bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miscible blends of poly(4‐vinyl phenol)/poly (trimethylene terephthalate)
Authors: Lee Li‐Ting , Woo E‐M 
Published: July 2004

AbstractA new miscible blend of all compositions comprising poly(4‐vinyl phenol) (PVPh) and poly(trimethylene terephthalate) (PTT) was discovered and reported. The blends exhibit a single composition‐dependent glass transition and homogeneous phase morphology, with no lower critical solution temperature (LCST) behavior upon heating to high temperatures. Interactions and spherulite growth kinetics in the blends were also investigated. The Flory–Huggins interaction parameter (χ12) and interaction energy density (B) obtained from analysis of melting point depression are negative (χ12 = −0.74 and B = −32.49 J cm−3), proving that the PVPh/PTT blends are miscible over a wide temperature range from ambient up to high temperatures in the melt state. FTIR studies showed evidence of hydrogen‐bonding interactions between the two polymers. The miscibility of PVPh with PTT also resulted in a reduction in spherulite growth rate of PTT in the miscible blend. The Lauritzen–Hoffman model was used to analyze the spherulite growth kinetics, which showed a lower fold‐surface free energy (σe) of the blends than that of the neat PTT. The decrease in the fold‐surface free energy has been attributed to disruption of the PTT lamellae exerted by PVPh in an intimately interacted miscible state. Copyright © 2004 Society of Chemical Industry
Synthesis and characterisation of hydrophobic modified polyacrylamide
Authors: Wu Shuhui , Shanks RA 
Published: July 2004

AbstractPolyacrylamide has been modified hydrophobically with low amounts of N‐alkyl groups by a transamidation method, using alkylamines. The amide group in the polymer backbone has been N‐substituted in water solutions, where the substituting amine is water‐soluble. The alkyl groups include N‐alkyl (up to octyl), N,N‐diethyl, N,N‐dipropyl, N‐isopropyl, N,N‐diisopropyl and N‐cyclohexyl groups. This transamidation method is more convenient compared with the traditional micellar copolymerisation methods and the direct method using alkyl halide substitution. However, a limitation of the method is due to the failure to achieve substitution of highly hydrophobic groups such as dodecyl. The mutual insolubility of dodecylamine and the potential substituted product, with N‐dodecyl substitution of polyacrylamide, makes it impractical to carry out the reaction in water. Other mixed solvents were used for the amine substitution, including water with dimethylsulfoxide and ethylene glycol, without transamidation occurring, since these solvents decreased the solubility of polyacrylamide. The NMR and IR spectra of modified polyacrylamides are reported. The mechanism of the reaction under acid‐ and base‐catalysed situations is discussed. Copyright © 2004 Society of Chemical Industry
Photochromic polyacylsemicarbazides based on azobenzene containing dihydrazide
Authors: Palanisamy Aruna , Radhakrishnan Ganga 
Published: July 2004

AbstractPolyacylsemicarbazides exhibiting photochromic behaviour were synthesised by solution polymerisation of azobenzene chromophore containing dihydrazide and various diisocyanates (aliphatic, cycloaliphatic and aromatic). A model compound was also prepared from o‐tolylene isocyanate and dihydrazide. The structures were confirmed by 1H NMR and FTIR techniques. The polymers were found to exhibit λmax values around 330 nm corresponding to the trans isomer which reduced with irradiation of the solutions of polymers in DMAc due to trans→cis isomerisation as observed by UV‐VIS spectrometry. The reverse reaction (cis→trans isomerisation) was found to take place photochemically when irradiated with visible light or when kept in the dark. The rates of isomerisation reactions were found to be independent of the chromophore concentration and the nature of the polymer backbone. The inherent viscosity of the solutions of polymers in DMAc reduced upon irradiation with UV light and was regained in the dark. Thermal studies showed that the polymer degradation started with the simultaneous cleavage of imino (NN) and aromatic azo (NN) bond and that recrystallisation occurred on heating the samples. Copyright © 2004 Society of Chemical Industry
Synthesis and electro‐optical properties of novel Y‐type polyurethanes containing dioxynitrostilbene
Authors: Lee Ju‐Yeon , Bang Han‐Bae , Park Eun‐Ju , Lee Won‐Jung , Rhee Bum Ku , Lee Seung Mook 
Published: July 2004

Abstract3,4‐Di‐(2′‐hydroxyethoxy)‐4′‐nitrostilbene (2) was prepared by the reaction of 2‐iodoethanol with 3,4‐dihydroxy‐4′‐nitrostilbene. Diol 2 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate and 1,6‐hexamethylenediisocyanate to yield novel Y‐type polyurethanes 3–5 containing dioxynitrostilbene as a non‐linear optical (NLO)‐chromophore. Polymers 3–5 were soluble in common organic solvents, such as acetone and DMF. These polymers showed thermal stability up to 280 °C in TGA thermograms with Tg values in the range of 100–143 °C in DSC thermograms. The approximate lengths of aligned NLO‐chromophores of the polymers estimated from AFM images were around 2 nm. The SHG coefficients (d33) of poled polymer films were around 4.5 × 10−8 esu. Poled polymer films had improved temporal and long‐term thermal stability owing to the hydrogen bonding of urethane linkage and the main‐chain character of the polymer structure, which are acceptable for NLO device applications. Copyright © 2004 Society of Chemical Industry
Synthesis and ring‐opening polymerization of macrocyclic aromatic sulfide oligomers
Authors: Liang Zhi‐An , Chen Ke , Meng Yue‐Zhong , Hay Allan S 
Published: July 2004

AbstractA series of macrocyclic(arylene sulfide) oligomers were synthesized by reaction of 4,4′‐oxybis(benzenethiol) with a number of difluoro compounds in dimethylformamide (DMF) in the presence of anhydrous K2CO3 under high dilution conditions. The difluoro compound can be 4,4′‐difluorobenzophenone, bis(4‐fluorophenyl)sulfone or 1,3‐bis(4‐fluorobenzoyl)benzene. Detailed structural characterization of these oligomers by matrix‐assisted laser desorption and ionization‐time of flight‐mass spectroscopy (MALDI‐TOF‐MS) demonstrated their cyclic nature. The MALDI‐TOF‐MS technique has proved to be a powerful tool to analyze these cyclics. These cyclic oligomers are amorphous and highly soluble in DMF and N,N′‐dimethyl acetamide. Moreover, these cyclic(arylene sulfide) oligomers readily underwent ring‐opening polymerization in the melt at 285 °C in the presence of 2,2′‐dibenzothiazole disulfide, affording linear, high molecular weigh poly(aromatic sulfide)s. These polymers are insoluble in most common solvents. Copyright © 2004 Society of Chemical Industry
Conformations of polysulfone‐block‐polydimethylsiloxane chains in solution and in the solid state
Authors: Bercea Maria , Airinei Anton , Hamciuc Viorica , Ioanid Aurelia 
Published: July 2004

AbstractPolysulfone block copolymers containing polydimethylsiloxane segments were obtained in solution by the condensation reaction of chloro‐terminated polysulfone oligomers and α,ω‐dihydrogensilyl‐polydimethylsiloxane. The conformations of the copolymer chains were investigated both in solution and in the solid state. Viscometric and UV absorption measurements were carried out in dilute dichloroethane solutions over a wide region of concentrations, in the temperature range 20–75 °C. The results point to a conformational transition phenomenon, located at around 55 °C, which is attributed to the transition from a segregated to a pseudo‐Gaussian conformation through a compressed‐segregated conformation. Copyright © 2004 Society of Chemical Industry
Relaxation kinetics in thiophene/3‐alkylthiophene random copolymers
Authors: Buzarovska Aleksandra , Arsov Ljubomir 
Published: July 2004

AbstractThe relaxation kinetics of several thiophene/3‐alkylthiophene (3‐methylthiophene and 3‐octylthiophene) random copolymers have been investigated using the cyclic voltammetric method. The first voltammograms, obtained after the polymer films were maintained at potentials corresponding to their neutral state for various periods of time, have been analyzed according to the procedure developed by Odin et al. Considerable suppression of the relaxation kinetics was achieved in copolymers containing thiophene rings substituted with longer alkyl groups (octyl). Copyright © 2004 Society of Chemical Industry
Swelling behavior of pH‐ and temperature‐sensitive copolymers containing 2‐hydroxy‐ethyl methacrylate and N‐vinyl‐2‐pyrrolidone crosslinked with new crosslinkers
Authors: Atta Ayman M , Arndt K‐F 
Published: July 2004

AbstractCopolymers of 2‐hydroxyethyl methacrylate (HEMA) and N‐vinyl‐2‐pyrrolidone (VP) and homopolymers of HEMA and VP were crosslinked in the presence of different mol% of melamine trimethacrylamide (MMAm) and melamine triacrylamide (MAAm) as crosslinkers by bulk radical polymerization. The resultant xerogels were characterized by extracting the soluble fractions and measuring the equilibrium water content. Lower critical solution transition temperatures (LCST) were measured by DSC. The properties of crosslinked HEMA and VP copolymers, VP and HEMA series were evaluated in terms of compositional drift of polymerization, heterogeneous crosslinking, and chemical structure of the relevant components. Soluble fractions of the crosslinked networks were reduced by varying the MAAm and MMAm concentrations. The influence of environmental conditions such as temperature and pH on the swelling behavior of these polymeric gels was investigated. The swelling behaviors of the resulting gels show pH sensitivity. This behavior is explained on the basis that amide groups of VP or crosslinkers could be hydrolyzed to form negatively charged carboxylate ion groups in the produced networks in response to an external pH variation. Copyright © 2004 Society of Chemical Industry
IPNs based on unsaturated polyester/epoxy: IV. Investigation on hydrogen bonding, compatability and interaction behavior
Authors: Shih Yeng‐Fong , Jeng Ru‐Jong 
Published: July 2004

AbstractA series of interpenetrating polymer networks (IPNs) based on unsaturated polyester/epoxy have been developed. The compatibility and interaction behavior of these IPNs have been investigated by DMA, DSC, SEM, FTIR and solid‐state NMR spectroscopies. The glass transition temperatures of IPNs were decreased and their transitions became broader as the content of unsaturated polyester increased in IPNs, based on our DMA and DSC study. The results of FTIR indicate that hydrogen bonding is present between the unsaturated polyester and epoxy. Insufficient degree of hydrogen bonding brought about immiscibility between IPN components. The analysis of proton spin‐lattice relaxation time in the rotating frame of the IPNs was also utilized to investigate molecular interaction between unsaturated polyester and epoxy. From relaxation curves, phase separation was found for the IPN samples with unsaturated polyester content higher than 30 %. This corroborates the DMA and SEM study. Copyright © 2004 Society of Chemical Industry
Synthesis and characterization of electrically conducting poly(o‐/m‐toluidine‐co‐o‐/m‐aminoacetophenone) copolymers
Authors: Savitha P. , Sathyanarayana D. N. 
Published: July 2004

AbstractA series of poly(o‐/m‐toluidine‐co‐o‐/m‐aminoacetophenone) copolymers combining the features of high conductivity and processibility are synthesized and characterized by a number of techniques including 1H NMR; thermogravimetry; IR, Raman, and UV–visible spectroscopy; scanning electron microscopy; and X‐ray diffraction. The copolymers are synthesized by the emulsion and inverse emulsion methods using conventional ammonium persulfate and a new oxidant, benzoyl peroxide, respectively. The influence of the polymerization conditions such as the monomer feed ratios, solvent, and the nonsolvent is investigated. The composition of the resulting copolymers is determined by 1H NMR analysis. The conductivity of the copolymers varies with the aminoacetophenone content in the feed and the polymerization conditions. It is interesting that the conductivity of the copolymers is higher than that of the corresponding homopolymers. The results are rationalized on the basis of the effect of the COCH3 substituent on the polymer structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4300–4310, 2004
Narrowly dispersed micrometer‐sized composite spheres based on diazonium–polystyrene
Authors: Yang Zhaohui , Cong Hailin , Cao Weixiao 
Published: July 2004

AbstractDiazonium group–substituted polystyrene (PS–N) micrometer‐sized spheres with narrow distribution were prepared from highly crosslinked polystyrene particles. Then a composite sphere was prepared with the micro‐PS–N sphere as core and submicrometer‐sized poly(styrene‐methyl methacrylate‐acrylic acid) [P(S‐MMA‐AA)] colloids or nanometer‐sized SiO2 particles as shell via columbic interaction. The ionic linkages between the core and shell convert to covalent bonds in the thermal treatment process. As a result, the composite sphere becomes very stable toward polar solvents as well as toward ultrasonic treatment. A hollow SiO2 micrometer‐sized sphere then was achieved by removing the core under sintering conditions (700 °C). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4284–4288, 2004
Amphiphilic membranes crosslinked and reinforced by POSS
Authors: Isayeva Irada S. , Kennedy Joseph P. 
Published: July 2004

AbstractThis article concerns the synthesis and characterization of novel tricomponent amphiphilic membranes consisting of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polydimethylsiloxane (PDMS) segments cocrosslinked and reinforced by octasilane polyhedral oligomeric silsesquioxane (octasilane‐POSS) cages. Rapid and efficient network synthesis was effected by cocrosslinking diallyl‐telechelic PEG (A‐PEG‐A) and divinyl‐telechelic PDMS (V‐PDMS‐V) with pentamethylpentacyclosiloxane (D5H), using Karstedt's catalyst in conjunction with Et3N cocatalyst and water. Films were prepared by pouring charges in molds and crosslinking by heating at 60 °C for several hours. The films were characterized by sol fractions and equilibrium swelling both in hexane and water, extent of crosslinking, contact angle hysteresis, oxygen permeability, thermogravimetric analysis, and mechanical properties. The crosslinking of octasilane‐POSS achieved by the same catalyst system was studied in separate experiments. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4337–4352, 2004
Enzyme immobilization to ultra‐fine cellulose fibers via amphiphilic polyethylene glycol spacers
Authors: Wang Yuhong , Hsieh You‐Lo 
Published: July 2004

AbstractUltra‐high specific surface cellulose fibers with an average diameter of 500 nm were generated from electrospinning and alkaline hydrolysis of cellulose acetate and used as porous supports for enzyme immobilization. The cellulose fiber surfaces were reacted with polyethylene glycol (PEG) diacylchloride to simultaneously add amphiphilic spacers and reactive end groups for coupling with a lipase enzyme. The quantity of reactive carboxylic acid on the fiber surfaces could be readily controlled by COCl/OH molar ratios and PEG lengths. The highest free acid (COOH) content of 1.0 mmol per gram of cellulose was obtained at 10 COCl/OH ratio with the 600‐Da PEG diacylchloride. Enzyme coupling on such PEG‐attached cellulose was optimal in the presence of a water‐soluble carbodiimide [1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC)] at a very low EDC/COOH molar ratio of 0.2 under acidic condition and at ambient temperature. Whereas the free lipase retained only 25% of its original activity, the fiber‐bound lipase possessed much superior retention of catalytic activity after exposure to cyclohexane (81%) and toluene (62%) and hexane (34%). The fiber‐bound lipase also exhibited significantly higher catalytic activity at elevated temperatures than the free form, that is, 10 times at 70 °C. The ultra‐fine, fibrous, and porous structures were retained throughout alkaline hydrolysis, activation, coupling, and activity assays. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4289–4299, 2004
Synthesis, characterization, and degradation of poly(anhydride‐co‐amide)s and their blends with polylactide
Authors: Zhang Zhi‐Qin , Su Xin‐Mei , He Han‐Ping , Qu Fan‐Qi 
Published: July 2004

AbstractIn attempt to improve the properties of polyanhydrides based on aliphatic anhydrides, we synthesized novel polyanhydrides containing amide groups in the main chains. In this work, N,N′‐bis(L‐alanine)‐sebacoylamide (BSAM) was prepared from natural amino acid and sebacic acid (SA) and characterized by IR and 1H NMR. In addition, polymers of PBSAM, P[1,6‐bis(P‐carboxyphenoxy) hexane (CPH)‐BSAM], and P(CPH‐SA), blends of P(CPH‐SA)/polylactide (PLA), P(CPH‐BSAM)/PLA were also prepared and characterized by IR, gel permeation chromatography, and differential scanning calorimetry. The hydrolytic degradation of polyanhydrides and their blends with PLA (number‐average molecular weight = 2.90 × 105) was evaluated in 0.1 M phosphate buffer pH 7.4 at 37 °C. The results indicate that the existence of amide, aromatic, and ester bonds in the main chain of polymers slows down the degradation rate, and the tendency becomes clearer with the increasing amount of them, and the copolymers and their blends with PLA possess excellent physical and mechanical properties. These can make them more widely used in drug delivery and nerve regeneration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4311–4317, 2004
Direct synthesis of linear low‐density polyethylene of ethylene/1‐hexene from ethylene with a tandem catalytic system in a single reactor
Authors: Alobaidi Fahad , Ye Zhibin , Zhu Shiping 
Published: July 2004

AbstractTandem catalysis offers a promising synthetic route to the production of linear low‐density polyethylene. This article reports the use of homogeneous tandem catalytic systems for the synthesis of ethylene/1‐hexene copolymers from ethylene stock as the sole monomer. The reported catalytic systems employ the tandem action between an ethylene trimerization catalyst, (η5‐C5H4CMe2C6H5)TiCl3 (1)/modified methylaluminoxane (MMAO), and a copolymerization metallocene catalyst, [(η5‐C5Me4)SiMe2(tBuN)]TiCl2 (2)/MMAO or rac‐Me2Si(2‐MeBenz[e]Ind)2ZrCl2 (3)/MMAO. During the reaction, 1/MMAO in situ generates 1‐hexene with high activity and high selectivity, and simultaneously 2/MMAO or 3/MMAO copolymerizes ethylene with the produced 1‐hexene to generate butyl‐branched polyethylene. We have demonstrated that, by the simple manipulation of the catalyst molar ratio and polymerization conditions, a series of branched polyethylenes with melting temperatures of 60–128 °C, crystallinities of 5.4–53%, and hexene percentages of 0.3–14.2 can be efficiently produced. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4327–4336, 2004
Synthesis and chirooptical properties of optically active poly(ester imide)s based on axially asymmetric 1,1′‐binaphthyls
Authors: Song Naiheng , Qi Wei , Qiu Xuepeng , Gao Lianxun , Ding Mengxian 
Published: July 2004

AbstractA series of optically active poly(ester imide)s (PEsI's) has been synthesized by the polycondensation reactions of new axially asymmetric dianhydrides, that is, (R)‐2,2′‐bis(3,4‐dicarboxybenzoyloxy)‐1,1′‐binaphthyl dianhydride and (S)‐2,2′‐bis(3,4‐dicarboxybenzoyloxy)‐1,1′‐binaphthyl dianhydride, and various diamines with aromatic, semiaromatic, and aliphatic structures. The polymers have inherent viscosities of 0.45–0.70 dL/g, very good solubility in common organic solvents, glass‐transition temperatures of 124–290 °C, and good thermal stability. Wide‐angle X‐ray crystallography of these polymers shows no crystal diffraction. In comparison with model compounds, an enhanced optical rotatory power has been observed for the repeat unit of optically active PEsI's based on aromatic diamines, and it has been attributed to a collaborative asymmetric perturbation of chiral 1,1′‐binaphthyls along the rigid backbones. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4318–4326, 2004
Structural study of the influence of partially crystalline poly(ethylene butene) random copolymers on paraffin crystallization in dilute solutions
Authors: Radulescu Aurel , Schwahn Dietmar , Monkenbusch Michael , Fetters Lewis J. , Richter Dieter 
Published: July 2004

AbstractRandom crystalline–amorphous copolymers containing ethylene and butene segments, yielded from dilute‐solution, and self‐assembled to one‐dimensional, needle‐shaped aggregates, can modify wax crystal structures through the cocrystallization of the copolymer and wax molecules into hairy platelets. These copolymers show selectivity in their wax crystal modification capacities that depends on the ethylene content of the backbone. Thus, it has been qualitatively established that a copolymer containing larger crystallizable polyethylene sections [poly(ethylene butene) with 7.5 ethyl branches per 100 backbone carbons (PEB‐7.5)] is very efficient for longer wax molecules (C36), whereas for shorter waxes (C24), its efficacy diminishes. Here we present a quantitative evaluation of the small‐angle neutron scattering results obtained in a complex study of the self‐assembling behavior of PEB‐7.5 and paraffin waxes (C24 and C36) in decane and of cocrystallization for different polymer–paraffin combinations and solution conditions. The richness of the morphologies was evaluated with a contrast variation technique and the application of structural models. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3113–3132, 2004
Dornase alpha and exhaled NO in cystic fibrosis
Authors: Grasemann Hartmut , Lax Hildegard , Treseler Jennifer W. , Colin Andrew A. 
Published: July 2004

AbstractNitric oxide (NO) that is produced within the airways can be measured in the exhaled air. Concentrations of exhaled NO (FENO) are decreased in cystic fibrosis (CF) and, in cross sectional studies, have been shown to be even lower in patients with more advanced pulmonary disease. This may result from retention and metabolisation of NO within viscous airway secretions. Treatment with recombinant human DNase I (dornase alpha) modifies the rheological properties of airway secretions and thereby improves pulmonary function even in young and apparently healthy patients with CF. We studied FENO and pulmonary function in children with CF with little clinical evidence of lung morbidity in a two‐year randomized double‐blind placebo‐controlled study with nebulized dornase alpha. Mean age at enrollment was 8 years (range 6 to 11 years), mean forced vital capacity (FVC) was 112% (range 86 to 133%), and mean forced expiratory volume in one second (FEV1)was 109% (range 88 to 128%) of predicted values. In five of six (83%) of the dornase alpha treated patients, FENO changed in parallel to changes in pulmonary function tests while no such correlation was observed in any of the eight patients receiving placebo. This difference between treatment groups was statistically significant for both FVC (P = 0.026, Wilcoxon‐test) and FEV1 (P = 0.042). These data suggest that FENO may serve as a surrogate measure for evaluating the effectiveness of interventions that affect airway clearance in CF. Pediatr Pulmonol. © 2004 Wiley‐Liss, Inc.