bluuebunny/crossref_metadata_2025_split huggingface dataset:
Macromolecular engineering of polylactones and polylactides. XV. Poly(D,L)‐lactide macromonomers as precursors of biocompatible graft copolymers and bioerodible gels
Authors: Barakat I. , Dubois Ph. , Jérôme R. , Teyssié Ph. , Goethals E. 
Published: April 2003

AbstractThe functional aluminum alkoxide, Et2AlO(CH2)2O‐C(O)C(CH3)CH2, is a very effective initiator for the (D,L)‐lactide (LA) polymerization in toluene at 707deg;C. The coordination‐insertion type of polymerization is living and exclusively yields linear P (D,L)‐lactide macromonomers of a predictable molecular weight and a narrow molecular weight distribution. IR and 1H‐NMR studies show that the methacryloyl group of the initiator is selectively and quantitatively attached to one chain end, whereas the second extremity is systematically a hydroxyl function resulting from the hydrolysis of the living growing site. α,ω‐Dimethacryloyl‐P(D,L)‐lactides, i.e., α,ω‐macromonomers, have also been successfully synthesized by the additional control of the termination step, i.e., by reaction of Al alkoxide end groups with methacryloyl chloride. α‐Macromonomer and α,ω‐macromonomer P(D,L)‐lactides are easily free‐radical copolymerized with 2‐hydroxyethyl methacrylate (HEMA), resulting in a hydrophilic poly (HEMA) backbone grafted with hydrophobic P(D,L)‐lactide subchains and a biodegradable amphiphilic network, respectively. © 1994 John Wiley & Sons, Inc.
Synthesis, doping, and processing of high molecular weight poly(o‐methoxyaniline)
Authors: Mattoso Luiz H. C. , Faria Roberto M. , Bulhões Luis O. S. , MacDiarmid Alan G. 
Published: April 2003

AbstractHigh molecular weight poly(o‐methoxyaniline) was synthesized using a novel method in which the polymerization occurs in the presence of a neutral salt. The molecular weight of the polymer was greatly affected by the quenching procedure employed to conclude the polymerization. Conventional doping of the base form of poly(o‐methoxyaniline) produced a yellow coloration of the doping solution and polymer degradation. It was found that the molecular weight of the polymer decreased significantly after washing or doping with certain aqueous acid media. The gelation conditions of N‐methyl pyrrolidinone (NMP) solutions and film preparation were also investigated for polymers of various molecular weights. The gelation time in NMP decreased drastically with the increase in the polymer molecular weight (the same for solution concentration and temperature), until a critical point was reached after which its decrease was very slow. Flexible, free‐standing, and stretchable films were readily obtained from the higher molecular weight polymers. Good quality doped gel films with conductivity of up to 1 S/cm were obtained under optimized doping conditions. © 1994 John Wiley & Sons, Inc.
Influence of the morphology of polypropylene films on the formation and evolution of irradiation‐induced peroxy‐radicals
Authors: Dogué I. Louis Joseph , Mermilliod N. , Genoud F. 
Published: April 2003

AbstractTo gain some knowledge on the influence of a substrate morphology upon radiochemical grafting efficiency, the formation and the evolution of irradiation induced peroxy‐radicals were measured by ESR in two polypropylene (PP) films of different origins. The creation rate of peroxy‐radicals was found to be almost proportional to the irradiation dose in the film presenting the best crystallinity, the bi‐oriented PP, while it saturates in the unoriented one. The recombination kinetics of the radicals appeared to be controlled by their diffusion in the matrix and the corresponding diffusion coefficients are dependent on the matrix itself and on its evolution under irradiation. It is suggested that the crystalline order of the matrix is the parameter governing the mobility and thus the lifetime of the radicals. © 1994 John Wiley & Sons, Inc.
Effect of the presence of polymer in miniemulsion droplets on the kinetics of polymerization
Authors: Miller C. M. , Blythe P. J. , Sudol E. D. , Silebi C. A. , El‐Aasser M. S. 
Published: April 2003

AbstractSolution of polystyrene in styrene were dispersed in an aqueous gel phase comprising sodium lauryl sulfate, cetyl alcohol, and water using an emulsification process known to produce monomer droplet sizes inthe submicron size range (referred to as miniemulsion droplets). The shelf‐life stabilities of these miniemulsions were studied to determine their relative droplet sizes, and the emulsions were concommitantly polymerized in an isothermal batch reaction calorimeter. The polymerization kinetics and final particle sizes produced were compared with miniemulsion and conventional emulsion polymerizations prepared using equivalent recipes without the addition of polystyrene. The results indicate that polymerization of miniemulsions prepared from polymer solutions produce significantly different kinetics than both miniemulsion and conventional emulsion polymerizations. In general, a small amount of polymer greatly increases the rate of polymerization and the final number of particles produced in the polymerization to the extent where even conventional polymerizations carried out above the critical micelle concentration of the surfactant polymerize more slowly. The results are explained by considering the system to be comprised of small, stable pre‐formed monomer‐swollen polymer particles which are able to efficiently capture aqueous phase radicals. This enables the system to produce a large final number of particles, similar to the initial number of pre‐formed polymer particles, as opposed to miniemulsions and micelles in which only a relatively small fraction of the initial number of species (droplets or micelles) become polymer particles. © 1994 John Wiley & Sons, Inc.
Functionalization of poly (aryl ether ether ketone): Synthesis of bromomethylated PEEK and its functionalization
Authors: Wang Fei , Roovers Jacques 
Published: April 2003

AbstractBromomethyl poly (aryl ether ether ketone) has been prepared from methyl poly (aryl ether ether ketone) (MePEEK) and has been used as the precursor to many forms of functionalized PEEK. MePEEK was brominated directly with bromine. Bromination takes place exclusively at the methyl group. The reaction conditions for bromination have been studied. The bromination level can be controlled by the amount of bromine used, up to 90% of the methyl groups can be brominated to mono‐bromo and di‐bromo methyl PEEK. Modification reactions have been carried out on the brominated methyl PEEK. The bromomethyl group has been converted to different functional groups, such as  CH2OH,  CH2OCH3,  COOCH3,  CH2CN,  CH2COOH  CH2OCOCH3,  CH2N+H (CH2CH3)2Br−,  CH2N (CH2CH3)2,  CH2N+ (CH2CH3)3 Br−. Published 1994 John Wiley & Sons, Inc.
Macromlecular engineering of polylactones and polylactides. XVI. On the way to the synthesis of ω‐aliphatic primary amine poly (ϵ‐caprolactone) and polylactides
Authors: Stassen S. , Archambeau S. , Dubois Ph. , Jerome R. , Teyssie Ph. 
Published: April 2003

AbstractSince bromides are well‐known precursors of primary amines, diethylaluminum 12 bromo‐1‐dodecyl oxide has been prepared and used as an initiator for the ring‐opening polymerization of ϵ‐caprolactone and L‐lactide. Uner strictly controlled conditions, the end‐functionalization of the polyesters in quantitative and the bromo end‐group is easily converted into an azide group whatever the polymeric backbone. The subsequent reduction of the azide into the expected primary amine has been investigated by catalytic transfer hydrogenation (CTH) in DMF and by hydrolysis in the presence of triphenylphosphine in THF, respectively.The hydrolysis reaction (PΦ3/H2O) is perturbed by a coupling reaction, which involves a protonate secondary amine and leads to a twofold increase in the polyester molecular weight. The CTH method gives rise to the expected ω‐NH2 poly (ϵ‐caprolactone), in contrast to polylactide which seems to be unstable toward the nascent amine end group. Whatever the polarity of the medium (DMF or THF), aminolysis of polylactides is observed to occur and leads to the formation of an internal amide. © 1994 John Wiley & Sons, Inc.
Ion‐Free latex films as dual‐phase electrolytes: Styrene–butadiene rubber and nitrile–butadiene rubber synthesized by emulsion polymerization with poly‐(vinyl pyrrolidone) stabilizer
Authors: Steven Rutt J. , Ichino Toshihiro , Matsumoto Morihiko , Nishi Shiro 
Published: April 2003

AbstractIon‐free latices of styrene‐butadiene rubber (SBR) and nitrile‐butadiene rubber (NBR) were synthesized by emulsion polymerization with use of poly (vinyl pyrrolidone) (PVP) stabilizer. The goal was to prepare ion‐free latex films, possessing dual‐phase latex particle morphology, and swell the films with liquid electrolyte to yield dual‐phase polymer electrolytes (DPE). SBR/PVP latex was prepared readily, but NBR/PVP latex was sensitive to coagulation. Differential scanning calorimetric (DSC) and scanning electron microscopic (SEM) analyses of latex films provided morphological evidence concerning particle structure and phase separation. Blends of NBR/PVP and PB/PVP latices (PB = polybutadiene) were also investigated, but particle structure was not present in the blended latex film, even though particle structure was present in the individual NBR/PVP and PB/PVP latex films. After extensive swelling of SBR/PVP latex films, PVP was extracted from the films, and ionic conductivities greater than 10−3 S/cm were achieved. © 1994‐John Wiley & Sons, Inc.
Fine control of the porous structure and chromatographic properties of monodisperse macroporous poly(styrene‐co‐divinylbenzene) beads prepared using polymer porogens
Authors: Wang Q. Ching , Švec František , Fréchet Jean M. J. 
Published: April 2003

AbstractThe porous structure of monodisperse macroporous beads can be controlled by using soluble polymers with well‐defined structural characteristics as part of the porogenic mixture. In general, the use of linear polystyrene as a porogen in the preparation of poly (styrene‐co‐divinylbenzene) beads shifts the pore size distribution towards larger pores. While a direct correlation between pore size and molecular weight of the porogen has been established, the chemical composition of the polymer porogen has no effect on the porous and chromatographic properties of the beads. These findings suggest that the average molar volume of the porogenic system is important while the miscibility of the polymer porogen with the crosslinked polymer that is formed is of little relevance. © 1994 John Wiley & Sons, Inc.
Preparation and block copolymerization of oligodihexanoylchitin having hydroxy groups at both ends
Authors: Chiba Koji , Kadokawa Jun‐Ichi , Yamashita Kanako , Tagaya Hideyuki , Karasu Masa 
Published: April 2003

AbstractThe preparation of oligodihexanoylchitin (3) having hydroxy groups at the both ends was carried out by an acid hydrolysis of a parent dihexanoylchitin in a mixed solution of acetic acid and conc. hydrochloric acid (11 : 1 in volume) at a room temperature. After 13–21 h, the products were isolated and their molecular weights were calculated as 7400–1100 by GPC analyses. The structure of the product 3 was determined by 1H and 13C‐NMR and IR spectra. The IR spectra of the products yielded for longer hydrolysis times than 30 h, however, indicated the occurrence of the dehexanoylation. The block copolymerization of 3 with poly (propylene glycol) (PPG) using 4,4'‐methylenedi (phenyl isocyanate) (MDI) as a coupling reagent gave the block copolymer 6. The molecular weight of 6 as obrained by GPC was 52,000. © 1994 John Wiley & Sons, Inc.
Macro‐azo‐initiators composed of various polyesters: Their syntheses, thermal properties, and application to block copolymerization
Authors: Haneda Yasuhiko , Terada Hiroyuki , Yoshida Michie , Ueda Akira , Nagai Susumu 
Published: April 2003

AbstractVarious aliphatic polyesters such as poly (ethyleneadipate), poly (tetramethylene adipate), poly (caprolactone), and poly (carbonate) were condensed with 4,4'‐azobis‐4‐cyanopentanoyl chloride to prepare macro‐azo‐initiators. Their thermal properties, observed by differential scanning calorimetry, showed similar decomposition behavior to each other. Block copolymers containing each of these polyesters as a block segment combined with polystyrene or poly (methylmethacrylate) have been derived by the polymerization of monomers initiated with these macro‐azo‐initiators. © 1994 John Wiley & Sons, Inc.
Perfectly alternating segmented polyimide‐polydimethyl siloxane copolymers via transimidization
Authors: Rogers M. E. , Glass T. E. , Mecham S. J. , Rodrigues D. , Wilkes G. L. , McGrath J. E. 
Published: April 2003

AbstractNew strategies for the synthesis of perfectly alternating segmented polyimide‐polydimethyl siloxane copolymers were developed by utilizing a transimidization method. Imide oligomers endcapped with 2‐aminopyrimidine were reacted with aminopropyl terminated (dimethyl siloxane) oligomers to afford perfectly alternating segmented imide siloxane copolymers. The polymerization was conducted in solvents such as chlorobenzene and chlorofrom. High molecular weight, fully imidized perfectly alternating segmented imide siloxane copolymers were obtained within 2 h at temperatures of 60‐110°C. The mechanism of the reaction was further elucidated via model compounds and NMR characterization. The block copolymers exhibited two Tgs due to the microphase separation of the polyimide and polysiloxane phases. The Tg of the polyimide phase was a function of the length of the polyimide block. However, partial phase mixing was also evident from the DSC results on the imide siloxane copolymers prepared with low molecular weight polyimide segments. Thermooxidative stability and tensile properties of the perfectly alternating segmented imide siloxane copolymers were found to be principally dependent on the amount of poly (dimethyl siloxane) incorporated in the copolymer and did not correlate with the poly (dimethyl siloxane) or polyimide block lengths. The stress‐strain behavior of both solvent cast films or molded films is also reported. © 1994 John Wiley & Sons, Inc.
Chain transfer by addition–substitution–fragmentation mechanism. I. End–functional polymers by a single‐step free radical transfer reaction: Use of a new allylic linear peroxyketal
Authors: Colombani Daniel , Chaumont Philippe 
Published: April 2003

AbstractA new chain transfer agent, ethyl 2‐[1‐(1‐n‐butoxyethylperoxy) ethyl] propenoate (EBEPEP) was used in the free radical polymerization of methyl methacrylate (MMA), styrene (St), and butyl acrylate (BA) to produce end‐functional polymers by a radical addition–substitution–fragmentation mechanism. The chain transfer constants (Ctr) for EBEPEP in the three monomers polymerization at 60°C were determined from measurements of the degrees of polymerization. The Ctr were determined to be 0.086, 0.91, and 0.63 in MMA, St, and BA, respectively. EBEPEP behaves nearly as an “azeotropic” transfer agent for styrene at 60°C. The activation energy, Eatr, for the chain transfer reaction of EBEPEP with PMMA radicals was determined to be 29.5 kJ/mol. Thermal stability of peroxyketal EBEPEP in the polymerization medium was estimated from the DSC measurements of the activation energy, Eath = 133.5 kJ/mol, and the rate constants, kth, of the thermolysis to various temperature. © 1994 John Wiley & Sons, Inc.
Synthesis and dielectric analysis of aliphatic poly(carbonate‐sulfone)s based on 1,4‐bis(3‐hydroxypropylsulfonyl) butane
Authors: Zhang Tianhong , Litt Morton H. , Rogers Charles E. 
Published: April 2003

AbstractHigh molecular weight aliphatic poly(carbonate‐sulfone) homopolymer (PC‐343) and random copolymer (PC‐343‐10) were synthesized from 1,4‐bis(3‐hydroxypropylsulfonyl)butane (Diol‐343) and a 1/1 molar mixture of Diol‐343 and 1,10‐decanediol, respectively. As a comparison, an aliphatic polycarbonate homopolymer (PC‐10) was prepared from 1,10‐decanediol. While PC‐10 exhibited a single melting peak during its DSC heating scan, both PC‐343 and PC‐343‐10 exhibited multiple reproducible first‐order transitions during DSC heating scans. Both PC‐343 and PC‐343‐10 showed broad reflections in their WAXD diagrams; the crystalline order of PC‐343 is higher than that of PC‐343‐10. Based on the DSC and WAXD results and our discovery on the liquid crystalline behavior of aliphatic poly(carbonate‐sulfone)s from 1,3‐bis(hydroxypropylsulfonyl)propane, we suggest PC‐343 and PC‐343‐10 are liquid crystalline and the liquid crystalline phase formation is directed by the dipole–dipole interactions between sulfone groups. Films were obtained from these polymers by compression molding and dielectric analyses were conducted on them. One glass transition related dielectric relaxation was observed in PC‐343‐10. One glass transition related dielectric relaxation and one sub‐glass transition related dielectric relaxation were observed in PC‐343. The glass transition temperature increases with the increase of sulfone content in the polymers. A dramatic rise in dielectric constant with temperature was observed in PC‐343 and PC‐343‐10 at low frequencies, which is probably due to the sulfone dipole interaction with the electrical field. © 1994 John Wiley & Sons, Inc.
Novel thermooxidatively stable poly(ether‐imide‐benzoxazole) and poly(ester‐imide‐benzoxazole)
Authors: Sundar Raj A. , Mathias Lon J. 
Published: April 2003

Abstract4‐Hydroxy‐5‐nitrophthalimides were produced via nucleophilic aromatic substitution (NAS) of 4,5‐dichloro phthalimide substituents by potassium nitrite. The use of a N‐phenyl‐phthalimide having a protected 4′‐hydroxyl group allows concurrent deprotection and nitro reduction to amine to give the 4‐hydroxy‐5‐amino‐N‐(4′‐hydroxyphenyl) phthalimide. This key intermediate is the precursor to a poly (ether‐imide‐benzoxazole), and is the condensable monomer for a poly (ester‐imide‐benzoxazole). Benzoxazole monomer formation via condensation with p‐fluorobenzoyl chloride afforded 2‐(4′‐fluorophenyl)‐5,6,‐N‐[4′(‐hydroxyphenyl) imide]‐benzoxazole, which was polymerized under NAS conditions to produce a poly(ether‐imide‐benzoxazole) having an endothermic transition at 454°C with weight retention of 90% at 500°C in both air and nitrogen. Solution polycondensation of the 4‐hydroxy‐5‐amino‐N‐(4′‐hydroxyphenyl) phthalimide monomer with isophthaloyl chloride afforded a poly(ester‐amide‐imide) which was isolated and thermally cyclodehydrated in the solid state under vacuum to give a poly(ester‐imide‐benzoxazole) having 95% weight retention at 500°C in both air and nitrogen, with no detectable DSC transitions up to 500°C. © 1994 John Wiley & Sons, Inc.
Synthesis of tridimensional polymers by the copolymerization of phenylglycidylether with aromatic diglycidylethers
Authors: Ronda Joan Carles , Serra Angels , Mantecón Ana , Cádiz Virginia 
Published: April 2003

AbstractCopolymers from phenylglycidylether and several aromatic diglycidylethers are prepared using different ratios of difunctional comonomers and the AIP/ZnCl2 initiator system. It is found that the percentage of incorporated comonomer depends on the nature of the aromatic moiety introduced. The copolymers are characterized by 13C‐NMR spectroscopy and turn out to be completely regular and with a high degree of isotacticity (about 80%) that confirms the high degree of regio‐ and stereoselectivity of the initiator system used. The thermal characteristics of copolymer networks are investigated using differential scanning calorimetry and thermogravimetry. Two fusion endotherms are observed which vary with the degree of crosslinking. By thermogravimetric analyses the thermal stability is found to increase when the crosslinking degree does. © 1994 John Wiley & Sons, Inc.
Optically active polymers containing side‐chain azobenzene moieties: Photochromic and photoresponsive behavior of copolymers of N‐(4‐azobenzene) maleimide with (−)‐menthyl vinyl ether and (+) (S)‐2‐methylbutyl vinyl ether
Authors: Angiolini Luigi , Caretti Daniele , Carlini Carlo , Altomare Angelina , Solaro Roberto 
Published: April 2003

AbstractPhotochromic behavior and photoisomerization kinetics of optically active copolymers of trans‐N‐(4‐azobenzene) maleimide (ABM) with (−) ‐menthyl vinyl ether (MtVE) and (+) (S) ‐2‐methylbutyl vinyl ether were studied by UV spectroscopy under irradiation at 348 nm. The resulting data have been compared with those of the corresponding copolymers containing also trans‐N‐(4‐azobenzene) maleamic acid co‐units as well as of low molecular weight model compounds. The photoresponsive behavior has been also investigated by circular dichroism measurements at various extents of photoisomerization. The results are discussed in terms of structural requirements of the macromolecules. © 1994 John Wiley & Sons, Inc.
Random thermotropic elastomers. I. Effects of substitution and hard/soft segment lengths on properties
Authors: Sonpatki M. M. , Ravindranath K. , Ponrathnam S. 
Published: April 2003

AbstractSyntheses of segmented copoly(ether‐ester)s with (oxy‐2‐methyl‐1,4‐phenyleneoxycarbonyl‐1,4‐phenylene carbonyl)/(oxy‐2‐chloro‐1,4‐phenyleneoxycarbonyl‐1,4‐phenylene carbonyl) (methyl‐/chloro‐substituted) hard segments and poly(oxytetramethylene) soft segments, are reported. The methodology consisted of staged addition melt condensation of terephthaloyl chloride, poly(oxytetramethylene)glycol (POTMG;
\[
\bar M_n
\] = 250, 650, 1000, 2000) and methyl‐/chloro‐hydroquinone. Lengths of hard and soft segments were varied while the weight ratio of hard to soft segment was maintained constant. Copolymers were characterised for solubility behavior, and by infrared spectroscopy, x‐ray diffraction, DSC, and polarizing microscopy. Thermal properties were found to be dependent on length of soft segment as well as on the type of substituent in the mesogenic core. In both methyl‐ as well as chloro‐substituted copoly(ether‐ester)s soft segment glass transition temperature (Tgs) was obtained between −40 and −50°C. All copoly(ether‐ester)s are elastomeric at room temperature (25°C). These polymers exhibit thermotropic liquid crystalline behavior and were easily sheared and aligned in liquid crystalline state. © 1994 John Wiley & Sons, Inc.
Emulsion polymerization of butyl acrylate: Spin trapping and EPR study
Authors: Kim Soon Sam , Westmoreland David G. 
Published: April 2003

AbstractThe propagating radical in the emulsion polymerization reaction of butyl acrylate was detected by Electron Paramagnetic Resonance (EPR) spectroscopy using two spin‐trapping agents, 2‐methyl‐2‐nitrosopropane (MNP) and α‐(4‐pyridyl 1‐oxide)‐N‐tert‐butylnitrone (PyOBN). Through analysis of hyperfine structure of the spectra obtainedfrom the trapped radicals, the propagating radical is inferred to be the well known acrylate radical,  [CH2CH(COOC4H9)]nCH2CH(COOC4H9). © 1994 John Wiley & Sons, Inc.