bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of degree of phosphorylation on intrinsic and thermal properties of poly(styrenephosphonate diethyl ester)s
Authors: Sun Jing , Cabasso Israel
Published: April 2003

The intrinsic and thermal characteristics of poly(styrenephosphonate diethyl ester)s (PSP) are described. The properties of the polymer prepared by two synthetic procedures, phosphorylation of monodispersed polystyrene and polymerization of vinylbenzenephosphonate ester, are compared with chloromethylated polystyrene and with each other. Empirical formulas are presented for the relationships between the degree of polymerization, degree of phosphorylation, molecular weight, and intrinsic viscosity (in methanol and toluene). Thermal analysis reveals a sharp drop in Tg with an increase in degree of phosphorylation; Tg of the fully phosphorylated polystyrene is in the range of 9–30°C. The Tg ΔCp values show significant decrease with augmentation in the degree of phosphorylation, yielding a value of 14 cal g−1 for the fully phosphorylated polymer, compared with ∼ 29 cal g−1 for the parent polymer. The PSP is shown to have substantial capacity for dissolving heavy metal salts, such as UO2(NO3)2, causing significant elevation in the Tg.
Synthesis and characterization of poly(t‐butyl methacrylate‐b‐isoprene‐b‐t‐butyl methacrylate) block copolymers by anionic techniques
Authors: Long T. E. , Broske A. D. , Bradley D. J. , McGrath J. E.
Published: April 2003

Poly(t‐butyl methacrylate‐b‐isoprene‐b‐t‐butyl methacrylate) block copolymers have been synthesized in a controlled manner by anionic techniques. The block copolymers demonstrated predictable chemical composition and stereochemistry, and narrow molecular weight distributions. The addition of a polar solvent was required after complete conversion of the diene block in order to preserve the high 1,4 microstructure of the diene phase and to facilitate the efficient crossover to the poly(t‐butyl methacrylate) lithium enolate. Thermomechanical analysis (TMA) of the triblock copolymers demonstrated a microphase separated morphology. The glass transition temperatures of the diene phase and acrylic phase were approximately −70 and 120°C, respectively. Cast films of the block copolymers from polar and nonpolar solvents were optically clear and elastic.
The interaction of hydrogen and ammonia plasmas with polymethacrylic esters, studied by static secondary ions mass spectrometry
Authors: Lub J. , Van Vroonhoven F. C. B. M. , Benninghoven A.
Published: April 2003

The interactions of H2 and NH3 plasmas with the surfaces of various poly(alkylmethacrylate)s and of poly(phenylmethacrylate) have been studied with XPS and SSIMS. Experiments on poly(methylmethacrylate) reveal that during short treatment times with the NH3 plasma chain, scission takes place and nitrogen is not incorporated into the surface. The chain scission also takes place with the H2 plasma. With the aid of SSIMS results, the nature of the chain scission could be deduced. Comparison of these results with those on poly(n‐butylmethacrylate) and poly(t‐butylmethacrylate) reveals a reaction mechanism in which hydrogen atoms generated in both plasmas play an important role in the chain scission process. After longer treatment time with the NH3 plasma, the poly(methylmethacrylate) surface becomes deoxygenated and nitrogen is incorporated into surface structures of low molecular weight. Experiments on poly(phenylmethacrylate) reveal that already during short treatment times with the NH3 plasma, nitrogen is incorporated into the aromatic ring. Chain scission does not play an important role. One of the processes with the H2 plasma is hydrogenation of the aromatic ring, leading to poly(cyclohexylmethacrylate).
Syntheses and properties of polysulfides containing spiroorthocarbonate moiety
Authors: Tagoshi Hirotaka , Endo Takeshi
Published: April 2003

Polysulfides (PI and PII) having spiroorthocarbonate moiety in the main chain were synthesized by the polyaddition of unsaturated spiroorthocarbonate (1 or 2) and dithiols in excellent yields. It is confirmed by DSC and x‐ray measurement that PII is the crystalline polymer. PI and PII were treated with a cationic catalyst such as BF3 · OEt2 and BzS+SbF to afford the crosslinked polymer and to partially undertake the main chain scission. Further, it was also found in the reaction of PI and PII with adipoyl chloride as the crosslinking reagent that PI underwent cleavage of the main chain, but PII mainly gave crosslinked polymers.
A new differential scanning calorimetry based approach for the characterization of peracid resin
Authors: Hsiue Ging‐Ho , Huang Wen‐Kuei , Chu Hsiao‐Lung
Published: April 2003

Differential scanning calorimetry was used to trace the heat of decomposition of the peracid groups (ΔHd) in the oxidized EVA‐g‐AA resin. From the correlation between ΔHd and the oxidation capacity measured by iodometry, it was found that 35 ± 5 cal of energy evolved per miliequivalent of peracid group decomposed. The ΔHd values are also useful in finding the optimum condition for oxidation of acid groups and can be used to investigate the distribution of active peracid groups across the matrix. The stability and the activation energy of decomposition of grafted type peracid resin were also studied, where the activation energy of decomposition was calculated to be 13.4 kcal/mol.
Emulsifier‐free emulsion copolymerization of styrene and butyl acrylate. I. Kinetic studies in the absence of surfactant
Authors: Guillaume J. L. , Pichot C. , Guillot J.
Published: April 2003

Soapless emulsion copolymerization of styrene (S) and n‐butyl acrylate (BuA) has been investigated using two types of initiator and different comonomer feed mixtures. When using K2S2O8 as initiator, the particle size and size distribution of the final latexes (500 nm and 1.003, respectively) is not significantly affected by the comonomer feed composition, whereas the molecular weight and surface characteristics were found to sharply change at high butyl acrylate content. Based on the most probable particle nucleation mechanism and type of chain termination in the monomer swollen particles, a tentative explanation of these results has been proposed. Replacing persulfate by a carboxylic initiator (4‐4′‐azobiscyanopentanoic acid) results in the formation of stable particles as α observed with the persulfate, provided the aqueous phase pH is fixed in between 6 and 7. Results on the initiator residue location as a function of the conversion point out that the particle flocculation mechanism is strongly significant in the preparation of such latexes.
Head‐to‐head vinyl chloride–vinyl acetate copolymer
Authors: Tarshiani Y. , Dreyfuss M. P.
Published: April 2003

Addition chlorination of cis‐1,4‐polybutadiene in the presence of acetic acid as a cosolvent resulted in the formation of head‐to‐head vinyl chloride–vinyl acetate copolymer. Chlorine analysis, IR, and NMR spectra of the chlorinated polybutadiene indicated that reaction was primarily double bond addition; there was little evidence for substitutive chlorination. Acetate was incorporated by nucleophilic participation of the acetic acid cosolvent. The extent of incorporation of the acetate group in the polymer chain was a function of the acetic acid concentration. Both the glass transition temperatures and the densities of the chloroacetylated polymers decreased as the degree of acetylation increased.
Preparation and properties of aromatic polyamides and aromatic polyesters derived from 4,4′‐sulfonyldibenzoic acid
Authors: Manami Hiroshi , Nakazawa Mikio , Oishi Yoshiyuki , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

Aromatic polyamides (aramids) having inherent viscosities of 0.3–1.6 dL/g were prepared by the direct polycondensation of 4,4′‐sulfonyldibenzoic acid with various aromatic diamines using triphenyl phosphite and pyridine as condensing agents. Aromatic polyesters (polyarylates) with inherent viscosities of 0.3–1.2 dL/g were prepared by the phase‐transfer catalyzed, two‐phase polycondensation of 4,4′‐sulfonyldibenzoyl chloride with various bisphenols. Most of the aramids and some polyarylates were soluble in a variety of solvents such as dimethylacetamide, N‐methyl‐2‐pyrrolidone, and m‐cresol, and afforded transparent, flexible, and tough films from the polymer solutions. The aramids and the polyarylates had glass transition temperatures in the range of 200–350 and 260–310°C, respectively. These polymers containing sulfonyl group did not lose weight below 350°C, with 10% weight loss being recorded above 430°C in air.
Synthesis of the acetylacetone telechelate of polydimethylsiloxane and its gelation with Cr(III) and Fe(III)
Authors: Liao I‐Wei , Eichinger B. E.
Published: April 2003

The batch synthesis of acetylacetone end‐capped polydimethylsiloxane is described. Efforts to end‐link the telechelic polymer with several simple metal salts yielded poorly gelled systems, except for the cases where FeCl3 and CrCl3 · 3THF were used. With these salts, low but nonetheless appreciable, gel fractions of 45 and 40%, respectively, were obtained. The difficulty experienced in obtaining high gel fractions is traced to incomplete ligand exchange reactions in low polarity media.
Preparation and photochemical properties of poly[2‐(4‐benzoylphenyl)‐2‐(4‐propenoylphenyl)‐propane] and its copolymer with styrene
Authors: Lukáč Ivan , Evans Christopher H. , Scaiano J. C. , Hrdlovič Pavol
Published: April 2003

2‐(4‐Benzoylphenyl)‐2‐phenyl propane (4) was prepared by benzoylation of 2,2‐diphenylpropane (2). Acylation of (4) with 3‐chloropropanoic chloride gave 2‐(4‐benzoylphenyl)‐2‐(4‐propenoylphenyl)propane (5). A monomer 2‐(4‐benzoylphenyl)‐2‐(4‐propenoylphenyl)propane (6) was prepared through dehydrochlorination of (5). The homopolymer of 6 (P6) and the copolymer with styrene (P6 / S) were prepared by radical polymerization. Laser flash photolysis was employed to determine the absorption and emission spectra of transients, their lifetimes (τ) and the rate constant (kq) of triplet quenching in benzene at laboratory temperature for 4, P6, and P6 / S. P6 exhibits a transient absorption maximum in a different spectral region than do the model 4 and copolymer P6/S. The products of kq and τ determined by laser flash photolysis for these transients are higher than th Stern–Volmer constants based on inhibition of degradation. Degradation leading to formation of quenchers is the likely cause of this difference although crosslinking may also contribute. Irradiation of polymers (P6 and P6/S) at 366 nm leads to main chain scission with aquantum yield of 0.13 under N2 for P6 and 0.03 for P6/S. In this bichromophoric structural unit, the benzophenone residue absorbs about 80–90% of the incident energy. Its triplet energy is about 5 kJ mol−1 lower than that of the 1‐(4‐alkylphenyl)‐2‐propene‐1‐one chromophore. Different possible pathways of degradation are discussed namely the Norrish Type II reaction of the alkyl aryl ketone and direct reaction of triplet benzophenone with the main chain. In the mechanism favored the benzophenone triplet is proposed to be in equilibrium with the upper acetophenone‐like chromophore from which the Norrish Type II reaction leading to chain fragmentation takes place.
Thermotropic liquid crystalline poly(L‐glutamate) esters with long alkyl chain containing aromatic segment at terminal position
Authors: Hanabusa Kenji , Yanagisawa Kuniko , Higashi Jun‐Ichi , Shirai Hirofusa , Hayakawa Tadao , Hojo Nobumasa
Published: April 2003

Poly(L‐glutamate) esters (3a–3d) with long alkyl side chains containing a mesogenic aromatic segment at the terminal position were synthesized. The superstructure of these polypeptides in solution and film were found to hold a α‐helical conformation which was confirmed by CD, IR, and dichroic IR spectroscopy. The thermotropic liquid crystalline behavior was investigated by DSC, x‐ray diffraction, and polarizing microscopy with hot stage. Polymers 3a and 3b, having transesterification over 60%, were assumed at least to have two liquid crystalline states. Polymer 3c‐H‐95 exhibited one crystalline state and two liquid crystalline states; however, 3d‐H‐97 did not show distinct liquid crystalline states.
Preparation and properties of brominated poly(arylcarboxylate)s via interfacial polycondensation
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei
Published: April 2003

The interfacial polycondensation method has been used for the preparation of brominated poly(arylcarboxylate)s. Brominated poly(arylcarboxylate)s can be prepared easily by mixing a solution of diacid chloride in a water‐immiscible organic solvent with an aqueous alkaline solution of bisphenol in the presence of catalyst such as quaternary ammonium salts. First, in a dichloromethane‐water system using triethylbenzylammonium chloride (TEBAC) as the catalyst a series of 2,2‐bis(4‐hydroxy‐3,5‐dibromophenyl)propane (3,3′,5,5′‐tetrabromobisphenol A, TBBPA) with isophthaloyl (I) and terephthaloyl chlorides (T) has been prepared and some properties as inherent viscosity, solubility, crystallinity, and flammability have been measured. Copolymers prepared from TBBPA and mixed T/I with 33/67–67/33 molar ratios show good solubility and amorphous nature, and can be cast into transparent and tough films with limiting oxygen index of 58–59 (ANSI/ASTM D2683‐77). Second, the effects of some variables as the nature of organic phase and catalysts, concentration of reactants, and basicity of aqueous phase on the interfacial polycondensation of TBBPA with equal parts of T and I [T/I (50/50)] was investigated in some detail. Among the solvents tested dichloromethane was found to be the best solvent and quaternary ammonium salts such as TEBAC and tetra‐n‐butylammonium bromide (TBAB) were highly efficient catalysts. Poly(arylcarboxylate)s with the highest molecular weights were obtained at an acid chloride concentration of 0.2 mol/L in dichloromethane and a concentration of TBBPA of 0.1 mol/L in alkali when TEBAC was used as catalyst. A maximum of inherent viscosity was obtained at two equivalent amounts of alkali corresponding to bisphenol. Polycondensation of several combinations of T/I (50/50) with some other tetrabromobisphenols, such as 3,3′,5,5′‐tetrabromo‐4,4′‐biphenol, 3,3′,5,5′‐tetrabromobisphenol S, 3,3′,5,5′‐tetrabromo‐4,4′‐thiodiphenol, and 3,3′,5,5′‐tetrabromophenolphthalein, were carried out with limited success. Whereas, a more favorable result could be obtained by the mixed copolycondensation of these tetrabromobisphenols and bisphenol A (BPA) with T/I (50/50). Finally, the copoly(arylcarboxylate)s from TBBPA, BPA, T, and I were prepared and characterized. The incorporation of bromine on the polymer backbone caused a decrease of inherent viscosity, glass transition temperature, crystallinity, and thermal stability of copolyarylates, whereas it caused a great enhancement of flame retardancy.
The synthesis and XPS characterization of iodine containing plasma polymers
Authors: Munro Hugh S. , Ward Richard J. , Khor Eugene
Published: April 2003

Plasma polymers derived from iodobenzene and four copolymers with benzene of varying monomer ratios have been synthesized. Samples were analyzed for qualitative and quantitative information using x‐ray photoelectron spectroscopy. The optimum conditions whereby a higher iodine content is obtained in the plasma polymer have been achieved. The results indicate that the use of a copolymerization approach is better. These plasma polymers were subsequently exposed to an oxygen plasma and it was found that oxidation and etching of the surfaces of the plasma polymers does occur. The extent of iodine loss via oxygen plasma etching appears dependent on the character of the plasma polymer.
The influence of total monomers concentration and polymerization solvent on the “reactivity” of ω‐(p‐vinylbenzyl ether) macromonomers of poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Percec Virgil , Wang James H.
Published: April 2003

The influence of the total monomers concentration and of the copolymerization solvent on the reactivity ratio, r1, of methyl methacrylate (MMA) (M1) ω‐(p‐vinylbenzyl ether) macromonomer of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO–VBE) (M2) monomer pair was investigated. For two different molecular weights of PPO‐VBE macromonomers: Mn = 15,200 and Mn = 5,100, the determined reactivity ratio, r1, decreases with the increase in macromonomer concentration. Therefore the reactivity of the macromonomer, 1/r1, follows the opposite trend. The influence of monomers concentration on r1 is higher for higher molecular weight macromonomers. The nature of polymerization solvent also affects the value of reactivity ratio, r1. Micelle formation was demonstrated by 1H‐NMR spectroscopy performed on the resulting graft copolymers in different solvent mixtures. An attempt to explain the observed concentration and solvent effects based on the partition of comonomer concentrations between the bulk of solvent and around the growing chain is presented. Based on this explanation, the determined r1 represents a product of the partition coefficient, k, and the true reactivity ratio, r10.
Amphiphilic block copolymers of vinyl ethers by living cationic polymerization. II. Synthesis and surface activity of macromolecular amphiphiles with pendant amino groups
Authors: Kanaoka Shokyoku , Minoda Masahiko , Sawamoto Mitsuo , Higashimura Toshinobu
Published: April 2003

Amphiphilic block polymers of vinyl ethers (VEs).

\documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} [{\rm CH}_{\rm 2} {\rm CH}\left( {{\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm NH}_{\rm 2} } \right)\rlap{--} ]_m \rlap{--} [{\rm CH}_{\rm 2} {\rm CH}\left( {{\rm OR}} \right)\rlap{--} ]_n \left( {{\rm R: }n{\rm - C}_{{\rm 16}} {\rm H}_{{\rm 33}} ,{\rm }n{\rm - C}_{\rm 4} {\rm H}_{\rm 9} ;m \simeq 40,{\rm n} = 1 - 10} \right)$\end{document} were prepared, each of which consists of a hydrophilic segment with pendant primary amino groups and a hydrophobic poly(alkyl VE) segment. Their precursors were obtained by the HI/I2‐initiated sequential living cationic polymerization of an alkyl VE and a VE with a phthalimide pendant (CH2 = CHOCH2CH2Im; Im; phthalimide group), where the segment molecular weights and compositions (m/n ratio) could be controlled by regulating the feed ratio of two monomers and the concentration of hydrogen iodide. Hydrazinolysis of the imide functions gave the target polymers which were readily soluble in water under neutral conditions at room temperature. These amphiphilic block polymers lowered the surface tension of their aqueous solutions (0.1 wt%, 25°C) to a minimum ≃ 30 dyn/cm when the hydrophobic pendant R was n‐C4H9 (n = 4–9). The polymers with n‐C4H9 pendants in the hydrophobic segment exhibited a higher surface activity than those with n‐C16 H33 pendants. The surface activity of the polymers also depended on the pH of the polymer solutions; the surface activity increased in more basic solutions where the ionization of the amino group (NH2)2NH3⊕) is suppressed.
Catalytic hydrogenation activity of zerovalent palladium dispersed in functional porous polystyrene matrices
Authors: Bar‐Sela G. , Warshawsky A.
Published: April 2003

Zerovalent palladium catalysts, dispersed within functional, porous, crosslinked styrene‐divinylbenzene copolymers were prepared by impregnation of lipophylic [(C8H17)2NH+][PdCl4 = ] complexes followed by reduction with hydrazine or formaldehyde. A qualitative survey of the catalytic reactivity in hydrogenation of various alkenes differing in substitution degrees (styrene, +‐methylstyrene, etc.), and competitive reduction of exo/endo bonds (4‐vinylcyclohexene) was performed. The functional groups in the polymer, 2,4‐dinitrophenyl, aminomethyl, methoxybenzyl, dialkylaminomethyl, and pseudocrown were shown to have a major effect on catalyst activity. In the two series of polymeric supports, the polymeric adsorbents (Amberlites XAD‐2, XAD‐4, and XAD‐7) and functionalized Amberlite XE‐305, the general trend indicated preference of Pd0 catalysts dispersed on hydrophobic π‐acceptor type supports over hydrophobic supports, over polar basic or hydrophilic supports. This is generally true for both non‐polar (e.g., styrene) and polar (e.g., allylacrylate) olefins. The most active catalysts, carrying 2,4‐dinitro phenyl groups, also showed higher selectivity in reduction of the exo over endo double bond in 4‐vinylcyclohexene, in comparison to commercial Pd/C catalyst. Electron microscopy (SEM) showed very little change in the inner porous polymer structure and almost homogeneous metal distribution profiles. TEM provided particle sizes. The activity of the catalyst was 8‐fold higher with the smallest crushed particles (0.05–0.12 μm) than with the large (600 μm) noncrushed beads. The catalyst showed exceptional stability on storage (98% activity after 1 year) and marginal loss of activity after 21,000 catalytic cycles per Pd atom.
Triphase catalysis. I. Kinetics and mechanism of alkylation of phenylacetonitrile with alkyl halides catalyzed by aqueous naoh and polymer‐supported benzyltriethylammonium chloride
Authors: Balakrishnan T. , Babu S. Hari , Perumal A.
Published: April 2003

The alkylation and cycloalkylation of phenylacetonitrile (PAN) with excess of 1‐bromobutane and 1,4‐dibromobutane respectively catalyzed by aqueous NaOH and insoluble polystyrene‐bound benzyltriethylammonium chloride were studied and the rates depend upon several experimental parameters. The rate of cycloalkylation of PAN is five times faster than the alkylation and the former proceeds even in the absence of the solid catalyst. Both alkylation and cycloalkylation gave higher rates in reverse addition method than in direct addition. Deprotonation of PAN by hydroxide ion takes place without participation of the polymeric catalyst. The electrostatic force between the positive charge on the nitrogen atom of catalyst and carbanion is responsible for alkylation of active nitrile with polystyrene‐bound phase‐transfer catalyst. The rates of both the reactions increase with increased stirring speed, ring substitution, hydroxide ion concentration and catalyst amount and decrease with increased particle size and the degree of cross‐linking of the polymer. Apparent activation energies for the reactions were calculated. The kinetic results are discussed in terms of mass transfer and a combination of intraparticle diffusion and intrinsic reactivity limitations of the rates.
Thermal decomposition and carbonization mechanism of poly‐para‐phenyleneoxadiazole
Authors: Murakami M. , Yumoto Y. , Mizogami S. , Yasujima H. , Naitoh S. , Yoshimura S.
Published: April 2003

Thermal decomposition and carbonization mechanism of poly‐para‐phenylene‐1,3,4‐oxadiazole were investigated using FT‐IR, thermogravimetry, gas‐analysis, XPS, 13C‐CP/MASFT‐NMR, and elemental analysis. At temperatures above 500°C, the decomposition reaction proceeds preferentially on the oxadiazole ring, eliminating p‐aminocyanobenzene and p‐dicyanobenzene. Formation of carbodiimide compounds and their coupling followed in residual compounds, whose products are important intermediates leading to a planar and polyconjugated nitrogen‐containing (e.g., graphite‐like) carbon precursor.
Activation energy for urethane‐linkage formation. An improved calculation from the differential scanning calorimetry data
Authors: Hernández‐Sánchez F. , Vázquez‐Torres H.
Published: April 2003

Differential scanning calorimetry (DSC) has been utilized in several studies on polymerization kinetics, at different heating rates. However, there are several factors affecting the precision of kinetic parameters. In this work, the activation energy of urethane‐bond formation between 2,6‐tolylene diisocyanate and diethylene glycol is reported, the latter being in excess in order to minimize problems such as thermal transitions and incomplete reaction in the final step. The DSC technique was applied at different heating rates. Both the equal conversion and equal conversion rate options of the method are discussed. The latter appears to be a more adequate option for the system studied here. The results obtained show a good agreement with the model used.
Improved synthesis of polystyrene–poly(ethylene oxide)‐heparin block copolymers
Authors: Vulić I. , Loman A. J. B. , Feijen J. , Okano T. , Kim S. W.
Published: April 2003

A novel procedure for the synthesis of block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic block of poly(ethylene oxide) and a bioactive block of nitrous acid‐degraded heparin was developed. Amino‐semitelechelic polystyrene was prepared by anionic polymerization of styrene in cyclohexane, using sec‐butyllithium as initiator and N‐(benzylidene)trimethylsilylamide as terminator. After purification using preparative column chromatography, polystyrene with one amino group per chain and a narrow molecular weight distribution was obtained. The terminal amino group was used in the coupling reaction with amino‐telechelic poly(ethylene oxide) using toluene 2,4‐diisocyanate to produce amino‐semitelechelic polystyrene‐poly(ethylene oxide) diblock copolymer (PS‐PEO‐NH2). The block copolymer was purified by preparative column chromatographic separations and had a narrow molecular weight distribution. Approximately one amino group per chain was found. When methylene 4,4′‐diphenyl diisocyanate or hexamethylene diisocyanate were used as coupling agents low yields of PS‐PEO‐NH2 were obtained. Polystyrene‐poly(ethylene oxide)‐heparin triblock copolymer was synthesized in a DMF‐H20 (40:1, v/v) mixture by a coupling reaction of PS‐PEO‐NH2 with nitrous acid‐degraded heparin, in which aldehyde groups react with the primary amino groups of PS‐PEO‐NH2 at pH 7 in the presence of NaBH3CN via reductive amination. Using this procedure, 18–32% w/w heparin was incorporated, corresponding to ±1 PS‐PEO chain per heparin molecule. These procedures enable the synthesis of well defined heparin containing block copolymers, which will be further evaluated for thier blood compatibility.
Synthesis, decomposition, and initiator properties of macroazonitriles for the preparation of polymers with crown ether units
Authors: Tunca Umit , Yagci Yusuf
Published: April 2003

Macroazonitriles containing crown ether moieties and various amounts of N  Nunits in the main chain were prepared by solution polycondensatio between cis‐diamino dibenzo‐18‐crown‐6 (DADC) and adipoyl chloride (AC) or terephtaloyl chloride (TPC) with the addition of 4,4′‐azobis(4‐cyanopentanyl chloride) (ACPC). Decomposition of the azo linkage present in the polyamides, obtained by using TPC, were studied by DSC. The rate constants and activation energies for the decomposition were determined and a small effect of terephtaloyl group on the rate was observed. The kinetics of the polymerization of styrene by the poly(azoamide), obtained from ACPC and DADC were investigated in DMSO.
Photo‐induced “charge transfer” copolymerizations of donor monomers with acceptor monomers by irradiating their CT complexes
Authors: Li Tong , Lou Bin , Chu Guobei , Hall H. K.
Published: April 2003

The photo‐induced “charge‐transfer” copolymerization of various donor monomer‐acceptor monomer pairs was studied by irradiation of their CT complexes with 365 nm light. The influence of the donor and acceptor strength on the rate of polymerization shows that stronger donor/weaker acceptor pairs or weaker donor/stronger acceptor pairs favor copolymerization. The proposed initiation mechanism involves the formation of an excited complex, which then collapses to the tetramethylene diradical for initiation of free radical copolymerizations.
Grafting of polyesters from ultrafine inorganic particles: Copolymerization of epoxides with cyclic acid anhydrides initiated by COOK groups introduced onto the surface
Authors: Tsubokawa Norio , Kogure Akira , Sone Yasuo
Published: April 2003

The grafting of polyesters onto ultrafine inorganic particles, such as silica, titanium oxide, and ferrite, by use of potassium carboxylate (COOK) groups introduced onto the surface was investigated. The introduction of COOK groups onto the surface was achieved by the neutralization of acid anhydride groups, which were introduced by the reaction of 4‐trimethoxysilyltetra‐hydrophthalic anhydride with hydroxy groups on the surface: the amount of COOK groups introduced onto the surface of silica, titanium oxide, and ferrite was estimated to be 1.92, 0.94, and 0.62 mmol/g, respectively. It was found that the anionic ring‐opening copolymerization of epoxides with cyclic acid anhydrides is initiated by COOK groups introduced onto the surface. In the polymerization, polyester formed was effectively grafted onto the surface based on the propagation of the polymer from COOK groups on the surface: the percentage of grafting of polyester from chloromethyloxirane and phthalic anhydride onto silica, titanium oxide, and ferrite reached to 118.3, 82.1, and 7.5%, respectively. The rate of the polymerization and percentage of grafting increased with an increase in COOK group content of the ultrafine particles. The grafting of polyester onto these particles was confirmed by infrared spectroscopy. Polyester‐grafted ultrafine particles produced a stable colloidal dispersion in organic solvent.
Direct polycondensation of 4,4′‐azobis‐4‐cyanopentanoic acid with diols and diamines using 1‐methyl‐2‐chloropyridinium iodide
Authors: Matsukawa Kimihiro , Ueda Akira , Inoue Hiroshi , Nagai Susumu
Published: April 2003

Polyesters and polyamides derived from 4,4′‐azobis‐4‐cyanopentanoic acid (ACPA) were prepared by the direct polycondensation using 1‐methyl‐2‐chloropyridinium iodide (MCPI) as a condensation reagent at room temperature, in which the azo group was not decomposed. These polyesters and polyamides containing the azo groups could be used for effective initiators of radical polymerizations with some vinyl monomers.
Anionic polymerization of lactones initiated by alkali graphitides. V. Initiation mechanism and nature of the active centers
Authors: Gitsov Ivan , Rashkov Iliya B. , Panayotov Ivan M.
Published: April 2003

The initiation mechanism of the anionic polymerization of ϵ‐caprolactone (ϵ‐CL) under the action of the potassium graphitide KC24 was studied by 1H‐NMR spectroscopy of low molecular weight products of the polymerization. On the basis of the experimental results, the assumption was made that the initiation proceeds through a proton transfer from the monomer to the initiator. From the results of end group analysis it was assumed that the active centers of the growing polymer chain are of an alcoholate type. Comparative investigations were performed on the mechanism of ϵ‐CL polymerization under the action of anion‐radicals (potassium‐naphthylide) and alkali metals (K‐mirro). The results obtained showed that anion‐radicals initiate the polymerization predominantly via addition to the monomer and the pure alkali metals by proton transfer from the monomer to the initiator. The active centers of propagation in these systems were most probably of an alcoholate type in spite of the difficulties for direct proof of their nature.
Silyl enol ethers as monomer. II. Radical copolymerizations of α‐trimethylsilyloxystyrene with electron‐accepting monomers and acid‐catalyzed desilylation of the resulting copolymers
Authors: Nagai Katsutoshi , Chiba Keiji , Asada Keisuke , Masui Keikichi , Kuramoto Noriyuki
Published: April 2003

Radical copolymerizations of α‐trimethylsilyloxystyrene (TMSST), a silyl enol ether of acetophenone, with electron‐accepting monomers such as maleic anhydride (MA) and fumaronitrile (FN) were investigated. TMSST underwent alternating copolymerizations with both MA and FN irrespective of the feed composition, whereas it failed to copolymerize with diethyl fumarate (DEF). The alternating copolymers of TMSST with MA and FN were desilylated with concentrated hydrochloric acid as a catalyst to form polymers containing γ‐lactone rings. The formation of the lactone rings was also observed in the desilylation of an alternating copolymer of TMSST with acrylonitrile (AN) under the similar conditions.
Thermoset resins containing sterically hindered alkyne groups for reduced crosslink density
Authors: Unroe Marilyn R. , Reinhardt Bruce A.
Published: April 2003

A series of thermoset matrix materials with phenylethynyl and phenoxyphenylethynyl end groups were prepared to assess the extent of crosslinking in the cured resins by thermoanalytical and thermomechanical methods. These novel materials with varying flexibility and thermal stability of both the end group and backbone were evaluated against a group of materials known to contain a substantial number of primary acetylenic thermal crosslinking sites. The evaluation indicated increased thermooxidative stability of the secondary acetylenic materials over the primary acetylenic systems at or below 600°F (312°C). However, above 600°F, the secondary systems were less thermooxidatively stable than the primary structures due to the thermal decomposition of the phenyl pendants near 400–450°C (750–842°F). Cure exotherms for the monomers exhibited typical Gaussian behavior with discernable cure onsets and maxima. Cure maxima for the secondary acetylene quinoxalines were close to their thermal decomposition temperature (450°C). Percentages of weight retained varied from 64 to 92% after isothermal aging at 600°F for 200 h in circulating air. Glass transition temperatures of the secondary systems more closely approximated the values calculated for linear homopolymers of similar structure. The increased linearity of the cured secondary systems is further verified by fracture analysis which indicated a 20% increase over the room temperature value of the observed KQ for its comparable primary system analog.
Synthesis and the preliminary analysis of block copolymers of 3,3′‐bis(azidomethyl)‐oxetane and 3‐nitratomethyl‐3′‐methyloxetane
Authors: Talukder Mostafa A. H. , Lindsay Geoffrey A.
Published: April 2003

The preparation of poly[3,3′‐bis(azidomethyl)oxetane‐b‐3‐nitratomethyl‐3′‐methyloxetane‐b‐3,3′‐bis(azidomethyl)oxetane], BAMO–NMMO–BAMO triblock copolymer, was attempted by using p‐bis(α,α‐dimethylchloromethyl)benzene (p‐DCC) with silver hexafluoroantimonate (AgSbF6) to initiate the sequential polymerization of NMMO and BAMO. The analysis of the polymer by different techniques such as nuclear magnetic resonance (NMR), infrared (IR) spectroscopy, and differential scanning calorimetry (DSC) show that the structure of the polymer is composed of a two‐phase domain structure of amorphous NMMO phases and crystalline BAMO phase. The molecular weight distribution of the polymer, determined by gel permeation chromatography‐low angle laser light scattering (GPC‐LALLS) was fairly narrow which indicates that the chains could be propagating by a quasi‐living ionic mechanism. Thermogravimetric analysis (TGA) shows that the decomposition temperature of the polymer is about 204°C, which indicates good thermal stability of the polymer.
Polyamideimides containing carbonyl and ether connecting groups
Authors: Havens S. J. , Hergenrother P. M.
Published: April 2003

Polyamideimides were prepared from the reaction of trimellitic anhydride chloride with seven diamines containing carbonyl and ether groups between the aromatic rings. Several of these polyamideimides were semicrystalline as evidenced by wide angle x‐ray diffraction and differential scanning calorimetry. Glass transition temperatures ranged between 187 and 245°C and crystalline transition temperatures ranged between 317 and 416°C. A series of copolyamideimides from a mixture of 1,3‐bis(4‐aminophenoxy‐4′‐benzoyl) benzene and 1,4‐bis(4‐aminophenoxy‐4′‐benzoyl) benzene were similarly prepared. These copolyamideimides were semicrystalline and formed tough, solvent resistant films with good tensile properties.
Polymerization photoinitiated by carbonyl compounds. IX. Methyl methacrylate polymerization photoinitiated by anthraquinone in presence of triethylamine
Authors: Encinas M. V. , Majmud C. , Lissi E. A.
Published: April 2003

Addition of triethylamine (TEA) notably increases the efficiency of anthraquinone (AQ) as photoinitiator of methyl methacrylate (MMA) free radical polymerization in nonpolar solvents. On the other hand, when alcohols or acetonitrile are employed as solvents the addition of TEA decreases the AQ photoinitiated polymerization rate. The polymerization efficiency measured in nonpolar solvents decreases when the MMA concentration increases. These results are explained in terms of quenching of the AQ‐TEA charge transfer complex by MMA. This conclusion is supported by the decrease in AQ photoconsumption and AQH2 formation produced by the monomer addition.
Polymeric oxidizing reagents based on polyacrylamides: Effect of the nature and extent of crosslinking on reactivity
Authors: George Benny K. , Pillai V. N. Rajasekharan
Published: April 2003

Acrylamide was copolymerized with N,N′‐methylene‐bis‐acrylamide (NNMBA), tetraethyl‐eneglycol diacrylate (TEGDA), and divinyl benzene (DVB) in different proportions to afford crosslinked polyacrylamides with varying nature and extent of crosslinking. These insoluble polymers were functionalized with the N‐bromoamide function and the reactivity of the resulting polymeric N‐bromoamide was investigated under different conditions. The capacities of the reagents varied from 6.7 mequiv / g for the linear polymeric reagent to 1.1 mequiv / g for the 15% DVB‐crosslinked reagent. Oxidation of benzoin to benzil was used as the model reaction. Investigation of the reaction under different conditions of solvent and varying molar excess revealed a significant influence of the nature and extent of crosslinking in deciding the extent of reaction. In the case of NNMBA‐crosslinked reagents, the reactivity increased up to 10% crosslinking and then decreased. The reactivity of the reagents increased up to 15% crosslinking in the case of TEGDA‐crosslinked ones and for DVB‐crosslinked reagents the reactivity decreased with crosslinking. The polarity of the crosslinking agent and its molar percentage on the polymeric reagent (crosslink density) are factors affecting the solvent compatibility, which in turn, is decisive in the facilitation of the reactions.
Solution polymerization of methyl methacrylate using trioctylmethylammonium persulfate initiator: Kinetics of polymerization and activation parameters for the primary decomposition of the initiator
Authors: Gupta G. N. , Mandal B. M.
Published: April 2003

The kinetics of solution polymerization of methyl methacrylate using trioctylmethylammonium persulfate (aliquat persulfate) at 60°C has been studied in t‐butyl alcohol, N,N‐dimethyl formamide, acetonitrile, dioxane, acetone, and methyl ethyl ketone. The rate of polymerization depends markedly on the solvent used. The initiator exponent is close to 0.5 in the first three solvents but larger than this value in the other three solvents. The overall activation energy of the polymerization has been determined in all the solvents. The rate constants and activation parameters for the primary decomposition of the initiator have been determined in the first three solvents where ideal polymerization conditions prevail. The activation parameters for the decomposition of AQ2S2O8 in the organic solvents depend on the type of solvent. They are very different from those of the free S2O2−8 ion in water. These differences have been explained taking into consideration the various ionic forms in which the initiator exists in the studied solvents using a previously postulated model of the activated state.
13C‐NMR study of crosslinking and long‐chain branching in linear polyethylene induced by 60Co gamma ray irradiation at different temperatures
Authors: Zhu Qingren , Horil Fumitaka , Kitamaru Ryozo , Yamaoka Hitoshi
Published: April 2003

H‐type crosslinking and Y‐type long‐chain branching have been examined for linear polyethylene samples irradiate at different temperatures with 60Co gamma rays in vacuum by solution‐state 13C‐NMR spectroscopy. In this study, relatively low molecular weight samples were irradiated with doses less than a gel dose in both solid and molten states. Resonance lines associated with H‐links and Y‐branches have clearly been observed for each irradiated sample and their radiation yields significantly depend on the irradiation temperature and the morphology of the samples. In particular, the G‐value for the production of Y‐branches is higher than that for H‐links at lower temperatures, while the latter is superior to the former at higher temperatures. This may be due to the decrease in the concentration of the primary radicals, which are formed by main‐chain scissions and associated with the production of Y‐branches, by the recombination with small fragments at higher temperatures. The radiation yields of methyl branches and double bonds are also briefly discussed.
Fluorinated poly(ether sulfone)s
Authors: Feiring Andrew E. , Wonchoba Edward R. , Arthur Samuel D.
Published: April 2003

New fluorinated poly(ether sulfone)s were prepared from bisphenols and α,ωbis(4‐fluorophenylsulfonyl)perfluoroalkanes. The fluorinated sulfone monomers were synthesized by reaction of 4‐fluorobenzenethiol salts with perfluoroalkylene diiodides, followed by oxidation. Sodium carbonate mediated polymerization gave high molecular weight polymers in excellent yield. The polymers are generally soluble in chlorinated hydrocarbons and some dipolar solvents, are amorphous with Tg's in the range of 120–160°C and are stable to 400°C. They form clear, colorless films by solution casting. Cast films have dielectric constants and dissipation factors somewhat below those of typical poly(ether sulfone)s, and show good permeability and selectivity for O2/N2 gas separations.
Anionic polymerization of acrylates. I. Polymerization of 2‐ethylhexylacrylate in nonpolar solvents
Authors: Vlčcek Petr
Published: April 2003

Initiation with a combined initiator n‐butyllithium/lithium tert‐butoxide in the ratio 1:6 brings the anionic polymerization of 2‐ethylhexylacrylate (EtHA) in toluene and n‐heptane at temperatures between −78 and −20°C up to a quantitative conversion. In the initial stages of the process the molecular weight distribution (MWD) of the products is polymodal as a result of the stablizing function of the alkoxide; MWD of the final product after a complete consumption of the monomer is medium, being visibly dependent on the reaction temperature and without any distinct content of low‐molecular weight components, which suggests a sufficient activity of all growth centers, and thus an essential restriction of side termination reactions.
Lifetime of living polymers in cationic polymerization. III. Living polymerization of isobutyl vinyl ether initiated by a cationogen/etalcl2 system in the presence of 1,4‐dioxane as an added base
Authors: Choi Won Ok , Sawamoto Mitsuo , Higashimura Toshinobu
Published: April 2003

The concentration ([P*]) and lifetime (half‐life) of the propagating species were measured in the living cationic polymerization of isobutyl vinyl either initiated by the 1‐(isobutoxy) ethyl acetate [CH3COOCH (OiBu) CH3]/ethylaluminum dichloride (EtAlCl2) system in the presence of excess 1,4‐dioxane in n‐hexane at 0 to +70°C; the acetate serves as a cationogen that forms an initiating vinyl ether‐type carbocation. The measurements were based on the end‐capping reaction with sodiomalonic ester [Na⊕⊖CH (COOEt)2], which was shown to react rapidly and quantitatively with the living growing end. From the terminal malonate group of the quenched polymers, [P*] was determined by 1H‐NMR spectroscopy. In contrast to its constancy during the polymerization, [P*] progressively decreased with time after the complete consumption of monomer. The postpolymerization decay was first order in [P*], and the lifetime (half‐life) of the living end was determined from the decay rate constant. The lifetime increased on lowering polymerization temperature, decreasing EtAlCl2 concentration, and increasing dioxane concentration. In particular, the “base‐stabilized” living ends, generated by the CH3COOCH (OiBu) CH3/EtAlCl2/dioxane system, turned out extremely stable at 0°C (half‐life > 5 days in the absence of monomer).
Synthesis and characterization of new photosensitive poly (oxyaryleneoxydisilane)s from 1,2‐bis (diethylamino) tetramethyldisilane and various bisphenols
Authors: Padmanaban Munirathina , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

A new class of polymers containing a photosensitive disilane unit in the polymer main chain with inherent viscosities between 0.1 and 0.59 dL/g was prepared by the melt polycondensation of 1,2‐bis (diethylamino) tetramethyldisilane and various bisphenols. The polymers were characterized by UV, IR, 1H‐NMR, and elemental analysis. Poly(oxyaryleneoxydisilane)s were soluble in a variety of common organic solvents and have a wide range of glass transition temperatures varying between −65 and 135°C, depending on the arylene structure. Most of the polymers were stable up to 350°C in both air and nitrogen atmospheres. The inherent viscosity of the polymer containing the 1,6‐napthalene unit decreased drastically upon UV light irradiation, indicating its photodegradation.
Redox behavior of pyridinium salts and their polymers having radical stabilizing groups
Authors: Kitamura Naoya , Nambu Yoko , Endo Takeshi
Published: April 2003

The redox behavior of pyridinium salts having various substituents capable of stabilizing pyridinyl radicals at the 4‐position was investigated by cyclic voltammetry in water with a platinum electrode, and their redox potentials were more positive in the order of 4‐substituents of acetyl > cyano > carbomethoxy > carbamide groups. Sodium dithionite was found to be suitable for a chemical reducing agent of the pyridinium salts. Two types of homopolymers with pendant 4‐carbamido‐pyridinium groups were prepared and their redox potentials were more positive than the corresponding model compounds. The positive shift might be caused by charge repulsion between the neighboring pyridinium cations on the polymer main chain in the oxidized state.
Radical copolymerization of 2‐ethylacrylic acid and methacrylic acid
Authors: You Hong , Tirrell David A.
Published: April 2003

Copolymers of 2‐ethylacrylic acid (EAA) and methacrylic acid (MAA) were prepared in bulk and in N,N‐dimethylformamide (DMF). Although precipitation of the copolymers was observed in bulk, the reaction mixtures remained apparently homogeneous in DMF. Best‐fit terminal‐model reactivity ratios were determined by a nonlinear least squares technique to be rMAA = 1.14 and rEAA = 0.23 in bulk, and rMAA = 1.91 and rEAA = 0.09 in 50% DMF solution. Examination of 13C‐NMR spectra provided convincing evidence for the formation of statistical copolymers. Copolymerizations richer in MAA provided copolymers of higher molecular weights.
Kinetic study of the cationic photopolymerization of epoxy monomers
Authors: Decker C. , Moussa K.
Published: April 2003

The photoinitiated cationic polymerization of di‐epoxy monomers has been studied using real‐time infrared (RTIR) spectroscopy. The polymerization rate and the amount of unreacted monomer were determined directly from the conversion vs. time curves recorded. The cure speed was greatly increased by using a Kr+ laser (337.4 nm) as radiation source. A 0.25 s exposure proved sufficient to make react more than 60% of the epoxy groups. The overall polymerization quantum yield was evaluated to be 200 mol photon‐1. Dark polymerization was shown to develop extensively after the UV exposure for about 30 min and may represent up to 80% of the total process. The hardening of the UV‐cured tack‐free coating was found to occur mainly in the dark, leading after 1 h to a very hard and glassy material. A bimolecular chain termination process is postulated to account for the decay profile of the reactive species observed after UV exposure.