bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma polymers containing sulfonate groups
Authors: Inagaki N. , Hirao H. 
Published: April 2003

AbstractModification of plasma‐polymers prepared from phenylsilane with sulfur trioxide was investigated by FT/IR spectroscopy and ESCA. The sulfonation of phenyl groups in the plasma‐polymers occurred rapidly within 1 min when exposed to SO3 gas. The S/C and O/C atomic ratios determined by ESCA for the modified polymers were 0.138 and 0.418, respectively. The sulfonation made the plasma‐polymers electrically conductive. The conductivity was sensitive to moist atmosphere. The logarithm of the impedance at 120 Hz decreased linearly with increasing the relative humidity. The plasma‐films containing sulfonate groups may be a new material for moisture sensor devices.
Alkali cation binding of polymers with different sized crown ethers and photodimerizable units
Authors: Shirai Masamitsu , Ueda Akihiko , Tanaka Makoto 
Published: April 2003

AbstractThe polymers which have different sized crown ethers as alkali cation binding sites and photodimerizable cinnamoyl units were prepared by the cationic copolymerization of corresponding monomers. The crown–cation complexation ratio (1:1 or 2:1) was investigated by measuring quantum yields ϕ of the photodimerization of the crown‐connected cinnamoyl units in the presence of alkali metal chlorides and also by measuring the shift of λmax of alkali metal picrates in THF on addition of the crown polymers. A significant 1:2 complex formation of alkali cations with two different sized crown ether units in the side chain of the polymers was confirmed. The alkali metal cation binding ability and selectivity of the polymers, which were studied by a method of picrate salts extraction, were markedly different from those expected from the combination of polymers of same ring‐size crown ether units. When irradiated with ultraviolet (UV) light, the cinnamic acid ester groups of the polymers caused dimerization even in dilute solutions. The cation binding ability of the polymers was largely enhanced by the photodimerization of the cinnamoyl moieties with suitable template cations.
Thermal degradation of polyacrylamide and poly(acrylamide‐co‐acrylate)
Authors: Leung W. M. , Axelson D. E. , Van Dyke J. D. 
Published: April 2003

AbstractThe thermal degradation behavior of polyacrylamide and poly(acrylamide‐co‐acrylate) was studied by differential scanning calorimetry, thermogravimetric analysis, gas chromatography/mass spectrometry, and carbon‐13 solid state nuclear magnetic resonance. The degradation products over the temperature range of 115–450°C were characterized. Mechanisms are proposed for the degradation processes involved.
Living carbocationic polymerization. IV. Living polymerization of isobutylene
Authors: Faust R. , Kennedy J. P. 
Published: April 2003

AbstractTruly living polymerization of isobutylene (IB) has been achieved for the first time by the use of new initiating systems comprising organic acetate‐BCl3 complexes under conventional laboratory conditions in various solvents from −10 to −50°C. The overall rates of polymerization are very high, which necessitated the development of the incremental monomer addition (IMA) technique to demonstrate living systems. The living nature of the polymerizations was demonstrated by linear Mn versus grams polyisobutylene (PIB) formed plots starting at the origin and horizontal number of polymer molecules formed versus amount of polymer formed plots. DPn obeys [IB]/[CH3COORt · BCl3]. Molecular weight distributions (MWD) are very narrow in homogeneous systems (Mw/Mn = 1.2–1.3) whereas somewhat broader values are obtained when the polymer precipitates out of solution (Mw/Mn = 1.4–3.0). The MWDs tend to narrow with increasing molecular weights, i.e., with the accumulation of precipitated polymer in the reactor. Traces of moisture do not affect the outcome of living polymerizations. In the presence of monomer both first and second order chain transfer to monomer are avoided even at −10°C. The diagnosis of first and second order chain transfer has been accomplished, and the first order process seems to dominate. Forced termination can be effected either by thermally decomposing the propagating complexes or by nucleophiles. In either case the end groups will be tertiary chlorides. The living polymerization of isobutylene initiated by ester. BCl3 complexes most likely proceeds by a two‐component group transfer polymerization.
Spectroscopic examination of linear poly(ethylenimine) containing nucleic acid pendants as polynucleotide analogs
Authors: Lan Ming‐Jye , Overberger C. G. 
Published: April 2003

AbstractThe NMR spectra and UV absorptions of polynucleotide analogs with a poly(ethylenimine) (PEI) backbone containing adenine, cytosine, and hypoxanthine pendants have been examined. As has been shown in single‐stranded polynucleotides, these polymers also exhibited base stacking behavior in aqueous solution as well as in 2,2,2‐trifluoroethanol. Such stacking resulted in significant UV hypochromicities and observed differences in the NMR spectra compared to the corresponding model compounds. From continuous variation mixing experiments, well‐defined base pairing interactions were observed between complementary graft polymers in aqueous solutions. Enhanced UV hypochromicity due to such interactions was also observed.
Synthesis of linear poly(ethylenimine) containing nucleic acid pendants as polynucleotide analogs
Authors: Lan Ming‐Jye , Overberger C. G. 
Published: April 2003

AbstractPolynucleotide analogs with a linear poly(ethylenimine) (PEI) backbone and adenine, cytosine, and hypoxanthine pendants were synthesized. Linear PEI was synthesized by the cationic ring‐opening polymerization of 2‐H‐2‐oxazoline, followed by acid hydrolysis. 2‐(Adenin‐9‐yl)‐ and 2‐(N6‐benzyladenin‐9‐yl)‐, 2‐(cytosin‐1‐yl)propanoic acids in addition to 2‐(adenin‐9‐yl)‐3‐methyland 3‐(cytosin‐1‐yl)butanoic acids were synthesized from their respective nucleic acid bases. 2‐(Hypoxanthin‐9‐yl)propanoic acid and 3‐(hypoxanthin‐9‐yl)butanoic acid were converted from the corresponding adenine derivatives by reaction with nitrous acid. Grafting reactions of pendant groups onto various molecular weight PEI backbones were carried out at room temperature, using the coupling agent norborn‐5‐ene‐2,3‐carboximido diphenyl phosphate (PPONB), generally resulting in percent graft values greater than 90%. PPONB showed selectivity against the amino group of adenine and cytosine rings. The appropriate model compounds were also prepared.
Functional polymers and sequential copolymers by phase transfer catalysis. 24. The influence of molecular weight on the thermotropic properties of a random copolyether based on 1,5‐dibromopentane, 1,7‐dibromoheptane, and 4,4′‐dihydroxy‐α‐methylstilbene
Authors: Percec Virgil , Nava Hildeberto , Jonsson Håkan 
Published: April 2003

AbstractThe influence of molecular weight on thermal transitions and on their thermodynamic parameters is discussed for a random thermotropic liquid crystalline copolyether based on the reaction of a 1:1 molar mixture of 1,5‐dibromopentane and 1,7‐dibromoheptane with 4,4′‐dihydroxy‐α‐methylstilbene. Optimum phase transfer catalyzed polyetherification reaction conditions were established for the synthesis of polymers containing bromoalkane chain ends only over a wide variety of molecular weights. All these copolyethers present a crystalline and an enantiotropic nematic mesophase over the entire range of molecular weights studied. Both the thermal transitions and their thermodynamic parameters are strongly molecular weight‐dependent up to Mn = 10,000–12,000, after which they remain constant. The enthalpies and entropies of isotropization of the copolyethers are higher than those of melting. This is in contrast to the same thermodynamic parameters of the corresponding homopolyethers. The enthalpies and entropies of isotropization of both homopolymers and copolymers present similar values, suggesting that copolymerization does decrease the degree of order in the crystalline phase but does not significantly change the alignment degree of the mesogenic units in the nematic mesophase.
Preparation and properties of dimethyl phosphonomethyl methylsiloxane dimethylsiloxane copolymers
Authors: Juengst Clifford D. , Weber William P. 
Published: April 2003

AbstractDimethyl phosphonomethylheptamethylcyclotetrasiloxane (II) and 1, 3‐bis(dimethyl phosphonomethyl)tetramethyldisiloxane (III) have been prepared by Arbuzov reaction of trimethyl phosphite with bromomethylheptamethylcyclotetrasiloxane (I) and 1, 3‐bis(bromomethyl)tetramethyldisiloxane, respectively. Dimethyl phosphonomethylmethylsiloxane dimethylsiloxane copolymers have been prepared by acid‐catalyzed ring‐opening polymerization of II with hexamethyldisiloxane (MM) as an end‐capping reagent and by reaction of II with III as an end‐capping reagent. Dimethylsiloxane polymers with dimethyl phosphonomethyldimethylsiloxy end groups have been prepared by acid‐catalyzed polymerization of octamethylcyclotetrasiloxane (D4) and III. Under these conditions hydrolysis of the dimethyl phosphonate ester groups was a problem. On the other hand Arbuzov reaction of trimethyl phosphite with bromomethylmethylsiloxane dimethylsiloxane copolymer gave a dimethyl phosphonomethylmethylsiloxane dimethylsiloxane copolymer with uniform properties. These polymers have been characterized by1H‐,13C‐,29Si‐, and31P‐NMR spectroscopy. Their molecular weight distributions have been determined by gel permeation chromatography (GPC) and their thermal stability measured by TGA.
Cationic grafting from carbon black. VII. Grafting of polyacetals by cationic ring‐opening polymerization of trioxane and 1,3‐dioxolane initiated by CO+ClO4− groups on carbon black
Authors: Tsubokawa Norio 
Published: April 2003

AbstractThe cationic ring‐opening polymerization of trioxane and 1,3‐dioxolane was found to be initiated by CO+CIO4− groups on a carbon black surface, which were introduced by the reaction of COCI groups with AgCIO4. The activation energy of the ring‐opening polymerization of trioxane was estimated to be 15.5 kcal/mol. In the polymerization system, poly(oxymethylene) and poly(1,3‐dioxolane) formed were effectively grafted onto carbon black depending upon the propagation of these polymers from the carbon black surface; for instance, the grafting ratio of poly(oxymethylene) onto carbon black increased with an increase in conversion and went up to about 180%. Although the grafted chain of poly(oxymethylene) was subject to stepwise thermal depolymerization from the chain ends, the thermal stability of poly(oxymethylene)‐grafted carbon black was improved by acetylation of hemiformal end groups. The molecular weight of ungrafted poly(oxymethylene) formed in the polymerization was determined to be 1.8–2.0 × 104. Furthermore, the copolymerization of trioxane with 1,3‐dioxolane, styrene, and other comonomers initiated by CO+CIO4− groups and the thermal stability of these acetal copolymer‐grafted carbon black were investigated.
Polymerization of silylacetylenes by W and Mo catalysts
Authors: Tajima Hiroshi , Masuda Toshio , Higashimura Toshinobu 
Published: April 2003

AbstractPolymerization of HCCSiMe3 homologues (HCCSiMe2R; R = n‐C6H13, CH2CH2Ph, CH2Ph, Ph, and t‐Bu) was studied by use of W and Mo catalysts. W catalysts provided polymers in good yields from all these monomers. Mo catalysts gave mainly a polymer from HCCSiMe2–t‐Bu, but virturally only cyclotrimers from sterically less croweded monomers (R = n‐C6H13, CH2CH2Ph, CH2Ph, and Ph). Polymers with flexible R groups (n‐C6H13, CH2CH2Ph, and CH2Ph) were totally soluble, their number‐average molecular weights being 7000–18,000. Polymers with inflexible R groups (Ph and t‐Bu) were partly insoluble. Every polymer was a yellow rubber or powder, and had the structure, \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH} = {\rm C}\left( {{\rm SiMe}_{\rm 2} {\rm R}} \right)\rlap{--} ]_n $\end{document}. The results were compared with the polymerization and polymer of HCCSiMe3.
Synthesis and characterization of ABA triblock copolymers containing poly(2,6‐dimethyl‐1,4‐phenylene oxide) as A blocks and tetramethyl bisphenol‐A polysulfone as B blocks
Authors: Tingerthal Jeanne M. , Nava Hildeberto , Percec Virgil 
Published: April 2003

Abstractα, β‐Bis(hydroxyphenol) tetramethyl bisphenol‐A polysulfone (PSUT) was synthesized by two different methods, one using a strong base, the other using a weak base. The bifunctional polysulfone containing tetramethyl bisphenol‐A chain ends was exploited as a model telechelic that can be used for the preparation of ABA triblock copolymers containing poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) as A segments and PSUT as B segments. PSUT and PPO were incorporated into triblock copolymers by an oxidative coupling copolymerization of PSUT with 2,6‐dimethylphenol or by the redistribution of PPO in the presence of PSUT. The mechanism of block copolymerization is discussed. DSC studies indicate that short immiscible PPO and PSUT segments incorporated into a triblock copolymer do not exhibit phase separation. Polymer blends of the PPO–PSUT–PPO triblock copolymers with PPO homopolymer were analyzed by DSC. Both miscible and phase‐separated blends can be prepared depending on the molecular weight of both PPO homopolymer and of the PPO segment present in the triblock copolymer. Polymer blends of the PPO–PSUT–PPO triblock copolymer with PSUT were miscible at all compositions.
Kinetics of retarded polymerization: Investigation of the retardation of V5+–thiourea initiated polymerization of methyl acrylate by phenol
Authors: Mohanty A. K. , Singh B. C. , Misra M. 
Published: April 2003

AbstractThe kinetics and mechanism of the retarding action of phenol on the V5+–thiourea initiated polymerization of methyl acrylate (MA) have been studied within the temperature range of 30–50°C. The effects of retarder (phenol), metal ion (V5+), monomer (MA), sulfuric acid, some organic solvents and inorganic salts on the percentage and rate of polymerization have been studied. The remarkable observation of the present study is the positive intercept obtained from the plot of [M]/Rp vs. 1/[M]. This type of observation is significantly different from previous studies on retarded polymerization. The values of composite rate constants k0kt/kikpkK have been calculated from plots of [M]/Rp vs. 1/[M]. On the basis of experimental findings a reaction mechanism has been suggested, and a suitable rate expression has been proposed and explained.
Polymerization and oxidation of pyrrole by organic electron acceptors
Authors: Kang E. T. , Neoh K. G. , Tan T. C. , Ong Y. K. 
Published: April 2003

AbstractSimultaneous chemical polymerization and oxidation of pyrrole have been initiated by organic electron acceptors, 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone (DDQ) and tetrachloro‐o‐benzoquinone(chloranil). The polypyrrole (PPY) complexes so produced are semiconductive and granular in nature. For the PPY–DDQ and PPY–chloranil complexes obtained from bulk polymerization, the respective electrical conductivities (σ) are of the order of 10−1 and 10−3 ohm−1 cm−1. However, σ is substantially lower for the complexes prepared in solvent media. Both complexes are relatively stable in the atmosphere. Thin uniform films of the PPY–organic acceptor complexes have also been synthesized on SnO2 electrode by electrochemical polymerization in acetonitrile. The physicochemical properties of the PPY–organic acceptor complexes prepared chemically under the various experimental conditions are examined in detail.
The measurement of ozone permeability in silicone polycarbonate copolymers using 10,10′‐dimethyl‐9,9′‐biacridylidene as an optical probe
Authors: Surgi Marion R. , Hodgeson Jimmie A. 
Published: April 2003

AbstractThe permeability (SD) of ozone in a silicone polycarbonate copolymer has been measured by monitoring the depletion of 10,10′‐dimethyl‐9,9′‐biacridylidene (DBA) impregnated into the polymer. The quantity (2SD)1/2 varies linearly with membrane thickness. Extrapolation of this linear relationship to zero thickness provides a positive y‐intercept that can be taken to be the intrinsic permeability of ozone in the silicone portion of this copolymer [SD = 115 ± 17 × 10−9 (cm3 gas) cm sec−1 cm−2 (cmHg, ΔP)−1]. This result compared favorably with the modeled permeability of ozone in silicone homopolymers [142 ± 15 × 10−9 (cm3 gas) cm sec−1 cm−2 (cmHg, ΔP)−1]. The lower permeability determined for the copolymer, when compared with the modeled value, was attributed to a reduced mobility of the amorphous silicone blocks caused by the presence of the crystalline polycarbonte blocks. The permeability was shown to be independent of ozone concentrations, flow rate, temperature, and humidity over the ranges used in these experiments. This method identifies a technique that may be useful in quantitating the permeability of ozone in packaging materials, tire sidewalls, and industrial polymers.
NMR studies of ionomers. 3. Synthesis and microstructure of poly(ethyl acrylate‐co‐lithium acrylate)
Authors: Simmons Alexandra , Natansohn Almeria , Eisenberg Adi 
Published: April 2003

AbstractCopolymers of ethyl acrylate (EA) with lithium acrylate (LiA) with relatively low contents of LiA units (up to 30%) were synthesized by alkaline hydrolysis of poly(EA). 13C‐NMR spectra of these copolymers registered in a mixture of deuterated benzene with deuterated methanol (85:15 v/v) presented configurational splittings of the ester methylene, methylene main chain, and ester carbonyl group signals. Assignments of these splittings were made and Bernoulli statistics with a meso probability of 0.48 could fit both poly(EA) and poly(EA‐co‐LiA). Only the CO signal of the copolymer was sensitive to sequence distribution and indicated that the LiA units have a tendency to be isolated on the chain. Two‐dimensional HETCOR pulse sequence helped to assign the main chain proton spectrum.
Spectroscopic study of the complexes of poly(N‐methacryloyl‐L‐asparagine) with palladium (II)
Authors: Lekchiri Abdennbi , Morcellet Joëlle , Morcellet Michel 
Published: April 2003

AbstractThe complexes formed between palladium (II) and a polymeric ligand derived from L‐asparagine, poly(N‐methacryloyl‐L‐asparagine) (PNMAsn) have been investigated by electronic absorption and circular dichroism. N‐isobutyroyl‐L‐asparagine (NIBAsn) was also synthesized and studied with the purpose of comparison with its polymeric analog. NIBAsn gives two complexes: at low pH, an optically active complex between one carboxylate and one secondary amide nitrogen (so‐called 1N complex), and at higher pH, a 2N complex involving the primary and secondary amide group. This complex is also optically active. PNMAsn gives at low pH a 1N complex similar to that of NIBAsn, but at higher pH the 2N complex is formed between two carboxylate groups and two secondary amide groups of two different side chains of the polymer. At very high pH this 2N complex is hydrolyzed, i.e., the carboxylate‐palladium bonds are replaced by hydroxyle‐palladium bonds, and the complex becomes optically inactive.
Potentiometric titration behavior of poly(ethylene glycol methyl ether)‐b‐poly(ethylenimine)
Authors: Overberger C. G. , Peng Lin 
Published: April 2003

AbstractPoly(ethylene glycol methyl ether)‐b‐poly(ethylenimine hydrochloride) was characterized using potentiometric and viscosimetric titration methods. The average chemical compositions of the polyamine hydrochloride salts estimated by the acid‐base titration,1H‐NMR, and elemental analysis were compared. The apparent dissociation constant, pK, and the inherent viscosity of the polyamine hydrochloride were found to be highly dependent on the degree of neutralization. Very strong coulombic interactions among the charged sites were observed at low pH's for this polymer.
Synthesis and characterization of liquid crystalline poly(N‐acylethyleneimine)s
Authors: Rodriguez‐Parada Jose M. , Percec Virgil 
Published: April 2003

AbstractThe synthesis of three cyclic imino ethers containing mesogenic groups attached to the heterocyclic unit through flexible spacers is described. Cationic ring‐opening isomerization polymerization of two of them, i.e., 2‐[4‐(4‐methoxy‐4′‐biphenyloxy)butyl]‐2‐oxazoline (MeOBiph‐4‐Oxz) and 2‐[6‐(4‐methoxy‐4′‐biphenyloxy)hexyl]‐2‐oxazoline (MeOBiPh‐6‐Oxz) provided thermotropic liquid crystalline (LC) poly(N‐acylethyleneimine)s, whereas the polymerization of 2‐[4‐(4‐phenylphenoxy)butyl]‐2‐oxazoline (BiPh‐4‐Oxz) led to a crystalline polymer.
Preparation and characterization of macroporous polystyrene resins containing ethynyl groups and transition metal acetylide complexes
Authors: Yamaguchi H. , Shinohara K. , Sonogashira K. , Yamaguchi K. 
Published: April 2003

AbstractEthynylated polystyrene resins were prepared as functionalized polymer supports by the iodination reaction of macroporous polystyrene resins and reacted with transition metal diethynyl complex (Mt = Ni) and metal halides (Mt = Rh, Pd, and Pt) in a basic solvent using cuprous iodide as a catalyst to obtain macroporous polystyrene resins containing organotransition metals. The distribution of the metal acetylide complexes in the modified macroporous resins was determined by an electron probe microanalyzer. A gradient in the transition metal distribution was observed in any case of the modified resins. The stability of the organotransition metal complexes in the polymer matrix could be compared with a low molecular weight analogous complex quantitatively.
Preparation and properties of some cardopolyamides containing phenoxathiin‐10,10‐dioxide and phenoxaphosphine units
Authors: Reddy T. Ashok , Srinivasan M. 
Published: April 2003

AbstractSeveral new cardopolyamides containing phenoxathiin‐10,10‐dioxide and phenoxaphosphine units were prepared by condensing 3,3‐bis(4‐aminophenyl)‐phthalide (PDA), 9,9‐bis(4‐aminophenyl) fluorene (FDA), and 9,9‐bis(4‐aminophenyl)‐10‐anthrone (ADA) with 2,8‐dichloroformylphenoxathiin‐10,10‐dioxide (PDC) and 2,8‐dichloroformyl‐10‐phenylphenoxaphosphine‐10‐oxide (PPDC) in DMAc. A low temperature solution polycondensation technique was employed throughout. The cardopolymides were obtained in 80–92% yield and showed inherent viscosities in the range 0.41–0.6 dL/g. All the polymers were characterized by IR spectra, density, solubility, crystallinity, and thermal analysis.
Polytetrafluoroethylene–iron oxide composite. Interactions with acrylic acid and vinyl acetate
Authors: De Barros Glaucione Gomes , Galembeck Fernando 
Published: April 2003

AbstractIron oxide finely dispersed on polytetrafluoroethylene (PTFE) affects the behavior of this polymer with regard to acrylic acid and vinyl acetate sorption. Acrylic acid photopolymerization and grafting onto x‐ray preirradiated PTFE are also affected. Infrared, Mossbauer, and ESR spectroscopies show that PTFE‐embedded iron oxide is not transformed to iron acrylate, although it is converted to iron acetate by exposure to acetic acid. X‐ray‐induced polytetra‐fluoroethylene free radicals are longer lived in the polymer‐oxide composite than in plain polytetrafluoroethylene.
Synthesis of the aldehyde of oligomeric polyoxyethylene
Authors: Paley M. Steven , Harris J. Milton 
Published: April 2003

AbstractConjugates of polyoxyethylene with proteins and surfaces are of much importance in various biotechnical applications. Consequently, methods for preparing the aldehyde of POE are of interest because of the potential ready attachment of this compound to proteins and aminated surfaces by reductive amination. In this work we describe the results of attempts to prepare an oligomeric POE aldehyde by six routes, two of which proved to be effective. Two previously published routes, manganese‐oxide and DMSO/Ac2O oxidation were ineffective. The aldehyde was shown to be unstable in the presence of base and thus of little use for reductive amination. On the other hand, the benzaldehyde derivative, which we also synthesized, is stable, easy to prepare, and undergoes ready reductive amination.