bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of polymers by pyrolysis/chemical ionization mass spectrometry
Authors: Conway D. C. , Marak Roman
Published: April 2003

Two addition‐type polymers, polystyrene and polypropylene, and two condensation‐type polymers, poly(ethylene terephthalate) (Mylar) and poly(hexamethylene adipamide) (nylon‐6,6), were pyrolyzed directly in the ion source of a mass spectrometer by chemical ionization (CI) to reduce fragmentation. The spectra are relatively easy to interpret because most ion peaks occur at a mass corresponding to the ion formula M±H or M + 3H, where M is the formula of a fragment of the original polymer chain. Oligomer peaks were observed for the addition‐type polymers. The intensities of the protonated dimer and monomer were measured as a function of time for styrene (S) and propylene (P). It was found that essentially all the HS+2 was produced by the reaction of HS+ with S, but at least part of the HP+2 was formed by proton transfer to P2. The absence of the analogous reaction in styrene is presumably a result of the reduced volatility of S2.
Plasma polymerization of tetrafluoroethylene. IV. Comparison of ethylene and tetrafluoroethylene by measurement of electron temperature and density of positive ions
Authors: Yanagihara Kenji , Yasuda H.
Published: April 2003

The double probe method was applied to plasma of tetrafluoroethylene (TFE) and ethylene and the electron temperature (Te) and density of positive ions (np) were measured at various discharge wattages. The probe current‐probe voltage diagrams for TFE were different from those for ethylene. The shape of its diagram indicates that a considerable number of negative ions exist in TFE plasma. The levels of np for TFE were also nearly six times greater than those for ethylene at the same discharge current. The dependence of TFE polymer deposition and the chemical structure of the polymer, based on ESCA data on discharge current, was related to Te and np measured by the probe method. The values of Te and np may not be directly related to the polymer formation in a plasma; the method provides a direct measure of plasma energy density where plasma polymerization takes place, whereas it cannot be accurately estimated by the input energy of a discharge. It was found that plasma energy density based on (npTe) for TFE plasma and that for ethylene differ significantly at the same level of input parameter (W/FM), where W is the discharge wattage, F is the volume flow rate, and M is the molecular weight of the monomer.
Gamma radiation‐induced bulk polymerization of some methyl aryloxymethacrylates
Authors: Devarajan R. , Balakrishnan T. , Santappa M. , Viswanathan B.
Published: April 2003

The kinetics of γ‐radiation‐induced bulk polymerization of methyl phenoxymethacrylate and methyl paracresoxymethacrylate was studied at dose rates of 0.3 and 0.075 Mrad/h and at temperatures of 0 and 30°C. The polymerization was first order with respect to the monomers and the rate of polymerization had a direct dependence on dose rate. The activation energy value for the polymerization of methyl phenoxymethacrylate was 1.2 and 0.7 kcal/mol for methyl paracresoxymethacrylate. The polymerization proceeded predominantly by an ionic mechanism.
Poly‐Schiff bases. I. Preparation of poly‐Schiff bases from 4,4′‐diacetyl diphenyl ether (DDE) with various diamines
Authors: Patel M. S. , Patel S. R.
Published: April 2003

Thermally stable and semiconducting poly‐Schiff bases are synthesized by condensing 4,4′‐diacetyl diphenyl ether with o‐, m‐, and p‐phenylene diamines, benzidine, and ethylene diamine under different experimental conditions. These bases are insoluble in common organic solvents. They are characterized by infrared (IR) and viscosity measurements, thermal analysis, and the study of electricel properties at various temperatures. Variation of electrical conductivity σ with temperature followed the empirical relation σ = σ0e−E*/kT.
Amphiphilic block copolymer of 9‐vinylphenanthrene and methacrylic acid: Fluorescence quenching of phenanthrene residue in aqueous medium
Authors: Morishima Yotaro , Itoh Yoshihiro , Hashimoto Toshihiko , Nozakura Shun‐Ichi
Published: April 2003

Amphiphilic block copolymers of 9‐vinylphenanthrene (VPh) and methacrylic acid (MA) were prepared by a two‐step living anionic polymerization of VPh and trimethylsilyl methacrylate followed by hydrolysis of the trimethylsilyl ester groups. Bis(2‐hydroxyethyl) terephthalate, an oxidative quenching agent with amphiphilic nature, strongly quenched the fluorescence of phenanthrene groups in the block copolymer in aquecus solution. Apparent second‐order rate constants kq for the quenching ranged in the magnitude of 1011−1012M−1 s−1 in the borate (pH 9) and phosphate (pH 7) buffers, whereas those in DMF solution were found to be ∼109M−1 s−1. No such difference in kq for the aqueous and DMF solutions was observed with the related random copolymer. The results suggest that a considerable increase in the effective concentration of the quencher around the VPh sequences in the block copolymer resulted from hydrophobic association. Fumaric acid (FA), an anionic quencher, did not quench the fluorescence of the copolymer at pH 9 and 7, presumably because of the lack of accessibility of the quencher to the copolymer due to electrostatic repulsion. However, in neat water in which only a part of the carboxyl groups of MA sequences are dissociated and therefore the charge effect is minimized, FA quenched the fluorescence, with the kq value approximating the diffusion control limit.
Photopolymerization initiated by charge transfer complex. II. Photopolymerization of methyl methacrylate with the use of γ‐picoline–bromine charge transfer complex as photoinitiator
Authors: Lenka Subasini , Nayak Padma L.
Published: April 2003

Polymerization of MMA was carried out in the presence of visible light (440 nm) with the use of γ‐picoline‐bromine charge transfer complex as the initiator. The rate of polymerization Rp increases with increasing monomer concentration and the monomer exponent was computed to be unity. The rate of polymerization increases with increasing initiator concentration. The initiator exponent was computed to be 0.5. The reaction was carried out at three different temperatures and the overall activation energy was calculated to be 4.5 kcal/mol. The polymerization was inhibited in the presence of hydroquinone. Kinetic and other evidence indicates that the overall polymerization takes place by a radical mechanism.
Spectroscopic examination of polyethylenimine backbone polynucleotide models
Authors: Ludwick Adriane G. , Overberger C. G.
Published: April 2003

The UV absorptions of nucleic acid analogs with a polyethylenimine (PEI) backbone and uracil‐ and thymine‐containing pendants have been examined. For the solvents used (water, basic aqueous solutions, and DMSO), significant hypochromicity is observed. The uracil‐containing polymers have been shown to interact with polyA in an aqueous solvent at pH 7 (tris buffer). The interaction is proportional to the size of the polymer. A correlation is attempted between the properties of the analogs and their biological activity.
Ring‐opening polymerization of 5,6‐anhydro‐glucose and ‐allose derivatives. Effect of substitutional or configurational difference at the position of sugar monomers on polymerization behavior
Authors: Uryu Toshiyuki , Kitano Kissho , Matsuzaki Kei
Published: April 2003

The ring‐opening polymerization of 5, 6‐anhydro sugar derivatives, which are substituted oxiranes, was carried out to obtain (5→6)‐glycan derivatives and to elucidate the reactivities of the monomers. 5,6‐Anhydro‐3‐O‐benzyl‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (BAIGF) (1), 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐allofuranose (AIAF) (2), and 5,6‐anhydro‐3‐O‐benzyl‐1,2‐O‐isopropylidene‐α‐D‐allofuranose (BAIAF) (3) were used for polymerization. The monomer 1 was polymerized by anionic catalysts KOH and tert‐BuOK in high yield, while cationic catalysts gave polymers in low yield. On the other hand, the monomer 2 was polymerized by a variety of Lewis acids and strong bases as catalyst in high yield. The monomer 3 was polymerized by anionic catalyst into insoluble polymer. The polymers anionically obtained from these monomers have stereoregular structures composed of CH2CHRO backbone, but the degree of polymerization was limited below 20 by various factors such as termination and chain transfer. The effects of substitution and difference of the configuration at position 3 on polymerization behavior were elucidated by comparing the polymerizabilities and the polymer structure prepared from these monomers with those from 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (AIGF) (4). In addition, copolymerization of AIGF with AIAF was carried out using PF5 and NaOH as catalysts in order to examine the difference in monomer reactivity, giving rAIGF = 0.81 and rAIAF = 0.29 for the anionic polymerization.
Functional polymers. XIII. Synthesis and polymerization of 2(2‐hydroxy‐5‐methylphenyl)‐5‐vinyl‐2H‐benzotriazole
Authors: Yoshida Shohei , Lillya C. Peter , Vogl Otto
Published: April 2003

The synthesis of 2(2‐hydroxy‐5‐methylphenyl)‐5‐vinyl‐2H‐benzotriazole was accomplished in seven steps starting from 4‐ethylaniline. Acetylation and nitration followed by hydrolysis gave 2‐nitro‐4‐cthylaniline which was diazotized, condensed with p‐cresol, and reduced to 2(2‐hydroxy‐5‐methylphenyl)‐5‐ethyl‐2H‐benzotriazole. As in previous cases, the ethyl group was transformed to the vinyl compound by bromination with N‐bromosuccinimide and dehydrobromination of the 1‐bromoethyl compound. Monomer grade 2(2‐hydroxy‐5‐methylphenyl)‐5‐vinyl‐2H‐benzotriazole was polymerized and copolymerized with styrene, methyl methacrylate, and n‐butyl acrylate.
Synthesis of hydroxyl‐terminated polycarbonates of controlled number‐average molecular weight
Authors: Riffle J. S. , Shchori E. , Banthia A. K. , Freelin R. G. , Ward T. C. , McGrath J. E.
Published: April 2003

Hydroxyl‐terminated polycarbonates are important starting materials for the synthesis of multiblock copolymers. Earlier papers from our laboratory and elsewhere have demonstrated their utility in siloxane, aryl ether, and ester systems. One synthesis problem that must be addressed is the control of the number‐average molecular weight and hence block size of the polycarbonate oligomeric precursor. The facile phosgene‐hydroxyl reaction is often difficult to monitor precisely. The present article describes a novel, simple, and convenient technique for the synthesis of hydroxyl‐terminated polycarbonates of well‐controlled number‐average molecular weight. The approach involves an in situ blocking of some of the phenolic groups either prior to or during phosgenation. The protecting groups are easily removed after the polymerization is complete. In a practical laboratory experiment the technique does not require any additional step beyond that necessary for the preparation of nonfunctional polycarbonates of controlled molecular weight. The method is demonstrated in this article with the polycarbonate of bisphenol‐A via the use of trimethylchlorosilane, trifluoroacetic anhydride, and trifluoroacetic acid as blocking groups. Ultraviolet, 19F‐NMR, and 1H‐NMR measurements as well as vapor‐pressure osmometry were used to characterize the oligomers.
The action of a benzotriazole light stabilizer in wool. II. The mechanism of photostabilization
Authors: Leaver Ian H.
Published: April 2003

A study was made of the photoprotective effect of a sulfonated hydroxyphenylbenzotriazole light stabilizer in wool fabric. Investigations of the absorption, luminescence quenching, and photostabilizing properties of the benzotriazole showed that optical screening is the key mode of operation. Excited‐state quenching is of little practical importance. The protective effect of the stabilizer is strongly dependent on the exposure conditions. There is a good correlation between UV screening ability and photoprotection at wavelengths near 300 nm where the fiber has maximum photosensitivity but the correlation in the spectral region of 314–390 nm is poor. The failure of the benzotriazole to provide good protection in the near‐UV region of the spectrum is attributed mainly to the sensitizing action of a small number of fluorescent molecules of the stabilizer, the internal hydrogen bond of which has been disrupted by the influence of the polar environment of the substrate.
Magnesium‐chloride‐supported high‐mileage catalysts for olefin polymerization. II. Reactions between aluminum alkyl and promoters
Authors: Chien James C. W. , Wu Jiun‐Chen
Published: April 2003

The reactions between AlEt3 and the modifiers, promoters, and coactivators of a typical magnesium‐chloride‐supported, high‐activity propylene polymerization catalyst were studied. Infrared, MS analysis of the gas evolved, and GC–MS of the hydrolysis products for the reaction between AlEt3 and p‐cresol showed rapid and quantitative reactions with p‐cresol either in the support or solution. The reaction products from AlEt3 and esters were hydrolyzed, acidified, and dehydrated. The resulting carbonyl and olefinic compounds were identified by GC–MS. Proton and carbon nuclear magnetic resonance (NMR) techniques were also used to study these reactions. The expected intermediates were found in the PMR and CMR spectra. The mechanisms of reactions were proposed. The results of this study showed that when AlEt3 and esters are used as coactivators reaction products that can significantly influence the performance of the catalyst are formed.
Magnesium‐chloride‐supported high‐mileage catalysts for olefin polymerization. III. Electron paramagnetic resonance studies
Authors: Chien James C. W. , Wu Jiun‐Chen
Published: April 2003

Electron paramagnetic resonance (EPR) was used to study a MgCl2‐supported, high‐mileage olefin polymerization catalyst. Anhydrous Toho MgCl2 was the starting material. Treatment with HCl at an elevated temperature, ethyl benzoate by ball‐milling, p‐cresol, AlEt3, and TiCl4produced a catalyst that contained a single EPR observable Ti+3 species A, which was strongly attached to the catalyst surface, had a D3h symmetry, and no other Ti+3 ion in an immediately adjacent site. Species A constitutes only 20% of all the trivalent titaniums; the remainder is EPR‐silent and may be attributed to those Ti+3 ions that have adjacent sites occupied by one or more Ti+3 ions. Activation with preformed AlEt3/methyl‐p‐toluate complexes produced a single Ti+3 species (C) with rhombic symmetry and displaying 27Al superhyperfin splitting which has attributes for a stereospecific active site. This species is unstable under polymerization conditions and is transformed to another species with axial symmetry and solubilization. Both processes could lead to catalyst deactivation and loss of stereospecificity. Catalysts activated by AlEt3 and methyl‐p‐toluate separately in various sequential orders produced a multitude of EPR‐observable Ti+3 species with varying degrees of motional freedom deemed detrimental to stereospecific polymerization of α‐olefins.
Thermal properties of random copolyesters of PET and 3‐ and 3,5‐bromo‐substituted p‐hydroxybenzoic acids. II
Authors: Balachandar M. , Balakrishnan T. , Kothandaraman H.
Published: April 2003

Melt‐polycondensation of poly(ethylene terephthalate) (PET) and 3‐bromo‐p‐acetoxybenzoic acid or 3,5‐dibromo‐p‐acetoxybenzoic acid in different mole ratios yielded random copolyesters. The copolyesters have higher Tgs than PET because of an increase in mol % of the substituted p‐oxy‐benzoate units and follow Wood's equation for copolymer Tgs. Using this equation, we calculated the Tgs of the homopolymers of 3‐bromo‐p‐oxybenzoate and 3,5‐dibromo‐p‐oxybenzoate, which are not available experimentally, to be 113 and 123°C, respectively. Up to certain percentages of the comonomer composition the copolyesters exhibited cold crystallization and melt transitions which we attribute to the crystallizable segments of PET. The variation in melting temperatures in the composition of the copolymer was explained by Flory's theory. The differences in the melting behavior of the polymer, annealed at various crystallization temperatures for a constant time interval, throws light on the morphological changes that took place in it. Using the Hoffman and Weeks method, we determined the extrapolated equilibrium melting temperatures of these copolyester which were used to calculate the enthalpy of melting for the crystallizable units.
Plasma polymerization of hexafluoroethane
Authors: Masuoka Toshio , Yasuda H.
Published: April 2003

It was found that when hydrogen is mixed in a plasma, hexafluoroethane polymerization is accelerated. ESCA and IR spectroscopy were used to characterize the resulting polymers and to reveal the reaction mechanism. At relatively low hydrogen/hexafluoroethane ratios and radio‐frequency powers of 30 and 100 W (13.56 MHz), no hydrogen could be detected in the polymers with IR spectroscopy. However, after the ratio had increased above one, the hydrogen content increased abruptly. Thus, hydrogen might be looked upon as a sort of scavenger for active fluorine species. ESCA deconvolution analysis of the C1s peaks of the polymers indicated that the polymer structures were uniform throughout the reactor in the hydrogen/hexafluoroethane system at 30 W, even though the distribution of the deposition rate could still be observed. By examining sodium chloride powder exposed to the plasma with IR spectroscopy, it was possible to detect various fluorosilicates, which indicated ablation of the reactor's glass wall by the plasma.
Contribution to the study of self‐avoiding random walks (SARW) confined to strips and capillaries
Authors: Lautout‐Magat Marguerite
Published: April 2003

A flexible chain that can assume all possible positions on a lattice without intersection of segments (self‐avoiding random walk, SARW) has been used for a long time as a model of polymers in highly dilute solution, taking into account the excluded volume. In this article, we extend to a SARW subject to spatial constraints an analytical accurate method we have established for a SARW on an unbounded lattice. We now consider a square or cubic lattice extending without limit in the x direction but confined to D layers in the other directions. This is a model for the study of constrained macromolecules the behavior of which is important for instance in connection with the properties of thin polymeric films or fibers, or with the solubility of biopolymers in lipid bilayer membranes. We give recurrence relationships for calculating Cn, the total number of configurations, and xn, the mean x projection of the end‐to‐end separation, for a chain length n. Our method, being analytical, allows a considerable economy of computational time with respect to other methods such as Monte Carlo calculations. It enables us to investigate the asymptotic behavior of xn and to write the partition function of the system.
Functional polymers. XVI. Synthesis and polymerization of 2(2‐hydroxy‐5‐isopropenylphenyl)‐2H‐benzotriazole and a new synthesis of 2(2‐hydroxy‐5‐vinylphenyl)2H‐benzotriazole
Authors: Nir Zohar , Vogl Otto , Gupta Amitava
Published: April 2003

2(2‐Hydroxy‐5‐isopropenylphenyl)2H‐benzotriazole was synthesized in 40% overall yield starting from o‐nitroaniline. Diazotization in aqueous hydrochloric acid gave o‐nitrophenyl diazonium chloride which was condensed with p‐hydroxyacetophenone; the azo compound was reduced to 2(2‐hydroxy‐5‐acetylphenyl) 2H‐benzotriazole with zinc powder in sodium hydroxide solution and the 2‐hydroxy group of the compound was acetylated. Treatment of the acetyl compound with methyl Grignard reagent resulted in the methylation of the 5‐acetyl group to 2[2‐acetoxy‐5(2‐hydroxy‐2‐propyl)phenyl]2H‐benzotriazole which was then dehydrated with potassium hydrogen sulfate to the desired 2(2‐hydroxy‐5‐isopropenylphenyl)2H‐benzotriazole. This monomer did not homopolymerize, but was copolymerized readily with styrene, methyl methacrylate, and n‐butyl acrylate with azobisisobutyronitrile as the initiator. 2(2‐Acetoxy‐5‐acetylphenyl)2H‐benzotriazole was also reduced with sodium borohydride to form 2[2‐acetoxy‐5‐(1‐hydroxyethyl)phenyl]2H‐benzotriazole which was dehydrated and hydrolyzed to the known 2(2‐hydroxy‐5‐vinylphenyl)‐2H‐benzotriazole. This route provides a novel and simpler synthesis of 2(2‐hydroxy‐5‐vinylphenyl)2H‐benzotriazole.
Spectrophotometric studies of CT complexes of poly(N‐vinylhalogenocarbazole)s with 2,4,7‐trinitrofluorenone
Authors: Pielichowski Jan , Obrzut Jan
Published: April 2003

The effect of chlorine, bromine, and iodine at the 3 and 3,6 positions on a carbazole ring with thermodynamic properties, that is, enthalpy, entropy, and a stability constant of CT complex poly(N‐vinylcarbazole–2,4,7‐trinitrofluorenone), were studied in a temperature range of 268–323 K. The discussion of the results obtained, based on linear free‐energy relationships, stressed the advantageous influence of the halogen substituent in the carbazole ring on the properties of the poly(N‐vinylcarbazole)–2,4,7‐trinitrofluorenone complex.
On the interaction of triphenylmethyl salts with α‐methylstyrene
Authors: Velichkova R. , Panayotov I. M. , Doicheva J. , Heublein G. , Schutz H. , Adler P. , Spange S. , Wondraczek R.
Published: April 2003

The interaction of triphenylmethyl salts with α‐methylstyrene and 1,1‐diphenylethylene was investigated. With 1,1‐diphenylethylene at a monomer‐initiator ratio of 2 (room temperature), mainly 1,1,3‐triphenyl‐3‐methyl‐indane was isolated, whereas at a ratio of 100 (−10°C), the dimer 1,1,3,3‐tetraphenylbutene‐1 mainly formed. In both cases no addition of the trityl group was registered. In the interaction of α‐methylstyrene with Ph3C+SbCl at a monomer‐initiator ratio of 2(room temperature) a pure 1,3,3‐trimethyl‐1‐phenylindane was isolated and no addition of the trityl group to the double bond was recorded. The initiation reaction of α‐methylstyrene polymerization by trityl and chlorinated trityl salts was studied at temperatures from −20 to 0°C and different concentrations. The oligomers obtained with (pCI‐C6H4)3C+ were investigated by elemental analysis and fluorescence spectroscopy. The presence of Ph3CH in the reaction mixture was demonstrated by GLC and NMR spectra. The results obtained give evidence that the initiation of α‐methylstyrene polymerization involves hydride abstraction from the monomer.
Synthesis and characterization of thermoplastic polyesters and polyamides from sebacyl bisketene
Authors: Garner David P.
Published: April 2003

Sebacyl bisketene was generated in solution at −78°C. Copolymerization in solution at 0°C with the secondary diamines, piperazine and N,N′dimethyl‐1,6‐hexamethylenediamine, yielded the polyamides poly(1,4‐piperazylsebacyl) and poly[(methylimino)hexamethylene(methylimino)sebacyl], respectively. The polyamides were obtained in yields of 50–90%. The former had a glass transition temperature (Tg) at 30°C and a melting temperature at 165°C, whereas the latter had only a Tg at −15°C. The polymers were insoluble in the usual polyamide solvents. Copolymerization with the diol bisphenol A yielded poly(oxy‐1,4‐phenyleneisopropylidene‐1,4‐phenyleneoxysebacyl). The polyester was obtained in yields up to 99%. Gel permeation chromatography (GPC) determinations showed molecular weights up to 50,000 when acetone was the reaction solvent but only 12,000 when tetrahydrofuran (THF) was the reaction solvent; the Tg for the polyester varied with the molecular weight with a maximum at 15°C. Tensile properties were obtained for the polyesters with molecular weights greater than 35,000.
Poly(β‐pinenes) carrying one, two, or three functional end groups. I. The effect of reaction conditions on the polymerization of β‐pinene
Authors: Kennedy Joseph P. , Liao Tung‐Ping , Guhaniyogi Suhas , Chang Victor S. C.
Published: April 2003

β‐Pinene was polymerized with H2O/BCl3 (protic) and p‐dicumyl chloride and sym‐tricumyl chloride (nonprotic) inifer systems in CH2Cl2 or CH2Cl2/n‐C6H14 solvents from −10 to −70°C. The effect of solvent polarity, temperature, and monomer and inifer concentration on conversions and molecular weights was investigated. Low conversions and molecular weights, M̄n = 1300–2500, obtained under these conditions suggest rapid termination.
Synthesis of high‐molecular‐weight rodlike polyamides and block copolymers
Authors: Preston J. , Krigbaum W. R. , Kotek R.
Published: April 2003

High‐molecular‐weight polyamides containing p‐benzamide units can be obtained by polycondensation of monomers having preformed amide linkages in N‐methylpyrrolidone with added CaCl2 and LiCl in the presence of pyridine and triphenylphosphite (the conditions used by Higashi et al.). For example, the polyterephthalamide of 4,4′‐diaminobenzanilide having ηinh = 5.4 was obtained. Similarly, polycondensation of p‐phenylenediamine with N,N′‐bis(p‐carboxyhenyl)terephalamide produced a polymer having ηinh = 5.15. These results constitute the first demonstration that the phosphorylation reaction can be used to prepare rodlike polymers containing p‐benzamide units of molecular weights adequate for commercial‐quality fibers. Polymerization of p‐aminobenzoic acid using either Yamazaki or Higashi conditions does not lead to a polyamide having a high inherent viscosity. Block copolyamides having rigid and semiflexible blocks were prepared by using both Yamazaki and Higashi conditions. Block copolymers composed of p‐ and m‐benzamide units, and having ηinh = 3.0–3.1, were synthesized by using a rigid prepolymer obtained by applying the Yamazaki reaction to a monomer containing a preformed amide linkage, 4‐N‐(4′‐aminobenzamido)‐benzoic acid. Use of monomers having preformed amide linkages with Higashi conditions afforded block copolymers having inherent viscosities of up to 4.75.
13C‐NMR of ABS in the solid state. Characterization and relaxation studies
Authors: Jelinski L. W. , Dumais J. J. , Watnick P. I. , Bass S. V. , Shepherd L.
Published: April 2003

13C‐NMR spectra of bulk acrylonitrile‐butadiene‐styrene (ABS) resin are reported. The styrene‐co‐acrylonitrile (SAN) carbons can be observed selectively by using high‐power proton decoupling, cross polarization, and magic angle spinning (MAS). The polybutadiene (PBd) carbons can be observed selectively by using low‐power proton decoupling, with or without MAS. Methods and conditions for using 13C‐NMR to quantify the amount of PBd in solid ABS resins are developed. The 13C‐NMR results and results from iodine monochloride titrations for PBd content are in good agreement. Resonances of PBd in ABS in the solid state are assigned on the basis of triad sequences of cis, trans, and vinyl‐1,2 geometric isomers of butadiene. Computational methods are set forth for measuring directly from the 13C‐NMR spectra the percent of cis, trans, and vinyl‐1,2 isomers in PBd in the ABS resin. The NMR measurement of PBd microstructure appears to be preferable to infrared (IR) determinations. Relaxation parameters (T1 and NOE) are reported for PBd in bulk ABS as a function of temperature and are analyzed in terms of a distribution of rotational correlation times. These relaxation parameters are similar to those of nongrafted PBd and indicate that the local motions in grafted and nongrafted PBd are similar.
A comparison of the absolute reactivity of vinyl monomers. I. Kinetic studies on radical polymerization of vinyl monomers initiated by a Mn3+–diglycolic acid redox system
Authors: Elayaperumal P. , Balakrishnan T. , Santappa M. , Lenz R. W.
Published: April 2003

The kinetics of polymerization of acrylamide (AM), acrylic acid (AA), and acrylonitrile (AN) initiated by the redox system Mn3+–diglycolic acid (DGA) was studied. All three systems followed the same mechanism; namely, initiation by an organic free radical arising from the oxidation of diglycolic acid and termination by the interaction of polymer radicals with Mn3+ ion. The rate coefficients ki/k0 and kp/kt were related to monomer and polymer radical reactivity, respectively. An inverse relation between monomer and polymer radical reactivity was observed. Monomers with higher Q values gave higher ki/k0 values but lower kp/kt values. The e values of the monomers were important in determining the reactivities of monomers with nearly the same Q values.
Selective synthesis of structurally isomeric poly‐β‐ester and poly‐δ‐ester from β‐(2‐acetoxy‐ethyl)‐β‐propiolactone with Al and Zn catalysts
Authors: Araki Takeo , Hayase Shuzi , Nakamura Akira
Published: April 2003

It was found that structurally isomeric polymers were formed by the ring‐opening polymerization of β‐(2‐acetoxy ethyl)‐β‐propiolactone with (EtAlO)n and Et(ZnO)2ZnEt catalysts; that is, the Al catalyst catalyzed normal polymerization which led to poly‐β‐ester and the Zn catalyst formed isomerized poly‐β‐ester as the main product. The polymer structure was determined by nuclear magnetic resonance (NMR), T1‐value, thermal decomposition product, and (Tg). The NMR studies for the monomer–catalyst systems indicated that the Al catalyst interacted predominately with the lactone group, whereas the Zn catalyst interacted with the side‐chain ester group. These site‐selective interactions could be related to the difference in the stereoregulation by the two catalysts during the poly(β‐ester)‐forming polymerization process.
Metal chelates in vinyl polymerization: Bulk polymerization of acrylonitrile initiated by Cu(II)–imine complexes
Authors: Marjit D. N. , Kalpagam V. , Nandi U. S.
Published: April 2003

This article deals with the kinetics and mechanism of acrylonitrile (AN) polymerization initiated by Cu(II)–4‐anilino 3‐pentene 2‐one[Cu(II)ANIPO], Cu(II)–4‐p‐toluedeno 3‐pentene 2‐one [Cu(II)TPO], and Cu(II)–4‐p‐nitroanilino 3‐pentene 2‐one [Cu(II)NAPO] in bulk at 60°C. The polymerization is free radical in nature. The exponent of initiator(I) is ≃ 0.5. The initiation step is a complex formation between the chelate and monomer and subsequent decomposition of the intermediate complex giving rise to free radical and Cu(I). This is substantiated by ultraviolet (UV) and electron spin resonance (ESR) studies. The activation energies and kinetic and chain transfer constants have also been evaluated.
Kinetic study of the copolymerization of tetrahydrofuran‐3,3‐dimethyloxetane: Microstructure of the copolymers
Authors: Garrido L. , Guzmán J. , Riande E. , de Abajo J.
Published: April 2003

The cationic copolymerization of tetrahydrofuran‐(A)‐3,3‐dimethyloxetane (B) was studied at 0°C with BF3·OEt2‐epichlorhydrin and acetylhexafluoroantimonate as initiators. The values of the reactivity ratios, calculated by the Fineman–Ross and Kelen–Tüdos methods, were rA = 0.13, rB = 8.1 and rA = 0.13, rB = 7.9, respectively. These values are in satisfactory agreement with those obtained with a kinetic scheme in which depropagation reactions were considered. The product rArB was approximately equal to unity, which indicated an ideal random copolymerization. The copolymers were also analyzed by 1H‐NMR spectroscopy. Their spectra presented a doublet at 3.1 and 3.15 ppm that corresponded to the methylene protons of the dimethyloxetane units and allowed the determination of the probabilities P(AA), P(AB), and P(BB). Good agreement was found between the values calculated by spectroscopic methods and those obtained by using the classical probability theory of copolymerization.
Metal complexes with ligands—organic phosphites as polyolefin antioxidants. III. Kinetics and mechanism of the inhibiting action of individual stable Cu(i)‐complexes with phosphites
Authors: Pobedimskii D. G. , Kurashov V. I. , Kirpichnikov P. A.
Published: April 2003

The general features of behavior of kinetically labile complexes (metal phosphite) revealed earlier 1,2 provide the basis for the prediction of the activity of a new class of oxidation inhibitors. These are individual, stable metal complexes with organic phosphites as main ligands. The remarkable feature of these complexes, as shown as in this article on Cu(I) complexes, is the significant increase in the stoichiometric coefficient of inhibition f due to the suppression of the additional chain consumption of phosphite in the complex. The study of the initiated oxidation of styrene and solid isotactic polypropylene has proved that the phosphite complexes with Cu(I) ion are more effective than free, noncoordinated phosphites; quantitative characteristics of the inhibiting action of these complexes have been calculated. It is proved that termination of oxidation kinetic chains on the inhibitor molecules includes oxidation of coordinated phosphite without changing the oxidation degree of the central ion of metal. During inhibition of the oxidation of the substrate with mixtures of phosphite complexes of Cu(I) and phosphites (in styrene) or with aromatic amines (in polypropylene), the phenomenon of nonadditive strengthening (synergism) was discovered and the mechanism and kinetic regularities of synergism were revealed. This investigation of the phosphite complexes of the ions of Cu(I) presents new opportunities for controlled stabilization of polymers in uncontrolled conditions.
Phenazasiline‐containing polyamides and polyesters
Authors: Kondo Hitoshi , Sato Moriyuki , Yokoyama Masaaki
Published: April 2003

A Phenazasiline ring was incorporated into a polymer backbone by polycondensation of 2,8‐dichloroformyl‐5,10‐dihydro‐5‐methyl‐10,10‐diphenylphenazasiline (V) with aromatic diamines or bisphenols, and phenazasiline‐containing polyamides and polyesters were obtained. The polyamides were prepared by low‐temperature solution polycondensation in N‐methyl‐2‐pyrrolidone (NMP) in the presence of lithium chloride. The polyesters were synthesized by interfacial polycondensation in a mixture of 1,2‐dichloroethane and aqueous alkali in the presence of tetrabutylammonium chloride as an accelerator. These reaction conditions gave the corresponding polymers with high viscosities. The phenazasiline‐containing polyamides exhibited good solubilities in polar aprotic solvents such as dimethylformamide, dimethylacetamide, and NMP, and also in m‐cresol, although the polyesters showed limited solubilities in organic solvents. Under nitrogen, the phenazasiline‐containing polyamides and polyesters showed little degradation below 400°C and had good heat resistance.
Characterization of poly(D,L‐lactic acid) by gel permeation chromatography
Authors: Van Dijk J. A. P. P. , Smit J. A. M. , Kohn F. E. , Feijen J.
Published: April 2003

A number of samples of poly(D,L‐lactic acid) (PLA) with weight‐average molecular weights M̄w in the range 15,000–350,000 were prepared by a ring‐opening polymerization. The molecular weight distributions (MWDs) of these samples were determined by gel permeation chromatography (GPC). The method involves a universal calibration of the columns on the basis of polystyrene standards and a rapid iteration algorithm leading to the establishment of the Mark–Houwink relationship. In addition, osmometry and viscometry data are presented. The effect of hydrolytic degradation on the MWD of two PLA samples was studied by GPC.
The aging of living α‐methylstyryl oligomers. I. The kinetics of aging
Authors: Comyn J. , Glasse M. D.
Published: April 2003

Solutions of living oligomers of α‐methylstyrene in THF age in two ways. In “decay” the UV‐visible absorption of the anion slowly disappears but in “transformation” the peak at 340 nm is replaced by a new one at 430 nm. Decay follows first‐order kinetics, while transformation depends upon a photochemical process and requires the presence of excess monomer. This monomer is consumed in a second‐order reaction to produce an intermediate from which new anions are formed.
The mechanisms of latex particle formation and growth in the emulsion polymerization of styrene using the surfactant sodium dodecyl sulfate
Authors: Lichti Gottfried , Gilbert Robert G. , Napper Donald H.
Published: April 2003

A new method is presented that provides experimental information which is qualitatively and quantitatively sensitive to assumptions made as to the mechanisms of free radical entry and of latex particle formation in emulsion polymerization systems. The method consists of (1) obtaining (by electron microscopy) the full particle‐size distributions (PSDs) at several different times soon after the cessation of latex particle nucleation, (2) using these PSDs to determine the volume dependences of the various rate coefficients governing particle growth by fitting the data to the appropriate evolution equations, and (3) employing these empirical rate coefficients to find that time dependence of the nucleation rate which fits the early‐time PSD (again using the evolution equations). This method is quite sensitive to mechanistic assumptions: for example, one is able to determine whether or not the nucleation rate is an increasing or decreasing function of time. The technique is applied to a styrene nucleation system employing sodium dodecyl sulfate as surfactant at well above the critical micelle conventration. The data cannot be fitted even qualitatively by a simple one‐step nucleation mechanis, whether it involes micellar entry or homogeneous nucleation. It is found, on the other hand, that the results can be accurately fitted by assuming that coagulation events between primary colloidal particles, perhaps formed by homogeneous nucleation, dominate both the nucleation process and the entry of free radicals into mature latex particles. In addition, the data indicate that the rate of free radical entry into the latex particles decreases with increasing particle size, at least for particles of unswollen radius less than ca. 40 nm.
N‐chlorination of nylon fabric and polyurea‐6
Authors: Koutinas A. A. , Demertzis P. G.
Published: April 2003

In this article the preparation of N‐chloro Nylon fabric, with Nylon‐66 as weft and Nylon‐6 as warp is described. The N‐chlorination of this fabric was achieved by using tertiary butyl hypochlorite in carbon tetrachloride as the chlorinating agent. The percentage of N‐chlorinated amide groups in the fabric obtained was 30.6. Methods of preparation of N‐chloro polyurea‐6 are also reported. The N‐chlorination of these compounds was acheived in a heterogenious medium. N‐chloro polyurea‐6 was prepared by reacting it with tert‐butyl hypochlorite. In Polyuera‐6 the percentage of N‐chlorination was equal to 100. The 100% N‐chlorinated polyurea‐6 did not giveNHbands at 3.05 and 6.50 μ in the infrared spectra.
Structure‐reactivity relations of conjugated and unconjugated monomers: Acrylates and methyl vinyl ketone in copolymerization with styrene compared with vinyl esters in copolymerization with ethylene
Authors: Schrijver J. , German A. L.
Published: April 2003

This article describes the copolymerization of methyl vinyl ketone (MVK), methyl acrylate (MA), and methyl methacrylate (MMA) with styrene (St) as reference monomer at 3.4 MPa and 335 K with toluene as solvent. In addition, the effect of pressure on the binary copolymerizations of St‐Ma‐MMA is discussed. It appearsthat in case of conjugated monomers reactivity decreases as the electron‐donating character of the substituents increases, whereas the reverse is found in unconjugated monomers. This is explained by the finding that in conjugated monomers resonance effects induced by polar factors play a dominant role, whereas in unconjugated monomers mainly polar factors are governing the relative reactivities. The r values at 3.4 MPa are compared with those predicted by means of the Q‐e scheme and Patterns. No definite conclusions could be drawn about the applicability and validity of either scheme, although Patterns shows excellent result in case of the H function of Mayo. In vinyl ester copolymerizations and Le Noble and Asano's example of the menshutkin reaction one single factor (polarity and steric hindrance, successively) dominates ΔG#, ΔG and ΔV#. This allows a straight forward interpretation of the result with the Hammond postulate and is in full agreement with Evan's potential‐energy calculations. In conjugated monomers, however, an interplay of reasonance and polar factors is found. The general validity of these findings needs further experimental and theoretical support.
Carbon‐13 NMR of 1,2‐polybutadienes: Configurational sequencing
Authors: Kumar Devendra , Rao M. Rama , Rao K. V. C.
Published: April 2003

Carbon‐13 Fourier‐transform spectra (67.88 MHz) of 1,2‐polybutadienes (PBDs) (I–IV) were obtained. The triad and pentad intensities were calculated for the olefinic methylene carbon (C‐1). Bernoullian and first‐order Markov‐chain propagation statistics were tested to fit the experimental data. The pentad placements for the olefinic methine carbon (C‐2) were also assigned using the data calculated for the C‐1 carbon. Fine‐structure splitting due to placements higher than pentads was observed for both C‐1 and C‐2 carbons in PBD samples III and IV.
Azo initiators for the preparation of hydroxyl‐terminated polybutadienes
Authors: Idage B. B. , Vernekar S. P. , Ghatge N. D.
Published: April 2003

Azo compounds such as di(4‐hydroxybutyl)‐2,2′‐azobisisobutyrate, di(3‐hydroxybutyl)‐2,2′‐azobisisobutyrate, di(2‐hydroxypropyl)‐2,2′‐azobisisobutyrate, and di(2‐hydroxyethyl)‐2,2′‐azobisisobutyrate were prepared and used as initiators for the preparation of hydroxyl‐terminated polybutadienes (HTPBs) of molecular weight (M̄n) ranging from 2000 to 7500 and functionality between 1.90 and 3.0. The polymers were prepared by free‐radical solution polymerization in dioxane and toluene. The polymers obtained were characterized for their molecular weight, hydroxyl number, functionality, and instrinsic viscosity.
Isomerization of polyamide prepared from bicyclic oxalactam
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi
Published: April 2003

Anionic solution polymerization of bicyclic oxalactam, 8‐oxa‐6‐azabicyclo[3.2.1]octan‐7‐one (abbreviated as BOL), at 25°C yields the polyamide with both carbonyl and imino groups at the axial positions in the tetrahydropyran ring. On the other hand, the polyamide obtained by bulk anionic polymerization of BOL at 100°C has more complicated structures, probably due to the isomerizations and side reactions. The most frequent isomerization of the polyamide was the transfer of the carbonyl group adjacent to the tetrahydropyran ring from the equatorial to the axial position in the presence of base or acid catalyst at 25°C. Mechanisms are discussed from the viewpoint of the characteristic bonds in the polyBOL chain.
Polymerization of acrylonitrile initiated by a manganese(III) acetate glycerol redox system
Authors: Senapati Manjushree , Samal Narayan C. , Mishra Ranu , Tripathy Bibekananda , Rout Swoyam P. , Rout Mahendra K.
Published: April 2003

The kinetics of polymerization of acrylonitrile(AN) initiated by manganese(III) acetate in the presence of glycerol was investigated in the temperature range of 30–40°C. The effect of varying the concentrations of glycerol, sulfuric acid, acetic acid, metal ion, and monomer on the rate was studied. A suitable reaction scheme and rate expression have been proposed. Termination was mutual and was caused by the combination of two growing polymer radicals.
Polymerization of cyclohexene oxide with aluminum complex/silanol catalyst. VI. Oligomer and polymer effects
Authors: Hayase Shuzi , Onishi Yasunobu , Suzuki Shuichi , Wada Moriyasu
Published: April 2003

The activity of an aluminum complex/polysilanol polymerization catalyst was examined in order to confirm the dependence of catalytic activation on silanol chain length. Tris (acetylacetonato)–aluminum/silanol increased when silanols with an intramolecular hydrogen bond such as the trimer of diphenylsilanediol, polydiphenyl(4‐vinylphenyl)silanol, and polymeric silanol of silicone were used. However, when tris(ethylacetoacetato)aluminum or tris(salicylaldehydato)aluminum was used, the product obtained from the reaction of a part of the aluminum complex with the polysilanols had to be considered in any explanation of the catalytic activation. The active catalyst with such aluminum complexes was obtained when the silanols that had intramolecular hydrogen bonds and gave the appropriate ratio of the reaction between the aluminum complex and silanol were used.
Synthesis of poly(vinylamine) containing asymmetric nucleic acid base derivatives as grafted pendants
Authors: Overberger C. G. , Kikyotani S.
Published: April 2003

The preparations of new model polymers of polynucleotides with stereoregular poly(vinylamine) (PVAm) backbones and an optically active nucleic acid base derivative as a pending side chain are described. The grafting of (±)‐, (+)‐, and (−)‐2‐(thymin‐1‐yl) propionic acid to linear PVAm prepared either by hydrolysis of poly(vinyl acetamide) or poly(vinyl‐t‐butyl carbamate) has proven to be more difficult than the case of polyethyleneimine. This may be due to a combination of the low solubility and steric factors of PVAm. PVAm formed a complex with oximes such as ethyl‐2‐hydroxyimino cyanoacetate (EHICA), which activates the amino group of PVAm; it became soluble in polar solvents and gave higher percent graft. These carboxylic acid derivatives were grafted onto PVAm through amide bonds by direct coupling with sulfonic acid esters of hydroxybenzotriazoles to give optically active graft polymers. These coupling agents were found to be much superior reagents than DEPC regarding racemization. The related monomer and dimer model compounds were also prepared by the same method from 3‐aminopentane and (−)‐, (+)‐, and meso‐2,4‐diaminopentane, respectively. The dimer models were separated and purified by HPLC to give models for isotactic, heterotactic, and syndiotactic polymer models. The enantiomeric purity of the optically active monomer model was determined by 360‐MHz NMR spectroscopy using optically active shift reagents.
Spectroscopic studies of poly(vinylamine) containing optically active thymine derivatives as grafted pendants
Authors: Overberger C. G. , Kikyotani S.
Published: April 2003

The optical properties of poly(vinylamine) containing optically active (+)‐ or (−)‐2‐(thymin‐1‐yl) propionyl groups as grafted pendants (PT) and the related monomer (MT) and dimer models (DT) were investigated by UV, circular dichroism (CD), and NMR spectroscopy. Highly syndiotactic PT has a smaller hypochromicity versus MT and a larger optical rotation than the less syndiotactic PT in various solutions. These results are attributed to an interaction between the configurational arrangement of thymines, the conformation of the polymers, and base stacking between thymines. The interactions of these polymers with poly(adenylic acid) (polyA) were also studied and the results compared with other vinyl‐type nucleic acid model polymers. The isomers of the optically active dimer models [prepared from meso and (dl)‐2,4‐diaminopentane] were separated. The CD spectra of (+)‐D(−)T in CHCl3 and trifluoroethanol (TFE) displayed extremely solvent‐dependent exciton coupling of the π–π* (B2u) transition of the base chromophore, which was not observed in the other models or polymers, except the meso‐type dimer model (meso)‐D‐(−)T. This coupling decreased with increasing solvent dielectric constant, while UV hypochromicity increased. This behavior as well as the 360‐MHz NMR spectra suggest that (+)‐D(−)T exists in an extended form in solvents of low dielectric constant and gradually assumes a stacked conformation as the dielectric constant increases.