bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoinduced electron transfer at the polymer‐solution interface. I. Surface property‐reactivity relation
Authors: Tazuke Shigeo , Takasaki Ryuichiro 
Published: April 2003

AbstractPhotooxidation of leuco crystal violet(LCV) to the dye(CV+) by interfacial sensitization with polymer‐bonded pyrenyl groups was studied. Poly(ethylene‐g‐acrylic acid) was esterified by 1‐hydroxymethylpyrene in tetrahydrofuran (THF) (Film 1) or in acetonitrile (Film 2). Film 2 had a more condensed but thinner pyrene‐containing surface layer than Film 1. Differences in surface structure were investigated by fluorescence and absorption spectra, as well as by measuring contant angle to water as a function of the total amount of bonded pyrene. Films 1 and 2 behaved differently in the photoreaction, which was interpreted as due to the difference in the affinity of LCV solution to the film surface, hence the diffusion of LCV into the film. The quantum efficiency of CV+ formation (ϕcv+) is therefore the function of the thickness of the photoabsorbing layer and the effective reaction volume determined by the depth of LCV diffusion. The role of excimer formation and energy migration among pyrenyl groups was concluded to be of minor importance.
Catalysis of enantiomeric ester hydrolysis by N‐decanoyl‐L‐histidine in polymer domains
Authors: Ihara Yasuji , Kimura Yoshiharu , Nango Mamoru , Kuroki Nobuhiko 
Published: April 2003

AbstractCatalytic hydrolysis of enantiomeric substrates by N‐decanoyl‐L‐histidine was studied at pH 7.30, 0.02M phosphate buffer, and 25°C in the presence of quaternized polymers. The rate of reaction is remarkably accelerated in the presence of polyethylenimine derivatives, but the observed stereoselectivity depends on the structure of the substrates.
The incorporation of heavy metals into diazo‐type electron beam resists
Authors: Lewis C. R. 
Published: April 2003

AbstractMetals may be chemically incorporated into organic lithographic resists that contain or can be functionalized with OH groups. A wide range of metal incorporation (0.04–12% of total solids by weight) has been demonstrated for AZ‐1370 (Shipley), a diazo‐type photo‐ and electron resist. The novolac component of the resist is reacted with an organometallic halide, RyMX (R = alkyl, aryl; M = transition or main group metal; X = CI, Br; 1 ≤ y ≤ 4, depending on M) to introduce the corresponding organometallic function into the resist.
Synthesis, characterization, and solution properties of 5‐ethyl‐substituted poly(L‐prolines). Synthesis of cis‐ and trans‐5‐ethyl‐L‐proline and optically active poly(cis‐5‐ethyl‐D‐proline)
Authors: Yang Wayne W.‐Y. , Overberger C. G. , Venkatachalam C. M. 
Published: April 2003

AbstractThis article reports a continuation of our work on the substituent effects on the preferred helical conformations and the mutarotation of substituted poly(L‐prolines). The size of the substituent has been increased from a methyl group to an ethyl group in the 5 position. The purpose is twofold: (i) according to our theoretical conformational energy calculations, an ethyl group in the 5 position can exert a greater steric effect than can a methyl group; and (ii) the rotation‐isomerization of the ethyl group introduces a new intriguing fact to the problem. The cis isomer of 5‐ethylproline was synthesized by catalytic hydrogenation of Δ′‐2‐ethylpyrroline‐5‐carboxylic acid, whereas for trans‐5‐ethylproline, a chemical separation method involving p‐toluenesulfonyl chloride was used. The resolution of cis‐5‐ethylproline and the assignment of absolute configurations have been carried out by fractional crystallization and circular dichroism spectroscopic techniques, respectively. Poly(cis‐5‐ethyl‐D‐proline) was obtained from its corresponding N‐carboxyanhydrides via a ring opening polymerization.
Solid‐state thermal polymerization of sodium acrylate
Authors: Verneker V. R. Pai , Vasanthakumari R. 
Published: April 2003

AbstractInitiation and propagation processes in thermally initiated solid‐state polymerization of sodium acrylate have been studied. The kinetics of initiation, followed with the electron spin resonance technique, leads to an activation energy E of 28.8 kcal/mol, which is attributed to the formation of dimeric radicals. The activation energy of 16 ± 1 kcal/mol obtained for the solid‐state polymerization of sodium acrylate by chemical analysis and differential scanning calorimetry has been attributed to the propagation process.
The pyrolysis and nonflaming oxidative degradation of poly(vinylfluoride)
Authors: Chatfield Dale A. 
Published: April 2003

AbstractThe thermal degradation of poly(vinylfluoride) (PVF) was studied under slow heating conditions to 1000°C with and without the presence of air. The degradation products, classified as low‐boiling volatiles, high‐boiling volatiles, and nonvolatile residues, were analyzed quantitatively by gas chromatography—mass spectrometry and several spectroscopic methods. Initial stages of degradation begin at 420°C with the evolution of HF and benzene and rapidly reach a maximum in sample weight loss by 450°C. One‐third of this weight loss was in the form of hydrofluoric acid (HF) and at least 70 low‐boiling volatile compounds that consisted of substituted aromatics, unsaturated hydrocarbons, and multiple‐ring compounds, many of which contained a fluorine atom. The high‐boiling volatile fraction contained compounds with more aliphatic but less aromatic character than the low‐boiling. The nonvolatile residue retained 4% of the original fluorine content and exhibited strong unsaturated character. In the presence of oxygen HF, CO, and H2O were the major constituents of the low‐boiling volatiles; the organic fraction was essentially unchanged in composition but reduced in overall concentration. The overall weight‐loss process was bimodal in air and produced a thermally resistant residue that degraded by 650°C. A comparison of degradation products from poly(vinylchloride) with this work demonstrates that PVF forms more lower‐molecular‐weight, halogen‐containing compounds, whereas the former produced more HCl and nonvolatile residue containing a lower halogen content.
Conformational studies of poly(cis‐5‐ethyl‐D‐proline)
Authors: Yang Wayne W.‐Y. , Overberger C. G. , Venkatachalam C. M. 
Published: April 2003

AbstractTwo possible conformations for poly(cis‐5‐ethyl‐D‐proline) have been identified and characterized by using combinations of 1H‐ and 13C‐NMR, CD, and ORD spectroscopic techniques. Both forms have helical conformations similar to those of poly(L‐proline) characterized by different amide bonds (cis and trans). However, the carbonyl group of the amide in poly(cis‐5‐ethyl‐D‐proline) form II (trans) seems to be closer to perpendicular orientation with respect to the helical axis than in poly(L‐proline) form II. The pyrrolidine ring conformation of form I (cis) is probably β+γ−‐puckered, whereas for form II it is probably β+‐puckered in nature. The side‐chain ethyl groups prefer to adopt anti conformations to the C5H bond, or prefer to have χ = 180°, regardless which of the two forms poly(cis‐5‐ethyl‐D‐proline) may like to assume. The experimental results agree well with our previous theoretical conformational energy calculations.
The effect of methanethiol on the radiation chemistry of low‐density polyethylene
Authors: Zoepel F. J. , Silverman Joseph 
Published: April 2003

AbstractThe effect of methanethiol (CH3SH) on the radiation chemistry of low‐density polyethylene was examined by using intrinsic viscosity measurements, low‐angle laser light scattering, and infrared spectrophotometry. Radiation‐induced intermolecular linking was found to be almost completely inhibited in low‐density polyethylene by the presence of less than one weight percent of CH3SH during irradiation. The net yield of transvinylene was also reduced, probably by reaction of transvinylenes with methylthiyl radicals (CH3S). The inhibition of radiation‐induced intermolecular linking by CH3SH demonstrates that linking is a relatively slow process involving reactions of alkyl free radicals, and that prompt intermolecular links caused by rapid ionic, ion–molecule, or “hot hydrogen” processes are not significant in the radiation chemistry of low‐density polyethylene.
1H‐NMR study of structure and tacticity in p‐t‐butylstyrene/methyl methacrylate copolymers
Authors: Uebel J. J. , Dinan F. J. 
Published: April 2003

AbstractCopolymers prepared by the bulk copolymerization of p‐t‐butylstyrene (S) and methyl methacrylate (M) were analyzed by 1H‐NMR. The spectra showed fine structure in the δ 2.2–3.6 region similar to that reported for styrene/methyl methacrylate copolymers. Reactivity ratios for S‐M copolymers determined by classical composition measurements differed markedly from the same ratios determined by NMR when it was assumed that NMR peak‐triad assignments could be made by analogy with published styrene/methyl methacrylate assignments. A new set of peak‐triad assignments was proposed that reconciles this difficulty and gives good agreement between triad fractions measured by NMR and those calculated from theory.
Aromatic bisvinyl ethers: A new class of highly reactive thermosetting monomers
Authors: Crivello J. V. , Conlon D. A. 
Published: April 2003

AbstractAromatic bisvinyl ethers, prepared by the condensation of bisphenols with 2‐chloroethyl vinyl ether in the presence of sodium hydroxide, are a new class of thermosetting monomers. These new materials can be polymerized cationically by using diaryliodonium salts as photo and thermal initiators to produce crosslinked resins whose physical and thermal characteristics resemble those of epoxy resins.
The condensation of trimethylolphenol
Authors: Jones Robert T. 
Published: April 2003

AbstractThe intermolecular condensation reactions of 2,4,6‐trimethylolphenol (TMP) have been studied. The rate of disappearance of TMP from aqueous solutions at 40°C was measured over a range of pH 2–11. Concentrations of TMP were determined by HPLC. Major products, separated on the chromatograph and identified by PMR, were the o,p‐ and p,p‐dimers and a trimer. Reaction kinetics were second order in TMP concentration at low pH. At high pH kinetics were first order in total TMP concentration, contrary to the findings of earlier investigators. The reaction rate varied with pH in a complex manner. The variation is explained by separate acid‐catalyzed and base‐catalyzed mechanisms. A kinetic model is proposed in which the rate constants are independent of pH.
Polymeric catechol derivatives. IV. Polymerization behavior of 4‐vinylcatechols and some properties of their polymeric derivatives
Authors: Iwabuchi Susumu , Nakahira Takayuki , Inohana Akira , Uchida Hideki , Kojima Kuniharu 
Published: April 2003

AbstractThe polymerization and copolymerization of 4‐vinylcatechols, such as 2‐(0‐methyl)‐4‐vinylcatechol (I), 3,4‐dimethoxystyrene (II), and 3,4‐methylenedioxystyrene (III), were investigated in cyclohexanone at 30°C, using tri‐n‐butylborane as an initiator. The reactions yielded vinyl polymers and copolymers. The copolymerization parameters of I–III were determined; their Q and e values were found to be similar to those of styrene and vinylhydroquinone. The copolymerization of I–III gave copolymers of a highly alternating character. The thermal stability of the polymers and copolymers so obtained was also studied. The redox potentials of hydroloyzed poly(I) were examined; the reverse “polymer effect” was observed.
Synthesis and polymerization of methyl 3‐methylenecyclobutene‐1‐carboxylate and dimethyl 3‐methylenecyclobutene‐1,2‐dicarboxylate
Authors: Hall H. K. , Snow L. Glen 
Published: April 2003

AbstractThe two title monomers were synthesized. In both cases the key cyclobutane intermediates were obtained by cycloaddition of allene to acrylonitrile or chloromaleic anhydride. These two new monomers proved to be highly reactive in free radical polymerization, and each polymerized spontaneously in air at room temperature. Linear polymers were prepared in dimethyl sulfoxide solution at 35° with AIBN and UV light. At higher temperatures crosslinking became a problem in some instances. The structure of the polymers derived from 1,4 polymerization in the diene portion of the monomers was confirmed by 13C‐NMR, 1H‐NMR and IR spectra. Copolymers were prepared with methyl methacrylate, styrene, and p‐methoxystyrene and were always rich in the methylene‐cyclobutene monomers used. Films of homopolymers and copolymers could be cast from chloroform solution.
Syndiotactic 1,2‐polybutadiene with Co‐CS2 catalyst system. IV. Mechanism of syndiotactic polymerization of butadiene with cobalt compounds–organoaluminum–CS2
Authors: Ashitaka Hidetomo , Jinda Kazuya , Ueno Haruo 
Published: April 2003

AbstractA mechanism is proposed for the polymerization of syndiotactic 1,2‐polybutadiene (s‐PB) with soluble cobalt‐organoaluminum‐CS2. The proposed active species have structures which consist of side‐on coordination of CS2 to cobalt, anti‐π‐allyl growing end, cisoid bidentate coordination of butadiene, and activation by complex formation with organoaluminum at the nonbonded sulfur of the coordinated CS2. This proposal is based on findings for the aluminum‐free catalyst Co(C4H6)(C8H13)‐CS2. It is tentatively interpreted that syndiotactic 1,2 polymerization proceeds under the influence of the side‐on coordinated CS2, by which the reactivity between the terminal carbons of butadiene and the C3 of the π‐allyl end is enhanced.
The use of the error‐in‐variables model in terpolymerization
Authors: Duever T. A. , O'Driscoll K. F. , Reilly Park M. 
Published: April 2003

AbstractThe error‐in‐variables model (EVM) is a mathematical description of experiments in which there is error in all measured variables. This contrasts with ordinary least‐squares methods in which it is assumed that error is only present in the dependent variable or variables. EVM leads to statistical procedures which are able to obtain more efficient estimates of unknown parameters from data with error in all the variables than can be obtained by using least‐squares methods. One type of experiment to which EVM is applicable is the measurement of copolymer reactivity ratios. It has been applied recently to the binary case, but the only known method for estimating reactivity ratios in ternary systems is that of Rudin et al. which is based on ordinary least squares. The application of EVM to the problem is described in this article and the results are compared with those of Rudin et al.
Study of photopolymer. XVII. Synthesis of novel photosensitive polymers with pendant photosensitive group and photosensitizer groups
Authors: Nishikubo Tadatomi , Iizawa Takashi , Yamada Minoru , Tsuchiya Koichi 
Published: April 2003

AbstractNovel photosensitive polymers with pendant photosensitive group, such as cinnamic ester, and photosensitizer groups, such as N‐carbamoyl‐p‐nitroaniline and N‐carbamoly‐4‐nitro‐1‐naphthylamine, were synthesized from radical copolymerizations of (2‐cinnamoyloxy)ethylmethacrylate with photosensitizer monomers, such as p‐nitrophenylmethacrylamide and 4‐nitro‐1‐na‐phthylmethacrylamide, by using asobisisobutyronitrile (AIBN) in benzene and from the copolymerizations of (2‐hydroxy)ethylmethacrylate or (2‐hydroxy)ethylacrylate with photosensitizer monomers by using AIBN in DMF. This procedure was followed by condensation reactions of the copolymers with cinnamoyl chloride with pyridine as HCL acceptor in the same reaction flask. The photoreactivities of the polymers obtained were influenced by the concentration of photosensitive group and photosensitizer groups and their ratio in the polymer matrix. In addition, the photosensitivity of cinnamic ester groups attached to a soft polymer segment was higher than that of cinnamic ester group attached to a hard polymer segment when these polymers had the same pendant N‐carbamoyl‐p‐nitroaniline group as photosensitizer. Furthermore, the spacer length between the polymer chain and photosensitizer group was important for increasing the photoreactivity of the photosensitive group in the polymers with pendant cinnamic ester and N‐carbamoyl‐p‐nitroaniline groups.
Vinyl polymerization. 413. Polymerization of vinyl monomer initiated by poly(vinylbenzyltrimethyl)‐ammonium chloride
Authors: Ouchi Tatsuro , Izumi Tsutomu , Inaba Masaya , Imoto Minoru 
Published: April 2003

AbstractThe polymerization of vinyl monomer initiated by an aqueous solution of poly(vinylbenzyltrimethyl)ammonium chloride (Q‐PVBACI) was carried out at 85°C. Styrene, p‐chlorostyrene, methyl methacrylate, and i‐butyl methacrylate were polymerized, whereas acrylonitrile and vinyl acetate were not. The effects of the amounts of vinyl monomer, Q‐PVBACI, and water on the conversion of vinyl monomer were studied. The overall activation energy in the polymerization of styrene was estimated as 79.1 kJ mol−1. The polymerization proceeded through a radical mechanism. The selectivity of vinyl monomer was discussed by “a concept of hard and soft hydrophobic areas and monomers.”
Synthesis of stereoregular heteropolysaccharides having amino‐groups by ring‐opening copolymerization of 1,6‐anhydro‐azido‐sugar derivatives
Authors: Uryu Toshiyuki , Hatanaka Kenichi , Matsuzaki Kei , Kuzuhara Hiroyoshi 
Published: April 2003

AbstractThe cationic, ring‐opening copolymerization of 1,6‐anhydro‐2‐azido‐3,4‐di‐0‐benzyl‐2‐deoxy‐(2‐ABG), ‐3‐azido‐2,4‐di‐0‐benzyl‐3‐deoxy‐ (3‐ABG), ‐4‐azido‐2,3‐di‐0‐benzyl‐4‐deoxy‐β‐D‐glucopyranose (4‐ABG) with 1,6‐anhydro‐2,3,4‐tri‐0‐benzyl‐β‐D‐glucopyranose (LGTBE) was investigated with phosphorus pentafluoride as catalyst at low temperatures, giving highly stereoregular, (1→6)‐α‐linked copolymers with number‐average molecular weights of 3.90 × 104−9.27 × 104. Structure and composition of the copolymers were determined by 1H‐ and 13C‐NMR spectroscopies and elemental analysis, which indicated that copolymerization occurred in a stereoregular manner to give azido groups containing (1→6)‐α‐linked glucopyranan derivatives. The differences in polymerizability among the three azido monomers are discussed. Regioselective reduction of three kinds of heteropolysacharide derivatives which had different quantities of azido groups at C‐2, ‐3, or ‐4 position with lithium aluminum hydride and subsequent debenzylation of the copolymers with sodium in liquid ammonia produced amino‐group‐containing heteropolysaccharides.
Study of photopolymer. XIX. Novel syntheses of the polymers with pendant ester and chloromethyl groups by addition reactions of the copolymer of glycidyl methacrylate with acid chlorides
Authors: Nishikubo T. , Iizawa T. , Saito Y. 
Published: April 2003

AbstractPolymer with pendant cinnamic ester and chloromethyl groups was synthesized by the addition reaction of poly(glycidyl methacrylate–co–methyl methacrylate) (PGMA) with cinnamoyl chloride. Also, polymers with pendant benzoic esters and chloromethyl groups were synthesized by reaction of PGMA with the corresponding benzoyl chlorides. Furthermore, polymers with cinnamic or benzoic esters and alkylazide groups were prepared by the substitution reaction of the obtained polymers with sodium azide.
Batch and semicontinuous emulsion copolymerization of vinyl acetat–butyl acrylate. I. Bulk, surface, and colloidal properties of copolymer latexes
Authors: El‐Aasser M. S. , Makgawinata T. , Vanderhoff John W. , Pichot C. 
Published: April 2003

AbstractVinyl acetate (VAc)–butyl acrylate (BuA) comonomer mixtures with various composition were polymerized by batch and semicontinuous emulsion polymerization processes. PVAc and PBuA homopolymer latexes as well as the (VAc‐BuA) copolymer latexes were characterized with respect to particle size, molecular weight, acid end groups on particle surfaces, and colloidal stability against electrolytes. The surface and colloidal properties of these latexes were also compared before and after aging and acid hydrolysis. The average particle size of batch latexes was independent of copolymer composition, whereas for semicontinuous latexes it decreased with increasing BuA content and was always lower than that of the corresponding batch latex. The molecular weight distribution (MWD) for batch latexes was narrower and much less dependent on composition than that of the semicontinuous latexes; bimodal MWD was found in most semicontinuous latexes with a substantial amount of low MW fraction. The total weak and strong acid end groups on particle surfaces for semicontinuous latexes is higher, and more dependent on composition, than the batch latexes. Acid‐induced hydrolysis results in a drastic change in the type and concentration of the surface groups of the semicontinuous latex particles. Colloidal stability against electrolytes showed that both electrostatic (due to surface acid groups) and steric [due to surface poly(vinyl alcohol)] mechanisms are contributing. However, for semicontinuous latexes, increasing PVAc content above 50 mol % resulted in a proportional increase and ultimately dominant role of steric stabilization. The results were interpreted in terms of differences in reactivity ratios and water solubilities of the two monomers and their effects on the locus of initiation and growth in the two polymerization processes, as well as the monomer sequence within the polymer chain and degree of homogeniety of the copolymer composition within the particle.
Batch and semicontinuous emulsion copolymerization of vinyl acetate–butyl acrylate. II. Morphological and mechanical properties of copolymer latex films
Authors: Misra S. C. , Pichot C. , El‐Aasser M. S. , Vanderhoff J. W. 
Published: April 2003

AbstractVinyl acetate/(VAc)‐butyl acrylate/(BuA) copolymer latex films of various copolymer compositions were investigated for their morphological properties by electron microscopy techniques, and for their mechanical properties by dynamic mechanical spectroscopy (DMS), differential scanning calorimetry (DSC), and tensile strength measurements. Batch copolymer latex films showed domains of PBuA dispersed in PVAc matrix; the domain sizes were increased with increased BuA content. Semicontinuous latex films were homogeneous in composition. Glass transition temperatures Tg determined from DMS and DSC indicated the presence of two, low and high, transition temperatures for batch latex films. The two temperatures approached the individual homopolymers, with increased PBuA content up to 51 mol %. Semicontinuous latex films showed only one single Tg. Tensile properties of the batch copolymer films showed a higher ultimate tensile strength, higher Young's modulus, and lower percent elongation to break compared to semicontinuous latex films. These differences were found to reflect the effect of mode of monomer addition during the emulsion copolymerization process on the particle morphology, and confirmed earlier data on bulk, colloidal, and surface properties of the same copolymer latexes.
Anisotropic electrical conductivity of drawn elastomeric ionene–TCNQ salts
Authors: Watanabe Masayoshi , Takizawa Yoshio , Shinohara Isao 
Published: April 2003

AbstractElastomeric ionene–TCNQ salts with favorable electrical, mechanical, and processing characteristics were drawn mechanically. The electrical conductivity parallel and perpendicular to the drawing axis was investigated. Correlation between anisotropic conductivity and the change in microstructure was discussed. The resistivity ρ at 25°C of the simple salt (EI‐TCNQ0) and the complex salt (EI‐TCNQ0.5) were on the order of 105 and 102 Ω cm, respectively. In the drawn TCNQ salts, the ρ parallel to the drawing axis increased greatly; on the other hand, the ρ perpendicular to this axis increased slightly or was similar to the ρ of the undrawn TCNQ salts. The anisotropy in the ρ of EI‐TCNQ0.5 between the two directions reached 40 times. The activation energy also increased in the direction parallel to the drawing axis. In the undrawn TCNQ salts, the continuous conduction paths exist isotropically. With drawing, the continuous conduction paths, particularly in the direction parallel to the drawing axis, break or make a structural change. The anisotropic conductivity disappeared with time in EI‐TCNQ0; however, it was present in EI‐TCNQ0.5 even after 200 days under ambient conditions.