can be expressed by vR = aPvn, where vR is the polymerization rate relative to that of the blank experiment, Pv is the viscosity‐average degree of polymerization of PMAA, and a and n are constants depending on the reaction conditions and tacticity of PMAA. In the presence of excess monomer the rate enhancement decreased when the quantity of PVP produced corresponded to a stoichiometric ratio of 1:1 with the available PMAA. It is proposed that the template effect is caused mainly by delay of the bimolecular termination step of growing PVP radicals associated with PMAA. Diffusion of polymer radicals, and consequently termination, will be more impaired if the attached PMAA has a greater length (size) and if the binding forces between PVP radical and PMAA template are stronger. The latter implies that PVP forms the strongest complexes with syndiotactic PMAA. This is supported by experiments concerning complex stability.
Syntheses and reactions of optically active polymers. II. Preparations of optically active polymers containing quinine, L‐ephedrine, and L‐histidine residues and their reactions with α‐cyanoethylaquocobaloxime
Authors: Narita Mitsuaki
Published: April 2003

Preparations of polymers with bis(dimethylglyoximato)cobalt (cobaloxime) were investigated. 4‐Vinylpyridine was reacted with α‐cyanoethylaquocobaloxime to produce α‐cyanoethyl‐4‐vinylpyridinatocobaloxime (I) in 72% yield. It did not, however, polymerize by the use of azobisisobutyronitrile (AIBN) as an initiator. Polymers containing α‐cyanoethylcobaloxime were obtained by reactions of polymers with α‐cyanoethylaquocobaloxime (II). Poly(9‐O‐methacryloylquinine) (III), poly(O‐methacryloyl‐N‐methyl‐L‐ephedrine) (IV), poly[Nα‐(o‐vinylbenzyl)‐L‐histidine] (V), and poly(4‐vinylpyridine) (VI) were prepared and used in these reactions. Polymers V and VI were reacted with II to give polymers X, XI, XII, and XIII containing α‐cyanoethylcobaloxime.
Kinetics and thermodynamics of anionic polymerization of 2‐methoxy‐2‐oxo‐1,3,2‐dioxaphosphorinane
Authors: Łapienis Grzegorz , Penczek Stanisław
Published: April 2003

Kinetic activation parameters and thermodynamic functions describing the reversible anionic polymerization of 2‐methoxy‐2‐oxo‐1,3,2‐dioxaphosphorinane (1,3‐propylene methyl phosphate) were determined. Enthalpy and entropy of the anionic propagation ⇌ depropagation equilibrium were found to be close to those found previously by the present authors for the cationic polymerization, while the activation parameters of propagation and depropagation differ substantially for both processes and reflect the differences in the involved mechanisms. Thus, data for anionic polymerization (and cationic polymerization in parentheses) are: ΔH1s° = −0.7 kcal/mole (−1.1); ΔS1s° = −2.8 cal/mole‐deg (−5.4); ΔHp‡ = 26.7 kcal/mole, and ΔSp‡ = −6.1 cal/mole‐deg. The polymers obtained have low degrees of polymerization (DPn ≤ 10) because of the extensive chain transfer, leaving cyclic end groups in macromolecules. The presence, structure and concentration of the end groups have been determined by 1H‐, 31P‐, and 13C‐NMR spectra.
Stoichiometric formation of methyl methacrylate oligomer by triethylaluminum in the presence of azobisisobutyronitrile
Authors: Grotewold Juan , Hirschler Marcello M.
Published: April 2003

The yield of methyl methacrylate (MMA) polymerization as a function of triethylaluminum (TEA) concentration for a constant azobisisobutyronitrile (AIBN) concentration at 50°C has been measured. The polymerization yield does not differ markedly from that with AIBN alone as long as the initial TEA concentration is held smaller than four times the initial AIBN concentration. A sudden decrease in yield and molecular weight is observed at TEA/AIBN concentration ratios between 4 and 5. A plot of M̄w−1 vs. TEA gives a rate‐transfer constant of 89 1./mole‐sec. If the reaction mixture is vacuum‐evaporated with a previous addition of water, instead of precipitating the polymer, the formation of a considerable amount of MMA oligomer is detected for TEA/AIBN concentration ratios larger than 4. On the average, each TEA molecule in excess of four times the initial amount of AIBN yields one oligomer molecule. The data are consistent with a radical polymerization mechanism for the high molecular weight polymer and with a nonradical one for the oligomer formation.
Some properties of intermediate regions in interpenetrating polymeric networks
Authors: Lipatov Yu. S. , Chramova T. S. , Sergeeva L. M. , Karabanova L. V.
Published: April 2003

The molecular mobility in an interpenetrating polymeric network (IPN) based on crosslinked polyurethane (1) and styrene–divinylbenzene copolymer (2) was studied by broad‐line NMR spectroscopy and reversed gas chromatography. NMR and infrared investigations show the absence of chemical interaction between the two constituent networks. For an IPN in the temperature range −196 to 120°C transition regions corresponding to the individual networks and to an intermediate region were found, the latter being characterized by an additional transition at 25–60°C (NMR spectroscopy) and 44–78°C (gas chromatography). The existence of an intermediate region, presumably of loosely packed structure, leads to a shift in the beginning of the temperature transition in IPN to lower temperature and to a decrease in activation energies of relaxation in comparison with the individual networks. The activation energies in IPN are decreased with increasing weight fraction of the second network.
Kinetics of diffusion‐free radiation graft polymerization of styrene onto polyethylene
Authors: Rabie Abdelgawad , Odian George
Published: April 2003

The diffusion‐free radiation graft polymerization of styrene onto polyethylene has been studied. The grafting rate shows a dependence on monomer which is far different than what has been assumed. Further, the dependence on monomer changes with increasing dose rate as does the dependence of grafting rate on radiation dose rate. Three different regions of behavior are defined: (1) a region of low dose rate where the grafting rate is 1/2‐order in dose rate and 3/2‐order in monomer; (2) a region of intermediate dose rate where the grafting rate is intermediate between 1/2‐and zero‐order in dose rate and 5/2‐order in monomer; and (3) a region of high dose rate, where the grafting rate is independent of dose rate and at least 5/2‐order in monomer. Various possible mechanisms responsible for these effects are discussed, including the effects of viscosity on the initiation and termination reactions, the possibility of ionic graft polymerization, and energy transfer.
Antimony oxide–PVC synergism: Laser pyrolysis studies of the interaction mechanism
Authors: Lum R. M.
Published: April 2003

Laser‐probe pyrolysis is used to investigate the synergistic flame‐retardancy effect observed for antimony oxide (Sb2O3)–PVC combinations. Molecular beam‐mass analysis detection techniques permit direct sampling of the laser‐vaporized species without the need for intermediate product collection stages. Laser pyrolysis of a PVC formulation containing 3 phr Sb2O3 provides the first direct evidence for the production of volatile SbCl3 during thermal decomposition. Selective laser irradiation of PVC in the presence of unheated Sb2O3 in the sample cell reveals that HCl evolved from the polymer substrate rapidly reacts with Sb2O3(s) to form the volatile flame‐retardant species SbCl3. Similar results are observed for SbOCl(s). These reactions are distinct from those previously proposed, which involve the formation and subsequent thermal decomposition of intermediate solid‐phase antimony oxychlorides, and demonstrate that the antimony compounds, rather than serving only as inert sources for SbCl3, readily participate in direct chemical reactions with HCl. In addition to the composition of the reaction products, information is also obtained on their evolution characteristics from the sample cell.
Polystyrene resins with immobilized polyamines: Preparation, characterization, and ability to bind Cu(II) ions
Authors: Shambhu Manvendra B. , Theodorakis Michael C. , Digenis George A.
Published: April 2003

Three polyamine ligands, ethylenediamine (EDA), diethylenetriamine (DTA), and triethylenetetramine (TETA), were bound to three chloromethylated “popcorn” polystyrene resins (16, 50, and 100% phenyl ring substitution) with the use of pyridine as the reaction medium. The rate of chloride displacement decreased with increasing molecular weight of the amine and higher degree of resin chloromethylation, while the extent of multiple attachments to the polymer matrix increased. The additional crosslinking, a result of multiple attachments, caused the polyamine resins to swell to a lesser extent in pyridine and water. The ability of the insoluble polyamine–polystyrene resins to chelate Cu2+ ions from dilute solutions (200 ppm) was determined at pH 5. With EDA resins the capacity for Cu2+ increased with increasing amount of the bound polyamine, with DTA it remained unchanged, while with TETA it was found to decrease.
Polymerization of vinyl chloride with organolithium compounds. V. Fractionation and solution properties of high molecular weight poly(vinyl chloride)
Authors: Jíšová V. , Janča J. , Kolínský M.
Published: April 2003

A sample of high molecular weight poly(vinyl chloride) (PVC) was fractionated by classical precipitation fractionation and gel‐permeation chromatography (GPC) on a preparative scale. The fractions thus obtained were characterized by light scattering, viscometry, and by the GPC method. The measured weight‐average molecular weights M̄w, intrinsic viscosity [η], and polydispersity index M̄w/M̄n values were used for the determination of the Mark‐Houwink equation, [η] = KMa, for PVC in cyclohexanone (CHX) at 25°C valid for molecular weights from 100,000 to 625,000.
Phosphonylation of a polypentenamer and preparation of its hydrogenated derivatives
Authors: Azuma C. , Macknight W. J.
Published: April 2003

Phosphonylated derivatives of a polypentenamer (PP) containing 82% trans and 17% cis double bonds have been prepared by the free‐radical addition of dimethylphosphite to the double bonds and subsequent hydrogenation of the residual unsaturation. In this way derivatives were prepared containing approximately 5 and 10 mole % dimethylphosphonate side groups. These side groups were further reacted by hydrolysis or neutralization to form phosphonic acid and cesium phosphonate salts. Reaction conditions were so chosen that no backbone degradation occurred, and side reactions leading to crosslinking were avoided. The derivatives were characterized by gel‐permeation chromatography (GPC), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy, and nuclear magnetic resonance spectroscopy. It was found that increasing substituent concentration decreases the melting point Tm in the case of the hydrogenated derivatives and increases the glass transition temperature Tg in the case of the unhydrogenated derivatives. The free acid derivatives are the least thermally stable of all those studied and the hydrogenated derivatives are generally more stable than the unhydrogenated derivatives.
Determination of unsaturated structures in poly(vinyl chloride) by means of fourier transform 1H‐NMR spectroscopy
Authors: Caraculacu A. , Bezdadea E.
Published: April 2003

A method based on the PFT‐NMR technique was developed for a direct determination of unsaturated end groups in PVC. By using NMR proton spectra it was found that the unsaturated groups in PVC contain allylic chlorine atoms. Three types of unsaturated end groups were identified, corresponding to the following models: 3‐chloro‐1‐pentene, 2,3‐dichloro‐1‐pentene, and 1,2‐dichloro‐2‐pentene. The last two types could also correspond to some unsaturated groups on the backbone bearing allylic chlorine atoms. The presence of such groups would partially explain the PVC degradation.
New monomers and polymers. V. Study of the spontaneous polymerization of 5‐ethoxycarbonyl‐3‐formyl‐2‐pyrazoline
Authors: Braham J. N. , Noels A. F. , Teyssié Ph.
Published: April 2003

The 3‐formyl‐2‐pyrazolines (pyrazoline‐3‐carboxaldehyde) obtained by 1–3 dipolar additions of diazoesters to acrolein are unstable and smoothly polymerize through the aldehyde group to a polyacetal polymer. On the basis of spectroscopic data, this paper describes the structure of the isolated polymers, along with their properties and a polymerization mechanism. It is proposed that a nucleophilic attack of an heterocyclic amino nitrogen on another monomer formyl group leads to an internal ion pair, and that this latter promotes a polycondensation of other aldehydic units according to an anionic type of propagation. The results are polyacetal polymers of low molecular weight with conservation of the heterocyclic framework. However, numerous side reactions are possible and account for the relatively low molecular weights observed.
Oligomérisation anionique de l'ethylène. III. Application à la synthèse d'alcools à longue chaine
Authors: Magnin Henri , Rodriguez Firmin , Abadie Marc , Schué François
Published: April 2003

Living oligomers of ethylene obtained by n‐BuLi complexed with TMEDA have been deactivated by ethylene oxide. The nuclear magnetic resonance study of the product obtained allowed us to follow the influence of TMEDA toward the functionalization. Three products have been characterized:

By increasing the ratio [TMEDA]/[n‐BuLi] one obtains a decrease of the functionalization reaction.
D2‐m‐carborane‐siloxanes. III. Preparation and properties of trifluoropropyl‐modified polymers
Authors: Peters E. N. , Stewart D. D. , Bohan J. J. , Moffitt R. , Beard C. D. , Kwiatkowski G. T. , Hedaya E.
Published: April 2003

Linear D2‐m‐carborane‐siloxanes with one, two, and three trifluoropropyl moieties per repeat unit were prepared by the condensation reaction between bisureidosilanes and carborane disilanol. Molecular weights between 100,000 and 220,000 were obtained. Compared to fluorosilicones, the trifluoropropyl‐modified carborane‐siloxanes exhibited greater thermal and oxidative stability and in certain cases comparable solvent resistance. The swelling index for carborane‐siloxane elastomers decreased with increasing trifluoropropyl content, although this fluorocarbon moiety did compromise the thermal stability of the carborane system.
Calculation of the elementary rate constants of polymer‐analogous reactions and sequence analysis of products
Authors: Stoy V.
Published: April 2003

A method has been developed for the calculation of elementary rate constants of deceleration and acceleration reactions on polymers in which the reactivity of the group is influenced only by the character of the closest adjacent groups. It is suggested that this method may be valid if the calculation yields a rate constant k′3, which is independent of conversion. In this case, the sequence analysis of products can be performed by using Markovian first‐order statistics, and the rate constants thus obtained can be used for calculating the relative frequencies of variously long sequences of reacted and unreacted groups and their number‐average length. For markedly accelerated reactions, a simplified method of estimation of the average sequence length involving use of two of the three elementary rate constants, i.e., k1 and k′2, has been suggested.
Active polycondensation with hexamethylenediamine of sebacates having 1,4‐pyrone nuclei
Authors: Sanui Kohei , Tanaka Saeko , Ogata Naoya
Published: April 2003

Sebacates from alcohols having a 1,4‐pyrone nucleus were synthesized, and their reactivities toward diamine were investigated. The polycondensation reactions of di(6‐hydroxymethyl‐1,4‐pyron‐3‐yl) sebacate or di(2‐methyl‐1,4‐pyron‐3‐yl) sebacate with hexamethylenediamine took place easily even at room temperature to form a high molecular weight nylon 610 in a quantitative yield. The reactivities of these active diesters with diamine were much higher than that of the corresponding diphenyl ester and were almost comparable to those of acid chlorides. It was also found that inorganic salts such as lithium chloride, zinc chloride, or calcium chloride had a strong influence on the molecular weight of the resulting polyamide. The reactivity enhancement of the active diesters toward aminolysis could be attributed mainly to the acidic character of the leaving group.
Influence of the solvents on the γ‐ray polymerization of acrylic acid. II.
Authors: Laborie Francoise
Published: April 2003

The presence of plurimolecular H‐bonded aggregates in the acrylic acid allows the polymer to involve some stereoregular sequences. This effect is made easier when some polymer is already formed in the reacting medium: the aggregates are stabilized by hydrogen bonds with the polymer which gives rise to a matrix effect. Two groups of solvents have been characterized by examination of the monomer's association forms in solution. In a first group of solvents (methanol–dioxan–water), the aggregates are maintained and reinforced; in the second one, acrylic acid exists only as cyclic dimers (hydrocarbons–chlorinated solvents). The difference between the association forms of the monomer involves some important modifications on the kinetics of polymerization and the structure of the obtained polymers. In the solvents of the first group, the obtained polymers are crystallizable and may involve syndiotactic sequences, while in the presence of the solvents of the second group no crystallization or stereoregularity of the polymer can occur. A very close correlation is thus found between the aggregated structure of the monomer, the polymerization kinetics, and the structure of the polymers.
Effects of lithium bromide on the gel‐permeation chromatography of polyester‐based polyurethanes in dimethylformamide
Authors: Hann Nancy D.
Published: April 2003

The hydrodynamic volume changes of the polyester‐based polyurethanes, as dimethylformamide solutions with and without lithium bromide, were studied. Gel‐permeation chromatographic (GPC) and intrinsic viscosity techniques were employed as methods for characterization. Decreases in intrinsic viscosity as well as dramatic changes in the GPC chromatograms were observed. These observations are explained by the polarity of these polyester‐based polyurethane molecules and the resulting characteristics of molecular expansion, association, and polymer–column interaction normally associated with polyelectrolytes.
Photoinitiated polymerization of methyl methacrylate and methyl acrylate with 14C‐labeled benzoin methyl ethers
Authors: Carlblom L. H. , Pappas S. P.
Published: April 2003

Three 14C‐labeled benzoin methyl ether (α‐methoxy‐α‐phenylacetophenone) derivatives were utilized as photoinitiators in the polymerization of methyl methacrylate (MMA) and methyl acrylate (MA). The results of polymer end‐group analysis are in accord with a mechanism of benzoin ether photocleavage into initiator radicals and dispute earlier labeling studies which were interpreted as evidence for copolymerization of excited‐state benzoin ethers with reactive monomers. In MMA polymerization, the results indicate a preference for termination by disproportionation (∼60%) and provide evidence for primary radical termination at 0.041M photoinitiator (optically dense solutions) in neat MMA. Evidence for chain branching by initiator radical hydrogen abstraction from poly(methyl acrylate) (PMA) is also presented. The benzoyl and α‐methoxybenzyl radicals, produced on photolysis of benzoin methyl ether, appear to be equally effective in both initiation and hydrogen‐abstraction processes. Quantum yields at 366 and 313 nm indicate the absence of a wavelength effect.
Functional end‐group polymers derived from free‐radical chain transfer. I. Kinetic prediction of functionality
Authors: Athey R. D. , Mosher W. A. , Weston N. W.
Published: April 2003

The kinetic scheme describing chain transfer in free‐radical polymerizations, the Mayo equation, has been rearranged to yield the probability of generating a functional end group by chain transfer (e.g., to a disulfide). The prediction is that a mixture of functional and nonfunctional ends occurs. Examination of literature data shows a number of systems produce more functionality than predicted. Hence, the challenge to devise a new kinetic scheme to account for the increased functionality is made (e.g., by selective reaction of initiator with chain‐transfer agent).
Alternating ethylene–alkyl acrylate copolymers. II. Polymer properties
Authors: Logothetis A. L. , McKenna J. M.
Published: April 2003

Properties such as viscosity correlations and spectral data of alternating ethylene–ethyl acrylate copolymers are described. The proton and 13C‐NMR spectra show that there is a considerable amount of tacticity in these polymers. Although the alternating configuration predominates, there is also some random structure present. Terpolymers were prepared with cure‐site monomers, such as 2‐chloroethyl acrylate. The terpolymers were compounded with carbon black and cured to give vulcanizates with excellent properties. The cured products are resistant to oil, water, heat, and oxidation. They also have good low temperature properties (stiffening temperature −31°C, brittleness temperature −50°C), tensile properties (tensile strength 17.2 MPa, elongation at break 250%) and compression sets (25% at 150°C for 70 hr).
Copolymerization of ethylene with a homologous series of vinyl esters
Authors: Van der Meer R. , Van Gorp E. H. M. , German A. L.
Published: April 2003

The effect of the alkyl group on the relative reactivity of a homologous series of vinyl esters (2) has been studied with ethylene (1) as reference monomer, tert‐butyl alcohol as solvent, at 62°C and 35 kg/cm2. The experimental method was based on frequent measurement of the monomer feed composition throughout the copolymerization reaction by means of quantitative gas‐chromatographic analysis. Highly accurate monomer reactivity ratios were estimated in a statistically justified manner by a nonlinear least‐squares method applied to the integrated copolymer equation. The reactivity of the vinyl ester monomers towards an ethylene radical increased with decreasing electron‐with‐drawing ability of the ester group. All vinyl ester radicals considered turned out to have the same preference for their own monomer over ethylene (constant r2 = 1.50). Reactivity ratios are discussed in terms of the Q–e scheme and the Taft relation. It appeared that chiefly polar factors contribute to the observed relative reactivity, while probably resonance stabilization only plays a minor part. Steric hindrance seems to impair monomer reactivity, only from vinyl pivalate on. Relative reactivities of the vinyl esters are compared with literature values, where other reference monomers have been used.
Electrochemically initiated polymerization of styrene with tetraalkyl and ‐aryl group VA halide support electrolytes
Authors: Smith J. D. B. , Phillips D. C. , Davies D. H.
Published: April 2003

The electrochemically initiated polymerization of styrene in methylene chloride solvent with the use of platinum electrodes and tetraalkyl and ‐aryl group VA halides (i.e., quaternary ammonium, phosphonium, and arsonium compounds) as electrolyte has been investigated. The order of reactivity of the electrolytes with respect to polymerization rate and initiation efficiency was found to be: arsonium > phosphonium > ammonium. Mechanisms involving the electroreduction of the group VA quaternary halides to species capable of electroinitiating polymerization are postulated. The observed losses in solution conductivities during polymerization with the quaternary phosphonium and arsonium electrolytes indicate possible interaction between the initiating radical‐ionic species and the supporting electrolyte. In an attempt to further elucidate the mechanism of initiation in these systems, a separate series of experiments, employing the nonpolymerizing monomer, 1,1‐diphenylethylene, has been carried out.
Polymerization of propiolaldehyde. IV. Synthesis of a functional polymer having an ethynyl group
Authors: Kobayashi Kazukiyo , Sumitomo Hiroshi , Shibata Keiko
Published: April 2003

The cationic homopolymerization and copolymerization of propiolaldehyde were carried out with use of boron trifluoride etherate as an initiator at the temperatures of 0 to −78°C. Poly(ethynyl)oxymethylene was prepared by the homopolymerization at −78°C, but it was readily depolymerized to the monomer. The cationic copolymerization with styrene at −78°C proceeded almost exclusively through the aldehyde addition and a new functional copolymer was obtained. With a rise in polymerization temperature, the ethynyl addition was mixed slightly.
Synthesis of novel photodegradable poly(o‐nitrobenzaldehyde acetal) polymers
Authors: Petropoulos Constantine C.
Published: April 2003

The synthesis of novel photodegradable poly(o‐nitrobenzaldehyde acetals) is described. The polymers were prepared by condensing o‐nitrobenzaldehyde with a series of glycols. Polyesteracetals can also be prepared by first preparing the o‐nitrobenzaldehyde glycol acetal or polyacetal prepolymer and subsequent reaction with a diacid chloride. These polymers, although light sensitive, appear to be thermally stable since they were prepared in part by melt condensation techniques. The polymers are useful as positive working photodegradable polymers.
Polyurethanes. IV. Effect of poly(propylene glycol) tacticity on the properties of block copolyether‐urethanes
Authors: Shibatani K. , Lyman D. J. , Shieh D. F. , Knutson K.
Published: April 2003

Block copolyèther–urethane–ureas containing isotatic polypropylene glycols were synthesized and their dynamic mechanical properties compared to the analogous atactic structures. At poly(propylene glycol) molecular weights below 1000, tacticity appears to have little effect on the stress–strain properties of the block copolymers. At higher molecular weights, the ability of the isotatic polyglycol segments to crystallize under strain can effect cyclic deformation properties.
Anionic homopolymerization of ferrocenylmethyl methacrylate
Authors: Pittman Charles U. , Hirao Akira
Published: April 2003

Anionic polymerization of ferrocenylmethyl methacrylate (FMMA) was investigated using high‐vacuum techniques. Initiators used included n‐butyllithium, sodium naphthalide, potassium naphthalide, Grignard reagents (both C2H5MgBr and C6H5MgBr), sodium methoxide, and lithium aluminum hydride. FMMA polymerization was readily initiated by each of the above initiators with the exception of sodium methoxide. The molecular weight of poly(ferrocenylmethyl methacrylate) could be controlled by varying the monomer‐to‐initiator ratio when lithium aluminum hydride was used in tetrahydrofuran (THF). In this system, poly(ferrocenylmethyl methacrylate), soluble in benzene or THF, was prepared with M̄n as high as 277,000 with a relatively narrow molecular weight distribution compared to samples prepared by radical‐initiated polymerization. The Mark‐Houwink values of K and a, determined in THF, were K = 4.94 × 10−2 and a = 0.53 (when M = M̄n) and K = 3.72 × 10−2 and a = 0.51 (when M = M̄w). It is clear that the polymer is moderately coiled in THF.
Cografting kinetics of styrene and ethyl acrylate onto polyethylene
Authors: Takahashi Tohru , Yasukawa Tamio , Murakami Kenkichi , Ohmichi Hideki , Sasuga Tsuneo , Araki Kunio
Published: April 2003

Kinetic studies of cografting reactions of styrene (St) and ethyl acrylate (EA) onto preirradiated polyethylene (PE) have been investigated by means of bromine labeling and infrared spectroscopy. Kinetic data obtained from these methods, that is, the percent grafting, the number of graft chains, and growing rates, were obtained at temperatures of 0, 20, 40, and 50°C. The graft percent was virtually influenced by the degree of swelling. At 0°C, the mixing ratio of ethyl acrylate and styrene monomer before the beginning of the reaction was equal to the existence ratio in the graft chains after the reaction. Therefore, this reaction is considered to be diffusion‐controlled. On the contrary, at 20 and 40°C, the existence ratio in graft chains after the reaction. Therefore, this reaction is considered to be diffusion‐controlled. On the contrary, at 20 and 40°C, the existence ratio in graft chains agreed with the theoretical curve calculated from monomer reactivity ratio. The number of active graft chains for given times were 3∼5 × 10−7 mole/g PE and it decreased with temperature; 0 > 20 > 50°C. While the total number of graft chains is 5∼15 × 10−7 mole/g PE and it increased with temperature; 0 < 20 < 50°C. The growing rate were 1∼5 monomer/site/sec for 0°C, 2∼15 for 20°C.
NMR studies on the reaction between methacrylonitrile and trimethylaluminum
Authors: Koma Yasuo , Iimura Kazuyoshi , Kondo Shoichi , Takeda Masatami
Published: April 2003

The reaction of MAN with AlMe3 was studied by the 13C‐ and 1H‐NMR spectral measurement. In the presence of an excess of AlMe3, it was found that a 1:1 complex of MAN and AlMe3 is initially formed and subsequently dimethyl(α‐methyl isopropylidene amino)aluminum is produced by the reaction of the complex with AlMe3. The isolated product was pale yellow crystal (mp 39–40°C). The kinetics of the reaction were also examined.
Novel solvent effects in the photopolymerization of methyl methacrylate by use of quinoline–bromine charge‐transfer complex as photoinitiator
Authors: Ghosh Premamoy , Mitra Partha Sarathi
Published: April 2003

Photopolymerization of MMA was carried out at 40°C in diluted systems by use of quinolinebromine (Q–Br2) charge‐transfer complex as the initiator and chloroform, carbon tetrachloride, chlorobenzene, dioxane, THF, acetone, benzene, toluene, quinoline, and pyridine as solvents. The results showed variable monomer exponents ranging from 1 to 3. For chloroform, carbon tetrachloride, and chlorobenzene, the monomer exponent observed was unity; for other solvents used, the value of the same exponent was much higher (between 2 and 3). Initiation of polymerization is considered to take place through radicals generated in the polymerization systems by the photodecomposition of (Q–Br2)–monomer complex (C) formed instantaneously in situ on addition of the Q–Br2 complex in monomer. The kinetic feature of high monomer exponent is considered to be due to higher order of stabilization of the initiating complex (C) in presence of the respective solvents. In the presence of the retarding solvents, very low or zero initiator exponents were also observed, depending on the nature and concentration of the solvents used. The deviation from the square‐root dependence of rate on initiator concentration becomes higher at high solvent and initiator concentrations in general. This novel deviation is explained on the basis of initiator termination, probably via degradative chain transfer involving the solvent‐modified initiating complexes and the propagating radicals.
Chemical changes in polymeric photodielectric media used in holographic recording
Authors: Freilich Y. L. , Levy M. , Reich S.
Published: April 2003

Photochemical response of two thick photodielectric holographic recording systems was studied by using a 488 nm argon laser line. These systems are made of poly(methyl methacrylate) or poly(methyl α‐cyanoacrylate) with p‐benzoquinone as sensitizer. It was found that in both systems, photochemically induced branching, followed by crosslinking of the polymeric chains provide the major effects that modulate the index of refraction of these materials. The change in polymer structure as measured by intrinsic viscosity was correlated to the change in index of refraction, by which the holographic recording process is accomplished.
Polymerization of ordered tail‐to‐tail vinyl stearate bilayers
Authors: Enkelmann V. , Lando J. B.
Published: April 2003

This study is a continuation of previous work done in this laboratory which has demonstrated the possibility of polymerizing built‐up monomer multilayers in the solid state. In the present work, the formation, structure, and solid‐state polymerization of multilayers of vinyl stearate which can be built up by the method of Langmuir and Blodgett were studied. A new technique to polymerize such films under the water surface was developed. This made possible the formation of poly(vinyl stearate) multilayers with different molecular orientations through bilayer polymerization. The mechanism of deposition and the structure and properties of head‐to‐tail and head‐to‐head, tail‐to‐tail poly(vinyl stearate) multilayers were investigated by using Fourier‐Transform infrared spectroscopy, x‐ray diffraction, and electron diffraction.
Hydrolysis of activated esters catalyzed by L‐histidine graft copolymers
Authors: Overberger C. G. , Dixon K. W.
Published: April 2003

A graft copolymer of L‐histidine on polyethylenimine has been demonstrated to be an efficient catalyst for the hydrolysis of activated phenyl esters in aqueous systems. A lack of any significant cooperative effects between neighboring imidazoles or amines has been shown by a study of the catalytic solvolysis of p‐nitrophenyl acetate at varying pH. A similar study with 4‐acetoxy‐3‐nitrobenzoic acid has displayed a bell‐shaped pH‐rate profile indicative of electrostatic interactions between the catalyst and substrate. Hydrophobic interactions were also evident from an investigation of the hydrolytic rates of a series of 4‐acyloxy‐3‐nitrobenzoic acids. In an attempt to demonstrate stereospecific catalyzed reactions, the hydrolyses of optically active esters catalyzed by the optically active copolymer were studied.
Chloromethylation of polyphenylsiloxane prepolymers by silylation
Authors: Llauro M. F. , Bartholin M. , Guyot A.
Published: April 2003

Silylation of nonequilibrated phenyl‐T‐siloxane polycondensates by dimethylchloromethylchlorosilane involves only a small part of the silanol groups present in these prepolymers. At room temperature, silylation and condensation of the silanol groups occur at the same time. This condensation can be either intermolecular only or both intermolecular and intramolecular, depending on the initial condensation state of the prepolymer. It seems that no condensation reactions take place when the reaction is carried out with reflux. In any case, and even with strongly reactive disilazanes, no more than 35% of the silanol groups are consumed. The results give some information about a polymer, the structure of which is (after all) rather badly known.
Study on wholly aromatic polyamides containing methyl‐substituted phenylene linkage
Authors: Takatsuka Ryozo , Uno Keikichi , Toda Fujio , Iwakura Yoshio
Published: April 2003

In order to study the influence of chemical modification on properties of polyamides, wholly aromatic polyamides have been synthesized from p‐phenylenediamine, its 2,5‐dimethyl and 2‐methyl derivatives, m‐phenylenediamine, its 2‐methyl and 4‐methyl derivatives, and terephthaloyl and isophthaloyl dichlorides by solution polycondensation at low temperature. The thermal stability and solubility of the methyl‐substituted polyamides were compared with those of unsubstituted ones. The introduction of methyl groups in a polymeric chain led to a decrease in their thermal stability to different degrees depending on the positions of methyl groups, accompanied by an increase in their solubility. The unsymmetrical introduction of methyl groups in benzene rings had a greater effect on the increase in solubility of polyamide than did symmetrical methyl groups.
Radical polymerization of muconic acid and ethyl muconate
Authors: Bando Yoshifumi , Dodou Takeshi , Minoura Yuji
Published: April 2003

Muconic acid (Mu‐acid) was found to polymerize to trans‐1,4‐poly(Mu‐acid) with the use of azobisisobutyronitrile (AIBN) as an initiator. Similarly, a muconic acid derivative, ethyl muconate (EMu), was readily polymerized through a trans‐1,4 addition mechanism by the use of a radical or anionic catalyst, but did not polymerize when a cationic catalyst such as boron trifluoride etherate was used. Moreover, the copolymerization of Mu‐acid and EMu with various comonomers such as styrene, acryronitrile, and 2‐vinylpyridine was carried out and Q–e values of Mu‐acid and EMu are discussed. These substituted diene monomers always polymerized through trans‐1,4 addition with all catalysts and any comonomers.
Metal chelates in vinyl polymerization. I. Ferric dipivaloylmethide as an initiator
Authors: Prabha R. , Nandi U. S.
Published: April 2003

The behavior of the chelate, ferric dipivaloylmethide, Fe(DPM)3, in vinyl polymerization systems was investigated. The polymerization was found to be of free‐radical nature. The rate of polymerization was proportional to the square root of the concentration of the chelate. The monomer exponent was close to 1.5 for the Fe(DPM)3‐initiated polymerization of styrene and methyl methacrylate. The kinetic and transfer constants and activation energies for these systems have been evaluated. Spectral studies revealed the possibility of a complex formation between the chelate and the monomer. A kinetic scheme for the Fe(DPM)3‐initiated polymerization is derived based on this initial complex formation.
Metal chelates in vinyl polymerization. II. Mechanism of initiation by Fe(DPM)3
Authors: Prabha R. , Nandi U. S.
Published: April 2003

The nature of the interaction between the unsaturated monomer and the chelate, Fe(DPM)3, is studied in detail. The interaction is found to occur only in solution. The stoichiometry of interaction and the equilibrium constant are evaluated. With the help of spectral evidence, attempts are made to point out the specific sites of interaction.
Dielectric study of viscose rayon and viscose hydrocelluloses. I.
Authors: Shinouda H. G. , Hanna A. A. , Kinawi A.
Published: April 2003

Both dielectric and x‐ray results on viscose rayon and its hydrolysis residues show a rapid increase in the lateral order arrangement of the fiber chains in the earlier stages of hydrolysis. On the other hand, a divergence between the two measurements is found in the later stages of acid action. This is explained in terms of the role played by the fractions of molecular low dimensions which are in sensitive to x‐ray diffraction but contribute to the polarizability of the dielectrics.
Poly(vinyl chloride)–poly(ethylene oxide) block copolymers: Synthesis and characterization
Authors: Laverty John J. , Gardlund Zack G.
Published: April 2003

Poly(vinyl chloride)‐poly(ethylene oxide) block copolymers have been synthesized in solution and emulsion. The polymers were made by first synthesizing macroazonitriles through the reaction of 4,4′‐azobis‐4‐cyanovleryl chloride with hydroxy‐terminated poly(ethylene oxide) of varying molecular weights. These macroazonitriles had molecular weights in the range of 3000–88,000 and degrees of polymerization from 5 to 24. Thermal decomposition of the azolinkages in the presence of vinyl chloride monomer yielded block copolymers containing form 2 to 20 wt % poly(ethylene oxide). The structures of the block copolymers were characterized by spectrometric, elemental and molecular weight analyses. The possibility of some graft polymerization occurring via free‐radical extraction of a methylene hydrogen from the poly(ethylene oxide) was considered. Polymerization of vinyl chloride with an azonitrile initiator in the presence of a poly(ethylene oxide) yielded predominately homopolymer with some grafted poly(vinyl chloride).
Determination of alternation in copolymers by the excimer fluorescence method
Authors: Alexandru L. , Somersall A. C.
Published: April 2003

A novel method has been developed for the determination of the extent of alternation in copolymers in which one of the comonomers contains a fluorescent chromophore capable of intramolecular excimer formation. The ratio of excimer to monomer fluorescence intensity is linearly correlated with the fraction of adjacent fluorescent chromphores to isolated fluophores on the chain. The method is illustrated for the case of styrene‐acrylonitrile copolymers.
Functional monomers and polymers. XXXV. Oxidation of hydroquinone catalyzed by Cu(II)–polyelectrolyte complexes
Authors: Sato M. , Inaki Y. , Kondo K. , Takemoto K.
Published: April 2003

Oxidation of hydroquinone catalyzed by copper(II) complexes of poly‐1‐vinylimidazole, vinylamine‐vinylacetamide copolymer, and polyethyleneimine was studied in aqueous solution at 25°C. The rate of oxidation was determined spectrophotometrically over several pH values. The rate of copper(II) reduction was evaluated from copper(I)–cuproin complex formation, and the reoxidation of copper(I) to copper(II) was observed by visible spectroscopy. Among the copper(II) complexes, poly‐1‐vinylimidazole complex exhibited excellent catalytic activity, which amounted to over 20 times that of aqueous copper(II) ion solution, while the reduction of copper(II) in the former system was slower than that in the latter system. The reoxidation of copper(I) to copper(II) was found to be completed immediately in the presence of polymer ligands such as poly‐1‐vinylimidazole, while copper(I) ion was only slowly reoxidized. The discussion of the reaction mechanism emphasizes the importance of the reoxidation process.