bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bismaleimides and bisnadimides derived from 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene and their polymerization to heat‐resistant matrix resins
Authors: Mikroyannidis John A. , Koutsolelos Panayiotis G. 
Published: April 2003

AbstractSix new structurally different bismaleimides or bisnadimides based on 2,5‐bis(4‐aminophenyl)‐3,4‐diphenylthiophene (BADT) were synthesized and characterized by infrared (IR) and proton nuclear magnetic resonance (1H‐NMR) spectroscopy. Chain‐extension of several bismaleimides was accomplished by incorporating various imide, amide, and urea groups. The bismaleimide and bisnadimide prepared by reacting BADT with maleic or nadic anhydride, respectively, were soluble in various organic solvents. The monomers were thermally polymerized or by a Michael reaction with certain aromatic diamines. Curing behavior was investigated by differential thermal analysis (DTA). The thermal and thermo‐oxidative stability of polymers was evaluated by dynamic thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). The polymers derived from bismaleimide of BADT as well as from the bismaleimides chain‐extended by imide groups were stable up to 355–392°C in N2 or air and afforded anaerobic char yield 66–74% at 800°C. The polymers obtained by curing the bismaleimide‐diamine adducts showed a relatively lower thermal stability.
Effect of stirring on photoinitiated polymerization
Authors: Zanocco A. , Garrido J. , Lissi E. A. 
Published: April 2003

AbstractThe polymerization of methyl methacrylate photosensitized by benzion methyl ether over a wide range of initiator absorbances was investigated. Both the polymerization rate and the polymer molecular weight distribution are modified by stirring the solution at c.a. 700 rpm. The results obtained can be explained in terms of an inhomogeneous distribution of the polymeric macroradicals under nonstirred conditions. This effect can be related to the attenuation of the light beam across the reactor, and hence is determined by the optical density of the reacting mixture.
The surface photopolymerization of perfluorobenzene and photocopolymerization of perfluorobenzene/benzene: A possible model for plasma polymerization
Authors: Munro H. S. , Till C. 
Published: April 2003

AbstractESCA has been used to characterize films deposited from perfluorobenzene and perfluorobenzene/benzene vapors during plasma polymerization and irradiation with vacuum ultraviolet light. The films deposited by both methods are shown to be essentially the same. This indicates that similar electronically excited states are involved in the formation of the precursors to deposition in both methods and that reaction mechanisms involving ions do not need to be considered for the plasma polymerization of the monomers investigated.
Synthesis and characterization of phenyl‐pendant aromatic polythiazoles from bis‐α‐bromophenylacetyl compounds and dithioamides
Authors: Inoue Kazuto , Ueda Mitsuru , Imai Yoshio 
Published: April 2003

AbstractNovel phenyl‐pendant aromatic polythiazoles having inherent viscosities of 0.3–1.3 dL/g were synthesized by the solution polycondensation of bis[4‐(α‐bromophenylacetyl)phenyl] ether with aromatic dithioamides or dithiooxamide in dimethylformamide at 60°C. The polythiazole having m‐phenylene linkage was readily soluble in chloroform and m‐cresol, and transparent flexible film could be cast from the chloroform solution. Glass transition temperatures of these polythiazoles were in the range of 210–250°C. They started to decompose at about 500°C in air with 10% weight loss being recorded at around 570°C.
Processable, high temperature polymers from 1,4,5,8‐tetrahydro‐1,4;5,8‐diepoxyanthracene and bis‐dienes
Authors: Meador Mary Ann B. 
Published: April 2003

Abstract1,4,5,8‐tetrahydro‐1,4;5,8‐diepoxyanthracene reacts with various anthracene end‐capped polyimide oligomers to form Diels–Alder cycloaddition copolymers. The polymers are soluble in common organic solvents, and have molecular weights of approximately 21000 to 32000. Interestingly, these resins exhibit lower weight loss in air than in nitrogen. This is suggested to be due to dehydration (loss of water ranges from 2 to 5%) at temperatures of 390 to 400°C to give thermooxidatively stable pentiptycene units along the polymer backbone. Because of their high softening points and good thermooxidative stability, the polymers have potential as processable, matrix resins for high temperature composite applications.
Polycondensation of bis(p‐nitrophenyl) β‐truxinate with diamine
Authors: Iizawa Takashi , Miyaji Takatoshi , Nishikubo Tadatomi 
Published: April 2003

AbstractModel reaction of bis(4‐nitrophenyl) β‐truxinate (BNPT) with aliphatic amines proceeded quantitatively at room temperature. Accordingly, polycondensation of BNPT with various diamines was carried out at room temperature or 80°C. During the polycondensation of BNPT with diamines, the precipitation of polymer or the observed gelation of polymerization solution occurred, which may limit the molecular weight of the polymer. On the other hand, the reaction of BNPT with 1,3‐(4‐piperidyl)propane (DPP) proceeded homogeneously to give the polymer with relatively high molecular weight, and the obtained polyamide (P‐1e) showed excellent solubility in many solvents. The study of TG and DTA indicated that the obtained polymers were stable at lower temperature than around 270°C. The polymer prepared from the polycondensation of BNPT with hexamethylenediamine showed melting point and decomposition due to the imidation at 282°C. The photochemical reaction of these polymers was carried out in the film state. The irradiation of 254 nm light caused an absorption at 272 nm to appear and the molecular weight to decrease. This meant that the scission of cyclobutane ring in the main chain occurred to give cinnamamide structures. Also, the absorption at 272 nm decreased by the irradiation of 302.5 nm light. However, the UV spectrum of irradiated polymer did not agree with that of the original polymer. These results suggested that the dimerization of the resulting cinnamamide moieties occurred in the competition of their trans–cis‐isomerization. On the other hand, the rate of scission of cyclobutane ring of P‐1e was faster than that of the corresponding polyamide containing α‐truxillamide structure.
Synthesis of fluorine‐containing graft copolyamides by using condensation‐type macromonomers
Authors: Chujo Yoshiki , Hiraiwa Akihiko , Kobayashi Hisaaki , Yamashita Yuya 
Published: April 2003

AbstractFluorine‐containing graft copolyamides were prepared from condensation‐type macromonomers. Dicarboxyl‐terminated poly(perfluoroalkylethyl acrylate) was prepared by radical chain transfer polymerization and copolycondensed with diamines and dicarboxylic acids in the presence of triphenylphosphine and pyridine. Nylon‐6 films containing various amounts of the resulting graft copolyamides were obtained by heat pressing. Only 5 wt % of graft copolymers were sufficient to make nylon‐6 surfaces water repellent.
Synthesis and characterization of monomers and polymers of acrylated phosphonate esters derived from glycerol, D‐mannitol, D‐sorbitol, pentaerythritol, and dipentaerythritol
Authors: Cabasso Israel , Sahni Suresh K. , Vofsi David 
Published: April 2003

AbstractPhosphonic acid ester derivatives of glycerol, D‐mannitol, D‐sorbitol, pentaerythritol, and dipentaerythritol have been synthesized by transacetalation reactions with diethyl 2,2‐diethoxyethylphosphonate. These phosphonated derivatives of polyols and carbohydrates have been esterified to from the corresponding methacrylates. All these compounds have been characterized on the basis of their elemental analysis and spectroscopic (infrared including FT–IR, 1H‐, 13C‐, 31P‐NMR, and mass) methods. Transacetalation reactions with dialkyl 2,2‐dialkoxyethylphosphonate lead to the synthesis of 1,3‐dioxane derivatives in the case of D‐mannitol, pentaerythritol, and dipentaerythritol, whereas a mixture of both 1,3‐dioxane and 1,3‐dioxolane derivatives is obtained with D‐sorbitol and glycerol. The methacrylates of phosphonylated polyol derivatives show the capacity to dissolve and interact with metal salts such as bismuth bromide and uranyl nitrate. Some of the polymers obtained from these monomers have been characterized on the basis of their spectral and thermal (differential scanning calorimetry) properties.
Metallocene–methylaluminoxane catalysts for olefin polymerization. I. Trimethylaluminum as coactivator
Authors: Chien James C. W. , Wang Bor‐Ping 
Published: April 2003

AbstractEthylene was polymerized by Cp2ZrCl2–methylaluminoxane (MAO) catalysts where a portion of the MAO was replaced with trimethyl aluminum (TMA). At a total Al to Zr ratio of 1070, there is neither appreciable loss of productivity nor change in polymerization profile for TMA/MAO ≤ 10. The productivity is reduced only by two‐ to three‐fold for TMA/MAO ≤ 100 accompanied by a 10 min induction period. Aging of this catalyst did not affect the induction period, but improves its productivity. The kinetic isotope effect for radiolabeling with tritiated methanol is 2.0. About 40% of the Zr is active for the catalyst with {99 [TMA] + 1[MAO]} to Zr ratio of 100. The rate constants for propagation and chain transfer were obtained. The mechanisms for the mixed TMA and MAO cocatalyst system are discussed. The results of this work have important practical significance. MAO is a hazardous material to synthesize and only in low yields. The replacement of > 90% of MAO with TMA represents a substantial saving since as much as 0.1M of the former is commonly used for a polymerization.
Gel permeation chromatography of polyamide by N‐trifluoroacetylation
Authors: Ogawa Toshio , Sakai Masakazu 
Published: April 2003

AbstractSuccessful chromatograms were obtained for trifluoroacetylated nylon 12 (N‐TFA‐N) in gel permeation chromatography (GPC) with dichloromethane as eluent. It was confirmed that the method of universal calibration was applicable for N‐TFA‐N and polystyrene. The average molecular weights of nylon 12 were obtained from the chromatogram of N‐TFA‐N by use of the calibration curve for polystyrene. The stability of N‐TFA‐N in solution was examined from various angles. Satisfactory results are obtained, if the sample solution is measured within 48 h after preparation.
Polymerization of 1,3,5‐trithiane in the solid state initiated by UV‐irradiation. I. Polymerization conditions and polymer characterization
Authors: Andrzejewska Ewa , Żuk Aleksander , Garbarczyk Józef 
Published: April 2003

AbstractThe solid‐state 1,3,5‐trithiane polymerization initiated by UV‐irradiation was studied at various irradiation times and various polymerization temperatures. The conversion of monomer to polymer reaches limiting values (at longest) in about 30 min of reaction. The apparent activation energy of this process is somewhat higher than in the chemically initiated polymerization. Generated by UV, active centers, which initiate the polymerization, are stable. On the basis of X‐ray diffraction studies it was found that the prepared polythiomethylene has a hexagonal structure and high degree of crystallinity. In the polymer investigated, a new additional crystal phase is formed, which is not stable.
The synthesis and lithographic evaluation of a new organosilicon novolac‐based resist
Authors: Tarascon R. , Shugard A. , Dabbagh G. 
Published: April 2003

AbstractA novel material, bis(trimethylsilylmethoxy resorcinol) was synthesized by a phenoxide alkylation method. The new substituted resorcinol was then terpolymerized with 2‐methyl resorcinol and formaldehyde. We evaluated the preparation of this new polymer in terms of feed ratio of the reactants, reaction time, and temperature; and prepared a series of materials with different silicon content. Polymers which retained base solubility at high silicon content were blended with a dissolution inhibitor, and studied for their lithographic capabilities as positive, photo‐ or electron‐beam bilevel resists. When used in a photoresist formulation a dose of 120 mJ/cm2 allowed formation of submicron features. When used in an electron‐beam resist formulation 0.5 μm line/space patterns were obtained at a dose of 10 μC/cm2. Furthermore, these materials displayed etching ratios relative to hardbaked HPR206 of ≃ 1 : 10. This value is believed to be large enough to allow these resists to withstand reactive ion etching conditions for pattern transfer in a bilevel scheme.
Synthesis and use of α‐methoxyphenylmethylium hexachloroantimonate as a novel initiator for the polymerization of propylene oxide
Authors: Iijima Takao , Sakamoto Yuhshi , Kakiuchi Hiroshi 
Published: April 2003

Abstractα‐Methoxyphenylmethylium hexachloroantimonate was prepared from α‐methoxybenzyl chloride and antimony pentachloride at 0°C and isolated for the first time, and its visible and 1H‐NMR spectra were measured. This salt was used as a novel initiator for the polymerization of propylene oxide (PO) in the temperature range −20 to 30°C with dichloromethane as solvent. PO polymerized spontaneously but a limit yield was observed. The microstructure of PO polymer is amorphous by 13C‐NMR. The PO polymerization is thought to proceed in the conventional cationic mechanism on the basis of the polymerization behavior and the analyses of both the polymer structure and end groups attached to the PO polymer.
High‐molecular‐weight poly(p‐phenyleneterephthalamide) by CaCl2 promoted direct polycondensation with thionyl chloride in N‐methylpyrrolidone
Authors: Higashi Fukuji , Nishi Toshiharu 
Published: April 2003

AbstractThe direct polycondensation of terephthalic acid and p‐phenylenediamine hydrochloride (PPD.2HCl) with thionyl chloride was found to be significantly promoted in N‐methylpyrrolidone (NMP) by dissolved CaCl2 and tertiary amines. The inherent viscosity of the polymer obtained varied with the amount of CaCl2 and tertiary amines added. The reaction, when effectively promoted by CaCl2, proceeded homogeneously in the early state of polycondensation, and then resulted in a highly swollen gel. CaCl2 had to be present in the PPD.2HCl/tertiary amines/NMP solution as well as in the TPA/SOCl2/NMP mixture for the polycondensation to proceed to high molecular weight. Complexes of CaCl2, PPD.2HCl, and tertiary amines in NMP similar to the well known complex, CaCl2 · nNH3 (n = 2, 4, 8) was proposed to facilitate the polycondensation.
Preparation of poly(phenylene vinylene) from cycloalkylene sulfonium salt monomers and polymers
Authors: Lenz Robert W. , Han Chien‐Chung , Stenger‐Smith John , Karasz Frank E. 
Published: April 2003

AbstractTwo new types of p‐xylene bis‐sulfonium chloride monomers were prepared from cycloalkylene sulfides. The polymerization characteristics of these monomers to form poly(p‐xylene sulfonium chlorides), and the thermal elimination reactions of their polymers to poly(p‐phenylene vinylene), were compared with those of two monomers prepared from dialkyl sulfides. The cycloalkylene sulfonium chloride monomer polymerized to higher yields and to higher molecular weight polymers, which showed more efficient elimination reactions.
Functional monomers and polymers 159 synthesis and photochemical reactions of polymers containing thymine photodimer units in the main chain
Authors: Moghaddam Minoo Jalili , Hozumi Shigeo , Inaki Yoshiaki , Takemoto Kiichi 
Published: April 2003

AbstractPolyamides containing thymine photodimer units in the main chain were synthesized, and their photolysis by ultraviolet irradiation below 260 nm were studied in film state. Photodimers of thymine derivatives were obtained by photochemical reaction of the carboxylic acid derivatives of thymine in aqueous solution irradiated above 270 nm. An attempt was made to resolve the isomers of the photodimers, and the two kinds of cis isomers [cis–syn(head to head), and cis–anti(head to tail)] were isolated successfully. The polyamides were prepared by condensation of the photodimers with diamine using an activated ester method. The photodissociation of the thymine photodimer in the polymer main chain caused the breakage of the polymer chains, leading to the production of oligomers and dimer compounds containing thymine bases at the ends of the molecule. The dissociation rate of the polymer did not depend on the kind of the thymine photodimer which was in the main chain of the polymer.
Polymers by the reaction of bis(pyrylium salts) with diamines: A novel approach to ionene polymers
Authors: Katritzky Alan R. , Tarr Richard D. , Heilmann Steven M. , Rasmussen Jerald K. , Krepski Larry R. 
Published: April 2003

AbstractThe following reactions of pyrylium salts with amines are described: (1)bis(pyrylium salts) with amines; (2) diamines with pyrylium salts; and (3) bis(pyrylium salts) with diamines. Both (1) and (2) give bis(pyridinium salts) in high yields, and (3) gives the corresponding polymers which are isolated and characterized. This procedure was applied to cationic bis(pyrylium salts) to give cationic dimers and polymers, and further to zwitterionic bis(pyrylium salts) to yield the corresponding zwitterionic dimers and polymers.
Synthesis of optically active copoly(vinylamine–vinylalcohol) containing a pair of adeninyl and thyminyl pendant groups
Authors: Lu C. X. , Xiao Chaodong , Zhu Zhijian , Ji Aixue , Overberger C. G. 
Published: April 2003

AbstractPreparation of novel model polymers of polynucleotides with copoly(vinylamine–vinylalcohol) [P(Vam–Val)] backbone and a pair of adeninyl and thyminyl pendant groups is described. At first, direct, low temperature esterification was used to attach (−) and (±)‐2‐(thymin‐1‐yl)propionic acid [(−)TPA and (±)TPA], to the N–Cbz protected hydroxy polymer P(Vamz–Val) which was prepared by selective N‐protection of N‐benzyloxycarbonyloxy‐5‐norbornene‐2,3‐dicarboximide (CbzONB) with P(Vam–Val), at the hydroxy group via an ester bond. Two novel precursors P(Vamz–Ve(−)T) and P(Vamz–Ve(±)T) were obtained. Then the Cbz protecting group of P(Vamz–Ve(−)T) and P(Vamz–Ve(±)T) were removed by hydrobromic acid to give the hydrobromide salt of P(Vam–Ve(−)T) and P(Vam–Ve(±)T), respectively. Finally, the attachment of (±)‐2‐(adenine‐9‐yl)propionic acid [(±)APA] to linear P(Vam–Ve(−)T) and P(Vam–Ve(±)T) by selective N‐acylation with N‐hydroxy‐5‐norbornene‐2,3‐dicarboximide (HONB). This procedure gave the corresponding P(Vam–Val) having a pair of adeninyl and thyminyl pendant groups, such as P(Va(±)Ad–Ve(−)T) and P(Va(±)Ad–Ve(±)T). In contrast to the corresponding polymer models, the related segment model compounds were also prepared from threo‐2‐amino‐4‐pentanol without N‐blocking‐deblocking operations. The segment model compounds including four stereoisomers of highly optical purities, were separated and purified by reverse phase HPLC technique.
Living cationic polymerization of 2‐vinyloxyethyl phthalimide: Synthesis of poly(vinyl ether) with pendant primary amino functions
Authors: Hashimoto Tamotsu , Ibuki Hiroshi , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractCationic polymerization of 2‐vinyloxyethyl phthalimide (1) in CH2Cl2 at −15°C with hydrogen iodide/iodine (HI/I2) as initiator led to living polymers of a narrow molecular weight distribution (M̄w/M̄n = 1.1–1.25). The number‐average molecular weight of the polymers was in direct proportion to monomer conversion and could be controlled in the range of 1000–6000 by regulating the 1/HI feed ratio. However, when a fresh monomer was supplied to the completely polymerized reaction mixture, the molecular weight of the polymers was not directly proportional to monomer conversion. The polymerization of 1 by boron trifluoride etherate (BF3OEt2) in CH2Cl2 at −78°C gave polymers with relatively high molecular weight (M̄w > 20,000) and broad molecular weight distribution (M̄w/M̄n ∼ 2). The HI/I2‐initiated polymerization of 1 was an order of magnitude slower than that of ethyl vinyl ether, probably because of the electron‐withdrawing phthalimide pendant. Hydrazinolysis of the imide functions in poly(1) gave a water‐soluble poly(vinyl ether) (3) with aliphatic primary amino pendants.
Studies on the imidization of N‐substituted polymaleamic acids
Authors: Yang Chin‐Ping , Wang Sheng‐Sung 
Published: April 2003

AbstractA spectral method for determining the imidization from maleamic acid to maleimide was described. The formation condition and mechanism of polymaleimide compared with N‐phenyl‐maleimide (I) and 4,4′‐bis(N‐maleimido)‐diphenylmethane (II) were investigated. A series of N‐substituted maleimides were synthesized by the reaction of their corresponding maleamic acids with acetic anhydride and sodium acetate as a catalyst. The rate of dehydration reaction of N‐phenylmaleamic acid with Ac2O was determined at a mole ratio 0.1:1 of NaOAc to N‐phenyl‐maleamic acid and a second‐order constant K of 1.38 × 10−2 (mL/mol s) was obtained. The activation energies for the ring‐closure reaction of N‐phenylmaleamic acid and polyphenylene‐methylenemaleamic acid were 1.26 × 104 (cal/g mol) and 1.32 × 104 (cal/g mol), respectively. The decreasing order for the rate of N‐substituted maleimide formation was N‐(p‐methylphenyl)maleimide > I ≒ II > N‐(p‐chlorophenyl)maleimide. The result was attributed to the para‐substituent effect. These imidization reaction were observed qualitatively by IR spectra and analyzed quantitatively by 1H‐NMR spectra.
Polymerization of 1‐aryl‐2‐trimethylsilylacetylenes by transition metal catalysts(II)
Authors: Gal Yeong‐Soon , Choi Sam‐Kwon , Kim Chung‐Yup 
Published: April 2003

AbstractPolymerization of 1‐aryl‐2‐trimethylsilylacetylene (aryl = thienyl, furyl, and pyridyl) was carried out by transition metal catalysts. The polymer yield was generally low due to the steric hindrance. R4Sn (R = Me, n‐Bu, Ph) exhibits some cocatalytic activities with respect to polymer yield and molecular weight. On the other hand, the polymerization was decelerated when organoaluminum compounds were used as cocatalysts. The polymer yield increased in the following order: phenyl > thienyl > furyl > pyridyl, according to the aryl substituents. The NMR (1H‐ and 13C‐), IR, and UV‐visible spectra indicated that the resulting polymers have a linear conjugated polyene structure each containing the aromatic substituent and trimethylsilyl group. From 1H‐NMR integration, it was found that the resulting polymers are partially desilylated depending on the substituents of monomer and the polymerization conditions. The solubility behavior, stability and fluoride‐ion induced desilylation reaction of the polymers were also studied.
Grafting onto polypropylene II. Solvent effect on graft copolymerization of acrylonitrile by preirradiation method
Authors: Mehta I. K. , Sood D. S. , Misra B. N. 
Published: April 2003

AbstractAcrylonitrile (AN) has been graft copolymerized onto isotactic polypropylene (IPP) by the preirradiation method using Co60 as the source of gamma rays in the presence of ethanol, n‐propanol, isopropanol, n‐butanol, tert. butyl alcohol, and n‐pentanol. Alcohols vary in their ability to influence grafting of AN onto IPP and the following reactivity order was found: n‐pentanol > n‐butanol > tert.‐butanol > n‐propanol > ethanol > isopropanol. An attempt has been made to explain the observed reactivity pattern shown by different alcohols. Thermal behavior of the graft copolymer has been compared with that of IPP and irradiated IPP and it was observed that grafted IPP is thermally more stable than IPP and irradiated IPP.