bluuebunny/crossref_metadata_2025 huggingface dataset:
Gamma‐oxidation of linear low density polyethylenes: Ethylene–butene and ethylene–hexene copolymers
Authors: Tidjani Adams , Arnaud René
Published: April 2003

Different linear low density polyethylenes (LLDPEs) based on hexene and butene comonomer were irradiated with γ‐rays under air. The oxidation products have been quantified using NO and SF4 treatments by IR spectroscopy. An FTIR examination displayed unexpected products such as free hydroperoxides and trans‐vinylenes. It was found that the type of α‐olefin used to process LLDPE films may influence the mechanism of oxidation. Parameters such as the melt index and the density seem to affect the γ‐oxidation rate. © 1993 John Wiley & Sons, Inc.
Synthesis and some properties of a polyamide containing trans‐2,5‐linked tetrahydropyran rings in the main chain
Authors: Okada Masahiko , Hayakawa Toshiyuki
Published: April 2003

A novel polyamide containing trans‐2,5‐linked tetrahydropyran rings in the main chain, poly(trans‐tetrahydropyran‐2,5‐diyliminocarbonyl) (trans‐polyamide 6), was synthesized by the two‐stage polycondensation of ethyl or 2,2,2‐trifluoroethyl trans‐5‐aminotetrahydropyran‐2‐carboxylate (5b or 5c). The polycondensation was carried out first in m‐cresol at 180°C. The isolated polymer of a relatively low molecular weight was then allowed to react further in a solid state at different temperatures between 180 and 230°C under vacuum. The trans‐polyamide 6 thus obtained was soluble only in protic solvents such as m‐cresol, 2,2,2‐trifluoroethanol, 1,1,1,3,3,3‐hexafluoro‐2‐isopropanol, and trifluoroacetic acid. The viscosity numbers of 6 were up to 0.46 dL/g in m‐cresol at 25°C. DSC and TGA analyses of 6 showed that the thermal decomposition occurred at about 350°C in nitrogen, whereas a rapid weight decrease due to the thermooxidative decomposition started at about 300°C in air. The moisture sorption isotherm was determined on coarsely ground samples of 6 at 25°C and compared with those for the structurally‐related polyamides 2 and 4. © 1993 John Wiley & Sons, Inc.
Free radical copolymerization of furfuryl acrylate and 2‐hydroxyethyl‐methacrylate
Authors: Zaldívar Dionisio , Peniche Carlos , Bulay Anna , Román Julio San
Published: April 2003

Copolymers of furfuryl acrylate (F) and 2‐hydroxyethyl methacrylate (H) were prepared by free radical polymerization in DMF solution at 50°C, using 2,2′‐azobisisobutyronitrile (AIBN) as initiator. The reactivity ratios of both monomers were calculated according to the general copolymerization equation using the Fineman‐Ross and Kelen‐Tüdös linearization methods, as well as the Tidwell and Mortimer nonlinear least‐squares treatment. The reactivity ratios obtained were rF = 0.93 and rH = 1.42. The microstructure of copolymer chains is described on the basis of first‐order Markov statistics, and the copolymer glass transition temperatures were determined calorimetrically. The variation of Tg with the copolymer composition is discussed according to modern methods, considering the sequence distribution of monomeric units along the copolymer chains. Also the Tg of the corresponding homopolymers was determined giving the values Tg(F) = 321 K and Tg(H) = 358 K, whereas the Tg of the corresponding alternating diad has an average value of TgFH = 326 K. © 1993 John Wiley & Sons, Inc.
Monoesterification of styrene–maleic anhydride copolymers with alcohols in ethyl benzene: Catalysis and kinetics
Authors: Hu G. H. , Lindt J. T.
Published: April 2003

A kinetic investigation on the monoesterification reaction of the maleic anhydride residue (MA) in styrene‐maleic anhydride copolymers with aliphatic alcohols was carried out in ethyl benzene solution. By comparison to classic catalysts such as tributylamine (TBA) and pyridine, 4‐dimethylaminopyridine (4DMAP) is by far the most effective catalyst for this reaction. While both general base and nucleophilic mechanisms contribute to the reaction catalyzed by TBA or pyridine, a nucleophilic mechanism prevails with 4DMAP. This reaction is reversible, and its chemical equilibrium constant decreases significantly with increasing temperature. Both kinetic and thermodynamic results showed that in the presence of 4DMAP, the forward and reverse reactions are second and first order, respectively. The existence of side reactions, reactivity of two styrene‐maleic anhydride copolymers of different MA contents as well as two aliphatic alcohols of different lengths are also addressed. © 1993 John Wiley & Sons, Inc.
Fire‐ and heat‐resistant matrix resins based on ethynyl‐substituted aromatic cyclotriphosphazenes
Authors: Kumar Devendra , Gupta Alka D. , Khullar Mrignaini
Published: April 2003

A novel class of fire‐ and heat‐resistant matrix resins has been synthesized by thermal polymerization of ethynyl‐substituted aromatic cyclotriphosphazenes. Thermal polymerization of new tris[4‐(4′‐ethynylbenzanilido)phenoxy]tris(phenoxy) cyclotriphosphazene (III) and tris[4‐(4′‐ethynylphthalimido)phenoxy]tris(phenoxy)cyclotriphosphazene (VII) at 250°C for 1–1.5 h gave tough polymers. The thermal stabilities of the polymers were evaluated in nitrogen and in air by thermogravimetric analysis (TGA). The synthesised polymers were stable to 400–410°C and showed char yield of 78–65% at 800°C in nitrogen and of 78–69% at 700°C in air. The ethynyl‐substituted polymer precursor (III) was synthesised by the reaction of tris(4‐aminophenoxy)tris(phenoxy)cyclotriphosphazene (I) with 4‐ethynylbenzoyl chloride. The polymer precursor (VII) was synthesised by a solution condensation of I with 4‐ethynylphthalic anhydride followed by in situ thermal cyclodehydration at 150°C. The structure of polymer precursors was characterized using proton nuclear magnetic resonance (1H‐NMR), infrared (IR) spectroscopy, and elemental analysis. The curing of polymer precursors was monitored by differential scanning calorimetery (DSC) and IR spectroscopy. The synthesised matrix resins are potential candidates for the development of heat‐ and fire‐resistant fiber‐reinforced composites. © 1993 John Wiley & Sons, Inc.
Photocrosslinking of acrylated natural rubber
Authors: Le Xuan H. , Decker C.
Published: April 2003

Photocrosslinkable elastomers with pendent acrylate groups have been synthesized by ringopening reaction of epoxidized natural rubber with acrylic acid. The kinetics of the acrylation reaction has been studied by infrared spectroscopy and shown to obey a simple first‐order law. The acrylated natural rubber undergoes a fast crosslinking‐polymerization when it is exposed to UV radiation in the presence of an aryl ketone photoinitiator, with formation of a tridimensional polymer network within a few seconds. The cure kinetics has been studied in real time by monitoring the disappearance of the IR absorption of the grafted acrylate double bond. The rate of polymerization was found to increase linearly with the degree of acrylation of the rubber, reaching values up to 3 mol kg−1 s−1. The isoprene double bond, which is inactive in virgin natural rubber, also undergoes polymerization upon UV exposure when epoxy or acrylate groups are present. The UV‐cured polymer becomes totally insoluble in the organic solvents and exhibits remarkable mechanical properties, such as hardness, flexibility, and impact resistance. The gel fraction and the hardness were both shown to increase with the degree of acrylation and with the cure extent. © 1993 John Wiley & Sons, Inc.
Syntheses and some fluorescence properties of poly(2‐methacrylamido‐3‐arylpropionic acid)
Authors: Morishima Yotaro , Tominaga Yukio , Nomura Shigeki , Kamachi Mikiharu
Published: April 2003

2‐Methacrylamido‐3‐arylpropionic acid, where aryl is 1‐naphthyl (M1NpPA), 2‐naphthyl (M2NpPA), or 1‐pyrenyl (M1PyPA), was synthesized. Free radical polymerization gave polymers which were soluble in water at pH > 6. In aqueous solution, poly(M1NpPA) and poly(M2NpPA) exhibited strong excimer fluorescence as a dominant component, whereas poly(M1PvPA) showed weak monomer fluorescence as a main component. Excitation spectra and fluorescence quenching by Tl+ ions suggested that naphthyl groups in poly(M1NpPA) and poly(M2NpPA) interacted so as to form excimer sites, by which migrating excited singlets were trapped, leading to the strong excimer emission. It was suggested, however, that pyrenyl groups in poly(M1PyPA) were sterically so constrained that they could not attain the full‐overlap excimer conformation but could only interact to form self‐quenching sites, to which energy migration occurred, leading to weak fluorescence. © 1993 John Wiley & Sons, Inc.
Heat‐resistant polymers from melt‐processable bisimido‐bisphthalonitriles
Authors: Kumar Devendra , Razdan Uday , Gupta Alka D.
Published: April 2003

Heat‐resistant polymers which are processable into void‐free components and suitable for composite applications have been synthesized by thermal/chemical polymerization of four newly developed bisimido‐bisphthalonitriles containing silicon, ether, carbonyl, and hexafluoroisopropylidene groups. Thermal polymerization involving addition reactions was performed at 200–275°C for 2–10 h and then post‐curing at 310°C for 10 h. Polymers VI, VII, VIII, and IX were obtained. The thermal polymerization was monitored using infrared spectroscopy. Thermal polymerization was also carried out in the presence of an aromatic diamine. A polyhexasocyclane (V) was synthesized by condensation polymerization of ether containing bisimido‐bisphthalonitrile with 4,4′‐diaminodiphenyl ether in solvent phenol. The synthesized polymers were evaluated for thermal stability using dynamic thermogravimetric analysis (TGA). Polymers VII, VIII, IX, and X showed thermal decomposition temperature in the range of 475–500°C in nitrogen and air atmosphere. The char yield of the polymers was in the range of 60–69% in nitrogen at 800°C. This study indicated that synthesized thermosetting polymers from ether and keto containing bisimido‐bisphthalo‐nitrile are potential candidates for development of graphite composites. © 1993 John Wiley & Sons, Inc.
Polymer drying. VIII. Molecular interpretations of desorption from polystyrene–liquid systems
Authors: Errede L. A. , Henrich P. J. , Pearson R. , Van Bogart J. W. C.
Published: April 2003

The results obtained in time studies that monitored evaporation from liquid‐saturated poly(styrene‐co‐divinylbenzene) to virtual dryness at temperatures ranging from 20 to 80°C confirm those reported earlier for multireplicated time studies at 23 ± 1°C; i.e., when the residual composition (αt, in sorbed molecules per phenyl group) attains the glassy state composition, the value of αt thereafter is given by a linear combination of no more than six exponential decay functions. The logarithms of the rate constants (ki) for decay of these populations at a given temperature decreased linearly with i, the population identification number in the order of decreasing decay rate. The Arrhenius activation energy (ΔEi) for increase in ki with temperature was characteristic of the sorbed species, but it was independent of i. The logarithms of the frequency factors (Ai) decreased linearly with i, the slope of which was numerically equal to that observed for the corresponding ki relationships, signifying that the stepwise decrease of the latter at a given temperature is attributable primarily to a corresponding incremental decrease in entropy. It is suggested that this reflects discrete changes in the molecular structure of polymeric inclusion complexes formed during the transition from the rubbery to the glassy state, as discussed in the text. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of aromatic poly(ether sulfone)s containing pendant sodium sulfonate groups
Authors: Ueda Mitsuru , Toyota Hidetsugu , Ouchi Takao , Sugiyama Jun‐Ichi , Yonetake Koichiro , Masuko Toru , Teramoto Takero
Published: April 2003

Poly(ether sulfone)s containing pendant sodium sulfonate groups were prepared by the aromatic nucleophilic substitution reaction of 4,4′‐dichlorodiphenylsulfone (1) and sodium 5,5′‐sulfonylbis (2‐chlorobenzenesulfonate) (2) with bisphenols (3) in the presence of potassium carbonate in N,N‐dimethylacetamide. A new monomer 2 containing the sodium sulfonate groups was synthesized by the sulfonation of 1 with fuming sulfuric acid. The polycondensation proceeded smoothly at 170°C and produced the desired poly(ether sulfone)s containing the sodium sulfonate with inherent viscosities up to 1.2 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, m‐cresol, and dichloromethane. The thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 460°C in nitrogen atmosphere. Both the glass transition temperatures and hydrophilicity of the polymers increased with increasing their concentrations of sodium sulfonate groups. © 1993 John Wiley & Sons, Inc.
Thermally reversible polymer linkages. II. Linear addition polymers
Authors: Wagener K. B. , Engle L. P.
Published: April 2003

The stepwise addition polymerization reactions of bisazlactones [bis(2‐oxazolin‐5‐one)s] and a variety of 4,4′‐bisphenols have been studied for the purpose of making thermally reversible linear polymers. Thus polymerization occurs at or near room temperature, while depolymerization yielding the two monomer species occurs at elevated temperatures. The synthesis of oligomers in solution without the use of catalyst occurs for the reaction of bisazlactones with bisphenols containing an electron‐withdrawing moiety between the two phenol groups of the bisphenol. These oligomers regenerate the bisphenol and bisazlactone monomers upon heating to 165–200°C for several hours under dry box conditions. In many cases, these reactions follow the same patterns of reactivity observed in model studies. This chemistry may be useful for forming degradable or recyclable polymers, where shortchain prepolymers, or macromonomers, endcapped with azlactone and phenol moieties could be used to form high molecular weight polymers that are thermoreversible. Such a reaction system might also be used for preventing reactions of bisphenols and/or bisazlactones at low temperatures, with the desired reaction initiated by formation of the reactive species at elevated temperatures. Envisioned uses in this case might be thermally triggered crosslinking or polymerization reactions, or temperature controlled drug release. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of oligocyclosiloxanes via the hydrosilation of vinylsilanes and vinylsiloxanes with heptamethylcyclotetrasiloxane
Authors: Chang Pao‐Sun , Hughes Thomas S. , Zhang Yingchao , Webster Geoffrey R. , Poczynok Dana , Buese Mark A.
Published: April 2003

The preparation of oligocyclosiloxanes via hydrosilation reactions has been investigated. Hydrosilation reactions employing heptamethylcyclotetrasiloxane and vinyl‐containing silanes and siloxanes yielded a variety of oligocyclosiloxanes with various numbers of cyclosiloxane rings connected through tri‐, tetra‐, penta‐, hexa‐, hepta‐, or octafunctional junctions. The oligocyclosiloxanes were characterized by gas chromatography, IR spectroscopy, 29Si‐, 1H‐, and 13C‐NMR spectroscopy, elemental analysis, and vapor phase osmometry. The polycyclics were redistributed with hexamethyldisiloxane and the resulting fragments analyzed by gas chromatography. All results were consistent with the formation of isomeric oligocyclosiloxanes due to a lack of absolute regioselectivity of the hydrosilation reaction. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of new block copolymers based on poly(ether sulfone) and polyimides
Authors: Oishi Yoshiyuki , Nakata Shoichi , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

New poly(ether sulfone)‐polyimide block copolymers were synthesized from α,ω‐diamineterminated poly(ether sulfone) oligomer, aromatic diamines, and aromatic tetracarboxylic dianhydrides by low‐temperature solution polymerization and subsequent thermal imidization. The block copolymers were insoluble in organic solvents. The multiblock copolymers obtained by the two‐pot method showed microphase separation, while the random block copolymers by the one‐pot method had single phase morphology. The mechanical properties of the block copolymers were greatly improved by the introduction of polyimide into the poly(ether sulfone). © 1993 John Wiley & Sons, Inc.
Poly(N‐isopropylacrylamide). I. Interactions with sodium dodecyl sulfate measured by conductivity
Authors: Wu X. Y. , Pelton R. H. , Tam K. C. , Woods D. R. , Hamielec A. E.
Published: April 2003

Conductometric titration of poly(N‐isopropylacrylamide) (polyNIPAM) with sodium dodecyl sulfate (SDS) gave two apparent transitions labeled C1 and C2. The C1 transition was independent of polyNIPAM concentration in the 0.05–0.3 wt % range, whereas C2 was proportional to the polymer concentration. C1 corresponded to the onset of binding of surfactant with polymer. Arguments based on a simple mass action model for micellization are presented to show that C2, the second transition, is not due to any simple explanation such as being the point above which only free micelles are formed with surfactant addition. The cloud point of polyNIPAM increased with the amount of bound surfactant. This was attributed to electrostatic contribution of bound sulfate groups to the increased solubility of polyNIPAM. © 1993 John Wiley & Sons, Inc.
Studies on thermotropic liquid‐crystalline polymers: Part X. Synthesis and properties of crosslinkable aromatic copoly(ester)s containing conjugated double bonds
Authors: Hsu Keh‐Ying , Chang Teh‐Chou , Li Chen‐Hui
Published: April 2003

A series of aromatic copoly(ester)s containing conjugated double bonds was prepared from p‐phenylene bis(acrylic acid) (PPBA) with a mixture of methylhydroquinone (MHQ) and various hydroxycarboxylic acids in the presence of diphenylchlorophosphate (DPCP) and pyridine as a catalyst and solvent. The phase behavior of these polymers was studied by differential scanning calorimetry (DSC) and thermal optical polarized microscopy. Under an optical polarized microscope all copoly(ester)s show a nematic thermotropic liquidcrystalline phase. Upon heating, these polymers undergo a photocrosslinking reaction characterized by IR and solubility analysis. This crosslinking reaction also takes place in the liquid‐crystalline phase with the retention of the nematic order in the final crosslinked solid. © 1993 John Wiley & Sons, Inc.
Synthesis of nylon 6–clay hybrid by montmorillonite intercalated with ϵ‐caprolactam
Authors: Kojima Yoshitsugu , Usuki Arimitsu , Kawasumi Masaya , Okada Akane , Kurauchi Toshio , Kamigaito Osami
Published: April 2003

It was found that montmorillonite was intercalated with ϵ‐caprolactam. X‐ray diffraction revealed that the chain axes of the ϵ‐caprolactam were parallel to the montmorillonite plates. The intercalated montmorillonite was swollen by molten ϵ‐caprolactam at 200°C. ϵ‐Caprolactam and 6‐aminocaproic acid (accelerator) were polymerized with the intercalated montmorillonite at 260°C for 6 h, yielding a nylon 6‐clay hybrid. X‐ray diffraction and transmission electron micrography revealed that the silicate layers of the hybrid were uniformly dispersed in the nylon 6 matrix. Mechanical properties of the hybrid were improved. The strength and the modulus of the hybrid increased compared with the previously reported nylon 6 clay‐hybrid (NCH) synthesized by montmorillonite intercalated with 12‐aminolauric acid. The heat distortion temperature (HDT) of the hybrid was 164°C, which was 12°C higher than that of NCH. © 1993 John Wiley & Sons, Inc.
Photophysics of a polyether containing tetramethylanthracene units
Authors: Bruss J. M. (Tingerthal) , Sahyun M. R. V. , Schmidt E. , Sharma D. K.
Published: April 2003

PESA is a rigid rod polymer incorporating anthrylene units in its backbone. The photophysics of PESA in solution are representative of the isolated anthracene chromophore. In the solid state, strong interchain excimer emission is observed. Solid PESA undergoes efficient photocrosslinking which we assign to interchain anthracene dimer formation. Competitive quenching of photocrosslinking by diphenyliodonium hexafluorophosphate suggests that localized singlet excitation energy can migrate among chains until trapped by excimer formation. The excimer state is intermediate in photocrosslinking. © 1993 John Wiley & Sons, Inc.
Synthesis of polyimide and poly(imide‐benzoxazole) in polyphosphoric acid
Authors: Sakaguchi Yoshimitsu , Kato Yasuo
Published: April 2003

A polyimide made from 4,4′‐diaminodiphenyl ether (ODA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) was synthesized in polyphosphoric acid. Although the polymerization proceeded heterogeneously, a polyimide with an inherent viscosity of 0.90 was obtained, and a tough and flexible film was made from this polyimide. This polymerization was a one‐step reaction including polycondensation and imidization; this was also confirmed by a model reaction between aniline and phthalic anhydride. Utilizing this polymerization method, 3,3′‐dihydroxy‐4,4′‐diaminobiphenyl and 2 mol of 4‐aminobenzoic acid were reacted in PPA, then BPDA was reacted to obtain an alternate copolymer containing imide and oxazole rings. This reaction gave a homogeneous solution of the poly(imide‐benzoxazole). © 1993 John Wiley & Sons, Inc.
Ozone‐induced graft polymerization onto polymer surface
Authors: Fujimoto Keiji , Takebayashi Yoshihiro , Inoue Hiroyuki , Ikada Yoshito
Published: April 2003

Ozone‐induced graft polymerization was carried out to improve polymer surfaces. The polymers were exposed to ozone and the surface density of peroxides formed was determined by three methods; iodide, DPPH, and peroxidase method. The peroxide production could be readily controlled by the ozone concentration and the ozone exposure time. In addition, it was dependent on the kind of polymer. Further, it seemed probable that the ozone oxidation introduced peroxides not only on the outermost surface but also into a layer deeper from the outermost surface. Such polymeric peroxides were capable of initiating graft polymerization onto PU. All the physical and biological measurements on the grafted surface indicated that ozone‐induced graft polymerization has effectively made the PU surface covered with the grafted water‐soluble chains, their location being restricted to the film surface region. The interaction of the PU surface with blood components could be greatly reduced by the surface graft polymerization. © 1993 John Wiley & Sons, Inc.
FTIR studies of polyimides. II. Factors affecting quantitative measurement
Authors: Pryde C. A.
Published: April 2003

Measurement of imidization by IR spectroscopy has frequently been reported to give results that are either insensitive to changes in the latter part of the cure or in conflict with observations by other methods. However, an analysis of imide formation using the 1370 cm−1 band (CN stretch) in conjunction with the 1500 cm−1 aromatic band as an internal standard appears capable of giving precise, internally consistent measurements for the most commonly used polyimide structures, for samples that are measured in transmission. Measurements of imide content in ultrathin films by grazing incidence reflection spectroscopy appear to be at least semiquantitative. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of a self‐crosslinkable polymer from cardanol: Autooxidation of poly(cardanyl acrylate) to crosslinked film
Authors: John George , Pillai C. K. S.
Published: April 2003

Cardanyl acrylate (CA), a monomer that yields crosslinkable copolymers, was synthesized by the reaction of cardanol with acryloyl chloride. A linear polymer was obtained by solution polymerization of the monomer in toluene using 0.8% azobisisobutyronitrile as initiator. Upon removal of solvent, the polymer undergoes crosslinking on exposure to air (or UV light) to give an insoluble transparent film. However, in bulk and suspension polymerization the polymer undergoes in situ crosslinking in the absence of any crosslinking agent. The polymer was characterized by IR, NMR, DSC, and GPC. The crosslinking reaction of soluble polymer on exposure to air at ambient conditions was explained by the hydroperoxide theory. © 1993 John Wiley & Sons, Inc.
Water‐soluble copolymers. XLII. Cationic polyelectrolytes of acrylamide and 2‐acrylamido‐2‐methylpropanetrimethylammonium chloride
Authors: Mccormick Charles L. , Salazar Luis C.
Published: April 2003

The new monomer 2‐acrylamido‐2‐methylpropanetrimethylammonium chloride (AMP‐TAC, M2) has been synthesized. Free radical copolymerization with acrylamide (AM, M1) in feed ratios varying from 10 to 50 mol % AMPTAC gave the cationic ATAM series. Copolymer compositions were determined from 13C‐NMR. The reactivity ratio product r1r2 was found to be 0.62. Molecular weights varied from 1.4 to 16.5 × 106 g/mol for the copolymers. Turbidimetric studies showed aqueous solutions of the copolymers to be phase stable in the presence of CaCl2 and Na2CO3 up to 100°C. Solution behavior was independent of pH in the range of 3 to 11, and temperature in the range of 25 to 60°C. Intrinsic viscosities of the cationic copolymers decreased with the addition of electrolytes; however, some samples showed curvature in plots of intrinsic viscosity versus the inverse square root of ionic strength. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of new block copolymers based on poly(ether sulfone) and aramids
Authors: Oishi Yoshiyuki , Nakata Shoichi , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

New poly(ether sulfone)–aramid block copolymers were synthesized from an α, ω‐diamineterminated poly(ether sulfone) oligomer, aromatic diamines, and aromatic dicarboxylic acid chlorides by the low‐temperature solution polycondensation in N‐methyl‐2‐pyrrolidone. By the introduction of aramid into the poly(ether sulfone), the glass transition temperatures of the block copolymers rose and the mechanical properties were significantly improved. Microphase separation, which often takes place in many block copolymers, did not occur in the present block copolymers. © 1993 John Wiley & Sons, Inc.
Novel nonionic and cationic hydrogels prepared from N‐vinylacetamide
Authors: Akashi Mitsuru , Saihata Shinya , Yashima Eiji , Sugita Shuichi , Marumo Kuniomi
Published: April 2003

Poly(N‐vinylacetamide) (polyNVA) hydrogels were prepared by the copolymerization of N‐vinylacetamide (NVA) with divinyl compounds such as methylene‐bis‐acrylamide, methylene‐bis‐NVA, and butylene‐bis‐NVA in a high yield. The resulting hydrogels were more stable than polyacrylamide gel and showed quite a high swelling property in a wide range of pH (1–12) and even in a 5M NaCl solution. They showed not only typical characteristics nonionic hydrogels, but also an amphiphilic property and they swelled well in some organic solvents. When the gels were partially hydrolyzed, cationic hydrogels, i.e., crosslinked poly(NVA‐co‐vinylamine), were collected. The resulting superabsorbent hydrogels absorbed 400 times of water. © 1993 John Wiley & Sons, Inc.
Effects of the polymer‐support on the synthesis of 2,4‐dibromophenyl allyl ether in a triphase catalysis
Authors: Wang Maw‐Ling , Yu Chun‐Chi
Published: April 2003

The synthesis of 2,4‐dibromophenyl allyl ether by reacting allyl bromide with 2,4‐dibromophenol in an organic solvent/alkali solution by triphase catalysis was studied. A macroporous polymer pellet which served as the support of the catalyst was prepared by reacting styrene monomer with chloromethyl styrene and divinylbenzene through suspension polymerization. Tri‐n‐butylamine was immobilized on the surface of the polymer pellet to form the triphase catalysts. Immobilization of the catalyst on the polymer support carried out in a mechanical agitator was suggested to obtain a high catalyst reactivity. In the three‐phase reaction, the effects of agitation speed, and the characteristics of the catalyst pellet which affect the conversion of allyl bromide in the three‐phase catalytic reaction were examined in detail. Based on the experimental data, the optimum operating parameters for preparing the triphase catalyst to get a high yield of 2,4‐dibromophenyl allyl ether were: using a low degree of polymer crosslinking (2%), and small particle size. The yield of the product obtained from the present study is higher than that which was obtained in a two‐phase reaction. © 1993 John Wiley & Sons, Inc.
Optically‐active comb‐branch liquid crystalline polymers having the chiral center in the flexible spacer unit. III. Copolymers of (S)‐2‐(4′‐cyano‐4‐biphenylyloxy)‐1‐methylethoxy ethyl methacrylate and di[6‐(4‐methoxy‐4′‐oxybiphenyl) hexyl]‐2‐methylene butane‐1,4‐dioate
Authors: Cowie J. M. G. , Hunter H. W.
Published: April 2003

A new series of copolymers with optically‐active liquid crystalline side chain units has been synthesized from the comonomers (S)‐2‐[2‐(4′‐cyano‐4‐biphenylyloxy‐1‐methylethoxy]ethyl methacrylate (1) and di[6‐(4‐methoxy‐4′‐oxybiphenyl)hexyl]‐2‐methylene butane‐1,4‐dioate (4). Chiral nematic phases were exhibited by two members of the series, rich in monomer 1, while a smectic phase was exhibited in copolymers rich in 4. While it was thought possible that ordered chiral liquid crystalline phases may be induced by copolymerizing chiral mesogenic monomers with mesogenic derivatives of itaconic acid where the high side chain density encourages greater ordering in the system, no evidence of smectic C* phases could be found in the present systems. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of photosensitive polyimides from methylthiomethyl‐substituted 4,4′‐diaminodiphenylmethanes and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride
Authors: Chiang Wen‐Yen , Mei Wang‐Ping
Published: April 2003

A series of novel polyimides are synthesized by the reaction of 3,3′,4,4′‐benzophenonete‐tracarboxylic dianhydride (BTDA) with four methylthiomethyl‐substituted aromatic diamines: 3‐methylthiomethyl‐4,4′‐diaminodiphenylmethane (I), 3,3′‐dimethylthiomethyl‐4,4′‐diaminodiphenylmethane (II), 3,3′,5‐trimethylthiomethyl‐4,4′‐diaminodiphenylmethane (III), and 3,3′,5,5′‐tetramethylthiomethyl‐4,4′‐diaminodiphenylmethane (IV) in refluxing m‐cresol. The polyimide of diamine I and BTDA carrying only one pendant methylthiomethyl group in a repeating unit is readily soluble in m‐cresol, chloroform, and polar aprotic solvents. Increasing the number of the pendant group results in higher solubility. These fully imidized polyimides are also intrinsically photosensitive. The fraction of photoreactive benzophenone sites that relates to the rate and degree of completion of photocrosslinking reaction increases systematically with the increase of the pendant group content. As the average number of the pendant group in a repeating unit reaches 3, 63% of benzophenone sites are found to be photoreactive. These methylthiomethyl‐substituted polyimides possess moderate tensile strength which falls in the range of 67–81 MPa. As a result of the increase of methylthiomethyl content, this type of polyimide reveals higher glass transition temperature but lower thermal stability due to the considerable dimension of the pendant group and the ready cleavage nature of the CS bond. © 1993 John Wiley & Sons, Inc.
Polyisophthalamides with benzoyl pendent groups: Synthesis, characterization, and evaluation of properties
Authors: Lozano A. E. , De Abajo J. , De La Campa J. G.
Published: April 2003

Polyisophthalamides containing benzoyl pendent groups were prepared from 5‐benzoylisophthaloyl chloride and seven aromatic diamines, and their properties were compared with those of unsubstituted polyisophthalamides. The incorporation of one pendent benzoyl group per repeat unit brought about a decrease in the glass transition temperature of 10–30°C, relative to the unmodified polymers, while the thermal resistance (programmed TGA) remained unchanged or went down slightly. Other properties investigated were mechanical properties, solubility, and water absorption. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of liquid crystalline polyurethanes
Authors: Penczek Piotr , Frisch Kurt C. , Szczepaniak Barbara , Rudnik Ewa
Published: April 2003

Liquid crystalline polyurethanes were prepared from 4,4′‐bis(2‐hydroxyethoxy)biphenyl (BHBP) and 2,4‐tolylene diisocyanate (TDI). The effect of partial replacement of BHBP by 25–75 mol % poly(oxytetramethylene) diol (PTMO, Mn = 250) on the liquid crystalline properties was studied. The BHBP/TDI/PTMO polyurethanes were obtained by one‐ and two‐step polyaddition. The polyurethanes were investigated by DSC, polarizing microscopy, x‐ray, and IR spectroscopy. The molecular weight distribution was determined by GPC. The morphology of the polymers was investigated by the SALS method. Thermogravimetric investigations of the polyurethanes were also performed. All polyurethanes containing BHBP units have liquid crystalline properties. Partial replacement of BHBP by PTMO‐250 considerably changes the phase transition temperatures and the range of mesophase occurrence. More homogeneous polyurethanes were obtained, if the two‐step polyaddition method was applied. The polyaddition method affects the phase transition temperatures. © 1993 John Wiley & Sons, Inc.
Enzymatic polyesterification in organic media. Enzyme‐catalyzed synthesis of linear polyesters. I. Condensation polymerization of linear hydroxyesters. II. Ring‐opening polymerization of ϵ‐caprolactone
Authors: Knani Dafna , Gutman Arie L. , Kohn David H.
Published: April 2003

With the object to synthesize polyesters by enzymatic catalysis in organic media, two directions have been investigated: (1) the condensation polymerization of linear ω‐hydroxyesters and (2) the ring‐opening polymerization of lactones. The commercially‐available crude porcine pancreatic lipase (PPL), suspended in organic solvents, was the preferred enzyme for the reactions. In order to determine the optimal conditions for the condensation polymerization, the bifunctional methyl 6‐hydroxyhexanoate was used as a model compound to study the influence of the following parameters: type of the enzymecatalyst, kind of solvent, concentration, temperature, duration, size of the reaction mixture, and stirring. Film‐forming polyesters with a degree of polymerization (DP) up to about 100 were obtained from linear aliphatic hydroxyesters in n‐hexane at reflux temperature (69°C). Yet concurrently with the intermolecular condensation polymerization, macrolactones were also formed by intramolecular reaction. Two aromatic hydroxyesters did not react under these conditions. For the ring‐opening polymerization of lactones the reaction of ϵ‐caprolactone with methanol as the preferred nucleophile, was studied. Polyesters with a DP of up to 35 were obtained in n‐hexane at temperatures between 25 and 40°C. The degrees of polymerization of the polyesters were determined by comparative analyses of the end groups in the 1H‐NMR spectra and by determination of molecular weights either by vapor phase osmometry, gel permeation chromatography, or intrinsic viscosity. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of poly(2,6‐diarylphenylene oxide)s
Authors: Yang Hu , Hay Allan S.
Published: April 2003

The oxidative polymerization of 2,6‐diphenylphenol that contains substituents (fluoro, chloro, bromo, iodo, cyano, t‐butyl, phenoxy, methoxy, phthalimidyl) in the para‐positions of the pendant phenyl groups is described. The melting points of the monomers, with some exceptions, correlate with the glass transition temperatures and the melting points of the corresponding polymers. Random copolymers of some of these phenols with 2,6‐diphenylphenol have also been prepared and characterized. © 1993 John Wiley & Sons, Inc.
Direct polyesterification by use of phosphorus oxychloride and LiCl in pyridine
Authors: Higashi Fukuji , Kobayashi Akira , Shimazaki Hisashi
Published: April 2003

The reaction of the N‐phosphonium salt of pyridine derived from phosphorus oxychloride in pyridine was successfully used for the preparation of aromatic polyesters with high molecular weight when carried out in the presence of lithium chloride. In the copolycondensations of isophthalic and terephthalic acid with diphenols, the mode of reaction with the diacids was expected to produce several types of the diacid activated intermediates, which might control the sequences of the diacids in the copolymers. The possible variation of the sequences was studied in terms of the mode and copolymer properties such as glass transition temperatures and liquid crystalline transition temperatures. Competitive model reactions were carried out to discuss these relationships. © 1993 John Wiley & Sons, Inc.
Oxidation of polyethylene surface by glow discharge and subsequent graft copolymerization of acrylic acid
Authors: Wang Chee‐Chan , Hsiue Ging‐Ho
Published: April 2003

Plasma‐induced graft copolymerization of acrylic acid, which was incorporated into PE films, was investigated here. The influence of plasma conditions such as plasma treatment gases, power, pressure, time, monomer concentration, and graft copolymerization time on polymerization yield was determined. The samples were characterized by ESCA, IR, and water contact angle. A respective chemical shift of the C1s signal of Ar or O2 plasmatreated and untreated PE films was revealed by ESCA, in which the presence of the grafted PAAc was also verified. An increase in polymerization yield with plasma treatment duration and power was found. That the grafted copolymerization was limited to a very thin surface region was revealed by optical microscopy on the cross section of the grafted film. © 1993 John Wiley & Sons, Inc.
The mechanism of butadiene polymerization with the catalytic system NdCl3 · 3TBP(1C4H9)2AIH
Authors: Sabirov Z. M. , Minchenkova N. Kh. , Urazbaev V. N. , Monakov Yu. B.
Published: April 2003

The polymerization of butadiene with the catalytic system NdCl3 · 3TBP‐(1C4H9)2AlH (TBP‐tributyl phosphate) was studied. With regard to the anti‐syn‐isomerization of both free‐ and monomer‐complexed active centers, the kinetic scheme of the propagation reaction was shown to afford adequate descriptions of the experimental dependence of the polymer microstructure on the monomer concentration. Following the results of the quantum‐chemical calculations, it was assumed that the free molecules (1C4H9)2AlH coordinated competitively with the monomer molecules on the active centers in solution, which finally led to lower reactivity of the active centers. © 1993 John Wiley & Sons, Inc.
Synthesis of fusible and soluble conducting polyfluorene derivatives and their characteristics
Authors: Fukuda Masahiko , Sawada Keiji , Yoshino Katsumi
Published: April 2003

Conducting polyfluorene derivatives with alkyl chains—poly(9‐alkylfluorene)s and poly‐(9,9‐dialkylfluorene)s—have been synthesized by chemical polymerization utilizing FeCl3 as an oxidizing agent. The polymers obtained are found to be soluble in conventional organic solvents such as chloroform and have been characterized by 1H‐ and 13C‐NMR. The results indicate that the fluorene moeities are mainly linked in the 2,7′‐fashion to yield the straight chain polymer. The degree of polymerization is estimated (by gel permeation chromatography) to be of the order of 10. The polymers are found to be fusible and the thermal properties of the polymers have been characterized by differential scanning calorimetry. The glass transition temperature is found to decrease with an increase of the alkyl chain length. © 1993 John Wiley & Sons, Inc.
Star‐shaped polymers by living cationic polymerization. VII. Amphiphilic graft polymers of vinyl ethers with hydroxyl groups: Synthesis and host–guest interaction
Authors: Kanaoka Shokyoku , Sueoka Masanori , Sawamoto Mitsuo , Higashimura Toshinobu
Published: April 2003

Amphiphilic graft polymers of vinyl ethers (VEs) (6) where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(alkyl vinyl ether) segment were prepared on the basis of living cationic polymerization, and their properties and functions were compared with the corresponding amphiphilic star‐shaped polymers. In toluene at −15°C, the HI/ZnI2‐initiated living block polymer 2 of an ester‐containing VE (CH2CHOCH2CH2OCOCH3) and isobutyl VE (IBVE) was terminated with the diethyl 2‐(vinyloxy)ethylmalonate anion [3; ΦC(COOEt)2CH2CH2OCH  CH2] (2/3 = 1/2 mole ratio) to give a macromonomer (4), H[CH2CH(OCH2CH2OCOCH3)] m‐[CH2CH(OiBu)]nC(COOEt)2CH2CH2OCH  CH2 (m = 5, n = 15; M̄n = 2600, M̄w/M̄n = 1.13, 1.10 vinyl groups/chain). Subsequently, 4 was homopolymerized with HI/ZnI2 in toluene at −15°C. In 3 h, 85% of 4 was consumed and a graft polymer (5) was obtained [M̄w = 15000, DPn (for 4) = 6]. The apparent M̄w (10,900) of 5 by size‐exclusion chromatography (SEC) is smaller than that by light scattering as well as that (18,300) by SEC of the corresponding linear polymer with the almost same molecular weight, indicating the formation of a multi‐branched structure. Hydrolysis of the pendant esters in 5 gave the amphiphilic graft polymer 6 where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(IBVE) segment. The graft polymer 6 was found to interact specifically with small organic molecules (guests) with polar functional groups, and 6 differed in solubility and host‐guest interaction from the corresponding star‐shaped polymer. © 1993 John Wiley & Sons, Inc.
Polyelectrolyte titration using fluorescent indicator. I. Direct titration of anionic and cationic polyelectrolytes with 10−4N standard solutions
Authors: Tanaka Hiroo , Sakamoto Yumi
Published: April 2003

The polyelectrolyte titration, which was originally called colloid titration, is based on the stoichiometric reaction between positively charged colloidal particles and negatively charged ones. In the conventional method, the metachromatic color change of the indicator, toluidine blue, from blue to red‐purple has been applied for the determination of the end point in the titration. 2.5 × 10−3N potassium polyvinylsulfonate (KPVS) is usually used as the standard titrant. In this work, fluorescent indicators such as 6‐(p‐toluidino)‐2‐naphthalene sulfonate (TNS), acridine orange, etc., have been introduced. The fluorescence intensity was measured using the spectrophotometer equipped with magnetic stirrer and connected with a vinyl tube attached to the hand piston burette. For example, TNS is practically nonfluorescent, but it exhibits strong fluorescence when it is bound to a cationic polyelectrolyte (CP). The fluorescence of the TNS–CP complex is diminished by titration with KPVS standard solution since TNS is liberated from the complex by substitution with KPVS. After the equivalent point, the fluorescence intensity becomes constant and the end point can thus be detected by that point. It has been elucidated that the very dilute standard solution like 1 × 10−4N can be used because the sensitivity of fluorescence detection is extremely high. © 1993 John Wiley & Sons, Inc.
Polyelectrolyte titration using fluorescent indicator. II. Analysis of cationic starches and flocculants
Authors: Tanaka Hiroo , Sakamoto Yumi
Published: April 2003

In the conventional polyelectrolyte titration, toluidine blue (TB) has been used exclusively as an indicator. This is a very convenient method for analyses of polyelectrolytes with fairly high charge density, but it is very difficult, or impossible, to analyze samples with low charge density such as commercial cationic starches because of the unclear color change of TB at the end point. Also analyses of polyelectrolytes with ultrahigh molecular weights over 107 (such as common flocculants) are often accompanied by serious errors. Usually, the concentration of standard titrant is around 0.2 × 10−3 N. On the other hand, the standard titrant with very dilute concentration such as 1 × 10−4 N can be used in the polyelectrolyte titration using a fluorescent indicator because the sensitivity of fluorescence detection is extremely high. It has been elucidated that this method can be employed for accurate analyses of cationic starches, cationic and anionic flocculants, and also for determination of sulfonic and carboxyl groups contained in the same molecule by the titration at pH 2.8 and 9.5, respectively. © 1993 John Wiley & Sons, Inc.
Confirmation of the presence of imine bonds in thermally cured polyimides
Authors: Saini Ajay K. , Carlin Clifford M. , Patterson Howard H.
Published: April 2003

Model compounds for imines formed during the thermal curing of short chain polyimides have been synthesized and characterized. These compounds have imine bonds (CN) formed by the nucleophilic attack of primary amines on imide carbonyls. The CN stretching mode appears at 1649–1664 cm−1 in the Raman and infrared spectra of these compounds and the band assigned to the carbonyl mode in an imide ring with an imine bond appears near 1740 cm−1. These compounds have been prepared and characterized to verify the conclusions of a previously reported study in which bands observed in thermally cured short chain polyimides at 1656 and 1742 cm−1 were assigned as the CN and associated CO modes, respectively. It has also been confirmed that the CN stretching mode in the imide model compounds is inherently IR weak and can only be seen if the concentration of imine species is high. © 1993 John Wiley & Sons, Inc.
Functionalization of polypropylene by hydroboration
Authors: Chung T. C. , Rhubright D.
Published: April 2003

This article relates to functionalized polypropylene with high molecular weight and high crystallinity. The chemistry involves the hydroboration of poly(propylene‐co‐1,4‐hexadiene) with borane reagents, such as diborane and 9‐BBN. In turn, the borane‐containing polymers are very versatile and can be easily converted to various functionalized polymers under mild reaction conditions. Despite the heterogeneous reaction conditions, both hydroboration and interconversion reactions were very effective using appropriate solvents. Apparently, the double bonds in the side chains are located in the amorphous phase and are ready for reaction with reagents. Overall, this functionalization process preserves the molecular weight and most of the crystallinity of poly(propylene‐co‐1,4‐hexadiene). © 1993 John Wiley & Sons, Inc.
Studies on bulk polymerization of methyl methacrylate. I. Thermal polymerization
Authors: Clouet G. , Chaumont P. , Corpart P.
Published: April 2003

The thermal bulk polymerization of methyl methacrylate (MMA) in a wide range of temperatures has been studied using a dilatometric reactor. It is shown that, irrespective of the care taken to purify the MMA, the evolution of the time‐conversion curve can be explained only if we account for the presence of an impurity associated with the monomer acting as a free radical initiator. The activation energy for the decomposition of this impurity has been estimated as 98 kJ/mol. Having accounted for this impurity, the activation energy for the real thermal polymerization of the MMA has been estimated to be 75 kJ/mol. © 1993 John Wiley & Sons, Inc.
Ring dehydration mechanisms and kinetics of polyamic acid models in solution and in the solid state
Authors: Grenier‐Loustalot Marie‐Florence , Gillard Marguerite , Joubert Frédréric , Grenier Philippe
Published: April 2003

We have synthesized and studied the ring dehydration mechanisms and kinetics of polyamic acid models in solution and in the solid state using13C‐NMR (solid and liquid), HPLC, FTIR, and x‐ray diffraction. Results obtained in solution show the role of temperature, catalysts, and the basicity of the amine in ring dehydration mechanisms and kinetics, as well as conformation and intramolecular bonds in the amic acid bond in the solid state. © 1993 John Wiley & Sons, Inc.