bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compartmentalization of chromophores in a molecular composite consisting of amphiphilic polyelectrolyte‐surfactant ion complexes
Authors: Morishima Yotaro , Seki Michiko , Tominaga Yukio , Kamachi Mikiharu 
Published: April 2003

AbstractA molecular composite of an amphiphilic polyanion and cationic surfactants was prepared by treating a terpolymer [consisting of sodium 2‐acrylamido‐2‐methylpropanesulfonate, N‐(1‐adamantyl)methacrylamide, and a small mole fraction of N‐(1‐pyrenylmethyl)methacrylamide] with didodocyldimethylammonium bromide in aqueous solution. The molecular composite was soluble in organic solvents with a wide range of polarities. Fluorescence spectra indicated that the pyrenyl (Py) residues in the molecular composite experienced polar microenvironments even though the composite was dissolved in nonpolar solvents. Exciplex formation of the Py residue with 4,4′‐dicyanobenzene was strongly suppressed due to the polar microenvironments and steric “protection” of the chromophore. Photoinduced electron transfer (ET) from the Py residue to pyromellitic dianhydride (PMDA) in acetonitrile showed characteristics of long‐range ET between fixed donor and acceptor sites and yielded long‐lived transient Py cation radicals and PMDA anion radicals which persisted for tens of milliseconds. These findings imply that the micellelike structure of the parent amphiphilic polyelectrolyte formed in aqueous solution is retained, to some degree, in the molecular composite dissolved in organic solvents. © 1992 John Wiley & Sons, Inc.
Aspects of the chemical‐ and the radiation‐induced polymerization of biphenylyl acrylate (BPA)
Authors: Guthrie J. T. , Morton A. 
Published: April 2003

AbstractTwo chemical initiation routes have been used in the polymerization of biphenylyl acrylate. Radiation‐induced polymerization was used in a comparable study. In each instance, dimethyl formamide was used as the solvent. The radiation‐induced polymerizations were carried out over a range of dose rates and of monomer concentrations. The use of evacuated conditions provides a marked increase in chain length compared with products arising from polymerizations undertaken in air. Using evacuated systems as an example, for equivalent reaction times and conditions, the value of Mw increases in the order: AIBN initiated < BP initiated < radiation‐induced initiation. High conversion levels were recorded. For the radiation‐induced polymerization study, the initial rates of polymerization were calculated. The copolymerization of BPA with hydroxyethyl acrylate was also studied to give a guide to the relative reactivity status of the monomers. © 1992 John Wiley & Sons, Inc.
Polymerization of propylene catalyzed over highly active and stereospecific catalysts synthesized with Mg(OEt)2/benzoyl chloride/TiCl4
Authors: Kim Il , Choi Hong Ki , Han Taek Kyu , Woo Seong Ihl 
Published: April 2003

AbstractA series of monoester catalysts has been studied, each catalyst prepared by the reaction of magnesium diethoxide with benzoyl chloride [BzCOCl, to produce ethyl benzoate (EB) in situ] in the presence of excess titanium tetrachloride. Solid product and catalysts obtained by subsequent treatments with titanium tetrachloride were characterized by elemental analysis, IR spectroscopy, x‐ray diffraction, BET measurement, and thermal gravimetric analysis. The catalysts yielded very high activity (above 20 kg polymer/g Ti h atm) for the polymerization of propylene in slurry reactions. From the results of polymerization as well as catalyst characterization, the effects of internal and external Lewis bases on the isospecificity and stability of catalysts are discussed in detail. © 1992 John Wiley & Sons, Inc.
Poly(dimethylsilylene‐co‐diphenylsilylene)
Authors: Sartoratto Patrícia P. C. , Yoshida I. Valéria P. 
Published: April 2003

AbstractIn this work several polyorganosilylenes were synthesized including homo‐and copolymers containing SiMe2 and SiPh2 units. A Wurtz‐type coupling reaction of the respective dichlorodiorganosilanes with sodium metal, varying the Ph2SiCl2/Me2SiCl2 ratio was the chosen synthesis method. Products with different characteristics for solubility, structure (cyclic or linear), composition, and molecular weight distribution could be obtained depending on the comonomer ratios employed. The polysilane derivatives were characterized by infrared spectroscopy (IR), proton nuclear magnetic resonance (1H‐NMR), and gel permeation chromatography (GPC). Valuable information related to the comonomers' reactivities was obtained, such as molecular weight distribution, composition, and relationships between yields of soluble, insoluble, and cyclic materials of each polycondensation reaction. © 1992 John Wiley & Sons, Inc.
Preparation and properties of new random and block copolyamides derived from 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane, aromatic diamines, and isophthaloyl chloride
Authors: Oishi Yoshiyuki , Nakata Shoichi , Kajiyama Mikio , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractRandom and block disiloxane‐containing copolyamides were prepared through one‐ and two‐step procedures, respectively, by the low temperature solution polycondensation in chloroform containing triethylamine hydrochloride starting from 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane, an aromatic diamine [3,4'‐diaminodiphenyl ether (ODA) or m‐phenylenediamine], and isophthaloyl chloride. The random copolyamides exhibited composition‐dependent single glass transition temperature (Tg), and gave transparent and tough films by solution casting or hot pressing. The ODA‐based block copolyamides had two Tg's, and the solvent‐cast transparent films exhibited microphase separated morphology. The block copolymers gave better quality films than the single‐phase random copolymers. © 1992 John Wiley & Sons, Inc.
Synthesis and crosslinking of polyethers with nadimide derivative pendant groups
Authors: Galiá M. , Cádiz V. , Mantecón A. , Serra A. 
Published: April 2003

AbstractPolyethers with nadimide derivatives pendent groups have been prepared by ring‐opening polymerization of nadimide glycidyl derivatives. The structure of the linear polymers has been confirmed by spectroscopic methods. Properties such glass transition temperatures and thermal resistance have been measured and related to their chemical structure. Crosslinking studies have been carried out by DSC and TGA. Kinetic parameters could be obtained by dynamic method. The crosslinking causes an increase in Tg of the system and it has been possible to relate this increase to the chemical structure of the network. © 1992 John Wiley & Sons, Inc.
Aqueous polymerization of acrylamide initiated by cerium (IV)–ethylenediamine tetraacetic acid redox system
Authors: Hsu Wen‐Cheng , Kuo Jen‐Feng , Chen Chuh‐Yung 
Published: April 2003

AbstractEthylenediamine tetraacetic acid (EDTA) terminated polyacrylamide was obtained by using the EDTA–cerium(IV) ammonium nitrate [Ce(IV)] redox initiator in the aqueous polymerization of acrylamide. The polymerization behaviors as a function of the concentration of Ce(IV), EDTA, and acrylamide as well as temperature were studied. The consumption rate of cerium(IV) depends a first‐order reaction on the ceric ion concentration ([Ce(IV)]). The complex formation constant (K) and disproportionation constant (kd) of Ce(IV)–EDTA chelated complex are 1.67 × 104 and 3.77 × 10−3, respectively. The rate dependences of polymerization on monomer concentration and EDTA concentration both follow a second‐order reaction in the run of initial monomer concentration ([M]i) equal to 0.2 mol dm−3. The number average molecular weight increases linearly with the ratio of [M]i/[Ce(IV)]i. The mechanism and kinetics for the polymerization was proposed. The kinetic parameters involved were determined. © 1992 John Wiley & Sons, Inc.
Theoretical approach to cationic polymerization of alkenylfurans. II. Ab initio and semiempirical study of relevant steps in the reaction mechanism
Authors: Alvarez‐Idaboy J. Raul , Galano Annia , Montero Luis A. , Martínez Ricardo 
Published: April 2003

AbstractSCF ab initio and AM1 semiempirical calculations with full geometry optimization have been carried out to model the initial steps of alkenylfuran cationic polymerization. Semiempirical procedures have been used to model propagation steps. Proton affinities of the relevant neutral species as well as the heats of formation of probable dimers were calculated. The results allow the explanation of the experimental behavior. The capabilities of the employed methods to describe these type of processes is discussed. It is confirmed that competition between vinyl and ring site attacks is the most important feature in these systems. © 1992 John Wiley & Sons, Inc.
Synthesis and flammability of copolyisophthalamides. I. With phosphorus groups in the main chain
Authors: Gravalos K. G. 
Published: April 2003

AbstractThe influence of certain phosphorus substituted (OH, OMe, Me) 3,3'‐diphenylphosphine oxides on flammability and thermal stability of 1,3‐phenylene isophthalamide copolymers was investigated. Introduction of the above phosphorus groups along the backbone of poly(1,3‐phenylene isophthalamide) was performed in a random manner to a degree of ca. 5‐15 mol %. From the limiting oxygen index (LOI) measurements on copolymers, it was found that the diphenylphosphinic acid group has the highest flame retardance efficiency with an increase of LOI 44‐56%. From thermogravimetric analysis (TGA), it was found that the action of phosphorus groups is limited in the solid phase, increasing the char yield to 27‐42%. This was attributed to crosslinking reactions at the stage of amide bond decomposition. © 1992 John Wiley & Sons, Inc.
Photocrosslinking of copolymers of vinyloxyethyl methacrylate‐styrene initiated by sulfonium salts. II. Photocrosslinking behaviors
Authors: Lin Mao‐Peng , Ikeda Tomiki , Endo Takeshi 
Published: April 2003

AbstractVinylether was used as a cationically polymerizable moiety and incorporated into sidechain of polymers as copolymers of vinyloxyethyl methacrylate (VEM) and styrene (St). Photoirradiation of the copolymers containing a small amount of benzyl(4‐hydroxyphenyl) methylsulfonium salt (BSS) resulted in a high crosslinking density as evidenced by a low degree of swelling, which is ascribed to the high reactivity of the vinyloxy moieties. The sensitivity of this photoreaction is significantly high because of a large kinetic chain length of the cationic polymerization of vinylethers, while copolymers of glycidyl methacrylate and St showed crosslinking to much less extent when irradiated under the same condition. The ability of other sulfonium salts, (4‐hydroxyphenyl) methyl(4‐nitrobenzyl) sulfonium salt and (4‐hydroxyphenyl) methyl(1‐naphthylmethyl)sulfonium salt, to induce photocrosslinking was also examined. © 1992 John Wiley & Sons, Inc.
Graft copolymer of polymethyl methacrylate‐g‐polycarbonate urethane and the fully gelled grafted networks
Authors: Zhou Peiguang , Frisch H. L. 
Published: April 2003

AbstractWe have synthesized and characterized the graft copolymer of polymethyl methacrylate (PMMA)‐graft‐polycarbonate urethane (PCU) (designated PMMA‐g‐PCU) and the fully gelled mutually crosslinked network composed of both PMMA and PCU (designated as PMMA‐PCU‐N). Unlike the previously synthesized one phase PCU/PMMA simultaneous interpenetrating polymer networks (IPN's), both of these new materials exhibited two distinct Tg's (from DSC and DMA studies) at all compositions which we have studied. The two‐phase nature of the graft and network polymer was confirmed by TEM with domain sizes smaller than those found in the blends of the linear PCU and PMMA chains. In comparison with the corresponding IPN's, the PMMA‐g‐PCU and the PMMA‐PCU‐N were thermally less stable and had a lower ultimate strength. © 1992 John Wiley & Sons, Inc.
Melt‐processable oligoamides having internal acetylene groups in the backbone, and thermally stable polyamides therefrom
Authors: Takeichi Tsutomu , Kobayashi Akiko , Takayama Yuzi 
Published: April 2003

AbstractAromatic oligoamides of DP = 5 and 11 that have all meta‐phenylene linkages were prepared by controlling the ratio of isophthaloyl chloride and diamines [m‐phenylenediamine and bis(3‐aminophenyl)acetylene], and then end‐capped with aniline or 2‐aminobiphenylene. Aromatic oligoamides having para‐phenylene linkages were also prepared similarly using terephthaloyl chloride as a monomer. The oligoamides that have all m‐phenylene linkages were soluble in organic solvents such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide, though the oligoamides having p‐phenylene linkages were much less soluble. The oligoamides having acetylene units in the backbone showed exotherm due to crosslinking. The onset of the exotherm appeared at 310‐340°C for the oligoamides having all m‐phenylene linkages, and 330‐370°C for the oligoamides having p‐phenylene linkages. They were melt‐processed at 350 or 380°C for 1 h, giving tough and insoluble films from oligoamides having all m‐phenylene linkages and brittle films from oligoamides having p‐phenylene linkages. The films showed excellent thermal properties. For example, viscoelastic analyses showed little decrease of mechanical property up to 370°C, and Tg was not observed below the temperature. Thermogravimetric analyses also showed that thermal stability of the melt‐processed films were excellent. © 1992 John Wiley & Sons, Inc.
Kinetic analysis of the melt acidolytic (Co) polycondensation of fully aromatic polyesters
Authors: Vulić I. , Schulpen T. 
Published: April 2003

AbstractExperiments to determine the initial reaction rate constants of acidolytic (co)polycondensations of fully aromatic polyesters were conducted in the melt. The initial reaction rate was determined by constant monitoring of the evolution of acetic acid. Both homo‐polycondensation ofp‐acetoxybenzoic acid (pAcBA) and copolycondensation of 2 parts pAcBA, 1 partp,p'‐bisacetoxybiphenyl (BAcBP), and 1 part terephthalic acid (TPA) were studied in a batch reactor under nonisothermal conditions. Next to this, the effect of the presence of the catalystN‐methylimidazole (NMI) on the (co)polycondensations was checked. From the series of experiments it was concluded that the reactivities of acetoxy groups of pAcBA and BAcBP were equal. Furthermore, it was found that the catalyst NMI showed an accelerating effect in the homo‐ and copolycondensations, thereby acting as a “conventional catalyst.” The postulated reaction mechanism for the (co)polycondensations is in accordance with the reaction mechanism for acidolysis of esters by carboxylic acids as suggested by Loncrini. The reactivity of TPA could not be determined by the method used because of the poor solubility of TPA in the reaction mixture. © 1992 John Wiley & Sons, Inc.
Hydroxypropyl cellulose (HPC)‐stabilized dispersion polymerization of styrene in polar solvents: Effect of reaction parameters
Authors: Chen Yun , Yang Hung‐Wen 
Published: April 2003

AbstractDispersion polymerization of styrene in polar solvents in the presence of hydroxypropyl cellulose (HPC) produces latex particles from ca. 1 to 26 μm depending on reaction parameters. Increasing the initiator concentration or temperature decreases the molecular weight, but increases the particle size and breadth of the size distribution. The decrease in molecular weight with increasing Ri, caused by larger initiator concentration or higher temperature, is expected based of fundamental kinetic relationships. The inverse correlation between size and rate of initiation is rationalized by polarity (stabilizing ability) of the grafted HPC‐polystyrene formed in situ. High polar HPC‐g‐PS, which contains shorter graft polystyrene chain, stabilizes particles less effectively and this leads to larger particles. The primary influence of initial styrene concentration is a solvent effect: larger particles are obtained at high styrene concentration due to high solubility of polystyrene during the initial part of the reaction. The influence of the molecular weight of HPC is to change the polarity of the HPC‐g‐PS stabilizer. Comparison of particle growth of three critical polymerization systems suggests that the favorable continuous‐phase solubility parameter for dispersion polymerization of styrene is around 11.6 (cal/mL)1/2. Too high or too low polarity generates particles with broad size distribution because large particles are formed during the initial stage and nucleation continues as the polymerization proceeds. © 1992 John Wiley & Sons, Inc.
Novel carbamoyl phosphonate monomers and polymers from unsaturated isocyanates
Authors: Ignatious Francis , Sein Arjen , Cabasso Israel , Smid Johannes 
Published: April 2003

AbstractCarbamoyl phosphonate derivatives of methacrylic acid and α‐methyl styrene were synthesized in good yield by reacting dimethyl and diethylphosphite with isocyanato ethylmethacrylate (IEM) or with meta‐isopropenyl‐α,α‐dimethylbenzylisocyanate (m‐TMI). The IEM derivatives yield soluble homopolymers with common radical initiators. The m‐TMI carbamoyl phosphonates were copolymerized with styrene and with acrylates yielding soluble materials with better than 50 mol % incorporation of the phosphonate monomer. The side chain carbamoyl phosphonate group drastically lowers the Tg relative to those of the parent polymers. Thermogravimetric studies suggest the NHC(O)P(O)(OR)2 bond to be stable to about 225°C. The radiopacifying salt UO2(NO3)26 H2O yields transparent films with the phosphonate‐containing polymers. The Tg increases with uranyl content. © 1993 John Wiley & Sons, Inc.
Thermotropic copolyesters having ordered comonomer sequences and flexible spacers
Authors: Jin Jung‐Il , Kang Chung‐Seock , Chang Jin‐Hae 
Published: April 2003

AbstractA series of new copolyesters having ordered comonomer sequences were synthesized via multistep routes and their properties such as glass transition (Tg) and melting temperatures (Tm), crystallization tendency, and mesomorphic properties were compared with those of the corresponding random copolyesters. All of the present copolyesters contain 1,8‐octamethylene or 1,10‐decamethylene spacers and hydroquinone (HQ) and terephthalic acid (TPA) moieties. In general, both melting and clearing temperatures of the ordered sequence copolyesters were much higher than those of the random counterparts. Crystallization tendency, however, was comparable. All of the present copolyesters are thermotropic and form nematic phase in melts. © 1993 John Wiley & Sons, Inc.
Aqueous polymerization of acrylamide initiated by cerium(IV)–amino acid chelating agent redox initiators
Authors: Hsu Wen‐Cheng , Kuo Jen‐Feng , Chen Chuh‐Yung 
Published: April 2003

AbstractAmino acid‐type chelating agents such as nitrilotriacetic acid (NTA), nitrilotripropionic acid (NPA), iminodiacetic acid (IDA), and ethylenediamine tetraacetic acid (EDTA) were used in combination with cerium(IV) ammonium nitrate [Ce(IV)] as the redox initiators for the aqueous polymerizations of acrylamide (AM). The polymerization behaviors and polymer qualities were studied as functions of the concentrations of Ce(IV), chelating agent, AM, as well as temperature. The performances of the chelating agent redox systems varied with the natures of the chelating agents. The NTA–Ce(IV) initiator showed the most promising polymerization rate and conversion. The blank tests for the reactions of cerium and chelating agents were also conducted for finding mechanism of formation of free radicals and determining their complex formation constants (K) and disproportionation constants (kd). The mechanism for the polymerization was proposed and the kinetic parameters were evaluated. © 1993 John Wiley & Sons, Inc.
Amphiphilic copolymers with increased affinity for substrates
Authors: Takagishi Toru , Kim Young Joo , Hosokawa Toshitsugu , Morimoto Keiji , Kono Kenji 
Published: April 2003

AbstractThe copolymers of methyl quaternized 2‐dimethylaminoethyl acrylate and styrene, 2‐vinyl naphthalene, acrylic acid iso‐octyl ester, or acrylic acid n‐butyl ester have been prepared. Studies were made of the binding of a “binding probe,” methyl orange, by the copolymers in aqueous solution. The first binding constants and the thermodynamic parameters in the course of the binding were evaluated. Furthermore, the intensity of fluorescence of a hydrophobic fluorescent probe, 2‐p‐toluidinylnaphthalene‐6‐sulfonate, in the presence of these polymers was investigated. In addition, the fluorescence spectra of monomer and excimer emissions of the polymers with aromatic residues were measured. The excimer/monomer fluorescence intensity ratio was studied in the presence of various additives such as methyl orange, urea, methanol, and NaCl to gain an insight into the nature of microdomains in the polymer. The nature and phenomena of dye binding and hydrophobic fluorescent probe binding with the polymers are discussed. © 1993 John Wiley & Sons, Inc.
Effect of counterion condensation on the acid‐base equilibrium of a pH‐sensitive merocyanine dye covalently attached to polyelectrolytes
Authors: Morishima Yotaro , Higuchi Yuji , Kamachi Mikiharu 
Published: April 2003

AbstractEffects of monovalent and divalent counterions on the acid‐base equilibrium of a pH‐sensitive merocyanine dye covalently attached to copolymers of acrylic acid and acrylamide with varying charge densities (0.28 < ξ < 2.8) were investigated. Added chloride salts of Li+, Na+, K+, and NH+4 (< 0.2 mM) had essentially no effect on pK observed (pKobs) for the equilibrium. By contrast, the salts of Mg2+, Ca2+, Sr2+, and Ba2+ caused a significant decrease in pKobs for the copolymers with larger ξ. With smaller ξ, most likely when ξ < 0.5, no decrease in pKobs was observed upon addition of the salts of divalent cations. A competitive effect of Ca2+ and Na2+ ions on pKobs in the presence of an excess of Na+ ions implied that Ca2+ ions at very low concentrations were preferentially, and therefore exhaustively, condensed on the polyanions with sufficiently large ξ probably until effective charge density was lowered to 0.5. The observed difference in the influence of the monovalent and divalent cations on pKobs was discussed in terms of the difference in the microscopic behavior of the condensed monovalent and divalent cations. © 1993 John Wiley & Sons, Inc.
Thermal decomposition of glassy poly(di‐t‐butyl fumarate) as a topochemical reaction
Authors: Ermakov I. V. , Yashin V. V. , Litmanovich A. D. , Platé N. A. 
Published: April 2003

AbstractDecomposition of t‐butyl carboxylate (TBC) groups in a glassy poly(di‐t‐butyl fumarate) (PDTBF) at 140–170°C proceeds with a sharp acceleration caused by interchain interaction of TBC and carboxylic groups. According to selective dissolution data, at 70% degree of conversion the reaction system contains both unchanged PDTBF and a final product: poly(fumaric acid). For TBC groups decomposition in di‐t‐butyl fumarate (DTBF)–styrene copolymers above their Tg an apparent rate constant of autocatalysis increases with the increase of DTBF content in copolymer. Together with previously obtained x‐ray data these results lead to conclusions about the topochemical character of the PDTBF decomposition. The mechanism suggested includes thermal decomposition of TBC groups (initiation), autocatalytic growth of spheric clusters up to a critical size (an appearance of primary germs of the new phase), and growth and branching of thread‐like germs. A mathematical model based on these assumptions describes quantitatively the kinetic data. © 1993 John Wiley & Sons, Inc.