bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel triblock siloxane copolymers: Synthesis, characterization, and their use as surface modifying additives
Authors: Yilgor Iskender , Steckle Warren P. , Yilgor Emel , Freelin R. Gary , Riffle Judy S. 
Published: April 2003

AbstractSynthesis of novel triblock, polycaprolactone‐b‐polydimethylsiloxane (PDMS) and poly(2‐ethyl‐oxazoline)‐b‐PDMS copolymers were demonstrated. These materials were obtained via the ring‐opening polymerization of ϵ‐caprolactone or 2‐ethyl‐2‐oxazoline monomers by using organofunctionally terminated PDMS oligomers as initiators and comonomers. Segment molecular weights in these copolymers were varied over a wide range between 1000 and 2000 g/mol and the formation of copolymers with desired backbone compositions were monitored by 1H‐NMR spectroscopy and GPC. DSC and TMA studies showed the formation of two phase morphologies with PDMS (Tg, −120°C) and polycaprolactone (Tm, 50–60°C) or poly(2‐ethyl‐2‐oxazoline) (Tg, 40‐60°C) transitions respectively. The use of polycaprolactone‐b‐PDMS copolymers as surface modifying additives in polymer blends were also investigated. When these copolymers were blended at low levels (0.25–10.0% by weight) with various commercial resins such as, polyurethanes, PVC, PMMA, and PET, the resulting systems displayed silicone‐like, hydrophobic surface properties, as determined by critical surface tension measurements or water contact angles. The effect of siloxane content, block length, base polymer type and morphology on the resulting surfaces are discussed.
Aqueous polymerization of methyl methacrylate initiated by the redox system Ce(IV)–isopropyl alcohol. Kinetics and molecular weight
Authors: Fernández M. D. , Guzmán G. M. 
Published: April 2003

AbstractPolymerization of methyl methacrylate was carried out in aqueous nitric acid in the temperature range 26–40°C, with the redox initiator system ceric ammonium nitrate–isopropyl alcohol. A short induction period was observed, as well as the attainment of a limiting conversion, and the total ceric ion consumption with reaction time. The reaction orders were 1/2 and 3/2 with respect to the IPA and monomer concentration, respectively, within the range (3–5) × 10−3Mof Ce(IV). But at lower Ce(IV) concentration (≤ 1 × 10−3M), the order with respect to monomer and Ce(IV) changed to 1 and 1/2, respectively. The rate of ceric ion disappearance was first order with respect to Ce(IV) concentration and (RCe)−1was proportional to [IPA]−1. Both the rate of polymerization and the rate of ceric ion consumption increase with rise in temperature. The average‐molecular weight can be controlled by variations in IPA, Ce(IV), and monomer concentrations, and in temperature. A kinetic scheme involving oxidation of IPA by Ce(IV) via complex formation, whose decomposition gives rise to a primary radical, initiation, propagation, and termination of the polymeric radicals by bimolecular interaction is proposed. An oxidative termination of primary radicals by Ce(IV) is also included.
Synthesis and cationic polymerization of substituted 2,3‐dihydrofurans
Authors: Kim Jin‐Bong , Cho Iwhan 
Published: April 2003

AbstractCationic polymerization of substituted 2,3‐dihydrofurans has been performed to investigate the substituent effect on the ring‐opening polymerization. 2‐Phenyl‐2,3‐dihydrofuran (III), 2‐methoxy‐5‐phenyl‐2,3‐dihydrofuran (Va), and 2‐ethoxy‐5‐phenyl‐2,3‐dihydrofuran (Vb) were synthesized and polymerized with BF3 etherate and AlCl3 as acid catalysts. Va and Vb ring‐opening polymerized well to give the polymers with benzoyl as pendant group which were formed via cationic rearrangement during the ring‐opening process, while III polymerized via simple opening of ethylenic double bond to form a polymer with the retention of tetrahydrofuran ring in the main chain. The nature of substituted cyclic vinyl ethers depending on substituents was also discussed.
The synthesis and solution properties of some rigid‐chain, water‐soluble polymers: Poly[N,N′‐(sulfo‐phenylene)phthalamide]s and poly[N,N′‐(sulfo‐p‐phenylene)pyromellitimide]
Authors: Vandenberg E. J. , Diveley W. R. , Filar L. J. , Patel S. R. , Barth H. G. 
Published: April 2003

AbstractPoly[N,N′‐(sulfo‐phenylene)phthalamid]es and poly[N,N′‐(sulfo‐p‐phenylene)pyromellitimide] were prepared in water‐soluble form and were found to have unique solution properties, similar in some respects to xanthan. The polymer most investigated, poly[N,N′‐(sulfo‐p‐phenylene)terephthalamide] (PPT‐S), is produced as the dimethylacetamide (DMAC) salt by the solution polymerization of 2,5‐diaminobenzenesulfonic acid with terephthaloyl chloride in DMAC containing LiCl. The isolated polymer requires heating in water to dissolve; the resulting cooled solutions are viscous or gels at concentrations as low as 0.4%. They are highly birefringent, exhibit circular dichroism properties, and are viscosity‐sensitive to salt. Solutions of this polymer mixed with those of guar or hydroxyethyl cellulose give significantly enhanced viscosity. The polymer is relatively low molecular weight, ca. 5000 estimated from viscosity data. Some meta and para isomeric analogs of PPT‐S were prepared; these polymers have similar properties except they are more soluble in water, and higher concentrations are required to obtain significant viscosity. Poly[N,N′‐(sulfo‐p‐phenylene) pyromellitimide] (PIM‐S) was prepared similarly from 2,5‐diaminobenzenesulfonic acid and pyromellitic dianhydride. Its aqueous solution properties are similar to those of PPT‐S. It appears that these relatively low‐molecular‐weight rigid‐chain polymers associate in water to form a network that results in viscous solutions at low concentrations.
Synthesis of new polyamidoximes and their crosslinking by transition metal ions
Authors: Bicak Niyazi , Tunca Umit , Yagci Yusuf 
Published: April 2003

AbstractThree new polyamidoximes (PAO) having appropriate functionalities to bind transition metal ions were prepared. The polymers were obtained by the reaction of dichlorooximino ethane with the corresponding diamine. Characterization and crosslinking of PAOs via coordination with transition metal ions such as Ni(II), Co(II), Cu(II), and UO2(II) are presented. The crosslinked polymer complexes exhibit good thermal stability. It was also found that both square planar and tetrahedral coordination structures are present in the crosslinked polymers.
The effect of the third component on butadiene–propylene alternating copolymerization catalyzed by vanadium–aluminum system
Authors: Su Dan , Yu Dingsheng , Hu Liping , Jiao Shuke 
Published: April 2003

AbstractThe effects of five ethers and four AliBu2OR's with varied R' on butadiene–propylene alternating copolymerization were investigated. It was found that by adding the proper third component, both the conversion and the catalytic efficiency could be increased. The effect of the third component on the valence state of vanadium ion was also studied. A model of the active center of the ternary‐component catalyst system was proposed.
Studies on graft copolymerization onto cellulose derivatives. XXIX. Photo‐induced graft copolymerization of methyl methacrylate onto chitin and oxychitin
Authors: Takahashi Akira , Sugahara Yasusato , Hirano Yutaka 
Published: April 2003

AbstractGraft copolymerization of methyl methacrylate (MMA) onto chitin and oxidized chitin was carried out by a noncatalytic photo‐induced and a photo‐sensitized method. The isolation method of grafted chains without a decrease in their degree of polymerization (DP) by sulfuric acid hydrolysis and the effects of some factors on the conversion and the grafted chain length have been studied.In case of the photo‐induced graft copolymerization, if a small amount of dimethylformaldehyde (DMF) is added in the polymerization system, the induction period is shortened and the degree of grafting and the apparent number of grafted chains increase. The degree of grafting and the apparent number of grafted chains of the oxidized chitin containing a small amount of CO groups are greater than those of the untreated chitin, but a further increase in CO groups decreases these values.In the presence of this two species of the chitin samples, the polymerization reaction was carried out as functions of monomer and chitin concentrations. From these results, the mechanisms of the photo‐induced graft copolymerization were discussed. It is also clear that the conversion and the apparent number of grafted chains by the noncatalytic photo‐induced method are generally larger than those by the photo‐sensitized method, and the grafting activity with hydrogen peroxide (HPO) is higher than that with azobisisobutyronitrile (AIBN).
High photosensitivity in cis‐polyphenylacetylene films irradiated with 60Co γ‐ray
Authors: Mujie Yang , Jian Zhao , Aibing Li , Zhiquan Shen , Mingjian Zhang , Senhao Lin 
Published: April 2003

AbstractThis paper reports that 60Co γ‐ray irradiation can convert cis‐polyphenylacetylene (cis‐PPA) films prepared with rare‐earth coordination catalysts to highly photosensitive materials. The dependence of the photosensitivity on irradiation dose, preparation methods, and microstructure of the PPA films has been investigated by means of a potential discharge technique. The photosensitivity was enhanced with increasing irradiation dose. The critical dose to produce a light response was 5 × 103 Gy. The maximum surface potential discharge rate was 618 V/s, and the dark decay was approximately 2 V/s for cis‐PPA films irradiated with 60Co γ‐ray (dose: 2 × 105 Gy). The cis‐transoidal‐PPA and an electrophotographic photoreceptor device incorporating cis‐PPA showed a higher irradiation effect. The structure and properties of 60Co γ‐ray irradiated rare‐earth PPA films are similar to the unirradiated films.
Preparation and properties of aromatic polyamides from 5‐t‐butylisophthalic acid and various aromatic diamines
Authors: Yang Chin‐Ping , Oishi Yoshiyuki , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractAromatic polyamides (aramids) having pendant t‐butyl group were synthesized by the direct polycondensation of 5‐t‐butylisophthalic acid with various aromatic diamines in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. The aramids having inherent viscosities of 0.6–2.4 dL/g were obtained in quantitative yields. These polymers were readily soluble in various solvents such as NMP,N,N‐dimethylacetamide, dimethyl sulfoxide, and pyridine, and gave transparent, tough and flexible films by casting from the NMP solutions. The aramids had glass transition temperatures between 250 and 330°C, and started to lose weight around 350°C, with 10% weight loss being recorded at about 450°C in air.
Acid photogeneration from sulfonium salts in solid polymer matrices
Authors: McKean Dennis R. , Schaedeli Ulrich , MacDonald Scott A. 
Published: April 2003

AbstractThe major photoproduct from irradiation of triphenylsulfonium salts is a Brönsted acid. This photochemical process has been used in several polymer film applications where the acid is used for crosslinking of films or other acid catalyzed reactions. Despite the widespread application of these materials, very little is known about the efficiency of acid generation in polymer films or the extent of the catalytic chain. This paper describes the use of a merocyanine dye technique to analyze for acid production in polymer films. The amount of acid produced on irradiation can be determined by this method and the extent of the catalytic chain then be determined.
Alkoxy‐substituted diaryliodonium salt cationic photoinitiators
Authors: Crivello J. V. , Lee J. L. 
Published: April 2003

AbstractThis paper describes the synthesis and characterization of a series of (4‐alkoxyphenyl)phenyliodonium salts which are excellent photo‐ and thermal‐initiators for the cationic polymerization of vinyl and heterocyclic monomers. These compounds are easily prepared by straightforward synthetic techniques and display very good solubility and photoresponse characteristics which make them especially attractive for use in UV curing applications. Those compounds with alkoxy chains of eight carbons and longer are essentially nontoxic.
NMR study on microstructure of polymer produced by hydrosilation of styrene with poly(hydrogenmethylsiloxane)
Authors: Kuwae Yoko , Kushibiki Nobuo 
Published: April 2003

AbstractThe microstructure of the polymer formed by the hydrosilation of styrene with poly(hydrogenmethylsiloxane) was studied by 1H‐ and 13C‐NMR spectra. Two modes of addition in hydrosilation were found to occur randomly without the influence of the adjacent monomer unit by statistical analysis of sequence distribution of 29Si‐NMR spectrum.
Photocrosslinking of polyethylene. I. Photoinitiators, crosslinking agent, and reaction kinetics
Authors: Chen Yong Lie , Rånby Bengt 
Published: April 2003

AbstractHigh density polyethylene has been photocrosslinked in the melt by using 4‐chlorobenzophenone (4‐CBP) as photoinitiator and triallylcyanurate (TAC) as crosslinking agent. Various factors affecting the crosslinking process (photoinitiator used and its concentration, irradiation temperature and time, atmosphere, UV light source, light intensity) were examined. By optimizing the irradiation conditions, it was found that samples up to 2 mm thick could readily be crosslinked to high gel content (≈ 90%) with satisfactory homogeneity within very short irradiation times (≈ 15 s). The kinetic analysis of the crosslinking process showed a linear relation between log S and log t (S is the sol fraction t is the irradiation time). An induction period was observed, the length of which decreased with increasing concentration of 4‐CBP and increasing light intensity. An upper limit of gel content was also found for long irradiation times at a level depending on the concentration of 4‐CBP. The crosslinking rate was proportional to the second order of light intensity at lower intensity and changed to first order at higher light intensity. A mechanism based on the recombination of chain radicals through both allyl and alkyl type radicals of TAC was proposed.
The electrochemical preparation of soluble electrically conducting polymers of 3‐methoxythiophene with narrow distributions of molecular weight
Authors: Lowen Stephen V. , MacInnes David , Funt B. Lionel 
Published: April 2003

AbstractSolutions of 3‐methoxythiophene (MeOT) in dimethylformamide (DMF) were electrolyzed at controlled electrode potentials. The polymerizations were studied under homogeneous conditions in solutions in which the polymer was soluble in the medium, and no coating of the electrodes occurred. The reaction proceeded at high coulombic efficiency and a first order dependence on monomer concentration was observed. The molecular weights of the polymers were determined by gel permeation chromatography. All samples showed a narrow distribution of molecular weights, with Mw/Mn ranging from 1.01 to 1.07. The molecular weight was low (about 3000 Daltons) and did not change in magnitude during the course of the reaction from 10 to 86% conversion, or with change in electrode potential from 1.55 to 1.65 V vs. SCE. The data are interpreted on a model based upon the competitive formation of chemically unreactive bipolarons.
Interpolymer complex formation between helical poly(L‐proline) and random‐coil poly(methacrylic acid) through hydrogen bonding
Authors: Park Soon Moon , Jeon Seung Ho , Ree Taikyue 
Published: April 2003

AbstractInterpolymer complex formation between poly(L‐proline) (PLP) with helical structure and poly(methacrylic acid) (PMAA) with random‐coil structure through hydrogen bonding in aqueous medium has been studied by several experimental techniques, e.g., viscometry, turbidimetry, potentiometry, conductometry, scanning electron microscopy, and x‐ray diffraction methods.The decreases in reduced viscosity of the solution on addition of an increasing quantity of PLP to a constant amount of PMAA reveals the formation of a complex between PLP and PMAA. The minimum in reduced viscosity at a unit‐mole ratio [PLP]/[PMAA] = 1.0 suggests a 1 : 1 complex formation. A distinct change in the curves for turbidity, pH, and conductance versus [PLP]/[PMAA] supports this conclusion. A scanning electron micrograph for the 1 : 1 PLP–PMAA complexes shows that the PLP/PMAA complex has the shape of entangled long fibers. An x‐ray diffraction pattern for the PLP/PMAA complexes gives no diffraction patterns which appear in pure PLP, indicating the destruction of the helical structure of PLP due to the interpolymer complexation. Mixtures of PMAA with poly(γ‐hydroxy‐L‐proline) (PHLP) which has a similar conformation as PLP, but involves intra‐ or intermolecular hydrogen bonds, has also been investigated by vicometry measurements. The reduced viscosity of a solution of the mixed polymers increases with increasing [PHLP], indicating no complex formation. All the results reveal that the magnitude and the nature of the forces acting in the polymers play an important role in interpolymer complexation.
Cyclodehydration reaction of polyhydrazides. III. Influence of the sample history
Authors: Gebben B. , Rolevink E. , Mulder M. H. V. , Smolders C. A. 
Published: April 2003

AbstractThe influence of preparation history upon the thermal cyclodehydration reaction of polyhydrazide samples has been investigated. Solid polyhydrazide samples were prepared from DMSO solutions using the phase‐inversion technique. Significant differences in conversion rates were observed between samples prepared by nonsolvent immersion precipitation and by evaporation of solvent. It appeared that contact with the nonsolvent water during the sample preparation process has considerable influence on the conversion rate. Not only does the immersion in and washing with water lead to a better removal of the solvent also the pH of the water determines the rate of conversion. A distinct change in the conversion rate is found for washing water at a pH of 7. Basic washing solutions showing lower conversion rates than acid ones. A mechanism explaining these phenomena is proposed.
Thermoplasticization of wood. II. Cyanoethylation
Authors: Hon David N.‐S. , Luis Josefina M. San 
Published: April 2003

AbstractCyanoethylation was attempted to convert wood into thermoplastic material as a means to utilize low quality wood species as well as wood waste materials. Cyanoethylation reaction was conducted with control of the alkalinity of the reaction media, reaction temperature and time, and wood‐to‐acrylonitrile ratio. Cyanoethylated wood was purified and its nitrogen content and weight gain were determined. Fourier transform infrared (FTIR) spectroscopy was used to monitor the absorption peak of cyano group. Thermoproperties of cyanoethylated wood were analyzed by means of a differential scanning calorimeter (DSC) and a dynamic mechanical thermal analyzer (DMTA). Reaction mechanisms and chemistry influencing the thermoproperties of cyanoethylated wood were discussed.
Thermal stability and composition of the amylose–iodine complex
Authors: Fonslick Janée , Khan Arshad 
Published: April 2003

AbstractAmylose–iodine blue complex (absorbance band at 615 nm) was studied at different temperatures to examine the thermal stability and composition of the complex. Our direct experiment with amylose–iodine complex for composition determination suggests that with every 2.75 glucose units of amylose helix there is an iodine unit involved. The average I—I distance in the complex is found to be 3.0 Å, which is in excellent agreement with the value obtained from x‐ray diffraction study of model compounds (3.1 Å). As the temperature increases above 15°C, the observed decrease in concentration of the complex is primarily due to dissociation of iodine from the amylose helix.
Aspects of the radiation‐induced polymerization of 2‐vinyl anthraquinone
Authors: Gradwell A. J. , Guthrie J. T. , Webber S. E. 
Published: April 2003

Abstract2‐Vinyl anthraquinone has been polymerized, via radiation‐induced initiation, in dimethyl‐sulphoxide and in dichloromethane. Solvent to monomer ratios of 1 : 0.030 to 1 : 0.0167 mol have been examined for dose rates in the range 0.035 to 0.129 Gy s−1and exposure times in the range 1.44 × 104to 4.32 × 106s. Rates of polymerization were found to lie in the range from 2.4 × 10−8to 1.92 × 10−6mol L−1s−1. Values for the chain transfer constant to dimethyl‐sulphoxide and to dichloromethane have been calculated. In addition, values of the kinetic ratiok/kt, for the polymerization of 2‐vinyl anthraquinone have been estimated. The dependence ofRpon the monomer concentration and on the radiation intensity have been shown to be in broad agreement with a simplified steady‐state kinetic scheme. A value ofG(radical) for 2‐vinyl anthraquinone was obtained via electron spin resonance studies, and shown to be 0.24. ThisG(radical) value and those obtained indirectly from kinetic data are discussed in relation to the molar mass values obtained from the poly(2‐vinyl anthraquinone) products.
Synthesis of poly(dipeptide)s on the surface of functional micelle and reversed micelle
Authors: Hanabusa Kenji , Ye Xuanjing , Kurose Akio , Shirai Hirofusa , Hayakawa Tadao , Hojo Nobumasa 
Published: April 2003

AbstractAmphiphilic active 4‐dodecanoyl‐2‐nitrophenyl esters of dipeptide containing β‐alanine (1–5) were prepared and their polycondensation was studied in detail. The critical micelle concentrations of the active esters 1–5 were determined in water by the dye method and the apparent mean aggregation number of reversed micelles formed by model compound 6 was determined by the osmotic method. The results of polycondensation can be explained by assuming that aggregations such as micelle and reversed micelle play an important role in polycondensation. The obtained new poly(dipeptide)s were examined by IR, 1H NMR, x‐ray diffraction, and circular dichroism spectra.
Mechanism of alternating copolymerization of 4‐hydroxy‐4′‐vinylbiphenyl with α‐chloromaleic anhydride
Authors: Inoue Kenzo , Kaku Hisanori , Hayashi Hirokazu , Tanigaki Teiichi 
Published: April 2003

AbstractThe copolymerization of 4‐hydroxy‐4′‐vinylbiphenyl (HVB) with α‐chloromaleic anhydride (CMAn) was investigated in THF, 1,4‐dioxane, and acetonitrile. The formation of the 1:1 charge transfer complex between HVB and CMAn was confirmed spectroscopically, and the corresponding equilibrium constant (Keq) was determined as follows: Keq = 0.19, 0.11, and 0.058 mol/L in THF, 1,4‐dioxane, and CH3CN, respectively. The copolymer composition is affected by the solvent, i.e., the content of HVB in the copolymer obtained in THF or 1,4‐dioxane is lower than 50 mol % whereas the copolymer obtained in CH3CN has excess of HVB units. The maximum rate of copolymerization was observed at a 1:1 initial comonomer mole ratio, irrespective of the solvent polarity. Plots of Rp/[HVB] vs. [HVB] gave a straight line with a slope and an intercept for the copolymerization in THF whereas a straight line in CH3CN has no slope. On the basis of these results and 13C‐NMR spectra of the copolymers, the mechanism of the predominant formation of alternating copolymers is discussed.
Two‐dimensional NMR spectra of poly(N‐vinylcarbazole)
Authors: Natansohn Almeria 
Published: April 2003

AbstractTwo‐dimensional NMR spectra of commercially available poly(N‐vinylcarabazole) are presented and analyzed. Complete assignments for the aromatic region of the carbon spectrum are made using the edited spectrum and literature references for model compounds. The proton spectrum is assigned from its correlations with the carbon spectrum and with a J‐correlated two‐dimensional spectrum. One of the protons (number 1) is shifted to rather unusual high fields by the stacked structure of the carbazole rings, independent on the polymer tacticity. From the aliphatic carbon spectrum a meso probability of 0.45 is estimated for the commercial polymer, and another J‐correlated two‐dimensional spectrum helps assigning the triad and tetrad splittings in the aliphatic proton spectrum.