bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of novel polyarylates from 2,5‐bis(4‐hydroxyphenyl)‐3,4‐diphenylpyrrole and various aromatic dicarboxylic acids
Authors: Jeong Hwa‐Jin , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractA new tetraphenylated heterocylic diol, 2,5‐bis(4‐hydroxyphenyl)‐3,4‐diphenylpyrrole, was synthesized in three steps starting from 4‐methoxydeoxybenzoin. The tetraphenylpyrrole‐containing polyarylates having inherent viscosities of 0.28–0.88 dL/g were prepared from the diol and various aromatic dicarboxylic acid chlorides by both phase transfer catalyzed two‐phase polycondensation and high temperature solution polymerization methods. All the polyarylates were semi‐crystalline, and were readily soluble in a variety of solvents including N‐methyl‐2‐pyrrolidone, m cresol, pyridine, and 1,4‐dioxane. These polymers had glass transition temperatures in the range of 223–279°C, with no weight loss below 400°C in both air and nitrogen atmospheres. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of ran‐copoly (p‐phenylene sulfide sulfone/ketone)s
Authors: Senn Dwayne R. 
Published: April 2003

AbstractRandom copoly(p‐phenylene sulfide sulfone/ketone)s (PPSS/K) are prepared in high yield by the polycondensation of sodium hydrosulfide (NaSH) with bis(4‐chlorophenyl) sulfone (BCPS) and 4,4′‐dichlorobenzophenone (DCBP). The polymerization is conducted between 200–220°C, depending on the composition of the copolymer, and in the presence of water without any detrimental effects to the molecular weight. The copolymers with sulfone/ketone mole ratios (S : K) > 25 : 75 are amorphous, while the copolymers with S : K ratios ≤ 25 : 75 are crystalline. These materials form tough, creaseable films and exhibit a linear increase in the glass transition temperature with increasing sulfone content. Sulfuric acid solutions of the copolymers are dark orange to red and display an increasing λmax in the uv‐visible spectra as the S:K ratio of the copolymers decreases. © 1994 John Wiley & Sons, Inc.
Swelling kinetics and release characteristic of crosslinked chitosan: Polyether polymer network (semi‐IPN) hydrogels
Authors: Yao Kang De , Peng Tao , Feng Han Bao , He Yu Ying 
Published: April 2003

AbstractThe aqueous swelling kinetics of a series of crosslinked chitosan (cr‐CS) with glutaraldehyde (GA) interpenetrating polyether hydrogels have been studied as functions of pH, the N‐deacetylation degree of chitosan, the amount of crosslinking agent, the electrolyte composition in solution, temperature, and gel composition. Based on these results, the swelling mechanism of the hydrogels was discussed. The release profiles of chlorhexidini acetas from the semi‐IPN were also investigated. © 1994 John Wiley & Sons, Inc.
Studies on the formation of PEN. II. Polymerization of bis(hydroxyethyl) naphthalate by various metallic catalysts
Authors: Wang Chun‐Shan , Sun Yih‐Min 
Published: April 2003

AbstractBis(hydroxyethyl) naphthalate (BHEN) was polymerized to polyethylenenaphthalate (PEN) in the presence of various metallic catalysts. The influence of the nature and concentration of these catalysts on the rate of polymerization has been investigated. The order of decreasing catalytic influence of various metal ions on the polymerization of BHEN was found to be: Ti > Sb > Zn > Co > Pb > Ni(Mg). The effect of the reaction temperature has also been studied. The optimal concentration of these catalyst and reaction temperature were found to be 30 × 10−5 (mol/mol BHEN) and 285–293°C, respectively. Because of its insolubility in ordinary solvent, the molecular weight of PEN was measured using the light scattering method. © 1994 John Wiley & Sons, Inc.
Polymerization of avidin and streptavidin with aromatic bisbiotin ligands
Authors: Morgan H. , Fukushima H. , Taylor D. M. 
Published: April 2003

AbstractThe synthesis of a range of aromatic bisbiotin ligands is described and their ability to polymerize the proteins avidin and streptavidin is investigated. The formation of protein polymers is confirmed by gel chromatography and transmission electron microscopy. It is shown that the degree of polymerization depends not only on the length of the ligand but also on the stereochemistry of the group linking the distal biotin moieties. © 1994 John Wiley & Sons, Inc.
High flow addition curing polyimides
Authors: Chuang Kathy C. , Vannucci Raymond D. , Ansari Irfan , Cerny Lawrence L. , Scheiman Daniel A. 
Published: April 2003

AbstractA new series of high flow PMR‐type addition curing polyimides was developed, which employed the substitution of 2,2′‐bis(trifluoromethyl)‐4,4′‐diaminobiphenyl (BTDB) for p‐phenylenediamine (p‐PDA) in a PMR‐II formulation. These thermoset polyimides, designated as 12F resins, were prepared from BTDB and the dimethyl ester of 4,4′‐(hexafluoroisopropylidene)‐diphthalic acid (HFDE) with either nadic ester (NE) or p‐aminostyrene (PAS) as the endcaps for addition curing. The 12F prepolymers displayed lower melting temperatures in DSC analysis, and higher melt flow in rheological studies than the corresponding PMR‐II polyimides. Long‐term isothermal aging studies showed that BTDB‐based 12F resins exhibited comparable thermo‐oxidative stability to p‐PDA based PMR‐II polyimides. The noncoplanar 2‐ and 2′‐disubstituted biphenyldiamine (BTDB) not only lowered the melt viscosities of 12F prepolymers, but also retained reasonable thermal stability of the cured resins. The 12F polyimide resin with p‐aminostyrene endcaps showed the best promise for long‐term, high‐temperature application at 343°C (650°F). © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of poly[4‐(4‐hydroxyphenoxy) benzoic acid]
Authors: Yonetake Koichiro , Maruyama Kunio , Sugiyama Jun‐Ichi , Masuko Toru , Ueda Mitsuru 
Published: April 2003

AbstractPoly[4‐(4‐hydroxyphenoxy) benzoic acid] was prepared by the bulk polycondensation of 4‐(4‐acetoxyphenoxy) benzoic acid. Polycondensation was conducted at 350°C for 3 h under a reduced pressure of 0.1 mmHg and gave a polymer with X̄n of 255. The polymer was characterized by elemental analysis, IR spectroscopy, differential scanning calorimetry, and wide‐angle X‐ray measurement. The crystal/nematic and nematic/isotropic phase transition temperatures of polymer, which depend on the molecular weight, were observed at about 300°C and 410°C, respectively. The polymers with low molecular weights showed nematic textures above 300°C. This nematic/isotropic phase transition temperature is lower than that of poly (4‐hydroxybenzoic acid). This thermal behavior of polymer comes from ether units, which increase the flexibility (the rotation or torsion of skeletal bonds) of the polymer chain. © 1994 John Wiley & Sons, Inc.
Synthesis of crosslinked poly(styrene‐co‐sodium styrenesulfonate) latexes
Authors: Sunkara Hari Babu , Jethmalani Jagdish M. , Ford Warren T. 
Published: April 2003

AbstractLatexes of 100 nm diameter were synthesized by emulsifier‐free copolymerization of styrene, sodium styrenesulfonate, and 1–5 wt% divinylbenzene using persulfate initiator at 91°C. A shot growth method was used to incorporate a high density of sulfonate groups. Coefficients of variation of particle size were 0.04–0.08 without resort to seed growth polymerization. Redox initiation at 40–50°C produced larger, more polydisperse, and less colloidally stable crosslinked latexes. © 1994 John Wiley & Sons, Inc.
Role of N,N‐dimethyl‐para‐toluidine and saccharin in the radical polymerization of methyl methacrylate initiated by a redox system. I. Cumene hydroperoxide/copper saccharinate
Authors: Beaunez P. , Helary G. , Sauvet G. 
Published: April 2003

AbstractKinetics of methyl methacrylate polymerization initiated by a redox system [cumene hydroperoxide (CHP)/copper saccharinate] were studied in bulk at 20°C in the presence of accelerators such as N,N‐dimethyl‐p‐toluidine (DMPT) and o‐benzoic sulphimide (saccharin). Assuming a steady‐state concentration of propagating radicals, the polymerization rate depends on the square root of the initiation rate and the kinetic orders with respect to each compound in the initiation step may be deduced. Initiation is first‐order in CHP, copper saccharinate, and saccharin and second‐order in DMPT. A reaction scheme consistent with these orders is proposed. The main features are the following: (1) CHP reduces rapidly Cu(II) to Cu(I); (2) a small fraction of Cu(I) is complexed with DMPT; (3) the complexed ions (Cu+, DMPT2) are strong reductants with respect to CHP whereas uncomplexed Cu+ are almost inactive; (4) the decomposition of CHP is strongly catalyzed by saccharin (protonated CHP is 13000 times more reactive than free CHP). Thus both accelerators are necessary to get high polymerization rates. © 1994 John Wiley & Sons, Inc.
Role of N,N‐dimethyl‐para‐toluidine and saccharin in the radical polymerization of methyl methacrylate initiated by a redox system. II. Cumene hydroperoxide/iron saccharinate
Authors: Beaunez P. , Helary G. , Sauvet G. 
Published: April 2003

AbstractThe role of N,N‐dimethyl‐p‐toluidine (DMPT) and saccharin as accelerators in the polymerization of methyl methacrylate initiated by the redox decomposition of cumene hydroperoxide (CHP) in the presence of iron saccharinate has been kinetically investigated. DMPT reduces ferric ions to ferrous ions, so that an equilibrium is established between the two oxidation states. With the assumption of a steady‐state concentration of propagating radicals, the rate of initiation was deduced from the rate of polymerization and the kinetic orders with respect to each compound involved in the initiation step have been determined. The reaction is first‐order in CHP, iron saccharinate, and saccharine and second‐order in DMPT. In a proposed scheme, Fe2+ ions, complexed by two DMPT molecules, are much more reactive than uncomplexed Fe2+ and saccharin activates the decomposition of CHP by protonation of the OO bond. This mechanism, similar to that proposed in the case of copper saccharinate, explains the synergistic effect of both accelerators. © 1994 John Wiley & Sons, Inc.
Synthesis and properties of poly(amide‐imide)s derived from trimellitic anhydride, ω‐amino acids, and aromatic diamines
Authors: Hsiao Sheng‐Huei , Yang Chin‐Ping , Wu Feng‐Yueh 
Published: April 2003

AbstractSeven imidodicarboxylic acids II‐1 to 5, II‐10, and II‐11 were prepared from trimellitic anhydride and ω‐amino acids, such as glycine, β‐alanine, 4‐aminobutyric acid, 5‐aminopentanoic acid, 6‐aminohexanoic acid, 11‐aminoundecanoic acid, and 12‐aminododecanoic acid. Several aliphatic‐aromatic poly(amide‐imide)s were prepared by triphenyl phosphite promoted polycondensation reaction from the combination of 3‐(4‐carboxyphthalimido)propionic acid (II‐2) or 6‐(4‐carboxyphtalimido)hexanoic acid (II‐5) with various aromatic diamines and of all the imidodiacids with p‐phenylenediamine or 4,4′‐oxydianiline. All poly(amide‐imide)s were characterized by inherent viscosity, gel permeation chromatography (GPC) measurements, solubility, tensile test, wide‐angle X‐ray scatting patterns, differential scanning calorimetry (DSC) measurements, and thermogravimetric (TGA) analyses. Effects of structural changes such as polymethylene length and diamine moieties on the properties of poly(amide‐imide)s were studied. © 1994 John Wiley & Sons, Inc.
Use of V and V–Cr catalysts interchanged in “Y” zeolites for the polymerization of ethylene
Authors: Ismayel A. , Arribas G. , Celta D. , Sanchez G. 
Published: April 2003

AbstractEthylene polymerization has been studied in the presence of catalyst based on vanadium or vanadium‐chromium supported on a zeolite HY. The effect of vanadium over chromium has been investigated as a function of the sequence of exchange of metals on the support and metal contents. Both effects were investigated in relation to the characteristics of the polyethylene (PE) obtained. Low activity has been found for the V (II) zeolite HY catalyst. Moreover, vanadium acts either as an inhibitor or as a promoter for the polymerizing activity of the Cr (III)/zeolite catalyst, depending on the preparation method. © 1994 John Wiley & Sons, Inc.
Preparation and characterization of functional group gradient surfaces
Authors: Lee Jin Ho , Kim Heoung Woo , Pak Pyong Ki , Lee Hai Bang 
Published: April 2003

AbstractFunctional group gradient surfaces where the density of functional groups changes gradually along the sample length were prepared. The functional group ( COOH,  CONH2, and  OH group) gradient surfaces were produced by the treatment of low‐density PE sheets using a corona with gradually increasing power, followed by the graft copolymerization of acrylic acid and subsequent substitution reaction of carboxylic acid groups to amide or hydroxyl groups. The prepared gradient surfaces were characterized by the measurement of water contact angle, FTIR‐ATR, and ESCA. The gradient surfaces prepared can be used to systematically investigate the interactions of biological or other species in terms of the surface functional groups and their density of polymeric materials. © 1994 John Wiley & Sons, Inc.
Biodegradable and pH‐sensitive hydrogels: Synthesis by crosslinking of N,N‐dimethylacrylamide copolymer precursors
Authors: Yeh Ping‐Yang , Kopec̆ková Pavla , Kopec̆ek Jindr̆ich 
Published: April 2003

AbstractNovel pH‐sensitive hydrogels containing azoaromatic crosslinks were synthesized by the crosslinking of polymeric precursors. First, a reactive polymeric precursor was synthesized by copolymerization of N,N‐dimethylacrylamide, N‐tert‐butylacrylamide, acrylic acid, and N‐methacryloylglycylglycine p‐nitrophenyl ester. The hydrogel was prepared in the second step by the reaction of the polymeric precursor with N,N′‐(ω‐aminocaproyl)‐4,4′‐diaminoazobenzene. The hydrogels were characterized by the network structure, (that is, content of crosslinks, unreacted pendent groups, and cycles), the equilibrium swelling ratio as a function of pH, modulus of elasticity in compression, and the degradability in vitro. The results obtained indicated that the hydrogel network structure strongly depends on the reaction conditions such as polymer concentration, and the ratio of the reactive groups during the crosslinking reaction. The swelling and mechanical properties of hydrogels can be controlled by the modification of polymer backbone structure and/or the crosslinking density. The rates of hydrogel degradation depended on their degree of swelling. The higher the degree of swelling, the higher the degradability. The properties of the hydrogels suggest that they have a potential as carriers for colon‐specific drug delivery. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of bismaleimides derived from polyurethanes
Authors: Liao D. C. , Hsieh K. H. 
Published: April 2003

AbstractA series of novel bismaleimides (BMIs) were prepared from maleic anhydride and polyurethane prepolymers based on MDI (4,4′‐diphenylmethane diisocyanate) and polyether and polyester diols with various chain lengths. All the BMIs were characterized by IR, 1H‐NMR, and elemental analysis. DSC studies indicated that the thermal polymerization of the BMIs could be carried out in the temperature range of 102–245°C, and that curing behavior was significantly affected by the molecular weight of the BMIs. The crosslinked BMI elastomers showed good mechanical properties and much better thermal stability than that of the traditional polyurethane elastomers. The glass transition temperatures, mechanical, and dynamic mechanical properties were dependent on the types of polyols used and the resultant crosslink densities due to various chain lengths of the BMIs. © 1994 John Wiley & Sons, Inc.
Living cationic polymerization of isobutyl vinyl ether by EtAlCl2 in the presence of ether additives: Cyclic ethers, cyclic formals, and acyclic ethers with oxyethylene units
Authors: Aoshima Sadahito , Fujisawa Takashi , Kobayashi Eiichi 
Published: April 2003

AbstractThe living cationic polymerization of isobutyl vinyl ether (IBVE) was investigated in the presence of various cyclic and acyclic ethers with 1‐(isobutoxy)ethyl acetate [CH3CH(OiBu)OCOCH3, 1]/EtAlCl2 initiating system in hexane at 0°C. In particular, the effect of the basicity and steric hindrance of the ethers on the living nature and the polymerization rate was studied. The polymerization in the presence of a wide variety of cyclic ethers [tetrahydrofuran (THF), tetrahydropyran (THP), oxepane, 1,4‐dioxane] and cyclic formals (1,3‐dioxolane, 1,3‐dioxane) gave living polymers with a very narrow molecular weight distribution (MWD) (M̄ω/M̄n ≤ 1.1). On the other hand, propylene oxide and oxetane additives resulted in no polymerization, whereas 1,3,5‐trioxane gave the nonliving polymer with a broader MWD. The polymerization rates were dependent on the number of oxygen and ring sizes, which were related to the basicity and the steric hindrance. The order of the apparent polymerization rates in the presence of cyclic ether and formal additives was as follows: nonadditive ∼ 1,3,5‐trioxane ≫ 1,3‐dioxane > 1,3‐dioxolane ≫ 1,4‐dioxane ≫ THP > oxepane ≫ THF ≫ oxetane, propylene oxide ≫ 0. The polymerization in the presence of the cyclic formals was much faster than that of the cyclic ethers: for example, the apparent propagation rate constant k in the presence of 1,3‐dioxolane was 103 times larger than that in the presence of THF. Another series of experiments showed that acyclic ethers with oxyethylene units were effective as additives for the living polymerization with 1/EtAlCl2 initiating system in hexane at 0°C. The polymers obtained in the presence of ethylene glycol diethyl ether and diethylene glycol diethyle ether had very narrow molecular weight distribution (M̄ω/M̄n ≤ 1.1), and the M̄n was directly proportional to the monomer conversion. The polymerization behavior was quite different in the polymerization rates and the MWD of the obtained polymers from that in the presence of diethyl ether. These results suggested the polydentate‐type interaction or the alternate interaction of two or three ether oxygens in oxyethylene units with the propagating carbocation, to permit the living polymerization of IBVE. © 1994 John Wiley & Sons, Inc.
Styrene polymerization with some new macro or macromonomeric azoinitiators having peg units
Authors: Hazer Baki , Erdem Bedri , Lenz Robert W. 
Published: April 2003

AbstractSeveral new macroinitiators and macromerinitiators (macroinimers) were synthesized and evaluated for the bulk polymerization of sytrene at 60°C. Macroinitiators were prepared from the reaction of 4,4′‐dicyano‐4,4′ azovaleryl chloride (1) with poly(ethylene glycol) (PEG) with a Mω of 400 and with either benzoyl chloride, acetyl chloride, phenyl isocyanate, or poly(ethylene glycol) oleyl ether. Macromer initiators were also prepared from the reaction of 1 with PEG having Mω values of 200, 400, 600, 1000, or 1500 and with 4‐vinylbenzyl chloride. The bulk polymerization of styrene by macroinimers gave crosslinked styrene‐PEG block copolymers, while the polymerization by macroinitiators gave soluble copolymers. The molecular weights of the styrene‐PEG block copolymers obtained with macroinitiators having either oleyl, benzoyl, or phenyl urethane end groups were 22000–29000 g/mol. DSC measurements showed that the crosslinked block copolymers had crystalline PEG units with melting transitions ranging from 11–37°C. © 1994 John Wiley & Sons, Inc.
High solids content emulsion terpolymerization of vinyl acetate, methyl methacrylate, and butyl acrylate. I. Kinetics
Authors: Urretabizkaia Agustín , Asua José M. 
Published: April 2003

AbstractThe kinetics of the high solids content emulsion terpolymerization of vinyl acetate, methyl methacrylate, and butyl acrylate were investigated. The effect of feed flow rate, total amount of emulsifier, distribution of emulsifier between the initial charge and the feed, concentration of initiator, and solids content on the time evolution of the conversion, terpolymer composition, and total number of polymer particles were investigated. The experimental results were analyzed by means of a mathematical model that incorporated the main features of the system. © 1994 John Wiley & Sons, Inc.
High solids content emulsion terpolymerization of vinyl acetate, methyl methacrylate and butyl acrylate. II. Open loop composition control
Authors: Urretabizkaia Agustín , Arzamendi Gurutze , Unzué María J. , Asua José M. 
Published: April 2003

AbstractA method for the calculation of the optimal monomer addition policies for polymer composition control in emulsion terpolymerization is developed. The method is applied to reactors with and without limited heat removal capacity. A mathematical model that incorporates the main features of the vinyl acetate/methyl methacrylate/butyl acrylate high solids content emulsion terpolymerization system allows the calculation of the composition of the initial charge of the reactor and the time‐dependent monomer addition rates required. © 1994 John Wiley & Sons, Inc.
Preparation and photoreaction of copolymers derived from N‐(1‐phenylethyl)acrylamide and 7‐acryloyloxy‐4‐methyl coumarin
Authors: Chen Yun , Wu Jehng‐Daugh 
Published: April 2003

AbstractThe copolymers containing photoreactive 4‐methyl coumarin pendant groups have been prepared by radical copolymerization of N‐(1‐phenylethyl)acrylamide (M1) and 7‐acryloyloxy‐4‐methyl coumarin (M2) in DMF at 70°C. The monomer reactivity ratios (MRR) of M1 and M2 are estimated by Finenam‐Ross, Kelen‐Tüdos, Mayo‐Lewis, and YBR methods to be about r1 = 0.12–0.16 and r2 = 1.13–1.28. Dilute dioxane solutions of the copolymers (10−4‐10−5 M of 4‐methyl coumarin chromophores) are first photocrosslinked intramolecularly by irradiating 350 nm light (dimerization of 4‐methyl coumarin) and then photo‐cleaved at 254 nm (symmetric cleavage of cyclobutane). Tracing by an UV‐visible spectrophotometer, it is found that photocrosslinking and photocleavage proceed simultaneously when 254 nm is the light source and finally reaches to a dynamic equilibrium. However, only photocrosslinking can be observed under 350 nm light. Kinetic results show that both photocrosslinking and photocleavage are first‐order reactions. Moreover, photocrosslinking rate constant increases with mole fraction of M2 in the copolymer (F2). On the contrary, rate constant of photocleavage decreases with increasing F2. © 1994 John Wiley & Sons, Inc.
Phase‐Transfer catalyzed free‐radical polymerization of acrylonitrile
Authors: Balakrishnan T. , Arivalagan K. 
Published: April 2003

AbstractThe kinetics of phase‐transfer catalyzed free‐radical polymerization of acrylonitrile (AN) was carried out with water‐soluble initiator peroxomonosulphate (PMS) with phase‐transfer catalysts (tetrabutylammonium chloride and benzyltributylammonium chloride (TBAC and BTBAC) in tolune/water two‐phase systems in the temperature range of 45–55°C at fixed pH (4) and ionic strength. The rates of polymerization (Rp) were evaluated at various values of [PMS], [PTC], and [AN]. It has been observed that the rates of polymerization increase with an increase of [AN], [PMS], and [PTC]. A kinetic scheme has been proposed to account for the experimental observations. © 1994 John Wiley & Sons, Inc.
Analysis of 1H‐NMR spectra of various end‐functionalized polyisobutylenes
Authors: Si Jiaoshi , Kennedy Joseph P. 
Published: April 2003

Abstract1H‐NMR spectra of various telechelic (i.e., ∼ CH2C(CH3)2Cl, ∼ CH2C(CH3)CH2, ∼ CHC(CH3)2, and ∼ CH2CH(CH3)CH2OH capped) polyisobutylenes (PIB) have been analyzed. The products were prepared by living carbocationic polymerization followed by end‐group functionalization. Shielding and deshielding effects strongly influence the 1H‐NMR spectra of these products. Inductive effects (chlorine‐ended PIBs), magnetically anisotropic end‐groups (olefin groups and phenyl rings), allylic coupling (olefin end‐groups), chirality (hydroxyl end‐groups), and the interaction of these effects on the 1H‐NMR spectra are discussed. Numerous heretofore unidentified resonances have been assigned and better insight into the detailed structure of end‐functionalized PIBs has been obtained. © 1994 John Wiley & Sons, Inc.