bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of the relative reactivity of maleic anhydride and some maleimides in free radical copolymerization and terpolymerization
Authors: Florjańczyk * Zbigniew , Krawiec Włodzimierz , Such Katarzyna 
Published: April 2003

AbstractComposition data for the free radical copolymerization of maleic anhydride with N‐phenylmaleimide in toluene at 60°C have been obtained. Relative reactivity ratios in terminal and penultimate models using nonlinear least‐squares optimization routine have been determined. The standard error was found to be somewhat smaller in the penultimate model, but is still larger than the uncertainty estimated for the copolymer composition. Terpolymers of maleic anhydride and styrene with maleimide, N‐butylmaleimide, N‐phenylmaleimide, and N‐carbamylmaleimide were obtained. On the basis of analysis of the product composition at various monomer feeds the relative reactivity of maleic anhydride and maleimides in these reactions is compared and the influence of the structure of thesemonomers on the rate of some chain growth reactions is discussed.
Modification of polymer surfaces by two‐step plasma sensitized reactions
Authors: Foerch R. , Mcintyre N. S. , Hunter D. H. 
Published: April 2003

AbstractNew reaction products have been generated on polyethylene and polystyrene surfaces using a novel two‐step process. The first stage involves exposure to a downstream nitrogen plasma, and the second to either ozone or a corona discharge. It is observed that each of the two‐step reactions yields very different reaction products, with an apparent increase in the formation of CO functional groups in the former case and the formation of surface  NO2 groups in the latter case.
Polyimidines. XI. Polyimidines from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride
Authors: Mores Maryanne , Cassidy Patrick E. 
Published: April 2003

AbstractTwo new bis(benzylidenephthalide)monomers were synthesized by melt condensation of phenylacetic acid with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) and with 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA). A mixture of three isomers for each monomer was obtained and polymerized with diamines to produce new polyimidines. Polymerizations were conducted with m‐xylylenediamine (MXDA) or 4,4′‐oxydianiline (ODA) in quantitative yields for the undehydrated intermediate. Inherent viscosities ranged from 0.17 to 0.35 dL/g in N,N‐dimethylformamide (DMF) or N‐methyl‐2‐pyrrolidone (NMP). These intermediate poly(hydroxylactams) were thermally dehydrated to polyimidines which exhibited a 10% weight loss, as high as 546°C in nitrogen. Inherent viscosities of the dehydrated (cured) polyimidines ranged from 0.14 to 0.20 dL/g in NMP. Brittle films could be cast from NMP solutions.
Syntheses of flame‐retarding 4‐phosphonatomethyl‐2,6‐dibromophenyl trimellitate anhydrides and their reactivities toward epoxy resin
Authors: Yang Chin‐Ping , Lee Tzong‐Ming 
Published: April 2003

Abstract4‐Phosphonatomethyl‐2,6‐dibromophenyl trimellitate anhydrides (HDBBP–TMA) were prepared by the condensation of 4‐chloroformyl phthalic anhydride with corresponding 4‐hydroxy‐3,5‐dibromobenzyl phosphonates (HDBBP). These materials could be used to produce excellent flame retardance in epoxy resins when the substances were chemically combined with the polymer. The reactive‐type HDBBP–TMA showed much better phosphorus–bromine synergistic effects on the flame retardancy of epoxy resins than the additive‐type compounds such as HDBBP or the mixture of bromo compound (such as 2,6‐dibromo‐p‐cresol) and phosphorus compound (such as triphenyl phosphite). Meanwhile, the oxygen index of cured epoxy resin was proved to be relative to the extent of crosslinking. Reactivities of HDBBP–TMA toward epoxy were also studied by rheometer in comparison with those of trimellitic anhydride and its derivatives such as 4‐methylphenyl trimellitate anhydride and 4‐methyl‐2,6‐dibromophenyl trimellitate anhydride.
Chelate resin‐iron(II) complex: Adsorption and desorption of nitrogen monoxide at the dry state
Authors: Asanuma Hiroyuki , Toshima Naoki 
Published: April 2003

AbstractA chelate resin‐immobilized iron(II) complex was prepared from iron(II) and poly(styrenecodivinylbenzene) which is functionalized by iminodiacetic acid group. It is activated by drying after having been washed with methanol. The resin complex can rapidly adsorb nitrogen monoxide, and the nitrogen monoxide adsorbed on the complex can be released by the treatment with heat. The adsorption of nitrogen monoxide proceeds through the 1:1 complex formation of the NO molecule with the iron(II) atom, and its complex formation constant was calculated as 8330 atm−1 at room temperature from Langmuir plots. This value does not depend on the solvents used for washing. The activation of the resin complex by the treatment of washing with methanol is derived by increasing the amount of effective iron(II) ions due to the increase in the surface area. Moreover, this resin complex was revealed to have high complex formation constant with NO and high durability to dioxygen compared with an aqueous solution of ethylenediaminetetraacetato–iron(II) complex, which is the corresponding monomeric absorbent commonly used for nitrogen monoxide.
The formation of propylene fumarate oligomers for use in bioerodible bone cement composites
Authors: Domb Abraham J. , Laurencin Cato T. , Israeli Orli , Gerhart Tobin N. , Langer Robert 
Published: April 2003

AbstractPoly(propylene fumarate) (PPF) oligomers were synthesized by step polymerization using bis(2‐hydroxypropyl fumarate) or propylene bis(hydrogen maleate) as starting materials. Oligomers possessing identical degrees of polymerization (DP), but varying in their end group character (either hydroxyl or carboxyl) were first prepared and characterized, then used as part of a bone cement preparation consisting of oligomer, tricalcium phosphate, calcium carbonate, and methyl methacrylate. Compressive strength of the resulting composite appeared to be dependent on both the degree of polymerization of the PPF, and the nature of the oligomers' end groups.
Simulation of the latex particle morphology
Authors: Cal José C. De La , Urzay Rosa , Zamora Aranzazu , Forcada Jacqueline , Asúa José M. 
Published: April 2003

AbstractA model is presented for the simulation of the structuration of polymer particles under conditions in which the new polymer chains are compatible with the polymer previously formed. The model involves the calculation of the monomer concentration gradients within the particles due to discrepancies in thermodynamic interactions between the monomer and the different polymers present in each part of the polymer particle. In addition, the distribution of free radicals in the latex particle is taken into account. This distribution results from the anchoring of the hydrophilic end‐group of the growing polymer chain on the surface of the particle. The model was applied to the simulation of the polymerization of vinyl acetate on a butyl acrylate–vinyl acetate copolymer seed. It was found that the development of the particle morphology was mainly due to the profile of concentration of radicals in the particle. On the other hand, the effect of the monomer–polymer thermodynamic interactions on the particle morphology was found to be negligible. However, it has to be pointed out that this is because, for the system studied, the interaction parameters of vinyl acetate with polyvinyl acetate and polybutyl acrylate are nearly identical.
N,N,N′,N′‐tetramethylethylene diamine as a co‐catalyst in the anionic polylymerization of methyl methacrylate
Authors: Wesslén Bengt , Mattsson Gunnar 
Published: April 2003

AbstractAnionic polymerization of methyl methacrylate in toluene solution has been studied. The polymerizations were initiated by fluorenyllithium as well as by butyl‐, benzyl‐, and phenylmagnesium halides, and carried out in the presence of polar additives. Especially the organomagnesium initiators gave generally rise to highly isotactic polymers (mm = 0.90‐0.95) in the absence of solvating additives. In the presence of the bidentate ligand N,N,N′,N′‐tetramethylethylene diamine (TMEDA) at molar ratios of 1–2 relative to magnesium, highly syndiotactic polymers were obtained at −78°C (rr = 0.8–0.9), while at higher temperatures stereoblock polymers or stereocomplexes were formed. It is proposed that at low temperatures the magnesium cations are strongly solvated under the influence of TMEDA, with the formation of monomeric ion pairs. The large solvated magnesium cations will not have any directional influence on the monomer in the propagation step, with syndiotactic propagation as a result.
Thermal oxidation of blends of poly(vinyl methyl ether) and modified polystyrenes
Authors: Park Hyunkil , Pearce Eli M. , Starnes W. H. , Kwei T. K. 
Published: April 2003

AbstractThermal oxidation of blends of poly(vinyl methyl ether) and styrene copolymers containing hydroxyl groups as hydrogen‐bond donors was studied. The hydrogen‐bonding interaction provide for improved miscibility between the component polymers and more extensive crosspropagation/cross‐termination reactions. In addition to their contribution to improved miscibility, phenol groups in the copolymers exhibited apparent antioxidant and prooxidant effects.
Structure changes on polymer blends by means of phase growth on microheterophase surface
Authors: Ishizu Koji , Minematsu Satoru , Fukutomi Takashi 
Published: April 2003

AbstractWe have studied the structural changes on poly(2‐hydroxyethyl methacrylate) (PHEMA)/polystyrene (PS) blends by means of phase growth of microheterophase pattern on a template surface composed of poly[2‐hydroxyethyl methacrylate (HEMA)‐g‐styrene (S)] graft copolymer (lamellar shape). The PS macromonomer was synthesized by free radical polymerization of S monomer initiated by a functional initiator [2,2'‐azobis(2‐(2‐imidazolin‐2‐yl)propane: VA‐061] in the presence of a degradative chain transfer agent, followed by an end‐capping reaction with p‐chloromethylstyrene (CMS). Poly(HEMA‐g‐S) graft copolymers were prepared by free radical copolymerization of these vinylbenzyl‐terminated PS macromonomers with HEMA comonomer.
Phase transfer Pd(O) catalyzed polymerization reactions. I. Synthesis of 1,2‐(4,4′;‐dialkoxyaryl) acetylene monomers and 1,4‐Bis[2‐(4′,4″‐dialkoxyphenyl)ethynyl]benzene derivatives by phase transfer Pd(O)/Cu(I) catalyzed coupling reactions
Authors: Pugh Coleen , Percec Virgil 
Published: April 2003

AbstractSeveral 1,2‐(4,4'‐dialkoxyaryl)acetylene monomers containing similar or dissimilar substituents were prepared by one of three variations of a one pot phase transfer Pd(O)/Cu(I) catalyzed coupling of aryl halides with a protected acetylene. The three steps within a single flask involved first coupling of the appropriate 1‐halo‐4‐alkoxybenzene derivative with 2‐methyl‐3‐butyn‐2‐ol, followed by cleavage of the carbinol group to form an aryl acetylide, and finally a second coupling of an aryl halide with the aryl acetylide. Best results were obtained when elevated temperatures and solid‐liquid phase transfer reaction conditions were used. Some 1,4‐bis[2‐(4',4”‐dialkoxyphenyl)ethynyl]benzene compounds were also prepared.
End‐Functionalized polymers by living cationic polymerization. IV. Poly(vinyl ethers) with acidic or basic terminal groups by functional initiator method
Authors: Hashimoto Tamotsu , Takeuchi Etsu , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractCarboxylic acid or primary amine‐terminated poly(isobutyl vinyl ethers) were synthesized by living cationic polymerizations with functionalized initiators (CH3CHIOCH2CH2  X; X: that are the adducts of the corresponding vinyl ethers (CH2  CH  OCH2CH2X) with hydrogen iodide. In the presence of iodine, these initiators induced living cationic polymerization of isobutyl vinyl ether to give polymers with the α‐end group of X originating from the initiators. The polymer molecular weights were regulated by the monomer to initiator feed ratio and the molecular weight distributions were very narrow (Mw/Mn ≤ 1.15). Subsequent deprotection of the terminal group X led to polymers with a terminal carboxylic acid or primary amine. 1H‐ and 13C‐NMR analyses showed that the end functionalities of these polymers were all close to unity.
Preparation of polyamide‐imides via the phosphorylation reaction. II. Synthesis of wholly aromatic polyamide‐imides from N‐[p‐(or m‐) carboxyphenyl]trimellitimides and various aromatic diamines
Authors: Hsiao Sheng‐Huei , Yang Chin‐Ping 
Published: April 2003

AbstractWholly aromatic polyamide‐imides with high molecular weight (ηinh up to 1.7 dL/g in DMAc–5% LiCl) were obtained by the direct polycondensation reaction of N‐[p‐( or m‐) carboxyphenyl]trimellitimide [p‐(or m‐)CPTMI] and aromatic diamines by means of di‐ or triphenyl phosphite in N‐methyl‐2‐pyrrolidone (NMP)‐pyridine solution in the presence of lithium or calcium chloride. The factors affecting the phosphorylation reaction were investigated, in particular for the reaction of p‐CPTMI and 4,4'‐oxydianiline (ODA). Molecular weight of polymers varied with the amount of metal salts and showed maximum values at the concentration of 10‐15 wt % in the reaction mixture. Monomer concentration of 0.2 mol/L produced polymer of the highest viscosity. Higher concentrations produced gelation and yielded polymers of low molecular weight. A reaction temperature of about 120°C gave the best results. Among the solvents tested, NMP was significantly the most effective for the reaction. The highest inherent viscosity values, ηinh = 1.35 and 1.58 dL/g, were obtained with triphenyl phosphite (TPP)/monomer and diphenyl phosphite (DPP)/monomer molar ratios of 2.0. Excessive addition of phosphites did not cause a serious deleterious effect on the molecular weight of polymer. Polycondensations of several combinations of p‐or m‐CPTMI and aromatic diamines were carried out with satisfactory results.
Photoinduced conformational changes of azoaromatic polyaspartates containing octadecyl side chains
Authors: Ueno Akihiko , Adachi Kayo , Nakamura Junko , Osa Tetsuo 
Published: April 2003

AbstractCopolymers of p‐(phenylazo)benzyl‐L‐aspartate and n‐octadecyl‐L‐aspartate exist as right‐ and left‐handed α‐helices in solution at 25°C depending on the copolymer composition: the reversal of helix sense from a right‐ to left‐handed one occurs with increasing the azobenzene content. The α‐helices of the copolymers are very sensitive to trifluoroacetic acid (TFA), and are converted into random coil below 2.0% of TFA. Among the copolymers, the copolymer containing 47% azobenzene groups is unique since it exhibits a TFA‐induced conformational change from right‐handed α‐helix to random coil via left‐handed α‐helix. Upon UV light irradiation at 25°C, the copolymers containing 68 and 89% azobenzene groups caused the reversal in helix sense from a left‐ to right‐handed one. The conformations of the copolymers were dependent on temperature, mostly right‐handed and left‐handed α‐helices at lower and higher temperatures, respectively. On this basis, the copolymer containing 47% azobenzene groups could be made to undergo a photoinduced helix reversal at high temperatures.
Availability of surface hydroxyl groups in valonia and bacterial cellulose
Authors: Verlhac C. , Dedier J. , Chanzy H. 
Published: April 2003

AbstractThe chemical microstructural analysis (CMA) developed by Rowland and his school was applied to Valonia and bacterial cellulose and the results compared to those obtained with cellulose from cotton linters. It was found that the surface reactivity of Valonia was very small, roughly one half of that found for bacterial and cotton cellulose. Valonia and bacterial cellulose crystals were found to be of high surface perfection as their surface O(3)H was almost inaccessible. In contrast, in the cotton sample, this hydroxyl group was almost as accessible as in the fully disorganized native cellulose.
Bis(ethyl‐3‐Oxo‐Butanolato‐O1,O3) ‐bis(2‐propanolato)titanium (tyzor) DCR) as a reactant and catalyst in the polymerization of 2‐isocyanatoethyl methacrylate (IEM)
Authors: Graham John C. , Xu Xinmin , Jones Lonnie , Orticochea Margarita 
Published: April 2003

AbstractThe reaction of bis(ethyl‐3‐oxo‐butanolato‐O1,O3)‐bis(2‐propanolato)titanium(Tyzor DCR and 2‐isocyanatoethyl methacrylate (IEM) in refluxing hexane produced a mixture of trimer and polymers of 2‐isocyanatoethyl methacrylate which varied considerably from 23 to 92% polymer as the molar ratio of bis(ethyl‐3‐oxo‐butanolato‐O1,O3)‐bis(2‐propanolato)titanium(Tyzor DCR) to 2‐isocyanatoethyl methacrylate (IEM) varied from 1:4 to 1:32. The IEM 1‐nylon polymer which was soluble in cresol and phenol was characterized by FTIR, 1H‐NMR, and 13C‐NMR. This analysis also showed that the methacrylate carbon–carbon double bond survived our reaction conditions intact. Based on atomic absorption determination of titanium, the molecular weight of the polymer ranged between 3000 and 4000 g/mol. Thermal gravimetric analysis (TGA) showed the polymer to be stable in air to approximately 250°C.
Mechanism of radiation‐induced degradation of poly(methyl methacrylate) as studied by ESR and electron spin echo methods
Authors: Ichikawa Tsuneki , Yoshida Hiroshi 
Published: April 2003

AbstractThe role of radical species in the degradation of poly(methyl methacrylate) (PMMA) induced by γ‐irradiation has been studied by means of electron spin resonance and electron spin echo spectroscopy. The major radical species generated initially at 77 K are assigned to main chain  CH  and side chain  COOCH2 radicals, and  COOCH anion radical. Only the  COOCH2 radical converts to the scission‐type  CH2  C(CH3)COOCH3 radical on warming the sample of >180 K. A part of the  CH  radical disappears on warming the sample of >265 K. It is concluded that the scission of PMMA main chain occurs by the intramolecular process from the  COOCH2 radical as the precursor state.
Living polymerization of aryl substituted acetylenes by MoCl5 and WCl6 based initiators: The ortho phenyl substituent effect
Authors: Kunzler Jay , Percec Virgil 
Published: April 2003

AbstractThe polymerization of phenylacetylene initiated by MoCl5 and WCl6 based initiators was monitored directly in the NMR sample tube and demonstrated the presence of backbiting and intramolecular cyclization reactions. It was shown that the ratio of cis to trans structural units obtained by isomerization prior to double bond formation dictates the degree of backbiting and intramolecular cyclization reactions. This cis–trans ratio determines the length of cis–transoidal sequences present in the polymer backbone which are available for both backbiting and intrachain cyclization reactions. The cyclic trimers obtained in the metathesis polymerization of phenylacetylene are formed only through the cis–cisoidal‐induced backbiting and/or intramolecular reactions. The o‐trimethylsilylphenylacetylene follows a living mechanism of polymerization. This is due to the fact that the size of the ortho substituent suppresses the cis–transoidal to cis–cisoidal isomerization reactions and therefore eliminates the backbiting reactions. The steric hindrance provided by the size of the ortho substituent also eliminates interchain and intrachain reactions.
Synthesis of new amphiphilic block copolymers. Block copolymer of sulfonated glycidyl methacrylate and alkyl methacrylate
Authors: Leemans L. , Fayt R. , Teyssié Ph. 
Published: April 2003

AbstractWater‐soluble amphiphilic block copolymers consisting of a hydrophobic block of poly(alkyl methacrylate) and a hydrophilic anionic polyelectrolyte block have been synthesized by a living anionic polymerization of methyl methacrylate and glycidyl methacrylate and subsequent selective modification of the oxirane groups of the glycidyl methacrylate block into hydroxysulfonate groups by a phase transfer catalyzed sulfonation reaction. The block copolymers were characterized by a predictable motecular weight and a narrow molecular weight distribution while the yield was quantitative. These amphiphilic block copolymers display surfaceactive behavior in water and they are characterized by a critical micelle concentration.
Further studies on homopolymers and copolymers resulting from the reaction of polymaleic anhydride with alcohols and amines
Authors: Tsiourvas D. , Paleos C. M. , Dais Photis 
Published: April 2003

AbstractPolymaleic anhydride prepared by γ‐rays irradiation of maleic anhydride was used as a reactive polymer and reacted with certain long‐chain aliphatic amines and/or alcohols as well as with the mesogenic biphenylamine. The homopolymers and copolymers that were prepared, i.e., derivatives of N‐alkyl polymaleamic acid, monoesters of polymaleic acid, or mixed amide‐ester derivatives, were primarily investigated as far as their property to show thermotropic liquid crystalline character is concerned. By this investigation the structural features for the exhibition of mesomorphism by these polymers were determined.
Chemical modification of polynorbornene. II. Extended sulfonation processes
Authors: Planche J. P. , Revillon A. , Guyot A. 
Published: April 2003

AbstractIn the sulfonation of polynorbornene in dilute solution, the nature of the sulfonation agent mainly influences the reaction rate, according to its strength and also affects some side reactions (chain scission and crosslinking). The sulfonation can be carried out in suspension after swelling the highly porous powder in dichloroethane up to a 55% sulfonation ratio with preservation of the initial particular nature of the polymer; the latter may be then either partly or totally water soluble, depending on the initial size of the particles. Partial sulfonation, leading to ionomers, may be carried out in bulk at moderate temperature, in a mixing chamber, after gelification of the polymers, plasticized with CCl4.
Block interrupt polysilane derivatives
Authors: Miller R. D. , Fickes G. N. 
Published: April 2003

AbstractHigh molecular weight block interrupt polysilane derivatives have been prepared by the condensation of a number of α,ω‐dichloropolysilanes with some aromatic bis silanols. In this manner, polymers containing polysilane blocks of 2, 4, or 6 catenated silicon atoms have been prepared. The materials are thermally stable and the UV spectroscopic properties mimic those of the corresponding monomers. Although these materials bleach upon irradiation in the deep UV, surprisingly, the block interrupt polysilanes behave as negative resists upon exposure to 254 nm radiation. This behavior contrasts with that of standard polysilane homopolymers which usually function in a positive lithographic mode.
The preparation and γ‐ray sensitivity of comb block copolymers
Authors: Laivins G. , Worsfold D. J. 
Published: April 2003

AbstractA series of comb block copolymers have been prepared and subjected to 60Coγ irradiation. The copolymers contained a polyalkenesulphone backbone, and either polystyrene or polymethylphenylsiloxane as the sidebranches. The alkenes in the polysulphone were one of cycloheptene, 2‐hexene, or 2‐methylpentene‐1 giving a series of backbones of differing low ceiling temperatures. The combs were prepared by creating a macromer of the desired sidearm, and then copolymerizing into the main chain. On γ‐irradiation, backbone polysuphones depolymerized leaving behind the comparatively short and radiation resistant sidechains.