bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐strength fire‐ and heat‐resistant imide resins containing cyclotriphosphazene and hexafluoroisopropylidene groups
Authors: Kumar Devendra , Fohlen George M. , Parker John A.
Published: April 2003

High‐strength fire‐ and heat‐resistant polymers were obtained by the thermally induced melt‐polymerization of maleimido‐phenoxy cyclotriphosphazenes linked by hexafluoroisopropyliden‐ediphthalimide groups. These polymers show good thermal stability and high char yields: 78–80% at 800°C in nitrogen and 60–68% in air at 700°C. Graphite‐fabric laminates did not burn in pure oxygen, even at 300°C (LOI = 100%), and were tested for shear, flexural, and tensile strengths. Two monomers were synthesized by reacting tris(4‐aminophenoxy)‐tris(phenoxy) cyclotriphosphazene with maleic anhydride and hexafluoroisopropylidenediphthalic anhydride. The triamine was synthesized by a stepwise reaction of hexachlorocyclotriphosphazene with phenol and 4‐nitrophenol to give tris(4‐nitrophenoxy)‐tris(phenoxy)cyclotriphosphazene and reducing the nitro groups. The structures of cyclic phosphazene‐trimeric precursors and the polymers were characterized by FT‐IR, 1H‐NMR, 31P‐NMR, and mass spectroscopy. The curing behaviors of polymer precursors were evaluated by differential scanning calorimetry and thermogravimetric analyses.
Phenothiaphosphine‐containing polyamides and polyesters
Authors: Kondo Hitoshi , Sato Moriyuki , Yokoyama Masaaki
Published: April 2003

Phosphorus‐containing polyamides and polyesters, which had tricyclic fused rings (phenothia‐phosphine rings) in the main chain, were prepared and the properties of the resulting polymers were examined. These polymers were obtained at highly reduced viscosities in satisfactory yields by the polycondensation of 2,8‐dichloroformyl‐10‐phenylphenothiaphosphine 5,5,10‐trioxide with aromatic diamines or bisphenols. The polyamides and polyesters were soluble in polar aprotic solvents such as dimethylacetamide and N‐methyl‐2‐pyrrolidone; the polyesters were also soluble in chloroform. The polymers exhibited good heat resistance. The phenothiaphosphine‐containing polyamides and polyesters self‐extinguished immediately when flame was removed and were highly flame‐resistant. The polyester obtained from bisphenol A showed a limiting oxygen index value of 43.5.
New high‐yield, one‐step synthesis of polyglycolide from haloacetic acids
Authors: Pinkus A. G. , Subramanyam Ravi
Published: April 2003

In a new, one‐step synthesis, polyglycolide was prepared by the reaction of bromo‐ or chloroacetic acid with triethylamine in a nitromethane solution. It was discolored, by iodoacetic acid possibly as a result of iodine formed by the decomposition of triethylammonium iodide. The structure of polyglycolide was characterized by hydrolysis, 1H‐NMR and IR spectra, and x‐ray powder diffraction, which indicated partial crystallinity. A mechanism is proposed for the formation of polyglycolide. A lower limiting value of the number‐average molecular weight of 104 was determined by cryoscopy in 1,3‐dinitrobenzene for polyglycolide prepared from bromoacetic acid; the measurement was inaccurate because of the low solubility of the polymer. No significant effect of solvent (acetone, ether, or chloroform) on yield or melting point was observed; a higher yield was obtained in nitromethane. The polymer obtained with tri‐n‐propylamine and bromoacetic acid had properties similar to that obtained with triethylamine. No polymer was obtained with N,N‐dimethylaniline and bromoacetic acid or with triethylamine and bromoacetic acid in aqueous solution.
Direct mass spectrometry of polymers. X. Primary thermal fragmentation processes in totally aromatic polyesters
Authors: Foti Salvatore , Giuffrida Mario , Maravigna Pietro , Montaudo Giorgio
Published: April 2003

The thermal decomposition of a series of isomeric poly‐(oxphthaloyloxyphenylenes) (I–IV) and poly(m‐hydroxybenzoic acid) (V) was studied by Direct Pyrolysis–Mass Spectrometry. The results indicate that intramolecular exchange reactions predominate in the primary thermal fragmentation processes, causing the formation of cyclic oligomers which are subsequently cleaved to open‐chain fragments. The size and relative abundance of the cycles produced appear to be strongly influenced by steric factors, i.e., by the structure (para or meta) of the repeating unit in each polymer. Remarkably, in the case of poly(m‐hydroxybenzoic acid) the formation of cyclic oligomers containing up to seven repeating units is observed.
Linear condensation polymers of aromatic 1,3‐diamines with 3‐pyridinealdehyde
Authors: Kharas G. B. , Litt M. H.
Published: April 2003

In the presence of one equivalent of acid, m‐phenylenediamine and 2‐methyl m‐phenylenediamine react with pyridine‐3 aldehyde with C alkylation to produce linear polymers, poly(4,6‐R‐methylene m‐phenylenediamine) and poly(4,6‐R‐methylene 2‐methyl m‐phenylenediamine). These were characterized by UV, IR, and NMR spectroscopy. Comparison with model compounds confirmed the above structures. A secondary reaction noted at 25°C and higher for the polymer was the oxidative coupling of two neighboring aromatic diamines to produce substituted 2,7‐diamino acridine groups along the chain.
Phase‐transfer reactions catalyzed by phosphonium salts bound to macroporous polystyrene supports
Authors: Tomoi Masao , Hosokawa Yasunori , Kakiuchi Hiroshi
Published: April 2003

The rate of reaction of alkyl halides with aqueous sodium acetate or cyanide catalyzed by phosphonium salts supported on insoluble polystyrene resins, and rates of ion‐exchange of the chloride ion in the catalysts against the acetate ion, were studied as a function of catalyst particle size, the percentage of ring substitution, the morphology of polymer support, and distance between active site and polymer backbone. Rates of 1‐bromooctane or benzyl chloride with macroporous, 7–25% ring‐substituted catalysts increased with increasing ring substitution. Rates with macroporous catalysts increased as a heptamethylene spacer was introduced between the active site and the polymer backbone. Rates of ion‐exchange with macroporous catalysts were facilitated with increasing ring substitution or by the introduction of the spacer chain. A relation between the catalytic activity of macroporous or microporous catalysts and ion‐exchange rates under triphase conditions was discussed.
Syntheses and electrical conductivity of polyamides containing tetrathiafulvalene moieties in the main chain
Authors: Watanabe Masayoshi , Iida Tadashi , Sanui Kohei , Ogata Naoya , Kobayashi Tadahiko , Ohtaki Zentaro
Published: April 2003

Novel polyamides that contain tetrathiafulvalene (TTF) moieties were synthesized by direct polycondensation of Δ2,2′ ‐bi‐1,3‐dithiole‐4,4′(5′)‐dicarboxylic acid with aromatic diamines in the presence of triphenylphosphine, hexachloroethane, and pyridine. Complexes of these polyamides with bromine were TTF cation radical () salts which resulted from the charge transfer of TTF moieties to bromine. The electrical conductivity of undoped polyamides increased with a decrease in diamine length. By doping the bromine the conductivity of the polyamides was enhanced by 3–5 orders of magnitude and reached 10−5–;10−9S cm−1. Maximum conductivity was observed at the doping ratio of [Br]/[repeat unit] < 1. The electrical conduction in the bromine complexes may be attributed to the hopping of odd electrons of between TTF moieties.
Preparation and properties of aromatic polyesters and copolyesters containing phenylindane unit
Authors: Imai Yoshio , Tassavori Shahrzad
Published: April 2003

Aromatic polysters and copolyesters of high molecular weights with phenylindane units were prepared from combinations of 3‐(4‐hydroxyphenyl)‐1,1,3‐trimethyl‐5‐indanol and bisphenol A with isophthaloyl and terephthaloyl chloride by two‐phase polycondensation in a nitrobenzene‐water system with various phase‐transfer catalysts. The phenylindane‐containing polyesters and copolyesters were amorphous and readily soluble in a wide range of solvents that included chloroform, m‐cresol, tetrahydrofuran, and dimethylformamide. The glass transition temperatures of the phenylindane‐derived polyisophthalate and polyterephthalate were 235 and 253°C, respectively, which were higher than those of the corresponding bisphenol A analogs by some 50°C. These polymers began to lose weight around 400°C in air and nitrogen atmospheres.
Morphology of core‐shell latex particles
Authors: Muroi S. , Hashimoto H. , Hosoi K.
Published: April 2003

The progressive dissolution of carboxylated latex particles with increasing pH was utilized to investigate the internal structure of core‐shell latex particles, in comparison with that of copolymeric latex particles formed from the same monomers. The results indicated that in those latex particles which are formed when ethyl acrylate (EA) ‐methacrylic acid (MAA) or methyl acrylate (MA) ‐MAA mixture is polymerized in the presence of poly(MA‐MAA) or poly(EA‐MAA) seeds the shell is composed of the more hydrophilic poly(MA‐MAA) molecules relatively high in MAA content and the core is composed of both poly(MA‐MAA) and poly(EA‐MAA) molecules, regardless of the order of the stage feed, while the copolymeric latex particles are relatively uniform from surface to center in distribution of all components except MAA. Examination of the distribution of the carboxylic groups in all of the latex particles showed their concentration to be highest at the surface and to decrease with proximity to the center in accordance with other findings reported in the literature.
DTA studies on the thermal oxidation and crosslinking reactions of carboxyl‐terminated polybutadiene
Authors: Kishore K. , Pai Verneker V. R. , Dharumaraj G. Varghese
Published: April 2003

Studies on the thermal oxidation of carboxyl‐terminated polybutadiene in the presence of antioxidants have been carried out by dynamic DTA. Bis‐thioacetylacetonato nickel(II) compounds are found to be effective in inhibiting the air oxidation reaction in the polymer. The crosslinking reaction of the polymer through the double bonds present in the polymer molecule is desensitized by the antioxidants and the effect is more with N‐phenyl‐1‐naphthylamine. An exothermic peak formed at 270°C in the presence of tris(2‐methylaziridinyl‐1) phosphine oxide has been identified as the curing reaction. The infrared spectra of CTPB in the presence of MAPO at various temperatures confirm the various stages of reaction.
Structure and electric conductivity of vapor deposition polymerization products of cyanoacetylene
Authors: Matsumura K. , Tsukamoto J. , Takahashi A.
Published: April 2003

Cyanoacetylene can be polymerized from the vapor state onto an inactive surface of substrate at a temperature as low as 200°C. The polymerization first occurs by way of the carbon–carbon triple bond. The reaction product obtained at 1000°C contains nitrogen at a concentration as high as 13.7%. At least some of this nitrogen is in naphtiridine ring or rings similar to it. The product obtained at 400°C is amorphous, while the product obtained at 1000°C has at least partly graphite‐like crystalline structures with an apparent crystallite size (Lc) of about 17 Å. The electric conductivities of the products obtained at 400, 700, and 1000°C are 7.7 × 10−2, 91, and 1600 S/cm, respectively. These values are extremely high compared to the pyrolized PAN treated at the same temperature. Electric conductivity of the product obtained at 400°C is well explained by the variable range hopping model in 3‐dimensional amorphous materials. With the products obtained at the higher temperatures, conductivity cannot be accounted for by the hopping model. This is probably due to the development of graphite‐like structure.
Linear polythioesters. VIII. Products of interfacial polycondensation of 1,4‐di(mercaptomethyl)‐tetramethylbenzene with isomeric phthaloyl chlorides
Authors: Podkoscielny Wawrzyniec , Kowalewska Wanda
Published: April 2003

New polythioesters by interfacial polycondensation of 1,4‐di(mercaptomethyl)‐tetramethylbenzene with phthaloyl, isophthaloyl, and terephthaloyl chlorides were obtained. To determine the optimal conditions of interfacial polycondensation the influence of the following factors on yield and value of reduced viscosity were studied: type of organic phase, the quantitative ratio of aqueous to organic phase, concentration of hydrogen chloride acceptor, molar ratio of reagents, rate of acid chloride addition, contribution of benzyltriethylammonium chloride as a catalyst, and the temperature of the reaction. The yield of all reaction products and the reduced viscosity of polythioesters which were soluble in the mixture of phenol‐tetrachloroethane were found. A thorough examination was carried out only for the polycondensation of dithiol with isophthaloyl chloride. The structure of all polythioesters obtained under the model conditions was determined by elementary analysis and infrared spectra. Initial decomposition temperature and maximum rate of decomposition temperature were defined from the curves of thermogravimetric analysis. Some mechanical and electrical properties of the polythioesters were determined. The molecular weight was not measured because of the low solubility of the obtained polythioesters.
Synthesis and characterization of MDI‐butanediol urethane model compounds
Authors: Hwang Kirk K. S. , Wu Guosheng , Lin Shaow Burn , Cooper Stuart L.
Published: April 2003

Hard‐segment model compounds containing one to five 4,4′‐methylene bis(p‐phenylisocyanate) (MDI) units extended with 1,4‐butanediol (BD) were synthesized. The ends of the model compounds were reacted with ethanol. The melting point (Tm) of the model compounds increased with the number of MDI units to an extrapolated value of 299°C for the homopolymer using Flory's equation accounting for chain end defects. The ΔH of fusion was 5.3 kcal/mol. Intrinsic viscosity measurements in DMA solutions revealed a Mark Houwink exponent of 1.43 suggesting that the hard‐segment model compounds are rodlike in solution. Wide‐angle X‐ray diffraction showed that the percentage of hard‐segment crystallinity decreased as the oligomer length increased. Infrared spectroscopy studies showed that the distribution of hydrogen bond distances between CO and NH groups became broader with increasing segment length.
Flame‐retardant epoxy resins based on phthalide derivative
Authors: Lo Jeelin , Pearce Eli M.
Published: April 2003

The phthalide‐containing epoxy resins are synthesized and characterized in comparison with the bisphenol‐A epoxy resins in terms of thermal properties. Although both resins contain comparable amounts of halogens, the resulting flame retardancy is higher in the phthalide‐containing resin. The char formation upon pyrolysis is also enhanced by the phthalide functionality.
Cationic oligomerization of bicyclic oxalactam
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi
Published: April 2003

Cationic oligomerization of bicyclic oxalactam, 8‐oxa‐6‐azabicyclo[3.2.1]octan‐7‐one [abbreviated as BOL (1)], was carried out at 0–60°C with trifluoromethanesulfonic acid and borontrifluoride etherate as catalysts to obtain the oligomer mixture at high yield. From the structural analysis of the isolated dimer, a N‐(2(e)‐carbamoyltetrahydropyran‐6(e)‐yl)‐8‐oxa‐6‐azabicyclo[3.2.1]octan‐7‐one, the oligomerization proceeded through the 5C‐6N scission in (1) but not through the 6N‐7C (amide group) scission as generally observed in common lactams. This peculiar oligomerization must result from the protonation to the oxamide unit in the BOL molecule.
Temperature dependence of the laser‐initiated polymerization of a thiol‐ene system
Authors: Hoyle C. E. , Hensel R. D. , Grubb M. B.
Published: April 2003

The laser‐initiated polymerization of a thiol‐ene photopolymerizable system was studied. The laser was operated in single‐ and multiple‐pulse modes to generate exotherms, which were measured in a modified differential scanning calorimeter. Arrhenius plots of the polymerization, obtained by measuring polymerization exotherms at various temperatures, showed positive and negative portions. Pseudoactivation energies for the thiol‐ene polymerization increased rapidly at low conversions (<50%) of the thiol and ene chromophores. The results were comparable to those obtained from photopolymerization of multifunctional acrylate monomers.
Kinetics of polymerization of methyl methacrylate initiated with cyclohexanone. Part I
Authors: Kaim A.
Published: April 2003

The kinetics of radical polymerization of methyl methacrylate were investigated in a dioxane solution with cyclohexanone as initiator. It was found that the overall rate of reaction initiated with cyclohexanone (Rp) is proportional to the concentration of monomer and to the square root of the concentration of the initiator. The effect of temperature on the Rp in the temperature range of 65–95°C was discussed. The Arrhenius activation energy Ea estimated for the temperature range of 65–75°C was 137 kJ mol−1.
Synthesis and characterization of graft copolymers from lignin and 2‐propenamide
Authors: Meister John J. , Patil Damodar R. , Field Larry R. , Nicholson John C.
Published: April 2003

Free radical polymerization of 2‐propenamide in the presence of lignin, anhydrous calcium chloride, and cericion in photolyzed dioxane solvent produces a reaction product containing lignin‐(1‐amidoethylene) graft copolymer. Up to 49 weight percent of the product is poly(1‐amidoethylene) homopolymer. Photolysis products of dioxane and the presence of anhydrous calcium chloride are critical to the reaction. A maximum yield of polymer is obtained when the dioxane solvent is irradiated for 3 h in a Pyrex vessel and the reaction mixture contains 2.0 weight percent calcium chloride. Aqueous size exclusion chromatography of reaction products shows that the molecular size of the lignin‐(2‐propenamide) reaction product is significantly greater than that of unreacted lignin, that the side chain and the lignin backbone migrate as one unit through the column, and that mixtures of lignin and poly(1‐amidoethylene) are easily separated by the chromatographic column.
Preparation of soluble microgel by the copolymerization of methylmethacrylate with p‐divinylbenzene in the presence of tetrabromomethane
Authors: Chen Hui , Ishizu Koji , Fukutomi Takashi , Kakurai Toshio
Published: April 2003

Various types of soluble crosslinked polymers obtained from the copolymerization of methylmethacrylate (MMA) and p‐divinylbenzene (p‐DVB) in the presence of a transfer agent (CBr4) have been discussed in relation to the variation of the structure during the reaction time. When [p‐DVB]/[MMA] = 1.49 × 10−3 and [CBr4]/[MMA] = 1.28 × 10−4, only linear polymers (primary polymer; Mn = 1.0 × 105) with pendant vinyl groups are formed intially. Considerable branched structure is attained in rather large polymers (Mn = 2.5 × 105), but the number of pendant double bonds is not enough to reach the gelation. As the concentration of the transfer agent becomes high, the intermolecular crosslinking is depressed, and the formed polymers contain loops and short chains. At [p – DVB]/[MMA] = 7.43 × 10−3 and [CBr4]/[MMA] = 1.28 × 10−3, the shape of polymer with the same Mn became compact gradually with increasing reaction time. These results are considered to be useful for the preparation of soluble crosslinked polymer with controlled structure.
Hydroxamic acid polymers. Effect of structure on the chelation of iron in water: II
Authors: Varaprasad D. V. P. R. , Rosthauser J. , Winston A.
Published: April 2003

The effect of structure on the ability of hydroxamic acid polymers to chelate iron(III) was examined. The polymers were derived from acryloyl or methacryloyl backbones that bore side chains terminated in hydroxamic acids. The side chain length, which establishes the atomic chain distances between hydroxamic acid groups, had the most pronounced effect on the stability constant of the iron chelate. It was this atomic chain distance that determined how easily the three neighboring hydroxamic acids could fit the octahedral sphere of the iron. Other structural changes such as the presence or absence of methyl groups on the backbone or on the hydroxamic acid nitrogen had little measurable effect. The stability of the iron complexes appeared to be optimum at an 11‐atom spacing between hydroxamic acids and decreased with shorter or longer spacing distances.
Photocationic crosslinking of poly(2,3‐epithiopropyl methacrylate) and photo‐initiated cationic polymerization of its model compounds
Authors: Tsunooka Masahiro , Ueda Toshihiro , Tanaka Makoto , Egawa Hiroaki
Published: April 2003

Photocationic crosslinking of a poly(2,3‐epithiopropyl methacrylate) (PETMA) film containing 4‐N,N‐diethylaminobenzene diazonium tetrafluoroborate (DAC) was investigated. Very rapid photocrosslinking of PETMA was observed and the rate was greater than that of poly(glycidyl methacrylate) with DAC. Post‐heating of the irradiated PETMA film resulted in a decrease of the insoluble fraction. This decrease was explained by scission of crosslinking points by the BF3. In the present conditions, more than 0.3 wt % of DAC was required to insolubilize the PETMA film. Photopolymerizations of propylene sulfide (PS) and 2,3‐epithiopropyl pivalate (ETPP) in the presence of DAC were investigated. The polymerization of PS proceeded smoothly but addition of ethyl acetate to PS depressed the rate and the degree of polymerization. ETPP could not be polymerized but copolymerized with PS by this method. Addition of ETPP to PS depressed both the rate of the polymerization and the degree of polymerization. From these results, it is deduced that the photocrosslinking of a PETMA film is caused by a cationic polymerization of episulfide groups but the chain length is not large.
Surface degradation of wood by ultraviolet light
Authors: Hon David N.‐S. , Chang Shang‐Tzen
Published: April 2003

Wood is beautiful but sensitive to light. Because of the chromophoric system at its surface, ultraviolet light cannot penetrate it deeper than 80 μm. Surface characteristics of ultraviolettreated wood were analyzed by infrared and ultraviolet spectroscopy. Analyses of infrared spectra revealed that ultraviolet‐treated wood is rich in carboxylic and carbonyl chromophoric groups and poor in aromatic functional groups. Ultraviolet spectral studies suggest that water‐soluble low molecular weight fractions of degraded products from the wood surface are mainly derived from lignin. These degradation products contained carbonyl conjugated phenolic hydroxyl groups and had a weight‐average molecular weight of about 900, confirmed by gel permeation chromatography.
Bis(difluoroaluminum)organophosphonates and difluoroaluminumdiorganophosphinates
Authors: Flagg Edward E. , Schmidt Donald L.
Published: April 2003

Oligomers and polymers of the general types [RR′P(O)OA1F2]n, I, and [F2AlOP(R)(O)OAlF2]n, II, were prepared by the addition of phosphonic or phosphinic acids and hydrogen fluoride to etherated alanes. The hydrocarbon moieties (R,R′) on the phosphonic and phosphinic acids were important determinants of physical and chemical properties. When the alkyl moieties contained six or more carbon atoms type I oligomers were partially crystalline, soluble in tetrahydrofuran, and fused below 415°C. Type II polymers were soluble in tetrahydrofuran when n‐octyl or larger alkyl moieties were used, but these polymers tended to be amorphous and liberated solvated tetrahydrofuran below 225°C. Data are presented in support of inter‐monomer fluorine bridge bonding; that is, AlFAl bonds.
Crown ethers as ligands for stereospecific polymerization by Ziegler–Natta catalysts
Authors: Jarrin J. , Dawans F. , Marechal E. , Boileau S.
Published: April 2003

Some new TiCl4/Crown ether complexes were synthesized and used as polymerization catalysts with AlEt3 or AlEt2Cl as cocatalyst for the stereospecific polymerization of 1,3‐butadiene. As with most of the nucleophilic ligands the addition of crown ethers to Ziegler–Natta catalytic systems results in a decrease of the polymer conversion. But the Al/Ti molar ratio appears to be less critical for the complexed systems than for the uncomplexed ones. The presence of the crown ether in the surroundings of the catalytic sites presumably protects them from an excess of the organoaluminum cocatalyst. The side groups of the crown ether do not influence the microstructure of the polybutadiene obtained but they change the activity of the catalytic systems. Thus, the electron‐donating effect of the macrocyclic ligands seems to be less important than the sterical effect due to the rigidity and to the hole size of the crown ether.
Copolymers of vinylamine and vinylalcohol by acid hydrolysis of poly(N‐vinyl‐tert‐butylcarbamate‐co‐vinylacetate): Evaluation of reactivity ratios
Authors: Brouwer W. M. , Piet P. , German A. L.
Published: April 2003

Copolymers of vinylamine and vinylalcohol were prepared by hydrolysis of poly(N‐vinyltert‐butylcarbamate‐co‐vinylacetate) in 1:1 v/v % ethanol/HCl mixtures at room temperature. Reactivity ratios of the monomers N‐vinyl‐tert‐butylcarbamate (1) and vinylacetate (2) were calculated from monomer feed and copolymer composition data, according to the methods of Fineman–Ross and Kelen–Tüdös, yielding r1 = 1.14 ± 0.05, r2 = 0.47 ± 0.07, and r1 = 1.12 ± 0.07, r2 = 0.46 ± 0.03, respectively. From these values the average sequence length distribution of monomer units was derived showing that in the raction of N‐vinyl‐tert‐butyl carbamate and vinylacetate nearly Bernouillian (i.e., purely random) copolymers are formed, with a slight tendency toward alternation.
Determination of absolute rate constants for free radical polymerization of ethyl α‐fluoroacrylate and characterization of the polymer
Authors: Yamada Bunichiro , Kontani Takashi , Yoshioka Minoru , Otsu Takayuki
Published: April 2003

The absolute rate constants for propagation (kp) and for termination (kt) of ethyl α‐fluoroacrylate (EFA) were determined by means of the rotating sector method; kp = 1120 and kt = 4.8 × 108 L/mol.s at 30°C. The monomer reactivity ratios for the copolymerizations with various monomers were obtained. By combining the kp values for EFA from the present study and those for common monomers with the monomer reactivity ratios, the absolute values of the rate constants for cross‐propagations were also evaluated. Reactivities of EFA and poly(EFA) radical, being compared with those of methyl acrylate and its polymer radical, were found to be little affected by the α‐fluoro substitution. Poly(EFA) prepared with the radical initiator was characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Although the glass transition temperature obtained by DSC for poly(EFA) resembled that of poly(ethyl α‐chloroacrylate), its TGA thermogram showed fast chain de polymerization to EFA that was distinct from complicated degradation of poly(ethyl α‐chloroacrylate).
Functional monomers and polymers. CXVII. Photochemical reactions on oligo‐ and polyethyleneimines containing pendant thymine bases: Effect of the spacer
Authors: Suda Yasuo , Kono Michihiro , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

The photodimerization reaction of thymine bases incorporated in the modified oligo‐ and polyethyleneimines, in which α‐alanine or ß‐alanine unit was inserted between the main chain and the pendant thymine bases, was studied both in aqueous and in dimethyl sulfoxide solutions. It was found that the quantum yields for the photodimerization for the oligomers were closely related to the intramolecular interaction in the ground state, while those of the copolymers were not related to the ground state interaction. It was suggested that the singlet energy migration was present in the case of the polyethyleneimine derivatives. This result is discussed in terms of the effects of the nearest‐neighboring thymine units, the structure of the side chain, and the singlet energy migration, particularly for the copolymers.
Polymerization photoinitiated by carbonyl compounds. VI. Mechanism of benzil photoinitiation
Authors: Encinas M. V. , Lissi E. , Gargallo L. , Radic D. , Sigdman R.
Published: April 2003

The mechanism of the photoinitiation of the vinyl polymerization sensitized by benzil and 4,4′‐dimethoxybenzil was studied. The monomers considered were methacrylic acid esters and styrene derivatives. All these monomers are efficient quenchers of the excited triplet benzil. However, the initiation efficiency of the benzil is important only when styrene derivatives are employed as monomers. The main polymerization process follows a simple free radical mechanism. The initiation step is a consequence of the interaction (triplet benzil–monomer double bond) through a charge transfer complex.
Poly‐2‐vinylfuran, synthesis, characterization, and diels‐alder reaction with maleic anhydride
Authors: Küsefoǧlu Seli̇m H.
Published: April 2003

Poly‐2‐vinylfuran, synthesized by free‐radical polymerization of 2‐vinylfuran, was characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The pendant furan rings on the polymer backbone were then used as the diene component of a Diels‐Alder reaction with maleic anhydride. The juxtaposition of the furan rings at first suggested an “avalanche” Diels‐Alder reaction, in which the product of one cyclization would be the reactant of the next. A lack of polymer stereoregularity and the reversibility of the Diels‐Alder reaction, however, prevented its formation. On the other hand, when the dienophile was used in a 1:1 molar ratio with respect to furan the smooth reaction produced a new polymer, the maleic anhydride adduct of poly‐2‐vinylfuran, which characterized by NMR and IR spectroscopy, was air stable and soluble in a number of solvents up to 70% transformation. When heated to 160°C the polymer reverted to maleic anhydride and somewhat decomposed poly‐2‐vinylfuran.
Reactions in the presence of organic phosphites, II: Low‐temperature amidatior in solvent
Authors: Aharoni Shaul M. , Hammond Willis B. , Szobota John S. , Masilamani Divakar
Published: April 2003

Polyamides and related model compounds were prepared from carboxy acids and primary amines by reacting them with triphenylphosphite in an appropriate solvent at 100°C. The reactions proceeded in the absence of organic base but were accelerated by the addition of bases such as pyridine. Nevertheless, even the powerful combination of 13C and 31P NMR failed to indicate the presence of pyridinium phosphite in the reaction mixture. In the reaction of a primary amine and carboxyl groups a detectable amount of the diphenoxy aminophosphine intermediate was observed. The end products are the amides, phenol, and diphenyl phosphite. When primary amine was not present a slow formation of a phenyl ester of the carboxylic acid was evident. All the intermediate species and the end products were formed with or without added pyridine. A mixed anhydride of carboxylic acid and phosphite was never seen. The results in this article are fundamentally the same as those in the companion article (I) for which the data were obtained at 280°C in the absence of solvent and base. However, because the reaction went quickly to completion at 280°C, the diphenoxy aminophosphine intermediate was not observed. A mechanism for the amidation in which the diphenoxy aminophosphine is an initial reaction intermediate is proposed. This species reacts with the carboxylic acid through an intramolecular substitution to give an amide. This mechanism may be valid for the high‐temperature reactions as well. Several minor unclear points are indicated.
Catalyseurs Zieger‐Natta supportés sur MgCl2 pour la polymérisation stéréorégulée du propène. II. Système catalytique simple: Solide binaire MgCl2‐TiCl4 et solution cocatalytique triéthylaluminium, benzoate d'ethyle
Authors: Spitz R. , Lacombe J. L. , Guyot A.
Published: April 2003

The kinetics of propene polymerization in heptane slurry at 1–4 bars was studied with a catalytic system that consisted of a solid catalyst prepared by adsorption of TiCI4 on pure porous MgCl2 (by dehydrating MgCl2, 6 H2O with thionyl chloride) and a cocatalytic, heptanic solution of ethylbenzoate (BE) and triethylaluminium (TEA). At a temperature approaching 60°C/polymerization began immediately after the introduction of the monomer. The polymerization rate decreased continuously during the reaction. The loss in activity, however, was not due to a diffusional effect (e.g., blocking of the catalyst by the growing polymer). Studies of the ageing of the catalytic system showed a deactivation of the catalytic system itself as a function of the time of contact between the catalyst and the cocatalyst. The product of the thermal decomposition of the complex 1:2 formed by the reaction of BE with TEA was not associated with the deactivation process or stereospecific control, which depend on the BE/AI ratio and the presence of the complex.
New telechelic polymers and sequential copolymers by polyfunctional initiator–transfer agents (inifers). XLI. Kinetic and reactivity studies on sterically hindered inifers
Authors: Santos Raquel , Fehérvári Ágota , Kennedy Joseph P.
Published: April 2003

The kinetics of chain transfer to the bifunctional initiating and transfer agents (binifers) 1,4‐di(2‐chloro‐2‐propyl)benzene (p‐DCC), 1,3‐di(2‐chloro‐2‐propyl)‐5‐tert‐butylbenzene (m‐tBuDCC), and 1,3‐di(2‐chloro‐2‐propyl)‐4,6‐dimethylbenzene (m‐DMeDCC) in the polymerization of isobutylene has been investigated. Chain transfer to monomer was shown to be absent up to −20°C in CH3Cl/n‐hexane and CH2Cl2/n‐hexane mixtures using the m‐tBuDCC/BCl3 binifer system. Chain transfer constants (Ci) to m‐tBuDCC and kt/kp ratios determined in the range from −30°C to −80°C in CH3Cl/n‐hexane mixtures and pure CH3Cl solvent are reported, and the activation energy differences Etr,l − Ep and Et − Ep were calculated. Chain transfer constants to p‐DCC and m‐DMeDCC were determined by the use of pure CH3Cl diluent at −50°C. The chain transfer reactivity of five different inifers is discussed and compared based on CI values obtained under identical conditions, with special regard to the new, sterically hindered binifer m‐DMeDCC of extraordinary reactivity.
Semiconducting poly(monocyanoacetylenes)
Authors: Carlini Carlo , Chien James C. W.
Published: April 2003

Poly(monocyanoacetylenes) (PMCA) were synthesized by anionic, Ziegler–Natta, metathesis, and photo initiations. The Ziegler–Natta‐catalyzed polymers probably have highly stereoregular cis‐transoid structure that contains very few defects and the nitrile groups are difficultly cyclized. It has M̄n = 1100. PMCA obtained by anionic polymerization at −78°C has M̄n ∼ 4800; it is rich in trans‐transoid structures but probably contains other isomeric units as well. The unpaired spin concentrations in these polymers are very high, comparable to that in trans‐polyacetylene (PA) isomerized above 150°C. UV irradiation initiated rapid polymerization of cyanoacetylene in solid state at low temperature but the products were bleached in color after long irradiation. The unpaired spins in PMCA are immobile; nitrile cyclization causes some decrease in EPR linewidth and increase in room‐temperature conductivity (σRT). There was also a large increase in unpaired spin concentrations to about 200 monomer units/spin. Iodine doping increases σRT to about 10−3 (ω cm)−1 but the dopant is readily removed by evacuation and the polymer returns to its original insulating state. The properties of pristine and doped PMCA, such as EPR g‐value, ΔHpp, T1, T2, and σRT are very similar. The similarities persist after cyclization and doping for this pair of polymers. These properties are also compared with those of poly(methylacetylene), poly(phenylacetylene), poly(dicyanoacetylene) and PA, and the significance is discussed.
Composition equation for matrix copolymerization
Authors: Połowiński S.
Published: April 2003

A mechanism of matrix copolymerization in which a monomer (or macroradical) is complexed by matrix was considered. For this case a composition equation was formulated. It was shown that in general case reactivity ratios are dependent on the matrix concentration. The influence of the critical length of a complexed radical on the process of copolymerization is also discussed. A series of copolymerizations of methacrylic acid and styrene were carried out using various compositions of initial monomer mixtures. The process was performed in benzene in the presence of poly(ethylene glycol) as a matrix. The copolymerization were carried out at various ratios of the monomer being complexed (methacrylic acid) to the matrix. Compositions of the complexes prepared were determined by the NMR method. Reactivity coefficients for both monomers were found and the results are discussed on the basis of the derived equation.
Solid‐state polymerization of butadienes. Crystal structure and solution properties of a stereoregular amphoteric 1,4‐trans‐polybutadiene
Authors: Tieke B. , Chapuis G.
Published: April 2003

The double salt 1 consisting of the hydrochloride of 6‐amino‐2,4‐trans‐hexadienoic acid and cadmium chloride in a 2:1 stoichiometry polymerizes in the crystalline state if exposed to UV or γ irradiation. A stereoregular polymeric ampholyte is formed in an extended chain macroconformation, embedded in an inorganic matrix. The crystal structure of the polymerized crystals and the solution properties of the polymer are reported. Polymerized crystals are triclinic, space group P1, a = 7.2144 Å, b = 7.2447 Å, c = 18.5936 Å, α = 104.49°, β = 96.631°, γ = 95.706°, Z = 2. The structure consists of 2‐dimensional layers of polymer and inorganic CdCl6 octahedra alternatively stacked in the third dimension. The cadmium ions can be separated from the polymer by a precipitation as insoluble CdS. After separation from the inorganic material the polymer is soluble in strong acids and bases and insoluble in neutral water. From viscosity measurements of alkaline solutions of the polymer, an average molar mass of 4 × 104 g/mol can be deduced. The polymer selectively adsorbs divalent transition metal ions if suspended in an aqueous solution of transition metal salts. The structure of the resulting polymer–metal complexes is discussed.
Acyloin condensation of terephthaloyl chloride—a novel route to polyhydroxyketones
Authors: Nallaiah C.
Published: April 2003

Acyloin condensation of terephthaloyl chloride under homogeneous conditions using a sodium naphthalene radical anion system and under heterogeneous conditions using finely dispersed molten sodium with varying ratios of sodium to organic substrate gave mainly polymeric materials that were identified as polyhydroxyketones. IR, NMR, and DTA analyses indicate that these polymers are copolymers of benzoin and benzil hitherto unknown. The yields of polymers under homogeneous conditions were higher than those obtained under heterogeneous conditions, but the molecular weight distribution was similar to those obtained with molten sodium.
Studies of phosphazenes. XIX. New polyorganophosphazenes derived from the friedel–crafts reactions of hexa(aryloxy)cyclotriphosphazenes with polyhaloalkanes
Authors: Katti K. V. , Krishnamurthy S. S.
Published: April 2003

The reactions of hexa(aryloxy)cyclotriphosphazenes N3P3(OR)6[R = C6H5, C6H4CH3‐p] with polyhaloalkanes in the presence of anhydrous aluminium chloride yield new crosslinked phosphazene polymers which are characterized by elemental analysis, IR spectroscopy, and pyrolysis—mass spectrometric measurements. Soluble “prepolymers” are obtained by using stoichiometric quantities of the phosphazene and haloalkane in nitromethane as the solvent. The 1H and 31P NMR data for these “prepolymers” are presented. The thermal stability of the polymers derived from various haloalkanes decreases in the order 1,2‐ClCH2CH2Cl < CHCl3 > CH2Cl2 > CCl4. The thermal stability also increases with increasing amounts of the catalyst, reaching a maximum at 1:10 mol ratio of N3P3(OPh)6:AlCl3. The phosphazene polymers reported here possess much greater thermal stability compared to linear polyorganophosphazenes, [NPR2]n, as well as the polymers prepared by the Friedel–Crafts reactions of P(O)(OPh)3 and P(O)(OC6H4CH3‐p)3 with haloalkanes.
Synthesis and characterization of β‐forming poly[S‐(ω‐N‐carbazolylalkyl)‐L‐cysteine]s
Authors: Oshima R. , Wada T. , Kumanotani J.
Published: April 2003

Poly(L‐cysteine derivative)s containing carbazole groups in the side chains separated from the backbone by several distances have been synthesized. It is revealed by measuring the IR spectra that they assume the antiparallel‐chain pleated sheet (β‐conformation) in the solid films independent of side chain length. DSC thermograms, and CD and fluorescence spectra of the films of these polymers are also presented in relation to the alignment of side‐chain carbazole groups.
The kinetics of oxidative coupling of 2,6‐dimethylphenol with a copper‐diamine catalyst system
Authors: Mobley David P.
Published: April 2003

Reaction rate measurements show that a Michaelis‐Menten model proposed earlier is inadequate to describe the full course of the polymerization of 2,6‐dimethylphenol to poly(2,6‐dimethyl‐1,4‐phenylene oxide). Modification of this model to include the effects of catalyst deactivation during the reaction and difference in reactivity between the monomer and other oligomers resulted in much greater accuracy. The kinetic constants in the modified model were influenced by reaction temperature, system composition, and method of catalyst component addition.
Initiation reactions in thermal polymerization of vinyl monomers in the molten state
Authors: Verneker V. R. Pai , Santhanalakshmi K. N.
Published: April 2003

Evidence of the initiation process during uncatalyzed thermal polymerization of vinyl monomers is presented. DSC studies reveal a prominent endothermic effect just before the polymerization exotherm, which is substantiated by the identification of the free radicals produced in the initiation by a quick quenching technique and subsequent detection by ESR at low temperatures.
Poly(alkylene oxide) ionomers. XIII. Copolymers of trioxane with the epoxide and 1,3‐dioxolane of methyl 10‐undecenoate
Authors: Bansleben Donald A. , Janovic Zvonimir , Vogl Otto
Published: April 2003

Cationic copolymerization of 1,3,5‐trioxane with methyl 10,11‐epoxyundecanoate or methyl 7,8‐epoxyoctanoate and terpolymerization with 1,3‐dioxolane was successfully carried out. Co‐and terpolymerization of 1,3,5‐trioxane with 4‐(1‐carbomethoxynonyl)‐1,3‐dioxolane was also achieved. Feed compositions of the functional comonomers were varied from 5 to 40 mol %; in all cases the isolated copolymers contained less than 5% of the functional mer units. The composition of the copolymers showed that the methyl ω‐epoxyalkanoates were much less reactive than 1,3,5‐trioxane. A similar trend was observed with the functional dioxolane monomer, although significantly shorter induction periods were observed in comparison with the epoxy/trioxane copolymerizations. The oxymethylene copolymers and terpolymers were characterized primarily by their infrared spectra; however, the thermal and base stabilities of selected copolymers were also determined.
Development‐free vapor photoetching effect of azide‐type photopolymers
Authors: Hong Xiao‐Yin , Xiao Ji‐Qang , Zhou Zi , Pei Rong‐Xing
Published: April 2003

A new dry photoetching process that dose not required development step had been developed, utilizing the development‐free vapor photoetching effect of cinnamate‐type photopolymers.1–3 In contrast to obtaining positive patterns with cinnamate‐type photopolymers, this process with azide‐type photopolymers, which consist of axide crosslinking agent and polymers, gives negative patterns. Some preliminary studies on the development‐free vapor photoetching effect of azide‐type photopolymers were made. The results indicate that the polymers in this process only play the role of forming a film on the surface of silicon dioxide; and the crosslinking agent is the most important factor, which leads the difference of etching rate between the exposed and unexposed areas.
Mechanism of the thickening reaction of polyester resins: Study on models
Authors: Judas Didier , Fradet Alain , Marechal Ernest
Published: April 2003

The thickening reaction of polyester resins is investigated using model compounds, diesters or polyesters of 1,2‐propanediol and phthalic acid with dihydroxy or dicarboxy end groups. Soluble magnesium acetylacetonate was found to be an effective thickener, and for the first time it was possible to study a thickening reaction in homogeneous media (THF solutions). The results are compared with those obtained with MgO. The proposed mechanism supposes that the central step consists of the formation and the aggregation of magnesium carboxylates in ionic areas, with entanglement of attached polyester chains. This fits our experimental results better than the hypothesis of coordination of magnesium carboxylates by ester or hydroxyl groups of the chains2–6 or than the hypothesis of the formation of linear high molecular weight compounds.7–9
Radiation‐induced copolymerization of vinylene carbonate with methyl trifluoroacrylate
Authors: Otsuhata Kazushige , Watanabe Terutaka , Ishigaki Isao , Tabata Yoneho , Okamoto Jiro
Published: April 2003

Copolymerization of vinylene carbonate (VCA) with methyl trifluoroacrylate (MTFA) was carried out by gamma rays from 60Co at dose rates of 1 × 105 rad/h to 1 × 106 rad/h, temperatures of 0°C to 75°C, and molar ratios MTFA/VCA of 30/70 to 90/10 in the monomer mixture. By irradiation, VCA reacted with MTFA to give a white powder copolymer with low molecular weight. The copolymerization rate has a maximum at a concentration of 70 mol % VCA, and is proportional to the 0.92 power of dose rate. The apparent activation energy was 1.3 kcal/mol. Equimolar copolymer was obtained at molar ratio MTFA/VCA of 50/50 to 10/90. The reactivity ratios of both monomers, VCA and MTFA, were determined to be r(VCA) = 0.3 and r(MTFA) = 0.07, respectively.
New polypyromellitimide films based on cyclotriphosphazene and bisaspartimide derived diamines
Authors: Kumar Devendra
Published: April 2003

Three new thermally stable polypyromellitimide films were made by the thermal cyclodehydration of the corresponding polyamic acids obtained by the polymerization of pyromellitic dianhydride with 4,4′‐bis{N2‐[4‐(4‐aminobenzyl)phenyl]aspartimido} diphenylmethane, 4,4′‐bis{N2‐[4‐(4‐aminophenoxy)phenyl]aspartimido} diphenylether, and bis(4‐aminophenoxy)tetrakis (4‐phthalamic acid phenoxy)cyclotriphosphazene. The bis(4‐aminophenoxy)tetrakis (4‐phthalamic acid phenoxy)cyclotriphosphazene was obtained from hexakis(4‐aminophenoxy)cyclotriphosphazene involving its reaction with phthalic anhydride. The structure of these materials and precursors were characterized by using Fourier‐transform‐infrared (FT–IR) and proton nuclear magnetic resonance spectroscopy. The thermal stabilities of the films were evaluated by the thermogravimetric analysis, showing char yields at 800°C ranging from 68% to 58% in a nitrogen atmosphere and 24% in air atmosphere.
Dependence of computed copolymer reactivity ratios on the calculation method. I. Effect of experimental setup
Authors: Hautus F. L. M. , Linssen H. N. , German A. L.
Published: April 2003

Five calculation methods for estimating reactivity ratios are compared. Two of these methods are only valid at low conversion, two methods are assumed to be valid up to high conversion, and the fifth method is the integrated form of the copolymer equation. Data were simulated for selected couples of r‐values and two conversion levels. The data were randomly disturbed by normal error with mean zero. As (the) monomer feed ratio(s) will be drifting during the course of reaction, the influence of an approximated monomer feed ratio on the r‐values calculated was also examined. When conversion is low, all methods give estimates with low precision. High conversion results in larger precision, however, for several methods bias appears. For calculation methods that need information about an approximated monomer feed ratio, the influence of this approximation appears to be rather important especially if the r‐values are dissimilar or conversion is high.