bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of bridge group on the thermal stability of nitro‐substituted aromatic polyamides
Authors: Oh Sang Yeol , Pearce Eli M. 
Published: April 2003

AbstractThe effect of introducing a bridge group into the diamine moiety on the thermal stability of aromatic polyamides substituted with a nitro group in the diamine ring at the ortho position to the amide group was studied. Our present work showed that the bridge group, whether it was electron withdrawing or releasing, did not have a significant effect on the activity of the nitro group for the intramolecular cyclization reaction to poly(benzoxazole)s.
Contribution of size exclusion chromatography and thermal analysis methods in the study of the radiochemical behavior of plastic materials
Authors: Yagoubi N. , Baillet A. , Mur C. , Legendre B. , Pellerin F. , Ferrier D. Baylocq 
Published: April 2003

AbstractSterilization by irradiation techniques is considered to be an improved method to treat polluted products of human consumption. Secondary effects, that may be generated in the components of packaging materials, could induce organoleptic damage and some physico‐chemical modifications, observed especially in plastic materials. In order to demonstrate any such secondary changes, we have investigated the effects of beta‐irradiation (a treatment which could induce either a reticulation or a cleavage in a polymeric sequence) on three polymers; namely, low density polyethylene, polystyrene and polyvinyl chloride. The techniques used to identify irradiation‐induced modifications of these polymers were size exclusion chromatography and thermal analysis. Thermal analysis showed a decrease in the percentage of crystallinity of polyethylene after its radiosterilization. Exclusion chromatography highlighted a reticulation for irradiated polyvinyl chloride and polystyrene.
Resist performances and structure of phenolic resins using multi‐substituted phenols
Authors: Kajita Toru , Ota Toshiyuki , Tsuji Akira 
Published: April 2003

AbstractPositive photoresist systems comprising phenolic resin and quinonediazide are studied in detail. The structure of several novolak resins, which were synthesized from multi‐substituted phenols, are analyzed with 13C‐NMR. It is proved that these phenols are useful for the structural control of novolak resins. Phenols with two methyl substituents at meta‐positions especially show a remarkable structural effect to control methylene bond types of novolak resins.The alkaline dissolution rate is also investigated on novolak resins synthesized from multi‐substituted phenols to understand both the dissolution inhibition effect and the dissolution promotion effect. Key‐structure of novolak resins for realizing high resolution is elucidated.In addition, the molecular design concept of novolak resin is clarified from several standpoints. Unsubstituted aromatic carbon of resin, hydrophobic effect of methyl substitutent and suitable structure of low Mw parts of novolak resin are also explored.Furthermore, it is proposed that a resist using a resin, which is based on the molecular design concept, has enough potential to produce critical dimensions of 0.2 μm or less taking advantage of phase‐shifting technology.
193 nm resists and lithography
Authors: Kunz Roderick R. , Allen Robert D. , Hartney Mark A. , Hinsberg William D. , Horn Mark W. , Keast Craig L. , Rothschild Mordechai , Shaver David C. , Wallraff Gregory M. 
Published: April 2003

AbstractA review of recent efforts to develop photoresist materials and processes for 193 nm (ArF excimer laser) photolithography is reported. Three categories of resist processes are discussed: (1) conventional single layer, (2) bilayer and (3) surface‐imaged resist processes. To date, materials have been developed for each process which exhibit resolution to less than 0.25 μm with sensitivities of less than 50 mJ/cm2.
Lithographic performance of isomeric hydroxystyrene polymers
Authors: Dammel R. , Rahman M. D. , Lu P. H. , Elango V. 
Published: April 2003

AbstractThe synthesis and lithographic characterization of the three positional isomers of polyhydroxystyrene is described. Large differences in dissolution rates are found as a function of the position of the hydroxy group, which are explained in terms of intra‐ vs. intermolecular hydrogen bonding and steric shielding of the hydroxy group by the polymer backbone. In plots of log (dissolution rate) vs. developer strength, linear plots are observed for the 2‐ and 4‐isomers, while for poly(3‐hydroxystyrene), a break occurs in the plot, leading to two linear regions. While the 2‐hydroxy isomer is too slow and the 4‐hydroxy isomer too fast for use in conventional dissolution inhibition systems, the copolymerization of both allows any dissolution rate between these extremes to be chosen ( “dial a dissolution rate” copolymers). Determination of the copolymerization parameters of the corresponding 4‐ and 2‐acetoxystyrene precursors by the method of Kelen and Tüdös shows the polymerization to be nearly ideal and azeotropic (r1 = 0.76, r2 = 0.94). Analysis of the dissolution rates as a function of developer strength according to the Huang–Reiser–Kwei equation shows that the critical concentrations c* are a linear function of copolymer composition, whereas the penetration exponents in show a minimum near unity in the region of the 1 : 1 copolymer, down from the values of 3.2–3.3 observed for all three homopolymers. The 1 : 1 copolymer shows a dissolution rate comparable to novolak resins, and when formulated into a photoresist together with a diazonaphthoquinone sensitizer resolved 0.4μm features at a dose of 340 mJ/cm2. The thermal flow resistance of the resist was found to be improved over that of novolak resists although not to the degree expected from the increased Tg of the 1:1 copolymer.
Functionalized polymers for high‐resolution photolithography
Authors: Sebald Michael , Ahne Hellmut , Leuschner Rainer , Sezi Recai 
Published: April 2003

AbstractPolymers obtained by radical polymerization of maleic anhydride with different monomers are used in bilayer photoresists for the CARL (Chemical Amplification of Resist Lines) process. Aqueous‐based silylation of resist patterns with bisaminopropyl‐oligodimethylsiloxane enhances oxygen–plasma etch resistance and creates widened structures. Thus, the resolution capability of optical exposure tools can be used to the full extent and even structures beyond the optical resolution limit become accessible. Copolymerization of maleic anhydride with tBOC‐maleimide or methacrylic acid t‐butylester yields polymers for highly sensitive acid‐catalyzed deep UV resists. With the use of a KrF excimer‐laser stepper 0.25 μm structures are resolved.
The 1.4 and 248 nm radiation response of chemically amplified resists containing arylmethyl sulfone photoacid generators
Authors: Hanson J. E. , Pingor D. A. , Novembre A. E. , Mixon D. A. , Bohrer M. P. , Kometani J. M. , Tai W. W. 
Published: April 2003

AbstractThe X‐ray (1.4 nm) and deep UV (248 nm) radiation responses of chemically amplified photoresists incorporating arylmethyl sulfone photoacid generators were evaluated. The arylmethyl sulfones were primarily derivatives of benzyl phenyl sulfone, selected to reveal the importance of desulfonylation and internal abstraction with regard to the photochemical efficiency of acid generation. At 1.4 nm, benzyl phenyl sulfone gave a much more sensitive resist than dibenzyl sulfone, while the methyl derivatives of benzyl phenyl sulfone did not give much improvement over the parent compound. This suggests that desulfonylation is more important than internal abstraction for increased photochemical efficiency. At 248 nm, similar trends were observed, but with some modifications arising from the variation in extinction coefficient among the sulfones. Sensitivities at or below 20 mJ/cm2 were obtained for both wavelength ranges.
Excited state properties of a new photoinitiating system for laser imaging applications
Authors: Morlet‐Savary F. , Fouassier J. P. , Matsumoto T. , Inomata K. 
Published: April 2003

AbstractThe design of an efficient photosenzitizer/photoinitiator combination is partly governed by a better understanding of the excited state processes involved. In the present paper, the photochemistry of a thiopyrylium salt (TP) as photosensitizer and of a tetraperester of benzophenone, tetra t‐butyl peroxycarbonylbenzophenone (BTTB) as initiator, used in laser imaging applications has been investigated. The reactivity of the triplet states of both compounds BTTB and TP was studied by time‐resolved laser absorption spectroscopy. The laser excitation of TP leads to a long‐lived triplet state (lifetime 20–25 μsec) and a second species arising from the triplet state which cannot yet be characterized. Under laser excitation, BTTB gives a longlived transient arising from the cleavage of the peroxy bond. The short‐lived triplet state cannot be observed on the nanosecond timescale. The triplet state lifetime has been evaluated from quenching experiments and found to be about 1 ns in acetonitrile. The deactivation of the TP triplet state by BTTP was considered, the deactivation constant was found to be equal to 6.6 × 107 m−1/sec in acetonitrile. The initiation mechanism is discussed.
Progress in the chemistry of organosilicon resists
Authors: Gozdz Antoni S. 
Published: April 2003

AbstractRecent developments in the chemistry of organosilicon polymers for use as oxygen plasma‐resistant imaging materials in microlithography are reviewed. Various classes of resists, grouped according to molecular structure, are described with special emphasis on properties critical in microlithographic applications. In addition, several silylation schemes involving selective silylation of a non‐silicon‐containing resist material following patternwise exposure to actinic radiation are also described.
A novel UV‐sensitive photopolymerization system with microgel matrix
Authors: Sasa Nobumasa , Yamaoka Tsuguo 
Published: April 2003

AbstractA series of crosslinked microgels with quaternary ammonium ions on the surface was prepared by quaternization with N,N‐dimethylbenzylamine in the presence of microgel particles prepared by emulsion copolymerization of styrene (St), chloromethylstyrene (CMS) and divinylbenzene (DVB). Microgels with diameters in the range of 15–100 nm were successfully dispersed in organic solvents such as 2‐methoxyethanol and 2‐ethoxyethanol without an emulsifier. A photosensitive layer was formed by coating a photosensitive solution on a grained aluminum plate. The solution was comprised of the microgels, the multifunctional monomer and standard ultraviolet (UV) photoinitiators, such as 2,4‐diethyl thioxanthone (DETX)/ethyl p‐di‐ethylaminobenzoate (EPA). This gave a heterogeneous photosensitive layer which produced good polymer patterns after exposure to UV light followed by development in tap water. A typical polymer layer, consisting of the microgels (poly(styrene‐co‐N,N‐dimethylbenzylvinyl‐benzylammonium chloride‐co‐divinylbenzene)), DETX/EPA, and the multifunctional acrylate monomers, exhibited photosensitivity of 0.06 mJ/cm2 for UV light. This sensitivity is much higher than the homogeneous photopolymerization system with an analogous composition.
Synthesis and blending behavior of an oligoarylenevinylene. Design towards processable materials for LED applications
Authors: Oberski Josef , Bolle Babett , Schaper Andreas , Greiner Andreas 
Published: April 2003

AbstractA bisstyrenebenzene with improved solubility can be obtained by a lateral phenyl substituent on the phenylene ring. The phenyl substituted bisstyrenebenzene (PBSB) was synthesized by Pd‐catalyzed coupling of 2,5‐dibromobiphenyl and styrene. PBSB exhibits blue fluorescence in solution. Blends of PBSB and polystyrene or polycarbonate are homogeneous over a wide concentration range of PBSB, based on differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results were compared with the blending behavior of unsubstituted bisstyrenebenzene.
A synthetic hydrogel with thermoreversible gelation, III: an NMR study of the sol–gel transition
Authors: Yoshioka Hiroshi , Mori Yuichi , Cushman James A. 
Published: April 2003

AbstractThe sol–gel transition mechanism of a thermoreversible hydrogel composed of a copolymer comprising poly(N‐isopropylacrylamide) and poly(ethylene glycol) (PNIPAAm–PEG) was studied by NMR. The 1H– and 13C–NMR spectra measured on a PNIPAAm–PEG solution in 99.9% D2O showed a remarkable line width broadening of the PNIPAAm block of more than that of the PEG block, during thermally induced hydrogel formation. This result suggested that the mobility of the PNIPAAm block is more restricted than that of the PEG block during gelation. A crosslinked polymer network formation was ascertained by a sudden reduction in the spin‐lattice relaxation time (T1) of the residual HDO proton during gelation. The temperature dependency of the T1 values for the PNIPAAm and PEG blocks revealed that the microscopic condition of the PNIPAAm block in water was drastically changed during gelation, while that of the PEG block was unchanged. The experimental results from NMR supported the following gelation mechanism; that an aggregation of PNIPAAm blocks in the separate copolymers caused by hydrophobic interaction forms crosslinking points to give an infinite three‐dimensional network structure. The hydrated PEG chains in the copolymers provide the network with a swelling property in water, and prevent the aggregation from causing a macroscopic phase separation.
Charge transfer complexes and salts of ionenes
Authors: Kryszewski M. , Pȩcherz J. 
Published: April 2003

AbstractA review of the synthesis and properties of ionenes is presented. Particular attention is paid to the electrical and related properties of conductive teteracyano‐p‐quinodimethane (TCNQ) complex salts of ionenes containing ammonium or sulfonium groups in the main chain and to their chemical stability. The recent work on preparation of such ionenes with inorganic and organic counterions which show interesting linear and nonlinear optical properties is also discussed.It is shown that in the solid state ionenes act as a kind of a matrix fixing, in a chemically controlled way, positions and distribution of different kinds of counterions. Because the reaction of counterion exchange is easy in the case of ionenes it provides a convenient way to prepare a broad class of polyelectrolytes with many different properties.
Nonlinear optical properties of complexes of π‐conjugated polymers
Authors: Yang Chen‐Jen , Jenekhe Samson A. , Meth S. Jeffrey , Vanherzeele Herman 
Published: April 2003

AbstractNovel host–guest complexes of conjugated polyimines with gallium chloride have been proposed and studied as an approach to enhance the third‐order nonlinear optical properties of the host conjugated polymers. The third‐order nonlinear optical susceptibility χ(3) (–3ω;ω,ω,ω) of two conjugated polyimines and their GaCl3 complexes, measured by third harmonic generation spectroscopy in the wavelength range 0.9 ∼ 2.4 μm, shows that χ(3) is enhanced in the nonresonant region, whereas it is reduced in the resonant region due to complexation. These results are explained by complexation mediated modifiction of the electronic structure of the host polymers. Two theoretical models consisting of four electronic energy levels were found to give a good description of the frequency dispersion and resonances in the χ(3) (–3ω;ω,ω,ω) spectrum of the host–guest complexes. The resulting fitting parameters were used to predict the degenerate four wave mixing χ(3) (–ω;ω,–ω,ω) spectrum for the new materials. The results of the present study suggest that host–guest complexation is a promising approach for improving the third‐order nonli‐near optical properties of conjugated polymers.
X‐ray photoelectron spectroscopic studies of charge transfer interactions in electroactive polyaniline
Authors: Tan K. L. , Kang E. T. , Neoh K. G. 
Published: April 2003

AbstractFour modes of charge transfer interactions in polyaniline (PAN), viz. acid protonation, self‐doping, charge transfer interactions with organic acceptors, and charge transfer interactions with surface grafted functional polymers have been studied by X‐ray photoelectron spectroscopy (XPS). In the case of acid protonation, the protonation behavior of volatile and non‐volatile acid differs. The structures of sulfonated leucomeraldine (LM) and nigraniline (NA) are similar to those of sulfonated and self‐protonated emeraldine (EM). A substantially higher degree of charge transfer interaction with the organic acceptors is observed for EM film that has been subjected to one cycle of acid/base treatment. The charge transfer interactions with the organic acceptors have proceeded further than the pure formation of molecular complexes. Both pristine and Ar plasma or O3 pretreated EM films are susceptible to surface modifications by graft copolymerization. The protonic acid functional groups of the graft readily give rise to a self‐protonated EM surface.
Continuous, single‐component, crystalline networks in polymer matrix and their vapor doping
Authors: Jeszka Jeremiasz K. 
Published: April 2003

AbstractIt is shown, for the first time, that single‐component continuous networks of a low molecular weight electron acceptor additive can be grown in a polymer matrix. Such networks can be doped using, e.g., iodine vapor and converted into conductive CT complexes without losing continuity, thereby making the polymer film conductive. Polyethylene films with tetrathiotetracene networks are obtained, and their doping with iodine vapor in air is investigated by means of conductivity and spectrophotometry in the visible range. It is concluded that doping of the surface layer of the microcrystallites is sufficient to observe a significant increase in the film conductivity, which makes possible the use of such systems as sensors.
The effect of temperature on the behavior of poly(o‐chloroaniline) salts: conductivity and spectral studies
Authors: Palaniappan S. 
Published: April 2003

AbstractConducting poly(o‐chloroaniline) salis have been prepared by chemical polymerization of o‐chloroaniline with five different acids. Composition and the extent of dopant in poly(o‐chloroaniline) salt systems have been determined. Poly(o‐chloroaniline) samples have been heat treated at four different temperatures 150, 200, 275 and 375°C and characterized by electron paramagnetic, infrared and electronic absorption spectral measurements. Thermal stabilities of the chemically synthesized poly(o‐chloroaniline) salts have been studied by spectral methods. It was found that the polymer is apparently stable up to 200°C, and at around 275°C crosslinking takes place. It is inferred that the electron paramagnetic resonance signal observed in the conducting material does not arise from the current‐carrying species, but rather from neutral paramagnetic species. No definite correlation exists between conductivity and the extent of dopant or spin concentration.
Residual stress and deformation during rapid cooling process in an epoxy plate
Authors: Hwang Jae Young , Kim Sung Chul 
Published: April 2003

AbstractResidual stress in the epoxy plate during a rapid cooling process was measured by the layer removal method and calculated by the linear thermoviscoelastic theory considering specific volume relaxation. The relaxations of the tensile modulus and specific volume were measured by an Instron thermomechanical analyzer. When the starting temperature of the cooling process was near the glass transition temperature of the cured epoxy, the residual stress in the epoxy plate was smaller than when the starting temperature was higher than the glass transition temperature. However, the transient stress in the cured epoxy plate was higher when the starting temperature was near the glass transition temperature than when the starting temperature was higher than the glass transition temperature. The quenched epoxy plate was compressed in the direction parallel to the surface and expanded in the thickness direction.
Anisotropic dispersion polymerization of N‐(4‐aminobenzoyl)–caprolactam in polymer melts
Authors: Mülhaupt Rolf , Rösch Joachim 
Published: April 2003

AbstractWhen N‐(4‐aminobenzoyl)–caprolactam (PAC) is injected into polymer melts, dispersions of anisotropic polyaramide particles with average diameters of 100–400 nm and aspect ratios of 5–10 are formed within few minutes. At 200°C PAC dispersion polymerization yields caprolactam and predominantly poly(p‐phenylenebenzamide), whereas with increasing polymerization temperatures PAC ring‐opening polymerization accounts for the incorporation of 6‐aminocaproic acid units into the polyaramide backbone. Covalent bond formation between microparticle surfaces and functional groups of the matrix polymer provides excellent interfacial adhesion and stabilizes the anisotropic polyaramide microparticle dispersions. This in situ PAC dispersion polymerization during melt processing, producing polyaramide‐whisker reinforced thermoplastics, represents a versatile route to organic microcomposites exhibiting improved stiffness and strength.
Ordering processes in polyester thermoplastic elastomers
Authors: Fischer Christian , Economy James 
Published: April 2003

AbstractSynthesis of thermoplastic elastomers derived from poly‐tetramethylene glycol (PTME glycol), dimethylterephthalate and different mixtures of ethylene and butylene glycol is described. Extended heating near the crystalline melting point of these systems leads to a measurable increase in the melting point of 15–20°C. This ordering process can be reversed by heating at 250°C or well above the melting point. These results are interpreted in terms of sequence ordering within existing crystallites via interchain transesterification on heating near the melting point. Heating at 250°C is best explained as randomization of the ordered ester units.
ABS blends with phenoxy: morphology, thermal, mechanical and rheological properties
Authors: Choi Chi Hoon , Lee Soo Min , Kim Byung Kyu 
Published: April 2003

AbstractBlends of ABS (acrylonitrile–butadiene–styrene) with phenoxy(poly(hydroxyether bisphenol A)) were prepared using a Branender single screw extruder. Scanning and transmission electron micrographs (SEM, TEM) showed a typical two‐phase morphology; particle‐in‐matrix (90/10) (ABS/phenoxy by weight), 70/30, 10/90), island/sea (30/70) and co‐continuous (50/50) morphologies. The glass transition temperature (Tg) of SAN was almost unchanged in the blends, while the Tg of phenoxy increased by about 5 °C in the blends. The synergistic effect of tensile modulus and strength was noted in ABS‐rich blends, where a drastic drop of ductility was seen, and the results were interpreted in terms of rubber particle migration form SAN to phenoxy phase, which was visualized by TEM. Melt viscosity showed yield in ABS‐rich blends, and generally followed the log additivity.
Features of composites prepared by radical graft‐polymerization of styrene to a hydrophilic macromer adsorbed on ultrafine colloidal particles
Authors: Yoshinaga Kohji , Nagao Kenichi 
Published: April 2003

AbstractPolymer modifications of ultrafine monodispersed colloidal metal oxide particles, smaller than 80 nm in diameter, by the graft‐polymerization of styrene to a hydrophilic macromer adsorbed on the surface were investigated. The polymerization in ethanolic silica and titania colloid solution, which had negatively larger ζ‐potentials, −30 and −42 mV in neutral aqueous solution respectively, gave poly(styrene)–silica or titania composite, being of nonspherical shape. The modifications of colloidal particles, having lower surface energy, such as Al(OH)3 and CeO2–TiO2–SiO2 complex, led to the formation of spherical composites, ranging in size from 500 to 3000 nm, of scattered metal oxide or hydroxide particles.