bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of chain end group composition and concentration on the properties of bisphenol A–tetrabromobisphenol A copolycarbonates
Authors: Marks M. J. , Sekinger J. K.
Published: April 2003

The types and concentrations of end groups present in bisphenol A‐tetrabromobisphenol A copolycarbonates (BA‐TBBA coPCs) have major effects on the copolymer solution washability and thermal stability. Six types of coPC end groups are possible: two by monophenol capping of each comonomer, two phenolics (BA‐OH and TBBA‐OH), and two carbamates (one from each comonomer). BA‐TBBA coPCs were prepared by typical solution and interfacial methods and their phenolic and carbamate end group concentrations were correlated with their solution washability and thermal discoloration. Both phenolic and carbamate end groups proved deleterious to these two copolymer properties. An improved interfacial process that employs 4‐N,N‐dimethylaminopyridine as the coupling catalyst provides coPCs having low concentrations of phenolic and carbamate end groups and that, therefore, wash without emulsification and are thermally stable. © 1994 John Wiley & Sons, Inc.
Laser‐Induced generation of thin silicone layers with high chemical and spectral purity
Authors: Roth Wolfgang , Hoffmann Klaus W. , Kurz Wolfgang
Published: April 2003

Excimer lasers (ArF, λ = 193 nm, and KrF, λ = 248 nm) were used to generate polymers free of additives such as catalysts, initiators, or sensitizers. The layers obtained are of potential interest for medical applications and future molecular electronics. Dimethylpolysiloxanes and dimethylsiloxane copolymers that contain phenyl‐, n‐hexyl‐ or 3.3.3‐trifluoropropyl groups or silicon‐bound hydrogen atoms were crosslinked in the liquid phase, whereby layer thicknesses in the range from 1–300 μm were obtained. Disiloxanes and alkoxysilanes were deposited from the gas phase (LCVD, laser chemical vapor deposition) resulting in layer thicknesses below 1 μm. In almost all cases, organic layers with a smooth surface, transparency, and good adhesion were obtained on silicon as well as quartz substrates. © 1994 John Wiley & Sons, Inc.
Poly(terephthalic acid anhydride) as a latent monomer in polybenzoxazole synthesis
Authors: So Ying‐Hung
Published: April 2003

High molecular weight poly(p‐phenylenebenzobisoxazole) (PBO) was prepared from poly(terephthalic acid anhydride) (PTAA) and 1,3‐diamino‐4,6‐dihydroxybenzene dihydrogenchloride in polyphosphoric acid (PPA). PTAA may react directly with the o‐aminophenol groups to form benzoxazoles or react with PPA to generate terephthalic acid (TA) of very small particle size, which dissolves readily in PPA. PTAA provides the advantages of bypassing the requirement of small particle size TA, reducing the amount of water liberated by half, and possibly providing faster kinetics in PBO synthesis. © 1994 John Wiley & Sons, Inc.
Synthesis and thermal stability of the resins prepared from the reactions of 1,4‐bis(2,2‐dicyanovinyl)benzene with aromatic diamines and electrical conductivity of the resulting materials following pyrolysis
Authors: Diakoumakos Constantinos D. , Mikroyannidis John A. , Krontiras Christoforos A. , Pisanias Michael N.
Published: April 2003

New thermosetting resins were prepared from the reaction of 1,4‐bis(2,2‐dicyanovinyl)benzene with aromatic diamines in varying molar ratios. The thermal stability of these resins was correlated with their composition and the curing conditions. They were stable in N2 up to 370–448°C and afforded anaerobic char yields of 73–84% at 800°C after curing at 300°C for 20–60 h. The temperature dependence of the electrical resistivity of all resins pyrolyzed at 700°C for 15 h was studied in the temperature range from −173–327°C (100–600 K). The results showed that at room temperature the unpyrolyzed polymers have insulating properties, whereas a dramatic decrease in the electrical resistivity is observed following pyrolysis. The temperature dependence of the electrical resistivity suggests that all of the materials studied have semiconducting properties. The observed electrical conductivity is thermally activated with activation energies ranging from 0.03–0.06 eV. © 1994 John Wiley & Sons, Inc.
Synthesis of poly(γ‐methoxypropylmethylsilylene) and poly(γ‐methoxypropylmethylsilylene‐co‐di‐n‐hexylsilylene)
Authors: Hrkach Jeffrey S. , Matyjaszewski Krzysztof
Published: April 2003

The synthesis of γ;‐methoxypropylmethyldichlorosilane, and its subsequent polymerization and copolymerization with di;‐n;‐hexyldichlorosilane through the reductive coupling with sodium has been accomplished. The resulting polymers contain methyl ether side groups that allow further synthetic transformations on the polysilane backbone. For poly (γ;‐methoxypropylmethylsilylene) these groups impart solubility characteristics different than typical alkyl and aryl substituted polysilanes. These new polymers and copolymers have been characterized by GPC and 1H‐, 13C‐, and 29Si‐NMR. © 1994 John Wiley & Sons, Inc.
Radical polymerization of alkyl crotonates as 1,2‐disubstituted ethylenes leading to thermally stable substituted polymethylene
Authors: Matsumoto Akikazu , Shimizu Keiichi , Mizuta Keiichiro , Otsu Takayuki
Published: April 2003

Radical polymerization of several alkyl crotonates (RCr) was carried out in bulk or in benzene in the presence of radical initiators. Homopolymerization of RCr bearing bulky ester alkyl groups, e.g. tert‐butyl (tBCr), 1‐adamantyl (AdCr), and 3,5‐dimethyl‐1‐adamantyl crotonate (DMAdCr) proceeded to give a polymer with molecular weight of several thousands despite of the steric hindrance and chain transfer by the presence of the β‐methyl group, while the methyl and ethyl esters gave no polymer. The kinetics of the polymerization was examined in detail and absolute rate constants were evaluated by means of electron spin resonance spectroscopy. The propagation rate constants of RCr were 0.41–1.0 L/mol s, being much smaller than those of the corresponding methacrylates (530–570 L/mol s). The termination rate constants were also determined from the analyses of steady state and non‐steady state polymerizations. Radical copolymerizations of AdCr (M2) with several vinyl monomers (M1) were carried out in bulk at 60°C and the rate constants for cross propagations were calculated to examine reactivities of the monomer and its polymer radical. The structure and thermal properties of the resulting poly (AdCr) were also investigated. Onset temperature of decomposition and glass transition temperature of poly(AdCr) were revealed to be much high as 302 and 234°C, respectively. © 1994 John Wiley & Sons, Inc.
Synthesis and properties of poly(arylene ether imide ketone)s
Authors: Matsuo Shigeru , Mitsuhashi Ken‐Ichi
Published: April 2003

Poly(arylene ether ketone)s containing imide units were prepared by the aromatic nucleophilic displacement reaction of the potassium salts of bisphenols with bis(4‐fluorobenzoyl)phthalimides in N‐methyl‐2‐pyrrolidone at elevated temperature. The polymers having inherent viscosities of 0.34–0.77 dL/g were obtained in 2 h. The polymers exhibited glass transition temperatures ranging from 216 to 268°C and decomposition temperatures (5% weight loss under air atmosphere) ranging from 450–570°C mainly depending on the bisphenols used in the polymer synthesis. The isothermal TGA measurements (400°C under air or nitrogen atmosphere) revealed that the 4,4'‐biphenol‐ and hydroquinone‐based poly(arylene ether ketone imide)s belong to a superior class of heat resistant polymers. The mechanical properties of these polymers are also described. © 1994 John Wiley & Sons, Inc.
High‐yield synthesis and characterization of 1,2‐bis(p‐vinylphenyl)ethane
Authors: Li W.‐H. , Li K. , Stöver H. D. H. , Hamielec A. E.
Published: April 2003

The quantitative synthesis and complete characterization of 1,2‐bis(p‐vinylphenyl)ethane (p,p‐BVPE) and its meta‐, para‐mixed isomers are reported. These crosslinkers copolymerize randomly with p‐methylstyrene, leading to random crosslink distributions. The crosslinkers are prepared by Grignard coupling of (m,p)‐vinylbenzyl chloride in tetrahydrofuran at low temperature to give the statistical mixture of m,m‐, m,p‐, and p,p‐isomers in quantitative yield. Pure p‐vinylbenzyl chloride is converted to pure p,p‐BVPE. p,p‐BVPE has also been separated from the mixture of isomers. The isomers are characterized by elemental analysis, mass spectrometry, 1H‐NMR, and 13C‐NMR and by reversed‐phase HPLC. © 1994 John Wiley & Sons, Inc.
Novel synthesis of polymeric phase transfer catalyst containing polar unit
Authors: Iizawa Takashi , Yamada Yoichi , Ogura Yoshio , Sato Yuichiro
Published: April 2003

Soluble polymeric phase transfer catalysts (PTCs) containing benzyltributylphosphonium chloride moieties and p‐nitrophenoxy group or N,N‐dimethylacrylamide as a polar unit were prepared via two‐step reactions from polymers with chloromethyl group and polar units. These polymers were synthesized by copolymerization of p‐chloromethylstyrene and the corresponding monomer or substitution of some parts of chloromethyl group with potassium p‐nitrophenoxide. When the obtained polymers were added, the phase transfer catalyzed reaction of benzylchloride with solid potassium acetate to proceed smoothly. The catalytic activity was strongly affected by the content of phosphonium chloride and the varieties of comonomer unit in the polymeric PTC. The polymeric PTC containing N,N‐dimethylacrylamide unit showed much higher catalytic activity than the corresponding low molecular weight PTC when the phase transfer catalyzed reaction was carried out in low polar solvent. © 1994 John Wiley & Sons, Inc.
Synthesis of poly(ether‐ketone‐amide)s by palladium‐catalyzed polycondensation of aromatic dibromides containing ether ketone structure, aromatic diamines, and carbon monoxide
Authors: Ueda Mitsuru , Yokoo Takayoshi
Published: April 2003

Aromatic poly(ether‐ketone‐amide)s were prepared by the palladium‐catalyzed polycondensation of aromatic dibromides containing ether ketone units, aromatic diamines, and carbon monoxide. Polymerizations were carried out in N,N‐dimethylacetamide (DMAc) in the presence of palladium catalyst, triphenylphosphine, and 1,8‐diazabicyclo [5,4,0]‐7‐undecene (DBU), and resulted in poly(ether‐ketone‐amide)s with inherent viscosities up to 0.82 dL/g under mild conditions. The polymers were quite soluble in strong acid, dipolar aprotic solvents, and pyridine. Thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 400°C in nitrogen atmosphere. The glass transition temperatures of the polymers were about 200°C, which are higher than those of poly(ether‐ketone) analogues. These polymers also showed good tensile strength and tensile modulus. © 1994 John Wiley & Sons, Inc.
Macromolecular engineering of polylactones and polylactides. XV. Poly(D,L)‐lactide macromonomers as precursors of biocompatible graft copolymers and bioerodible gels
Authors: Barakat I. , Dubois Ph. , Jérôme R. , Teyssié Ph. , Goethals E.
Published: April 2003

The functional aluminum alkoxide, Et2AlO(CH2)2O‐C(O)C(CH3)CH2, is a very effective initiator for the (D,L)‐lactide (LA) polymerization in toluene at 707deg;C. The coordination‐insertion type of polymerization is living and exclusively yields linear P (D,L)‐lactide macromonomers of a predictable molecular weight and a narrow molecular weight distribution. IR and 1H‐NMR studies show that the methacryloyl group of the initiator is selectively and quantitatively attached to one chain end, whereas the second extremity is systematically a hydroxyl function resulting from the hydrolysis of the living growing site. α,ω‐Dimethacryloyl‐P(D,L)‐lactides, i.e., α,ω‐macromonomers, have also been successfully synthesized by the additional control of the termination step, i.e., by reaction of Al alkoxide end groups with methacryloyl chloride. α‐Macromonomer and α,ω‐macromonomer P(D,L)‐lactides are easily free‐radical copolymerized with 2‐hydroxyethyl methacrylate (HEMA), resulting in a hydrophilic poly (HEMA) backbone grafted with hydrophobic P(D,L)‐lactide subchains and a biodegradable amphiphilic network, respectively. © 1994 John Wiley & Sons, Inc.
Synthesis, doping, and processing of high molecular weight poly(o‐methoxyaniline)
Authors: Mattoso Luiz H. C. , Faria Roberto M. , Bulhões Luis O. S. , MacDiarmid Alan G.
Published: April 2003

High molecular weight poly(o‐methoxyaniline) was synthesized using a novel method in which the polymerization occurs in the presence of a neutral salt. The molecular weight of the polymer was greatly affected by the quenching procedure employed to conclude the polymerization. Conventional doping of the base form of poly(o‐methoxyaniline) produced a yellow coloration of the doping solution and polymer degradation. It was found that the molecular weight of the polymer decreased significantly after washing or doping with certain aqueous acid media. The gelation conditions of N‐methyl pyrrolidinone (NMP) solutions and film preparation were also investigated for polymers of various molecular weights. The gelation time in NMP decreased drastically with the increase in the polymer molecular weight (the same for solution concentration and temperature), until a critical point was reached after which its decrease was very slow. Flexible, free‐standing, and stretchable films were readily obtained from the higher molecular weight polymers. Good quality doped gel films with conductivity of up to 1 S/cm were obtained under optimized doping conditions. © 1994 John Wiley & Sons, Inc.
Influence of the morphology of polypropylene films on the formation and evolution of irradiation‐induced peroxy‐radicals
Authors: Dogué I. Louis Joseph , Mermilliod N. , Genoud F.
Published: April 2003

To gain some knowledge on the influence of a substrate morphology upon radiochemical grafting efficiency, the formation and the evolution of irradiation induced peroxy‐radicals were measured by ESR in two polypropylene (PP) films of different origins. The creation rate of peroxy‐radicals was found to be almost proportional to the irradiation dose in the film presenting the best crystallinity, the bi‐oriented PP, while it saturates in the unoriented one. The recombination kinetics of the radicals appeared to be controlled by their diffusion in the matrix and the corresponding diffusion coefficients are dependent on the matrix itself and on its evolution under irradiation. It is suggested that the crystalline order of the matrix is the parameter governing the mobility and thus the lifetime of the radicals. © 1994 John Wiley & Sons, Inc.
Effect of the presence of polymer in miniemulsion droplets on the kinetics of polymerization
Authors: Miller C. M. , Blythe P. J. , Sudol E. D. , Silebi C. A. , El‐Aasser M. S.
Published: April 2003

Solution of polystyrene in styrene were dispersed in an aqueous gel phase comprising sodium lauryl sulfate, cetyl alcohol, and water using an emulsification process known to produce monomer droplet sizes inthe submicron size range (referred to as miniemulsion droplets). The shelf‐life stabilities of these miniemulsions were studied to determine their relative droplet sizes, and the emulsions were concommitantly polymerized in an isothermal batch reaction calorimeter. The polymerization kinetics and final particle sizes produced were compared with miniemulsion and conventional emulsion polymerizations prepared using equivalent recipes without the addition of polystyrene. The results indicate that polymerization of miniemulsions prepared from polymer solutions produce significantly different kinetics than both miniemulsion and conventional emulsion polymerizations. In general, a small amount of polymer greatly increases the rate of polymerization and the final number of particles produced in the polymerization to the extent where even conventional polymerizations carried out above the critical micelle concentration of the surfactant polymerize more slowly. The results are explained by considering the system to be comprised of small, stable pre‐formed monomer‐swollen polymer particles which are able to efficiently capture aqueous phase radicals. This enables the system to produce a large final number of particles, similar to the initial number of pre‐formed polymer particles, as opposed to miniemulsions and micelles in which only a relatively small fraction of the initial number of species (droplets or micelles) become polymer particles. © 1994 John Wiley & Sons, Inc.
Functionalization of poly (aryl ether ether ketone): Synthesis of bromomethylated PEEK and its functionalization
Authors: Wang Fei , Roovers Jacques
Published: April 2003

Bromomethyl poly (aryl ether ether ketone) has been prepared from methyl poly (aryl ether ether ketone) (MePEEK) and has been used as the precursor to many forms of functionalized PEEK. MePEEK was brominated directly with bromine. Bromination takes place exclusively at the methyl group. The reaction conditions for bromination have been studied. The bromination level can be controlled by the amount of bromine used, up to 90% of the methyl groups can be brominated to mono‐bromo and di‐bromo methyl PEEK. Modification reactions have been carried out on the brominated methyl PEEK. The bromomethyl group has been converted to different functional groups, such as  CH2OH,  CH2OCH3,  COOCH3,  CH2CN,  CH2COOH  CH2OCOCH3,  CH2N+H (CH2CH3)2Br−,  CH2N (CH2CH3)2,  CH2N+ (CH2CH3)3 Br−. Published 1994 John Wiley & Sons, Inc.
Macromlecular engineering of polylactones and polylactides. XVI. On the way to the synthesis of ω‐aliphatic primary amine poly (ϵ‐caprolactone) and polylactides
Authors: Stassen S. , Archambeau S. , Dubois Ph. , Jerome R. , Teyssie Ph.
Published: April 2003

Since bromides are well‐known precursors of primary amines, diethylaluminum 12 bromo‐1‐dodecyl oxide has been prepared and used as an initiator for the ring‐opening polymerization of ϵ‐caprolactone and L‐lactide. Uner strictly controlled conditions, the end‐functionalization of the polyesters in quantitative and the bromo end‐group is easily converted into an azide group whatever the polymeric backbone. The subsequent reduction of the azide into the expected primary amine has been investigated by catalytic transfer hydrogenation (CTH) in DMF and by hydrolysis in the presence of triphenylphosphine in THF, respectively.The hydrolysis reaction (PΦ3/H2O) is perturbed by a coupling reaction, which involves a protonate secondary amine and leads to a twofold increase in the polyester molecular weight. The CTH method gives rise to the expected ω‐NH2 poly (ϵ‐caprolactone), in contrast to polylactide which seems to be unstable toward the nascent amine end group. Whatever the polarity of the medium (DMF or THF), aminolysis of polylactides is observed to occur and leads to the formation of an internal amide. © 1994 John Wiley & Sons, Inc.
Ion‐Free latex films as dual‐phase electrolytes: Styrene–butadiene rubber and nitrile–butadiene rubber synthesized by emulsion polymerization with poly‐(vinyl pyrrolidone) stabilizer
Authors: Steven Rutt J. , Ichino Toshihiro , Matsumoto Morihiko , Nishi Shiro
Published: April 2003

Ion‐free latices of styrene‐butadiene rubber (SBR) and nitrile‐butadiene rubber (NBR) were synthesized by emulsion polymerization with use of poly (vinyl pyrrolidone) (PVP) stabilizer. The goal was to prepare ion‐free latex films, possessing dual‐phase latex particle morphology, and swell the films with liquid electrolyte to yield dual‐phase polymer electrolytes (DPE). SBR/PVP latex was prepared readily, but NBR/PVP latex was sensitive to coagulation. Differential scanning calorimetric (DSC) and scanning electron microscopic (SEM) analyses of latex films provided morphological evidence concerning particle structure and phase separation. Blends of NBR/PVP and PB/PVP latices (PB = polybutadiene) were also investigated, but particle structure was not present in the blended latex film, even though particle structure was present in the individual NBR/PVP and PB/PVP latex films. After extensive swelling of SBR/PVP latex films, PVP was extracted from the films, and ionic conductivities greater than 10−3 S/cm were achieved. © 1994‐John Wiley & Sons, Inc.
Fine control of the porous structure and chromatographic properties of monodisperse macroporous poly(styrene‐co‐divinylbenzene) beads prepared using polymer porogens
Authors: Wang Q. Ching , Švec František , Fréchet Jean M. J.
Published: April 2003

The porous structure of monodisperse macroporous beads can be controlled by using soluble polymers with well‐defined structural characteristics as part of the porogenic mixture. In general, the use of linear polystyrene as a porogen in the preparation of poly (styrene‐co‐divinylbenzene) beads shifts the pore size distribution towards larger pores. While a direct correlation between pore size and molecular weight of the porogen has been established, the chemical composition of the polymer porogen has no effect on the porous and chromatographic properties of the beads. These findings suggest that the average molar volume of the porogenic system is important while the miscibility of the polymer porogen with the crosslinked polymer that is formed is of little relevance. © 1994 John Wiley & Sons, Inc.
Preparation and block copolymerization of oligodihexanoylchitin having hydroxy groups at both ends
Authors: Chiba Koji , Kadokawa Jun‐Ichi , Yamashita Kanako , Tagaya Hideyuki , Karasu Masa
Published: April 2003

The preparation of oligodihexanoylchitin (3) having hydroxy groups at the both ends was carried out by an acid hydrolysis of a parent dihexanoylchitin in a mixed solution of acetic acid and conc. hydrochloric acid (11 : 1 in volume) at a room temperature. After 13–21 h, the products were isolated and their molecular weights were calculated as 7400–1100 by GPC analyses. The structure of the product 3 was determined by 1H and 13C‐NMR and IR spectra. The IR spectra of the products yielded for longer hydrolysis times than 30 h, however, indicated the occurrence of the dehexanoylation. The block copolymerization of 3 with poly (propylene glycol) (PPG) using 4,4'‐methylenedi (phenyl isocyanate) (MDI) as a coupling reagent gave the block copolymer 6. The molecular weight of 6 as obrained by GPC was 52,000. © 1994 John Wiley & Sons, Inc.
Macro‐azo‐initiators composed of various polyesters: Their syntheses, thermal properties, and application to block copolymerization
Authors: Haneda Yasuhiko , Terada Hiroyuki , Yoshida Michie , Ueda Akira , Nagai Susumu
Published: April 2003

Various aliphatic polyesters such as poly (ethyleneadipate), poly (tetramethylene adipate), poly (caprolactone), and poly (carbonate) were condensed with 4,4'‐azobis‐4‐cyanopentanoyl chloride to prepare macro‐azo‐initiators. Their thermal properties, observed by differential scanning calorimetry, showed similar decomposition behavior to each other. Block copolymers containing each of these polyesters as a block segment combined with polystyrene or poly (methylmethacrylate) have been derived by the polymerization of monomers initiated with these macro‐azo‐initiators. © 1994 John Wiley & Sons, Inc.
Perfectly alternating segmented polyimide‐polydimethyl siloxane copolymers via transimidization
Authors: Rogers M. E. , Glass T. E. , Mecham S. J. , Rodrigues D. , Wilkes G. L. , McGrath J. E.
Published: April 2003

New strategies for the synthesis of perfectly alternating segmented polyimide‐polydimethyl siloxane copolymers were developed by utilizing a transimidization method. Imide oligomers endcapped with 2‐aminopyrimidine were reacted with aminopropyl terminated (dimethyl siloxane) oligomers to afford perfectly alternating segmented imide siloxane copolymers. The polymerization was conducted in solvents such as chlorobenzene and chlorofrom. High molecular weight, fully imidized perfectly alternating segmented imide siloxane copolymers were obtained within 2 h at temperatures of 60‐110°C. The mechanism of the reaction was further elucidated via model compounds and NMR characterization. The block copolymers exhibited two Tgs due to the microphase separation of the polyimide and polysiloxane phases. The Tg of the polyimide phase was a function of the length of the polyimide block. However, partial phase mixing was also evident from the DSC results on the imide siloxane copolymers prepared with low molecular weight polyimide segments. Thermooxidative stability and tensile properties of the perfectly alternating segmented imide siloxane copolymers were found to be principally dependent on the amount of poly (dimethyl siloxane) incorporated in the copolymer and did not correlate with the poly (dimethyl siloxane) or polyimide block lengths. The stress‐strain behavior of both solvent cast films or molded films is also reported. © 1994 John Wiley & Sons, Inc.
Chain transfer by addition–substitution–fragmentation mechanism. I. End–functional polymers by a single‐step free radical transfer reaction: Use of a new allylic linear peroxyketal
Authors: Colombani Daniel , Chaumont Philippe
Published: April 2003

A new chain transfer agent, ethyl 2‐[1‐(1‐n‐butoxyethylperoxy) ethyl] propenoate (EBEPEP) was used in the free radical polymerization of methyl methacrylate (MMA), styrene (St), and butyl acrylate (BA) to produce end‐functional polymers by a radical addition–substitution–fragmentation mechanism. The chain transfer constants (Ctr) for EBEPEP in the three monomers polymerization at 60°C were determined from measurements of the degrees of polymerization. The Ctr were determined to be 0.086, 0.91, and 0.63 in MMA, St, and BA, respectively. EBEPEP behaves nearly as an “azeotropic” transfer agent for styrene at 60°C. The activation energy, Eatr, for the chain transfer reaction of EBEPEP with PMMA radicals was determined to be 29.5 kJ/mol. Thermal stability of peroxyketal EBEPEP in the polymerization medium was estimated from the DSC measurements of the activation energy, Eath = 133.5 kJ/mol, and the rate constants, kth, of the thermolysis to various temperature. © 1994 John Wiley & Sons, Inc.
Synthesis and dielectric analysis of aliphatic poly(carbonate‐sulfone)s based on 1,4‐bis(3‐hydroxypropylsulfonyl) butane
Authors: Zhang Tianhong , Litt Morton H. , Rogers Charles E.
Published: April 2003

High molecular weight aliphatic poly(carbonate‐sulfone) homopolymer (PC‐343) and random copolymer (PC‐343‐10) were synthesized from 1,4‐bis(3‐hydroxypropylsulfonyl)butane (Diol‐343) and a 1/1 molar mixture of Diol‐343 and 1,10‐decanediol, respectively. As a comparison, an aliphatic polycarbonate homopolymer (PC‐10) was prepared from 1,10‐decanediol. While PC‐10 exhibited a single melting peak during its DSC heating scan, both PC‐343 and PC‐343‐10 exhibited multiple reproducible first‐order transitions during DSC heating scans. Both PC‐343 and PC‐343‐10 showed broad reflections in their WAXD diagrams; the crystalline order of PC‐343 is higher than that of PC‐343‐10. Based on the DSC and WAXD results and our discovery on the liquid crystalline behavior of aliphatic poly(carbonate‐sulfone)s from 1,3‐bis(hydroxypropylsulfonyl)propane, we suggest PC‐343 and PC‐343‐10 are liquid crystalline and the liquid crystalline phase formation is directed by the dipole–dipole interactions between sulfone groups. Films were obtained from these polymers by compression molding and dielectric analyses were conducted on them. One glass transition related dielectric relaxation was observed in PC‐343‐10. One glass transition related dielectric relaxation and one sub‐glass transition related dielectric relaxation were observed in PC‐343. The glass transition temperature increases with the increase of sulfone content in the polymers. A dramatic rise in dielectric constant with temperature was observed in PC‐343 and PC‐343‐10 at low frequencies, which is probably due to the sulfone dipole interaction with the electrical field. © 1994 John Wiley & Sons, Inc.
Novel thermooxidatively stable poly(ether‐imide‐benzoxazole) and poly(ester‐imide‐benzoxazole)
Authors: Sundar Raj A. , Mathias Lon J.
Published: April 2003

4‐Hydroxy‐5‐nitrophthalimides were produced via nucleophilic aromatic substitution (NAS) of 4,5‐dichloro phthalimide substituents by potassium nitrite. The use of a N‐phenyl‐phthalimide having a protected 4′‐hydroxyl group allows concurrent deprotection and nitro reduction to amine to give the 4‐hydroxy‐5‐amino‐N‐(4′‐hydroxyphenyl) phthalimide. This key intermediate is the precursor to a poly (ether‐imide‐benzoxazole), and is the condensable monomer for a poly (ester‐imide‐benzoxazole). Benzoxazole monomer formation via condensation with p‐fluorobenzoyl chloride afforded 2‐(4′‐fluorophenyl)‐5,6,‐N‐[4′(‐hydroxyphenyl) imide]‐benzoxazole, which was polymerized under NAS conditions to produce a poly(ether‐imide‐benzoxazole) having an endothermic transition at 454°C with weight retention of 90% at 500°C in both air and nitrogen. Solution polycondensation of the 4‐hydroxy‐5‐amino‐N‐(4′‐hydroxyphenyl) phthalimide monomer with isophthaloyl chloride afforded a poly(ester‐amide‐imide) which was isolated and thermally cyclodehydrated in the solid state under vacuum to give a poly(ester‐imide‐benzoxazole) having 95% weight retention at 500°C in both air and nitrogen, with no detectable DSC transitions up to 500°C. © 1994 John Wiley & Sons, Inc.
Synthesis of tridimensional polymers by the copolymerization of phenylglycidylether with aromatic diglycidylethers
Authors: Ronda Joan Carles , Serra Angels , Mantecón Ana , Cádiz Virginia
Published: April 2003

Copolymers from phenylglycidylether and several aromatic diglycidylethers are prepared using different ratios of difunctional comonomers and the AIP/ZnCl2 initiator system. It is found that the percentage of incorporated comonomer depends on the nature of the aromatic moiety introduced. The copolymers are characterized by 13C‐NMR spectroscopy and turn out to be completely regular and with a high degree of isotacticity (about 80%) that confirms the high degree of regio‐ and stereoselectivity of the initiator system used. The thermal characteristics of copolymer networks are investigated using differential scanning calorimetry and thermogravimetry. Two fusion endotherms are observed which vary with the degree of crosslinking. By thermogravimetric analyses the thermal stability is found to increase when the crosslinking degree does. © 1994 John Wiley & Sons, Inc.
Optically active polymers containing side‐chain azobenzene moieties: Photochromic and photoresponsive behavior of copolymers of N‐(4‐azobenzene) maleimide with (−)‐menthyl vinyl ether and (+) (S)‐2‐methylbutyl vinyl ether
Authors: Angiolini Luigi , Caretti Daniele , Carlini Carlo , Altomare Angelina , Solaro Roberto
Published: April 2003

Photochromic behavior and photoisomerization kinetics of optically active copolymers of trans‐N‐(4‐azobenzene) maleimide (ABM) with (−) ‐menthyl vinyl ether (MtVE) and (+) (S) ‐2‐methylbutyl vinyl ether were studied by UV spectroscopy under irradiation at 348 nm. The resulting data have been compared with those of the corresponding copolymers containing also trans‐N‐(4‐azobenzene) maleamic acid co‐units as well as of low molecular weight model compounds. The photoresponsive behavior has been also investigated by circular dichroism measurements at various extents of photoisomerization. The results are discussed in terms of structural requirements of the macromolecules. © 1994 John Wiley & Sons, Inc.
Random thermotropic elastomers. I. Effects of substitution and hard/soft segment lengths on properties
Authors: Sonpatki M. M. , Ravindranath K. , Ponrathnam S.
Published: April 2003

Syntheses of segmented copoly(ether‐ester)s with (oxy‐2‐methyl‐1,4‐phenyleneoxycarbonyl‐1,4‐phenylene carbonyl)/(oxy‐2‐chloro‐1,4‐phenyleneoxycarbonyl‐1,4‐phenylene carbonyl) (methyl‐/chloro‐substituted) hard segments and poly(oxytetramethylene) soft segments, are reported. The methodology consisted of staged addition melt condensation of terephthaloyl chloride, poly(oxytetramethylene)glycol (POTMG;
\[
\bar M_n
\] = 250, 650, 1000, 2000) and methyl‐/chloro‐hydroquinone. Lengths of hard and soft segments were varied while the weight ratio of hard to soft segment was maintained constant. Copolymers were characterised for solubility behavior, and by infrared spectroscopy, x‐ray diffraction, DSC, and polarizing microscopy. Thermal properties were found to be dependent on length of soft segment as well as on the type of substituent in the mesogenic core. In both methyl‐ as well as chloro‐substituted copoly(ether‐ester)s soft segment glass transition temperature (Tgs) was obtained between −40 and −50°C. All copoly(ether‐ester)s are elastomeric at room temperature (25°C). These polymers exhibit thermotropic liquid crystalline behavior and were easily sheared and aligned in liquid crystalline state. © 1994 John Wiley & Sons, Inc.
Emulsion polymerization of butyl acrylate: Spin trapping and EPR study
Authors: Kim Soon Sam , Westmoreland David G.
Published: April 2003

The propagating radical in the emulsion polymerization reaction of butyl acrylate was detected by Electron Paramagnetic Resonance (EPR) spectroscopy using two spin‐trapping agents, 2‐methyl‐2‐nitrosopropane (MNP) and α‐(4‐pyridyl 1‐oxide)‐N‐tert‐butylnitrone (PyOBN). Through analysis of hyperfine structure of the spectra obtainedfrom the trapped radicals, the propagating radical is inferred to be the well known acrylate radical,  [CH2CH(COOC4H9)]nCH2CH(COOC4H9). © 1994 John Wiley & Sons, Inc.
Palladium‐ and platinum‐catalyzed coupling reactions of allyloxy aromatics with hydridosilanes and hydridosiloxanes: Novel liquid crystalline/organosilane materials
Authors: Sellinger Alan , Laine Richard M. , Chu Vano , Viney Christopher
Published: April 2003

Pt‐and Pd‐catalyzed reactions of a set of allyloxyaromatic mono‐and diesters with selected silanes were examined to develop simple, mild methods of forming liquid crystal (LC)/ siloxane and LC/silsesquioxane polymers. Pt complexes catalyze hydrosilylation to give primarily (≤ 80% selectivity at 100% conversion) terminal silylation of the allyloxys. The catalyst, platinum‐1,3‐divinyltetramethyldisiloxane [Pt (dvs), gives the cleanest reactions, fewest side products, under the mildest conditions. Model studies of Pt(dvs) catalyzed hydrosilylation of 4‐allyloxy methylbenzoate gave relative reactivities (HSiO1.5)8≫ Et3SiH > HMe2SiOSiMe2H > Ph2SiH2. The cubic silsesquioxane, (HSiO1.5)8, is so reactive hydrosilylation is over in 1–3 h at 0°C. All other reactions required > 40°C and longer reaction times. Initial efforts to form high polymers by Pt‐catalyzed reactions of bis‐allyloxy aromatics with Ph2SiH2provide polymers with bimodal MW distributions (polystyrene),Mws ≈ 30 kDa, and PDIs ≈ 5. Pd catalysis gives quite different products resulting from loss of propene with coincident formation of SiO bonds, “oxysilylation.” The same products appear (10–15%) in some Pt catalyzed reactions. Palladium dibenzylideneacetone/ Ph3P[Pd(dba)2/Ph3P], gives the cleanest oxysilylation reactions. Relative oxysilylation activities are: Ph2SiH2> HMe2SiOSiMe2H > Et3SiH. Polymerization with Pd catalysts provides polymers withMws ≈ 11 kDa, and PDIs ≈ 2. Reaction of 1 equiv. of (HSiO1.5)8with 4 equiv. of 4‐(4‐allyloxy‐benzoyloxy) biphenyl gives relatively pure tetrasubstituted LC/silsesquioxane [Mn≈ 1860 Da, PDI ≈ 1.09 (styrene equiv.) vs. 1746 Da caled.] A detailed analysis of the products formed, the catalytic reactivity patterns of the his (allyloxy) aromatic diesters and their LC transitions is presented. © 1994 John Wiley & Sons, Inc.
The antioxidant role of α‐tocopherol in polymers. I. The nature of transformation products of α‐tocopherol formed during melt processing of LDPE
Authors: Al‐Malaika S. , Ashley H. , Issenhuth S.
Published: April 2003

The antioxidant role of α‐tocopherol (vitamin E) in low‐density polyethylene (LDPE), and the nature of its transformation products formed during extrusion of the polymer are investigated. The melt stabilizing effectiveness of α‐tocopherol was found to be very high, higher than that of the commercial hindered phenol antioxidants, Irganox 1076 and 1010, after single and multiple extrusion. The high antioxidant activity of α‐tocopherol as a melt stabilizer is due, at least in part, to its transformation products. The importance of the processing history and the parent antioxidant concentration on the transformation products is discussed. Transformation products of α‐tocopherol were analyzed after each of the four extrusion passes of the polymer. These were fractionated, analyzed, and characterized by HPLC and spectroscopy, respectively. The main products formed are diastereoisomers of dimers and trimers, as well as aldehydes; the relative concentration of each was shown to depend on processing severity (number of extrusion passes) and the initial concentration of α‐tocopherol. The dihydroxydimer was found to be formed at a high concentration relative to the other products and proportional with the initial concentration of tocopherol. Based on both the identity and distribution of transformation products, a mechanism is proposed for the melt stabilization effect of α‐tocopherol in LDPE. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of maleimide polymers with pendant pyrazole groups. IV. Copolymerization of pyrazole‐modified maleimides with vinyl ethers
Authors: Ameduri Bruno , Boutevin Bernard , Malek Fouad
Published: April 2003

The synthesis of maleimides that have pyrazolic or bipyrazolic pendant groups is described. Their homopolymerization and their copolymerization with 2‐chloroethyl vinyl ether (CEVE) is reported. The homopolymerizations of such maleimides were performed under various conditions and led to low molecular‐weight polymers. However, alternating copolymers were obtained from CEVE as comonomers whatever the monomers feed compositions. A similar behavior was also observed for maleimides that do not exhibit any spacer, whereas for bulky vinyl ethers, random copolymers were produced. A comparison of the thermal behavior between these copolymers (glass transition temperatures, Tg, and decomposition temperatures) and other copolymers having different spacers between the nitrogenated cycles and the chain are related. Thus, an important decrease of Tg, was observed when C3H6CO2CH2 groups were used as the spacer instead of methylene groups. Moreover, the thermal weakness of these copolymers may come from the substituents of the vinyl ether and is discussed. © 1994 John Wiley & Sons, Inc.
Characterization of novel modified amorphous poly (ether sulphone)s
Authors: Maes C. , Devaux J. , Legras R. , Parsons I. W. , Mcgrail P. T.
Published: April 2003

New high‐temperature amorphous polymers with chlorine, amine, and maleimide chain‐ends have been synthesized by nucleophilic polycondensation and fully characterized by 13C‐NMR, 1H‐NMR, and potentiometric titration. From chain‐end determination, number average molecular masses were calculated. It was confirmed that transetherification during the synthesis led to a randomized polymer of the monomer residues. For nominally amine‐ended polymers obtained by addition of m‐aminophenol at the end of the synthesis, a small amount of hydroxyl chain‐ends was observed. This is ascribed also to transetherification. Complete reaction of the amine chain‐ends with maleic anhydride was demonstrated. Reaction of hydroxyl chain‐ends with acetic anhydride was also observed. The thermal stability of these different polymers was investigated; lower thermal stability was observed for amine and maleimide‐ended polymers. By two different methods, a Tg around 270d°C was determined for these novel amorphous aromatic polymers. © 1994 John Wiley & Sons, Inc.
The role of the triplet state in the photosensitization of cationic polymerizations by anthracene
Authors: Nelson E. W. , Carter T. P. , Scranton A. B.
Published: April 2003

The photosensitization mechanism for cationic polymerizations initiated by diaryliodonium salts photosensitized by anthracene was investigated using fluorescence and phosphorescence spectroscopy. In situ photosensitizer fluorescence measurements confirmed that the photosensitization reaction proceeds by an electron transfer process. Transient phosphorescence studies demonstrated that electron transfer occurred from the triplet excited state of anthracene to the initiator, with an intrinsic kinetic rate constant of 2 × 108 L/mol s. Further evidence for the role of the triplet state was provided by an observed seven‐fold decrease in the polymerization rate upon addition of a triplet state quencher. Finally, numerical solution of the photophysical kinetic equations indicated that the triplet state concentration was approximately three orders of magnitude higher than that of the singlet state, and that 94‐96% of the active cationic centers are produced by reaction of the initiator with the triplet state. These results indicate that the electron transfer occurs primarily from the triplet state of anthracene, with the singlet state providing only a minor contribution to the photosensitization reaction. © 1995 John Wiley & Sons, Inc.
Trimethylsilyl triflate as an initiator for cationic polymerization: Improved initiation through the use of promoters
Authors: Hrkach Jeffrey S. , Matyjaszewski Krzysztof
Published: April 2003

Trimethylsilyl triflate (TMSOTf) can be used as an initiator for the cationic polymerization of alkenes and heterocycles. However, TMSOTf without additives and promoters acts inefficiently. Initiation in the cationic polymerization of tetrahydrofuran is slow because of unfavorable charge distribution in the trimethylsilyltetrahydrofuranium cation—a product of the reaction of monomer with TMSOTf. Acetone, 1,3‐dioxolane, and 1,2‐propylene oxide have been used as promoters to react with TMSOTf to create more reactive initiating species and to improve efficiency of initiation. Of these promoters, 1,2‐propylene oxide has been the most successful. When TMSOTf has been used to initiate the polymerization of 2‐methyl‐2‐oxazoline, unfavorable charge distribution in the N‐trimethylsilyl‐2‐methyl‐2‐oxiranium cation has produced an unreactive imine dimeric cation which extends the time required for polymerization to several weeks. 1,2‐Propylene oxide has been utilized to prevent formation of the imine dimeric cation by producing a more reactive initiating species. In the polymerization of isobutyl vinyl ether initiated by TMSOTf, 1,2‐propylene oxide has been shown to be ineffective as a promoter, but acetone can be used successfully. © 1995 John Wiley & Sons, Inc.
The effects of the charge density and structure of the polymer on the dye‐binding characteristics of some cationic polyelectrolytes
Authors: Vishalakshi B.
Published: April 2003

The interaction of various structurally different water‐soluble cationic polyelectrolytes with methyl orange, an anionic dye, has been studied. The changes in the UV‐Vis spectra of methyl orange in the presence of methyl and benzyl quaternized polyvinylpyridines and trialkylammonium and triphenylphosphonium salts of polyvinylbenzyl chloride have been used to investigate the effect of the structure on the dye‐binding characteristics of the polycations. The results are interpreted in the light of a simple theory of cooperative binding to a linear lattice. The extent of binding of the dye aggregates on the polymers has been calculated. The binding ability of the above‐mentioned polyelectrolytes has been found to depend on the nature of the substituent on the polycation. The contribution of the coulombic forces on binding of the dye by these polymers has been emphasized. © 1995 John Wiley & Sons, Inc.
Simulation model for the molecular weight distribution in emulsion polymerization
Authors: Tobita Hidetaka , Takada Yuko , Nomura Mamoru
Published: April 2003

A Monte Carlo simulation model for the kinetics of emulsion polymerization is proposed. In the present model, the formation of each polymer molecule is simulated by the use of only a couple of probability functions; therefore, the calculation can be handled well even on personal computers. It is straightforward to account for virtually any kinetic event, such as the desorption of oligomeric radicals and chain length dependence of kinetic parameters, and as a consequence very detailed information such as the full distributions of the dead polymer molecular weights and the macroradicals among various polymer particles can be obtained. When bimolecular terminations are the dominant chain stoppage mechanism, the instantaneous molecular weight distribution (produced in a very small time interval) becomes broader than that for homogeneous polymerizations due to a higher possibility that short and long polymer radicals react with each other if bimolecular reactions are fast enough. The increase in the polydispersity of the MWD is fairly large, especially when bimolecular termination by disproportionation is significant; however, the gel permeation chromatography (GPC) may not be a suitable analytical technique to detect such broadening since oligomeric peaks may not be observed in the elution curve. The present simulation method provides greater insight into the complicated phenomena of emulsion polymerizations. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of bismaleimide–polyurethane crosslinked copolymers
Authors: Liao D. C. , Hsieh K. H. , Kao S. C.
Published: April 2003

A series of novel crosslinked copolymers of bismaleimide (BMI) and polyurethanes (PU) were prepared by direct copolymerization of BMI monomer and urethane‐modified bismaleimide (UBMI). The copolymers were characterized by FT‐IR and solid state 13C‐NMR. The reaction rate of the BMI monomer can be significantly increased by copolymerization with UBMI. The crosslinked copolymers show good mechanical properties and high thermal stability. Studies on glass transition temperatures and dynamic mechanical properties indicate that the copolymer is a homogeneous system as the polyester‐type PU employed. The transmission electron microscopy (TEM) of the copolymer illustrated a one‐phase structure of the cured resins when the polyester‐type PU was incorporated. © 1995 John Wiley & Sons, Inc.
Factors affecting propagating fronts of addition polymerization: Velocity, front curvature, temperatue profile, conversion, and molecular weight distribution
Authors: Pojman John A. , Willis Jason , Fortenberry Dionne , Ilyashenko Victor , Khan Akhtar M.
Published: April 2003

Several properties of propagating fronts of addition polymerization were studied. A power function could be fit to the velocity dependence on initiator concentration, but not with the exponents predicted by current models or in agreement with other published work. Bubbles from the volatile by‐products of initiator decomposition were found to affect the front velocity and curvature. The front velocity for triethylene glycol dimethacrylate polymerization was found to depend linearly on temperature over a moderate range. The conversion of methacrylic acid in fronts varied greatly with initiator type and concentration. Benzoyl peroxide produced much lower conversion than t‐butyl peroxide, but fronts with tBPO propagated slower. A dual initiator system of BPO and tBPO produced rapidly propagating fronts with good conversion but the contribution of each initiator to the velocity was not additive. The possibility of chain branching was considered. The apparent molecular weight distributions were very broad, often trimodal, and found to depend on initiator type and concentration as well as the tube diameter. The temperature profiles were measured and found to be very sharp for BPO and broader for tBPO but both had front temperatures in excess of 200°C, indicating a high ceiling temperature. © 1995 John Wiley & Sons, Inc.