bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnesium chloride supported high mileage catalysts for olefin polymerization. XXI. Isospecific and regiospecific vanadium catalyst for propylene polymerization
Authors: Zhou Xinhua , Lin Shangan , Chien James C. W. 
Published: April 2003

AbstractSeveral CW–V catalysts were prepared by supporting VCl4 on Mg Cl2 with ethyl benzoate and CH–V catalysts prepared by reacting MgCl2.ROH, phthalic anhydride, and VCl4. These vanadium catalysts, activated with TEA (triethyl aluminum)/MPT (methyl‐p‐toluate) produce mainly (88–96%) refluxing n‐heptane insoluble isotactic PP. The active site has
\documentclass{article}\pagestyle{empty}\begin{document}$ k_{p,i} = 1580 \left( M {\rm s} \right)^{ - 1}, k_{tr,i}^{\rm A} = 2 \times 10^{ - 3} {\rm s}^{ - 1} , k_{tr}^{\rm H} = 3.8 \times 10^{ - 2} \left( {\rm torr} \right)^{ - {1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} {\rm s}^{ - 1}$\end{document}
for the isospecific ones and
\documentclass{article}\pagestyle{empty}\begin{document}$ k_{p,a} = 58 \left( M {\rm s} \right)^{ - 1} ,k_{tr,a}^{\rm A} = 3 \times 10^{ - 3} {\rm s}^{ -1}$\end{document}
for the nonspecific sites. Catalyst of VCl3 supported on MgCl2 has comparable productivity as the VCl4/MgCl2 catalyst but catalyst of VCl2 supported on MgCl2 exhibit only one‐ninth of the productivity. Extensive comparison has been made between the CW–V and the CW–Ti systems which revealed striking similarities between their polymerization behaviors. MgCl2 exerts profound influence on the stereochemical control of the vanadium ion on its activity for monomer coordination and insertion.
Novel conjugated polymer containing anthracene backbone: Addition polymer of 9, 10‐diethynylanthracene with 9, 10‐anthracenedithiol and its properties
Authors: Kobayashi Eiichi , Jiang Jian , Ohta Hirotoshi , Furukawa Junji 
Published: April 2003

Abstract9,10‐Diethynylanthracene was prepared by the alkaline hydrolysis of 9,10‐bis (trimethylsilylethynyl) anthracene. Another new monomer of 9, 10‐anthracenedithiol was prepared by the reduction of anthracene polydisulfide. A crystalline conjugated polymer of 9,10‐diethynylanthracene with 9,10‐anthracenedithiol was synthesized in a THF solution at 50°C by UV irradiation or by using radical initiators. The molecular weight (M̄n) of the insoluble polymer in THF is about 20000–30000 and the soluble is about 4000. From the sulfur content and IR spectrum of the insoluble polymer, it is realized that the obtained polymer has the alternating structure consisting of 9,10‐diethynylanthracene and 9,10‐anthracenedithiol units. X‐ray pattern indicated that the polymer has a layer structure. The conductivity of the undoped polymer was about 10−11S/cm, but enhanced up to 10−6 S/cm by doping with iodine. The enhancement of the conductivity seems to be the existence of the CT complex among the polymer backbone and iodine or iodine anion.
Preparation of sterically stabilized nanoparticles by desolvation from graft copolymers
Authors: Artursson Per , Brown Lyndon , Dix Jacqueline , Goddard Peter , Petrak Karel 
Published: April 2003

AbstractA new method is described for the preparation of sterically stabilized nanoparticles of defined size and polydispersity which are stabilized in aqueous solution by the presence of covalently linked monomethoxy–poly (oxyethylene) (MeOPOE) chains. The nanoparticles (100–270 nm mean diameter) were prepared by a process of desolvation of a graft copolymer prepared from poly(2‐aminoethylmethacrylate) (PAEMA) and MeOPOE. Reproducible desolvation was achieved by the addition of sodium phosphate buffer to the copolymer in aqueous solution to give particles which were crosslinked in situ with the addition of glutaraldehyde. The size (mean diameter) and polydispersity (Q) of the particles were determined by Photon Correlation Spectroscopy (PCS). The temperature at which the desolvation reaction was performed was found to influence the particle size; at low temperatures (5–12°C), small particles were produced (99–121 nm, Q = 0.090–0.121), whereas at much higher temperatures (40–55°C), particles as large as 224–275 nm (Q = 0.138–0.127) were generated. Other parameters such as the graft copolymer concentration, the amount of glutaraldehyde added, the pH of the sodium phosphate buffer added, and the reaction time were found to be of relative insignificance in influencing the particle size. In addition to those involved in drug delivery, our method of nanoparticle preparation may be of interest to those engaged in the preparation of particulate materials and colloidal dispersions for other specific applications (e.g. stabilized photographic emulsions).
A new type of functional polymer: Preparation and crosslinking of poly(allenyl glycidyl ether)
Authors: Mizuya Jiro , Yokozawa Tsutomu , Endo Takeshi 
Published: April 2003

AbstractThe radical polymerization behavior of alkoxyallene containing the epoxy group, allenyl glycidyl ether (I), was investigated to obtain the more reactive polymer. The desired polymer was successfully synthesized only by the copolymerization of I with acrylonitrile (AN) at 80°C in DMF, although the homopolymer of I was converted to the crosslinked polymer during its purification. The same number of epoxy and two kinds of methylene groups were simultaneously introduced onto the polymer through propagating allyl radical. The obtained copolymer, therefore, was readily converted to the gelled polymer with methods such as heating and treating with Lewis acids or amines. Further, the copolymer containing two kinds of methylene groups was prepared similarly from methoxyallene (II) and AN, and was also converted to the crosslinked polymer with the cationic catalyst. These copolymers of I or II with AN will be expected to be new types of reactive polymers.
Inverse emulsions in a molten salt/hydroxy‐terminated polybutadiene system using block copolymers as emulsifiers
Authors: Litt M. H. , Lin C. S. , Krieger I. M. 
Published: April 2003

AbstractBlock copolymers of poly(N‐t‐butylbenzoyl ethylenimine) and poly(N‐propionyl ethylenimine) (Bx/Ey and Bx/Ey/Bx) or poly (N‐lauroyl ethylenimine) and poly (N‐propionyl ethylenimine) (Ux/Ey) were synthesized by cationic ring‐opening polymerization of 2‐substituted δ2‐oxazolines. Inverse emulsions (salt‐in‐oil) were made using these block copolymers as emulsifiers, hydroxy‐terminated polybutadiene (HTPB) as the nonpolar phase and methyl ammonium ethane sulfonate (MAES) as the polar phase. These inverse emulsions (S/O) were then cured using a triisocyanate to give a dispersion of molten salt (MAES) droplets in polyurethane. Pore sizes of these cured inverse emulsions were measured from scanning electron photomicrographs as a function of stirring time and concentrations of block copolymer and molten salt. The results indicate that pores with diameters in the range of 1.5 X 10−6 m can be obtained using triblock copolymer Bx/Ey/Bx, and that the surfactant molecules can be spread as a monolayer at the MAES‐HTPB interface.
The effect of direct interchange reactions on the MWD of condensation polymers
Authors: Lertola James G. 
Published: April 2003

AbstractIn this theoretical study, a relationship has been developed for the transient molecular‐weight distribution (MWD) of a condensation polymer undergoing a direct interchange reaction. Direct interchange is one of several reactions which can take place in condensation polymers in the melt. When compared to the more well‐known reactions of polycondensation, degradation, and interchange of an end‐group with a condensation linkage, direct interchange has a more complex statistical effect on the MWD and is less commonly observed. However, these types of reactions can be quite important in some polymeric systems, such as in the reaction of poly (butylene terephthalate) with polycarbonate. The MWD relationship was developed from the species balance: The rate of accumulation of chains of a given molecular weight is equal to their rate of generation minus their rate of consumption. For this reaction, development of the generation term is quite complex; it is approached here by describing five probability situations which are determined by each possible combination of reactant and product chains. Example distributions computed from these equations show that different transient paths are followed under direct and end‐group interchange, but that both reactions lead to the equilibrium most‐probable distribution.
Synthesis and properties of polyetheretherketone–polydimethylsiloxane block copolymers
Authors: Corfield G. C. , Wheatley G. W. , Parker D. G. 
Published: April 2003

AbstractPolyetheretherketone‐polydimethylsiloxane (PEEK–PDMS) block copolymers were synthesized from the condensation of dimethylamino terminated PDMS and hydroxy terminated PEEK oligomers in 1‐chloronapthalene. Yields for block copolymers synthesised from low molecular weight PDMS oligomers were good but yields were significantly reduced when higher molecular weight PDMS oligomers were used. This was related to the limited solubility of higher molecular weight PDMS in the reaction solvent. Differential scanning calorimetry (DSC) studies indicated that phase separation of the block copolymers occurred at very short segment length (M̄n < 4000). A depression in the crystallinity of both the PEEK and PDMS phases in the block copolymer was observed. Thermogravimetric analysis (TGA) studies indicated that the PEEK–PDMS block copolymers displayed insufficient thermo‐oxidative stability to be melt‐processed successfully in PEEK based blends.
Silyl enol ethers as monomer. III. Radical polymerization and copolymerizations of 2‐trimethylsilyloxy‐1,3‐butadiene and desilylation of the resulting polymers
Authors: Nagai Katsutoshi , Asada Keisuke , Kuramoto Noriyuki 
Published: April 2003

Abstract2‐Trimethylsilyloxy‐1,3‐butadiene (TMSBD), the silyl enol ether of methyl vinyl ketone, was homopolymerized with a radical initiator to afford polymers with a molecular weight of ca. 104. Radical copolymerizations of TMSBD with styrene (ST) and acrylonitrile (AN) in bulk or dioxane at 60°C gave the following monomer reactivity ratios: r1 = 0.64 and r2 = 1.20 for the ST (M1)–TMSBD (M2) system and r1 = 0.036 and r2 = 0.065 for the AN (M1)–TMSBD (M2) system. The Q and e values of TMSBD determined from the reactivity ratios for the former copolymerization system were 2.34 and −1.31, respectively. The resulting polymer and copolymers were readily desilylated with hydrochloric acid or tetrabutylammonium fluoride as catalyst to yield analogous polymers having carbonyl groups in the polymer chains.
Emulsion polymerization: Determination of the average number of free radicals per particle by use of the number average volume of the particles
Authors: Chen Show‐An , Wu Kuo‐Wei 
Published: April 2003

AbstractFor emulsion polymerization in the zero order region (Interval II) a relation between the average number of free radicals per particle, n̄(t), and the particle number average volume of a particle, v̄n(t), is derived as dv̄n(t)/dt = Kn̄(t), where K is volume growth rate of a particle containing one free radical and is constant. This relation is also extended to copolymerization systems with an appropriate modification of the definition of K. By use of the data of particle size distribution (PSD), n̄ can be calculated without knowing the total number of particles. In conjunction with this relation, the recently developed light‐scattering technique for measuring the PSD in addition to the conventional transmission electron microscope technique can provide a quick route for determination of n̄. Styrene and methyl methacrylate emulsion homopolymerizations are taken as calculation examples.
Halomethylated polysulfone: Reactive intermediates to neutral and ionic film‐forming polymers
Authors: Warshawsky A. , Kahana N. , Deshe A. , Gottlieb H. E. , Arad‐Yellin R. 
Published: April 2003

AbstractHalomethylation of polysulfone (PS) with C8H17OCH2X (X = Cl, Br) in the presence of SnX4 (X = Cl, Br) led to PS–CH2X (X = Cl or Br or both) (Scheme 1). Under controlled conditions, PS–CH2X could be isolated and retains the good film forming properties of PS itself. Interhalogen exchange reactions occur in the presence of SnX4 (X = Cl, Br) under anhydrous conditions (Scheme 1), or a quaternary ammonium phase transfer catalyst R*R3N+X−, under aqueous conditions (Scheme 2). The exchange reactions with R*R3N+X−, are favored when R = C8C10, and with R = C4 only if n‐octanol is added; otherwise gelation occurs. Exchange in CHCl3 is attributed to dehydrohalogenation (and generation of dichlorocarbene) of the solvent in the presence of tetrabutyl ammonium hydroxide. Further chemical modifications of PS–CH2X by reaction with strong nucleophiles, led to hydroxymethyl polysulfone, acetoxymethyl polysulfone, and t‐butyl‐oxymethyl polysulfone (Scheme 3). Hydroxymethyl polysulfone sometimes gels under basic hydrolytic conditions and is best obtained by methanolysis of PS–CH2‐OAc. Both PSCH2OAc and PSCH2O‐t‐Bu are very stable, and provide a way to generate PSCH2Br on need by cleavage with HBr in acetic acid.Direct oxidations with DMSO or tetrabutyl ammonium dichromate (Scheme 4) or indirect oxidations (Scheme 5) produce polysulfone with pendent CHO, CO2R and PO3R groups. Finally, polysulfones with linker arms including, carboxy alkyl, hexaglycol or sulfonamido crowns are described (Scheme 6). The reaction products were characterized by 1H‐ and 13C‐NMR. Double irradiation experiments, proved unequivocally, that the first substitution occurred on the B ring of the bisphenol A moiety (see Table I); the second substitution occurs on the A ring in position a. Thermogravimetric analysis generally shows for all modified polysulfones an extra transition at a lower temperature. The area of this band agrees generally with the values expected from calculated substitution degrees.
Metallocene–methyl aluminoxane catalysts for olefin polymerization. VIII. Infrared spectra of anisotactic polypropylene
Authors: Chien James C. W. , Rieger Bernhard , Herzog H. Martin 
Published: April 2003

AbstractPolypropylenes obtained with the homogeneous racemic ethylene bis(indenyl) zirconium dichloride/methyl‐aluminoxane catalyst were fractionated by solvent extraction. The IR absorbance ratios, A998/A973 and A841/A973, were found to vary linearly with the homosteric sequence population, [m m m m] and [m m]. These results are compared with the results of a similar study by Burfield and Loi on commercial and laboratory polypropylenes of the conventional types.
Water‐Soluble imide‐amide copolymers. I. Preparation and characterization of poly [acrylamide‐co‐sodium N‐(4‐sulfophenyl) maleimide]
Authors: Hocking Martin B. , Syme David T. , Axelson David E. , Michaelian Kirk H. 
Published: April 2003

AbstractSodium N‐(4‐sulfophenyl) maleimide (SPMI) and its saturated succinimide counterpart were first prepared according to established methods. Hydrolysis experiments on these monomers monitored by 1H‐NMR showed that although SPMI monomer was about 15% hydrolyzed in D2O at 23°C in 24 h. Sodium N‐(4‐sulfophenyl) succinimide, which is similar in structure to the imide units in the copolymers, was only 1% hydrolyzed after 18 days at 23°C and 29% hydrolyzed after 18 days at 60°C. This indicated that the saturated imide rings in the copolymer might be sufficiently stable to hydrolysis for the copolymers to be useful. However, hydrolysis at high pH demonstrated that the imide rings would be rapidly saponified under alkaline conditions, destroying the structural rigidity that the intact rings might have provided in the copolymer chains. Sodium N‐(4‐sulfophenyl) maleimide (SPMI) was copolymerized with acrylamide in water at 30°C without cleavage of the imide ring. Water‐soluble poly [acrylamide‐co‐sodium‐N‐(4‐sulfophenyl) maleimide] (PAMSM) samples containing from 7.4 to 64 mol % imide were prepared. Photoacoustic FTIR and 13C‐NMR spectra were used to confirm the structure of the copolymers obtained. Elemental analysis was used to determine the imide content of the copolymers, and from this composition data reactivity ratios were calculated for the two component monomers.
Water‐Soluble imide‐amide copolymers. III. Preparation and characterization of poly (acrylamide‐co‐N,N‐diallylaniline) and poly (acrylamide‐co‐sodium N,N‐diallylsulfanilate)
Authors: Hocking Martin B. , Syme David T. , Axelson David E. , Michaelian Kirk H. 
Published: April 2003

AbstractN,N‐diallylaniline monomer was prepared in good yields, for use in preparation of homopolymer and for copolymerization with acrylamide. Functionalized N,N‐diallylaniline monomer, as sodium N,N‐diallylsulfanilate, was also prepared in good yields for copolymerization with acrylamide. Both monomers were fully characterized by elemental analysis, IR, and NMR. Poly (N,N‐diallylaniline) was obtained by polymerization of a strongly acidic aqueous solution of N,N‐diallylaniline initiated with hydrogen peroxide. Spectroscopic data from this homopolymer was used to facilitate spectral assignments of the new copolymers. Copolymers of acrylamide with N,N‐diallylamine were prepared at monomer feed ratios of 10, 20, and 30 mol % amine and gave 3.5, 7.4, and 8.9 mol % incorporation, respectively. Similar diallyl monomer incorporation rates were obtained for the copolymerization of sodium N,N‐diallylsulfanilate with acrylamide. With 10, 30, and 50 mol % of the sodium salt relative to acrylamide, 3.9, 8.4, and 19.2 mol % incorporation of the diallyl monomer was obtained.
Phase transfer Pd(0) catalyzed polymerization reactions. III. Polymerization by cross‐coupling of alkyl–boron compounds and aromatic halides catalyzed by PdCl2 (dppf) and bases
Authors: Cramer Edwin , Percec Virgil 
Published: April 2003

AbstractThis paper describes a novel polymerization reaction which consists of a sequence of hydroboration of a diolefin with 9‐borabicyclo[3.3.1]nonane (9‐BBN) followed by the intermolecular cross‐coupling of the resulting 1,1′‐bis(B‐alkanediyl‐9‐borabicyclo[3.3.1]nonanes with dihaloarenes. The reaction is performed in the presence of dichloro[1,1′‐bis(diphenylphosphino)ferrocene] palladium (II) [PdCl2 (dppf)], a base, and a phase transfer catalyst. Both steps are performed in the same reaction flask. Alternatively, this polymerization reaction can be applied to bifunctional monomers containing an olefin and a haloarene group, for example, p‐bromostyrene.
Synthesis of poly(ethylene terephthalate) in the presence of perfluoropolyethers. II. Effect of various catalysts
Authors: Pilati F. , Manaresi P. , Toselli M. , Re A. 
Published: April 2003

AbstractDimethylterephthalate and ethylene glycol have been polymerized to poly (ethylene terephthalate) (PETP) in the presence of perfluoropolyethers (PFPE) using various catalysts. The polymerizations were carried out at high temperature by the usual two‐stage method and the effect of the fluorinated compounds on the polymerization rate was investigated. Selective extractions were performed to estimated the fraction of PFPE bonded to PETP. In the presence of Fomblin ZDEAL®, a telechelic PFPE macromer bearing methyl ester end groups, the polymerization can only be carried out when the fluorinated macromer is added after the first stage is complete, because of the strong decrease of the transesterification rate with all the catalysts used. Polymerizations were therefore performed by adding Fomblin ZDEAL (10% wt) at the end of the first stage; about 30% of the amount of PFPE in the final products was found to be bonded to PETP for all the catalysts employed. In the presence of Fomblin Z/15®, a PFPE which has not functional end groups, the reaction rate is not decreased in the first stage, however, under the same reaction conditions, the intrinsic viscosity of final PETP is greatly reduced and the amount of PFPE in the resulting material is well below that initially added and is almost completely extractable meaning that a very limited fraction of PFPE is bonded to PETP.
Polymerization in nonuniform latex particles. II. Kinetics of two‐phase emulsion polymerization
Authors: Chern Chorng‐Shyan , Poehlein Gary W. 
Published: April 2003

AbstractA new theory, based on the concept of nonuniform distribution of free radicals in polymerizing latex particles, has been developed for the kinetics of two‐phase emulsion polymerization reactions. This theory also takes into account the diffusion controlled termination and propagation reactions to describe the gel effect and limiting conversion. The kinetic model permits prediction of the distribution of free radicals in the two polymer phases and rate of polymerization as a function of reaction conditions. Experimental data for polystyrene/polymethyl methacrylate and polymethyl methacrylate/polystyrene (postformed polymer/preformed polymer) in the literature have been used to assess the proposed idea of nonuniform distribution of free radicals in the latex particle.
Polymerization in nonuniform latex particles. III. Kinetics of grafting in emulsion polymerization
Authors: Chern Chorng‐Shyan , Poehlein Gary W. 
Published: April 2003

AbstractThe concept of nonuniform distribution of free radicals in polymerizing latex particles has been incorporated into the development of a kinetic model for grafting reactions. This theory permits prediction of grafting efficiency as a function of reaction conditions. It can also be used for evaluation of rate constants for grafting reactions. Experimental data for emulsion polymerization of styrene in the presence of polybutadiene seed latex have been used to assess the proposed grafting theory. The predominant grafting reaction appears to be the attack of growing polystyrene chains on the allyl hydrogen atoms of polybutadiene. The results further reinforce the hypothesis that the entering oligomeric free radicals do not distribute uniformly within the particle volume.
Characterization of a thermally imidized soluble polyimide film
Authors: Young Philip R. , Davis Judith R. J. , Chang A. C. , Richardson John N. 
Published: April 2003

AbstractA soluble aromatic poly (amic acid) film was converted to a soluble polyimide by staging at 25°C intervals to 325°C and characterized at each interval by several analytical methods. The behavior observed was consistent with an interpretation that a reduction occurred in molecular weight of the poly (amic acid) during the initial stages of cure before the ultimate molecular weight was achieved as a polyimide. This interpretation was supported by the results of solution viscosity, gel permeation chromatography, low angle laser light scattering photometry, and infrared spectroscopy analyses. The results of this study serve to increase our fundamental understanding of how polyimides are thermally formed from poly (amic acid)s.
Polymerization of methyl methacrylate with cupric laurate‐N,N‐dimethyl formamide as initiator system
Authors: Pal Prabir Kumar , Chaudhuri Ajit Kumar 
Published: April 2003

AbstractThe polymerization of methyl methacrylate with cupric laurate in combination with N,N‐dimethyl formamide as initiator was studied in carbon tetrachloride medium at 60°C. The rate of polymerization was found to be proportional to the 3/2th power of the monomer concentrations and to the square root of both cupric laurate and DMF concentrations. Spectroscopic investigations indicated a ternary complex formation involving cupric ion, methyl methacrylate, and DMF. A reaction scheme is suggested on the basis of these results and various kinetic constants have been evaluated.