bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soft and wet touch‐sensing system made of hydrogel
Authors: Sawahata Kiyoshi , Gong Jian Ping , Osada Yoshihito 
Published: April 2003

AbstractMechanical deformation of water‐swollen polyelectrolyte gels with carboxylic groups induces a spontaneous ionization, which in turn produces an electrical potential as large as a few millivolts. On the base of this phenomenon, a tactile sensor capable of lighting a photo diode array according to the amplitude of deformation has been made. This system may offer a soft and wet touch‐sensor due to its soft tissue‐like rheological characteristics.
Copolymerization of styrene and isoprene with Ni(acac)2‐methylalumoxane catalyst
Authors: Endo Kiyoshi , Masaki Koji 
Published: April 2003

AbstractCopolymerization of styrene (St) and isoprene (IP) with nickel(II) acetylacetonate [Ni(acac)2] and methylalumoxane (MAO) catalyst was investigated. It was found that the Ni(acac)2‐MAO catalyst is effective for the copolymerization of St and IP. From the copolymerization of St (M1) and IP (M2) and IP (M2) with the Ni(acac)2‐methylalumoxane catalyst, the monomer‐reactivity ratios were determined to be r1 = 1,18 and r2 = 0,88, i.e., ideal copolymerization was found to proceed to give perfectly random copolymers without formation of any homopolymer. The microstructure of IP units in the copolymers exhibits high cis‐1,4 contents.
Viscometric study of the coil‐globule transition of poly(N‐isopropylacrylamide) in solutions of surfactant
Authors: Staikos Georges 
Published: April 2003

AbstractThe coil‐globule transition of poly(N‐isopropylacrylamide) (systematic name: poly‐[1‐(isopropylaminocarbonyl)ethylene]) has been viscometrically investigated in low‐concentration aqueous sodium dodecyl sulfate solution. In this environment, even if the macromolecular coils collapse as the temperature increases above the lower critical solution temperature of the polymer, 34°C, the polymer does not precipitate. It seems that the hydrophobically collapsed macromolecular coils do not aggregate, but remain in solution with the aid of surface charges supplied by surfactant ions adsorbed through hydrophobic interactions.
Investigation on the surface orientation of cylindrical microdomains in styrene‐butadiene‐styrene triblock copolymers by scanning force microscopy/transmission electron microscopy
Authors: Gattiglia Ercole , Turturro Antonio , Ricci Davide , Bonfiglio Annalisa 
Published: April 2003

AbstractThe orientation of the microdomains at the free surface of solvent‐cast films of a polystyrene‐block‐polybutadiene‐block‐polystyrene triblock copolymer with cyclindrical morphology was studied by coupling transmission electron and scanning force microscopies (SFM‐TEM). It was found that the cylinders of polystyrene, which are assembled in grains randomly oriented in the bulk, tend to reorient with the main axis perpendicular to the surface. SFM investigation indicates that the hexagonal symmetry of the cylinders is also maintained at the free surface which is characterized by protrusions and corrugation with size and characteristic distances closely related to the cylindrical morphology visible in the bulk. Good quantitative agreement between TEM and SFM measurements is observed.
Poly(silamine)s as new electron‐beam resist materials
Authors: Nagasaki Yukio , Yamazaki Noriyuki , Deguchi Ken‐Ichiro , Kato Masao 
Published: April 2003

AbstractSeveral types of poly(silamine)s were prepared and their structure‐characteristics relationships were investigated. When a phenyl ring in the organosilyl unit and/or a cyclic structure in the amino unit was introduced, the glass transition temperatures were increased significantly in order to increase film formability. From the thermogravimetric analysis of the poly(silamine)s, it was found that the thermal decomposition of poly(silamine)s starts at ca. 380–400°C. On electron‐beam irradiation of the poly(silamine) films, degradation of the polymer took place. On the basis of these results, poly(silamine)s can be one of the candidates for new positive‐type polymeric resists.
Study of ionomer blends based on a polyurethane cationomer and an acrylic anionomer
Authors: Mahesh Gopalasamudram Narayanan , Ramesh Subramanian , Radhakrishnan Ganga 
Published: April 2003

AbstractPolyurethane and polyurethane cationomers were synthesized using 2,3‐dihydroxypyridine and 2,3‐dihydroxypyridine hydrochloride as chain extenders. Poly(butyl methacrylate‐co‐methacrylic acid) was synthesized by free radical solution polymerization and was converted into its sodium salt. The polyurethane cationomer and the acrylic anionomer were blended in different proportions in N,N‐dimethylformamide. Simple blends without ionic groups were also prepared. Miscibility enhancement in these systems was studied by means of differential scanning calorimetry and scanning electron microscopy.
Preparation of liquid crystalline polymers with monosubstituted ferrocenyl pendant groups and generation of unpaired electrons by complexation with tetracyanoethylene in the solid state
Authors: Tanaka Hitoshi , Hongo Takahiro , Hall H. K. 
Published: April 2003

AbstractLiquid crystalline (LC) polymers with monosubstituted ferrocenyl units in the side chain were prepared by radical polymerizations of the corresponding LC and non‐LC acrylates. It was demonstrated that polymerization is useful for the LC orientation and expands the LC temperature range. In addition, these mesogenic ferrocenes form a complex with tetracyanoethylene (TCNE) to give spin labeled molecules simply by mixing the ferrocenyl compounds with TCNE in the solid state at ambient temperature.
The role of the membrane‐assisted hydrophobic interaction between di‐, tri‐, or tetrapeptide catalysts and amino acid esters for the enhancement of stereoselective hydrolysis reactions
Authors: Ohkubo Katsutoshi , Urabe Kenji , Usui Satoshi , Sagawa Takashi 
Published: April 2003

AbstractThe peptide catalyst having the amino acid sequence (Z‐L‐Leu (or Phe)‐L‐His) was found to be the most stereoselective among the L‐histidyl group‐containing di‐, tri‐, or tetrapeptide catalysts in the hydrolysis of enantiomeric amino acid substrates in vesicular membranes. The role of the membrane‐assisted hydrophobic interaction between the peptide catalyst and enantiomeric substrates for the improvement of the hydrolysis stereoselectivity was demonstrated by means of direct measurements of nuclear Overhauser effect spectroscopy (NOESY) spectra of the interaction system and by the extremely high stereoselectivity itself obtained by intensifying the membrane‐promoted hydrophobic interaction between the catalyst and the substrates.
Structural study on poly(ether ether ketone ketone)‐poly(ether biphenyl ether ketone ketone) copolymers
Authors: Zhang Hongfang , Yang Baoquan , Mo Zhishen , Na Hui , Wu Zhongwen 
Published: April 2003

AbstractStructures of poly(ether ether ketone ketone)‐poly(ether biphenyl ether ketone ketone) copolymers were studied by using small angle X‐ray scattering and the one‐dimensional electron density correlation function method. The results revealed that structures of the aggregated state of the copolymers depend closely on the biphenyl content (nb). When nb = 0.35, invariant Q, long period L, average thickness of crystal lamellae d̄, electron density difference ηc − ηa and degree of crystallinity Wc, x assume minimum values.
Solvent induced structural transitions in a liquid crystalline polyester
Authors: Carotenuto Maurizio , Guadagno Liberata , Vittoria Vittoria , Galli Giancarlo , Chiellini Emo 
Published: April 2003

AbstractQuenched nematic films of a liquid crystalline polyester were crystallized either thermally or by solvent induced crystallization, and their structural organization was analyzed. All techniques show that the thermal crystallization transforms part of the nematic phase into a crystalline one, the remaining part leaving unchanged. By contrast, the solvent induced crystallization does transform a part of the nematic phase into a crystalline phase, leaving the residual part in a much more disordered state resembling the amorphous state.
Protonation of polyaniline with lightly sulfonated polystyrene
Authors: Fu Yueping , Weiss R. A. 
Published: April 2003

AbstractProtonation of polyaniline base with lightly sulfonated polystyrene in polar solvents such as dimethyl sulfoxide and N‐methyl‐2‐pyrrolidone was investigated by UV‐Vis absorption spectra. As the molar ratio of sulfonated polystyrene/polyaniline increases, the conversion from polyaniline base form to salt form is observed owing to increased protonation. The isosbestic point clearly shows that quinoid unit and semiquinoid unit are in equilibrium. They are functions of the sulfonic acid concentration and solvent media.
Enzymatic degradation of aliphatic polyesters copolymerized with various diamines
Authors: Nagata Minoru 
Published: April 2003

AbstractPoly(hexamethylene adipate) copolymers with 10–40 mol‐% (in feed) of aliphatic diamines of various methylene chain lengths were prepared by melt polycondensation. In vitro degradation was performed in buffer solution at 37°C with a lipase and was evaluated by weight loss of the films. The weight loss increased greatly by the copolymerization and showed a maximum at 10 mol‐% of comonomer content. Degradation also increased in a zig‐zag fashion with decreasing number of methylene chains in the diamine comonomers. Both effects on the enzymatic degradation are discussed.
Copolymerization of ethylene and styrene to a nearly‐alternating crystalline copolymer
Authors: Oliva Leone , Izzo Lorella , Longo Pasquale 
Published: April 2003

AbstractAn almost alternating stereoregular copolymer can be obtained by copolymerizing ethylene and styrene with the catalyst ethylenebis(1‐indenyl)zirconium dichloride activated by methylaluminoxane at −25°C. The regular microstructure pointed out by the NMR spectrum allows the copolymer to crystallize as shown by calorimetric and X‐ray diffraction measurements.
Recruitment of enzyme activity in albumin by molecular imprinting
Authors: Ohya Yuichi , Miyaoka Junya , Ouchi Tatsuro 
Published: April 2003

AbstractThe catalytic activity of bovine serum albumin (BSA) modified physically by molecular imprinting using transition‐state analogue (TSA) as a template molecule was studied. The resultant imprinted serum albumin (Imp‐BSA) showed the rate acceleration of dehydrofluorination reaction from (4R,4S)‐4‐fluoro‐4‐(4‐nitrophenyl)butan‐2‐one (1) and followed the type of Michaelis‐Menten reaction in ethyl acetate solution. The enzymatic activity of Imp‐BSA was competitively inhibited by (4R,4S)‐4‐hydroxy‐4‐(4‐nitrophenyl)butan‐2‐one (4).
The crystal structure and drawing induced polymorphism in poly(aryl ether ketone)s, 3. Crystallization during hot‐drawing of poly(ether ether ketone ketone)
Authors: Wang Shanger , Liu Tianxi , Mo Zhishen , Wang Junzuo , Xu Feng , Wu Zhongwen 
Published: April 2003

AbstractThe evolution of crystallinity and polymorphism during hot‐drawing of amorphous poly(ether ether ketone ketone) (PEEKK) as a function of strain rate, draw ratio, and temperature was investigated. In modification I, the competition of chain extension and molecular alignment is responsible for the strain rate and temperature dependence. Modification II crystallization is basically controlled by chain extension during stretching. The former can be transformed into the latter via relaxation during stretching or annealing at elevated temperature.
Redox polymerization of acrylamide to high molecular weights: effect of the mineral clay montmorillonite
Authors: Bera P. , Saha S. K. 
Published: April 2003

AbstractPolymerization of acrylamide with the redox couple Fe(III)/thiourea in the presence of the mineral clay montmorillonite has been investigated. Polyacrylamide is obtained in good yield having molecular weight (ca. 0.7–2.5 × 106) approximately one order of magnitude higher than without clay. Apparently, the locus of polymerization is the interlayer space of the clay.
Polymerization of N‐(2,3,4,5,6‐pentafluorophenyl)‐maleimide
Authors: Hagiwara Tokio , Kawashima Naoyuki , Hamana Hiroshi , Narita Tadashi 
Published: April 2003

AbstractA novel fluorine‐containing polymer, poly[N‐(2,3,4,5,6‐pentafluorophenyl)maleimide], was prepared by the anionic polymerization of N‐(2,3,4,5,6‐pentafluorophenyl)maleimide (PFPMI). Anionic polymerization with alkali metal tert‐butoxides gave poly(PFPMI) in 14–32% yield. Phenyllithium and sec‐butyllithium also afforded poly(PFPMI). No polymer was obtained with a radical initiator such as 2,2′‐azoisobutyronitrile. The polymerization took place only via the vinylene group of PFPMI and no appreciable side‐reaction occurred. The obtained poly(PFPMI) shows unimodal molecular weight distribution and begins to decompose at 325°C.
Synthesis of an amphiphilic triarm star copolymer based on polystyrene, poly(ethylene oxide) and poly(ε‐caprolactone)
Authors: Lambert Olivier , Dumas Philippe , Hurtrez Guy , Riess Gérard 
Published: April 2003

AbstractThe synthesis of an amphiphilic triarm star copolymer based on polystyrene, poly(ethylene oxide) and poly(ε‐caprolactone) block has been achieved by a novel strategy which consists in the preparation of a diblock copolymer, polystyrene‐block‐poly(ethylene oxide), having a protected anionic initiator group at the junction of the two blocks. After deprotection, this function is activated by a coloured and weakly basic carbanion. The generated alcoholate initiates the ε‐caprolactone anionic polymerization.
Complex formation of poly(ε‐caprolactone) with cyclodextrin
Authors: Harada Akira , Kawaguchi Yoshinori , Nishiyama Toshiyuki , Kamachi Mikiharu 
Published: April 2003

AbstractPoly(ε‐caprolactone) was found to form inclusion complexes with α‐cyclodextrin to give crystalline compounds. The complexes are stoichiometric one‐to‐one (cyclodextrin: monomer unit) compounds. The yields of the complexes decreased with increasing the molecular weight of the polymer. They were characterized by IR, 1H NMR, 13C CP/MAS NMR, and X‐ray diffraction. The inclusion modes are discussed.
Pd(II)‐catalyzed copolymerization of a norbornadiene derivative with substituted phenylacetylenes
Authors: Tamura Hiroshi , Kanamaru Hitoshi , Hirose Osamu , Yamamoto Seika 
Published: April 2003

AbstractCopolymerizations of diethyl 7‐oxabicyclo[2.2.1]hepta‐2,5‐diene‐2,3‐dicarboxylate (DOHDD) with phenylacetylene (PA) or p‐methoxyphenylacetylene (MeOPA) were successfully performed in chloroform using PdBr2 as catalyst. The products of reactivity ratios r1 · r2 for poly(DOHDD‐co‐PA) and poly(DOHDD‐co‐MeOPA) are 0.026 and 0.0077, respectively. These values suggest a maximum degree of alternating sequences of 86 and 92% in the two systems, hence a high alternating tendency. It is interesting to note that the present copolymerizations occur by combination of different types of monomer, alkene and alkyne.
Oligo(ether‐sulfones), 2. Synthesis of a novel macrocyclic aromatic ether sulfone bearing two carboxylic groups and the corresponding polyamide via direct condensation of the macrocycle with 4,4′‐diaminodiphenylmethane
Authors: Rodewald Barbara , Ritter Helmut 
Published: April 2003

AbstractA new macrocyclic arylene ether sulfone bearing two carboxylic groups, 4, was prepared by use of pseudo high dilution techniques. In a first step, 4,4‐bis[4‐(4‐(4‐chlorophenylsulfonyl)phenoxy)phenyl]pentanoic acid (3) was prepared from bis(4‐chlorophenyl)sulfone (1) and an excess of 4,4‐bis(4‐hydroxyphenyl)pentanoic acid (2). Then, the purified trimer 3 was cyclocondensed with 4,4‐bis(4‐hydroxyphenyl)pentanoic acid (2), yielding the bifunctionalized macrocycle 4. The existence of the ring‐shaped molecule was proved by use of MALDI‐TOF, NMR‐ and IR‐spectroscopy. The free carboxylic groups of 4 were used to build up polyamides that contain the macrocycle in the main chain and 4,4′‐diaminodiphenylmethane (5) as an aromatic diamine.
Stereospecific polymerization of styrene using a homogeneous lanthanide catalyst
Authors: Liu Li , Gong Zhi , Zheng Yulian , Jing Xiabin 
Published: April 2003

AbstractStereospecific polymerization of styrene was catalyzed by homogeneous neodymium phosphonate [Nd(P507)3]‐H2O‐Al(i‐Bu)3 catalytic system. The polymer was separated into isotactic polystyrene and atactic polystyrene by extracting the latter with boiling 2‐butanone. The conversion of styrene and the yield of isotactic polystyrene (IY) were influenced by the [H2O]/[Al(i‐Bu)3] mole ratio and the solvent polarity. The reaction is first order with respect to monomer at 70°C.
Isolation and cationic ring‐opening polymerization of 2,3,5,6‐tetrahydroimidazo[2,1‐b][1,3]oxazole to produce a thermally stable polyurea
Authors: Miyamoto Masatoshi , Watanabe Toshio , Kimura Yoshiharu 
Published: April 2003

AbstractA bicyclic pseudourea, 2,3,5,6‐tetrahydroimidazo[2,1‐b][1,3]oxazole (1), was isolated for the first time, and its cationic and spontaneous polymerizations were examined. Both polymerizations gave poly(1,3‐imidazolidin‐2‐one‐1,3‐diylethylene) (2) in high yields. The polymer is a crystalline solid with glass transition and melting temperature of 51°C and 286°C, respectively. Thermogravimetry showed that it is stable up to 450°C under nitrogen.
A novel and convenient route to ring‐opened poly(ferrocenylsilanes) with alkoxy, aryloxy, and amino substituents at silicon
Authors: Nguyen Paul , Lough Alan J. , Manners Ian 
Published: April 2003

AbstractA novel and convenient route to the first poly(ferrocenylsilanes) with alkoxy, aryloxy, and amino substituents at silicon is reported. The reaction sequence involves (i) unexpectedly facile and clean halogen replacement at the bridging atom of a readily accessible dichlorosilyl‐bridged [1]ferrocenophane by OR, OAr, and NR2 groups via reactions with aliphatic and aromatic alcohols and amines in the presence of an HCl acceptor and (ii) thermal or transition metal catalyzed ring‐opening polymerization of the new ferrocenophane.
Free radical polymerization within mesoporous zeolite channels
Authors: Ng Shau Mien , Ogino Shin‐ichi , Aida Takuzo , Koyano Keiko A. , Tatsumi Takashi 
Published: April 2003

AbstractFree radical polymerization of methyl methacrylate (MMA) within the uniform channels of the mesoporous zeolite MCM‐41 proceeds at 100°C to give a high molecular weight polymer (PMMA). The formation of long‐living propagating polymer‐radicals is observed by electron paramagnetic resonance (EPR). The molecular weight of PMMA within the mesopores can be controlled over a wide range by changing the monomer‐to‐initiator mole ratio.
Synthesis of end‐functionalized (1 → 6)‐2,5‐anhydro‐D‐glucitols via anionic cyclopolymerization of 1,2:5,6‐dianhydro‐3,4‐di‐O‐methyl‐D‐mannitol for preparing graft copolymers
Authors: Satoh Toshifumi , Miura Takahiro , Hatakeyama Takeshi , Yokota Kazuaki , Kakuchi Toyoji 
Published: April 2003

AbstractEnd‐functionalized (1→6)‐2,5‐anhydro‐3,4‐di‐O‐methyl‐D‐glucitols (3a–c) were synthesized by the anionic cyclopolymerization of 1,2:5,6‐dianhydro‐3,4‐di‐O‐methyl‐D‐mannitol (1), followed by treatment with a terminating agent such as 4‐vinylbenzyl (2a), oxetanyl (2b), and methacryloyl group (2c). The end‐functionalization proceeded in a high efficiency at 73–98%. The radical copolymerization of styrene with 3a yielded a polymer (5a) whose GPC trace exhibited a unimodal peak. 5a was polystyrene with (1→6)‐2,5‐anhydro‐3,4‐di‐O‐methyl‐D‐glucitol as pendant groups whose structure was confirmed by the 1H NMR spectrum.
Living atom transfer radical polymerization of 4‐acetoxystyrene
Authors: Gao Bo , Chen Xianyi , Iván Béla , Kops Jørgen , Batsberg Walther 
Published: April 2003

AbstractLiving atom transfer radical polymerization (ATRP) of 4‐acetoxystyrene (1), a protected 4‐vinylphenol, leading to poly(4‐acetoxystyrene) with well‐defined molecular weight and narrow molecular weight distribution was carried out in bulk with α,α′‐dibromoxylene(2)/CuBr/2,2‐bipyridine(bpy) as initiating system. A linear M̄n versus monomer conversion plot was found in good accordance with the theoretical line, indicating 100% initiating efficiency. The polymerization is first order in respect to monomer up to about 70% monomer conversion. Deviations from linearity at higher conversion in the first order plot are due to physical effects, i.e., to the increase of the viscosity of the reaction medium. The resulting 1‐bromo‐1‐phenylethyl‐telechelic poly(4‐acetoxystyrene) (3) is a precursor of the hydrophilic poly(4‐vinylphenol) and a potential new macroinitiator.
Computer simulation study of bulk atactic polystyrene in the vicinity of the glass transition
Authors: Lyulin Alexey V. , de Groot J.J. , Michels M.A.J. 
Published: April 2003

AbstractMolecular dynamics (MD) simulations of bulk atactic polystyrene have been performed in a temperature range from 100 K to 650 K at atmospheric pressure. Local translational mobility has been investigated by measuring the mean square translational displacements of monomers. The long‐time asymptotic slope of these dependencies is 0.54 at T>Tg, showing Rouse behavior. Cross‐over from motion in the cage to Rouse like dynamics has been studied at T>Tg with a characteristic crossover time follows a power law behavior as a function of T, as predicted by mode‐coupling theory (MCT). Local orientational mobility has been studied via the orientational autocorrelation functions, ACFs, (Legendre polynomials of the first and second, order) of both the main‐chain and side‐group bonds. The relaxation times of the orientational α‐relaxation follow the same power law (γ∼2.9) as the characteristic translational diffusion time. Below T>Tg both types of dynamics are described by the same activated law. The ACFs time‐distribution functions reveal the existence of activated local rearrangements already above T>Tg.
Behavior of a nematic liquid near a grafted solid surface
Authors: Brochard‐Wyart Françoise , Ou Ramdane Olivier , Tran Yvette , Auroy Philippe 
Published: April 2003

AbstractWe discuss the nematic order parameter and the polymer concentration profile for a solid surface carrying grafted chains. Different regimes are found, depending upon the polymer chain length and the grafting density. These ideas are compared with experimental results obtained with polystyrene in the presence of pentylcyanobiphenyl.
Weak segregation in molten statistical copolymers
Authors: de Gennes Pierre‐Gilles 
Published: April 2003

AbstractWe present a qualitative argument suggesting that a statistical (AB) copolymer should display a certain form of weak segregation, with A rich and B rich regions of size comparable to the coil radius. This should occur if the Flory parameter χ is larger than unity (much larger than for the phase separation of A and B of homopolymers) in agreement with detailed calculations by Frederikson, Milner and Leibler. We achieve a certain qualitative insight for the resulting microphase.