bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anionic polymerization of methyl methacrylate initiated with lithium diphenylamide (Ph2NLi) in the presence of divalent transition metal halide
Authors: Ihara Eiji , Todaka Tsuyoshi , Inoue Kenzo 
Published: December 2003

AbstractAnionic polymerization of methyl methacrylate (MMA) in the presence of divalent transition metal halide (MX2 = FeBr2, MnCl2, CoCl2, NiBr2) was investigated. Initiating systems with various combinations of MX2, lithium diphenylamide (Ph2NLi), and organolithium (RLi, where R = nBu, Me) were effective to giving a high yield of poly(methyl methacrylate)s (PMMAs) at −78 °C in toluene. The tacticity of the resulting PMMAs was highly dependent on the combination of the reagents used for the generation of the initiating systems within a syndiotactic (rr = 59%) to isotactic (mm = 65%) range. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 31–37, 2004
Nanoscopic confinement effects on ethylene polymerization by intercalated silicate with metallocene catalyst
Authors: Wang Qi , Zhou Zhiyin , Song Lixin , Xu Hong , Wang Li 
Published: December 2003

AbstractIn this article we report a study of in situ polymerization of ethylene by intercalated montmorillonite (MMT) with metallocene, allowing an investigation of the nanoscopic confinement effect of olefin polymerization and of the structure of polymer prepared in situ. Ethylene polymerization by intercalated MMT with metallocene and the varied aggregation morphology of the resulting polymer during polymerization were studied by X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The polymerization kinetics and the resulting polymer before and after destruction of the silicate registry were different. The laminated structure of silicate lowered the all‐reaction rate, including the propagation, chain transfer, and termination reactions, producing polymer of a high molecular weight. Moreover, the melting point of the polymer gradually increased during the in situ polymerization, indicating that nanoscopic confinement between solid surfaces affects the crystallization behavior of polyethylene via in situ polymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 38–43, 2004
Copolymerization of ethylene or propylene with α‐olefins containing hydroxyl groups with zirconocene/methylaluminoxane catalyst
Authors: Hagihara Hideaki , Tsuchihara Kenji , Takeuchi Kazuhiko , Murata Masahide , Ozaki Hiroyuki , Shiono Takeshi 
Published: December 2003

AbstractCopolymerization of olefins (ethylene and propylene) and 5‐hexen‐1‐ol pretreated with alkylaluminum was performed using [dimethysilylbis(9‐fluorenyl)]zirconium dichloride/methylaluminoxane as the catalyst. The copolymerization required extra addition of alkylaluminum to prevent deactivation of the catalyst when 5‐hexen‐1‐ol was pretreated with trimethylaluminum, whereas the triisobutylaluminum‐treated system did not require any addition of alkylaluminum. The molecular weight of the copolymer depended on the kind of alkylaluminum compound (masking reagent, additive, and cocatalyst). 13C NMR analysis proved that poly(ethylene‐co‐5‐hexen‐1‐ol) containing 50 mol % of 5‐hexen‐1‐ol acted as an alternating copolymer, whereas the poly(propylene‐co‐5‐hexen‐1‐ol) acted as a random copolymer. The surface property of the copolymers was simply evaluated by means of water drop contact angle measurement. It was found that the copolymers containing large amounts of 5‐hexen‐1‐ol units showed good hydrophilic properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 52–58, 2004
Synthesis of semiaromatic polyimides from aromatic diamines containing adamantyl units and alicyclic dianhydrides
Authors: Watanabe Yasufumi , Shibasaki Yuji , Ando Shinji , Ueda Mitsuru 
Published: December 2003

AbstractWe prepared new semiaromatic polyimides from alicyclic dianhydrides and aromatic diamines containing adamantyl and biadamantyl units. Polycondensations were performed in 1‐methyl‐2‐pyrrolidinone at room temperature for 7 h and then 80 °C for 23 h, giving poly(amic acid)s with inherent viscosities up to 0.58 dL/g. Poly(amic acid)s were converted to corresponding poly(imide)s by thermal treatment. Poly(imide)s showed relatively high thermal stability (5% weight loss around 450 °C) and low dielectric constants (2.69–2.79). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 144–150, 2004
Synthesis and characterization of novel poly(amide‐imide)s containing 1,3‐diamino mesitylene moieties
Authors: Lee Choonkeun , Iyer N. Padmanabha , Min Kyungwook , Pak Heyungsuk , Han Haksoo 
Published: December 2003

AbstractA series of poly(amide‐imide)s were prepared using a new monomer, 1,3‐bis(trimellitimido)‐2,4,6‐trimethyl benzene (BTB), with four different diamines: 1,4‐phenylene diamine (PDA), 2,4‐diamino mesitylene (DAM), 2,2′‐dimethyl‐4,4′‐diamino biphenyl (DMDB), and 2,2′‐bis(trifluoromethyl)‐4,4′‐diamino biphenyl (TFDB). They were prepared by the condensation method in N‐methyl‐2‐pyrrolidinone (NMP) solvent using triphenyl phosphate and pyridine as condensing agents. The synthesized poly(amide‐imide)s were characterized by Fourier transform infrared and 1H NMR techniques. Films were prepared and characterized using DSC, thermogravimetric analysis (TGA), a prism coupler, and a film dielectric property analyzer. DSC measurement showed that the glass‐transition temperatures of the polymers were in the range of 259–327 °C. TGA analysis showed 5% weight loss, in the range of 472–514 °C. The refractive index varied from 1.6004 to 1.6586 in the following increasing order: BTB‐TFBM < BTB‐DAM < BTB‐DMDB < BTB‐PDA. For the poly(amide‐imide) films, the birefringence varied in the range of 0.0319–0.0580, in the following increasing order: BTB‐DAM < BTB‐TFBM < BTB‐DMDB < BTB‐PDA. The capacitance method showed that the dielectric constant of poly(amide‐imide) varied with the diamine structure; no difference was found by the optical method. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 137–143, 2004
Synthesis of hydrophilic polymers in supercritical carbon dioxide in the presence of a siloxane‐based macromonomer surfactant: Heterogeneous polymerization of 1‐vinyl‐2 pyrrolidone
Authors: Galia Alessandro , Giaconia Alberto , Iaia Vincenzo , Filardo Giuseppe 
Published: December 2003

AbstractBatch free radical polymerization of 1‐vinyl‐2‐pyrrolidone (VP) in supercritical carbon dioxide (scCO2) was studied in the presence of a reactive polysiloxane surfactant (PDMS‐mMA). Phase behavior investigation showed that when the initial concentration of the surface active macromonomer was higher than 2.5% w/w with respect to the monomer, the reaction mixture, in the absence of efficient stirring, was initially opaque to the visible light, and it slowly turned to an orange tint. Polymerization experiments carried out with surfactant concentration higher than the aforementioned value proceeded with a fast kinetics, and led to the formation of spherical nanoparticles with almost quantitative yields (higher than 98% with a reaction time lower than 70 min). The effect of the concentration of the surface active macromonomer, the initiator and the monomer, and of the density of the fluid phase on the kinetics of the process and on the morphology of the particles was investigated. A marked decrease of the number‐average diameter of the polymer particles with the surfactant concentration was obtained without any particle agglomeration. A dependence on [Initiator]−0.16 of the particle diameter was observed. Such scaling law exhibits an exponent higher than any previously reported for dispersion processes and rather close to those foreseeable on the basis of Smith–Harkins kinetics for emulsion polymerization. Collected experimental results strongly suggest that the polymerization of VP in the presence of PDMS‐mMA could proceed with a nucleation mechanism different from that postulated in pure dispersion polymerization stabilized by graft‐forming surfactants. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 173–185, 2004
New fluorinated thermoplastic elastomers. II. Synthesis and characterization of perfectly alternating fluorinated polyimide–fluorinated polyhybridsiloxane block copolymers via polyhydrosilylation
Authors: Andre S. , Guida‐Pietrasanta F. , Rousseau A. , Boutevin B. , Caporiccio G. 
Published: December 2003

AbstractThe synthesis of perfectly alternating fluorinated polyimide–fluorinated polyhybridsiloxane block copolymers (FPI‐FPHSX) was achieved through polyhydrosilylation of α,ω‐diallylfluorinated polyimides (AT‐FPI) and α,ω‐dihydrosilane fluorinated–polyhybridsiloxanes (HT‐FPHSX). A series of three FPI‐FPHSX containing 15, 38, and 56 wt % of polyimide was synthesized and characterized by tuning the number‐average molecular weight either of the hard polyimide segments or of the soft polyhybridsiloxane segments. The influence of the soft and hard segment lengths on the behavior of the thermoplastic elastomer material was studied (hardness, surface tension, thermal stability). The FPI‐FPHSX block copolymers thermomechanical properties are also reported. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 200–207, 2004
Synthesis of C60‐containing polyphosphazenes from a new reactive macromolecular intermediate: Polyphophazene azides
Authors: Li Zhen , Qin Jingui 
Published: December 2003

AbstractA novel synthetic strategy was developed to prepare polyphosphazenes containing C60 moieties as side chains. Thus, a new reactive macromolecular intermediate, polyphosphazene azides (P1), was obtained from poly(dichlorophosphazene) by the direct nucleophilic substitution reaction. Then the azide group in P1 reacted with C60 molecules to afford the first example of C60‐containing polyphosphazenes (P2 and P3). The polymers are soluble in common organic solvents. Molecular structural characterization for the polymers was presented by 1H NMR, 13C NMR, IR, ultraviolet–visible spectra, and gel permeation chromatography. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 194–199, 2004
Oligomeric calix[4]arene‐thiacrown ether for toxic heavy metals
Authors: Tabakci Mustafa , Memon Shahabuddin , Yilmaz Mustafa , Roundhill D. Max 
Published: December 2003

AbstractA new oligomeric calix[4]arene‐thiacrown‐4 (5) was synthesized via a condensation reaction of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐bis‐(4‐aminobenzyloxy)‐calix[4]arene‐thiacrown‐4 (4) with adipoyl dichloride. In this oligomerization reaction only five/six calix[4]arene‐thiacrown‐4 units were linked in the oligomeric chain. The complexation studies of 5 were made with liquid–liquid‐ extraction and solid–liquid‐sorption procedures. For comparison, the extraction efficiencies of monomers 1, 3, and 4 to selected transition metals are reported. The selectivity of monomers 3 and 4 toward Cu2+, Hg2+, and Pb2+ was lost after oligomerization in the two‐phase extraction systems. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 186–193, 2004
Distribution of melamine in polyester–melamine surface coatings cured under nonisothermal conditions
Authors: Gamage N. J. W. , Hill D. J. T. , Lukey C. A. , Pomery P. J. 
Published: December 2003

AbstractThe influence of experimental cure parameters on the diffusion of reactive species in polyester–melamine thermoset coatings during curing has been investigated with X‐ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared. The diffusion of melamine plays a vital role in the curing process and, therefore, in the ultimate properties of coatings. At a low (<20%) hexamethoxymethylmelamine (HMMM) crosslinker concentration, the matrix composition is uniform, but at high HMMM concentrations, excess HMMM rapidly segregates to the air–coating interface. The rate of migration is governed by the difference in the surface free energies of polyester and HMMM and the concentration gradient of HMMM between the bulk and the surface. An increased rate of energy absorption also increases the rate of migration of HMMM to the surface. A physical model has been proposed to explain this surface segregation phenomenon in terms of cocondensation and self‐condensation reactions. It suggests that an appropriate amount of melamine can be segregated on the surface and allowed to self‐condense to form a desired thickness of a melamine topcoat through the control of the binder composition and cure conditions. This technique can be implemented to apply a melamine topcoat during cure. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 83–91, 2004
Synthesis and metal complexation of dihydroxyphosphino‐functionalized crosslinked styrene/maleic anhydride copolymers
Authors: McClain Aliecia R. , Hsieh You‐Lo 
Published: December 2003

AbstractCrosslinked styrene (St)/maleic anhydride (MA) copolymers were synthesized, hydrolyzed with dicarboxylic acid, and converted to bear dihydroxyphosphino functionalities. The St–MA copolymers were prepared by azobisisobutyronitrile‐initiated polymerization in toluene at 90 °C in the presence of 2, 10, or 20% divinylbenzene crosslinker. The MA moiety was hydrolyzed into dicarboxylic acid to improve the hydrophilicity of the copolymers. The phenyl ring of St was phosphorylated with phosphorus trichloride in the presence of aluminum chloride and then hydrolyzed and oxidized with nitric acid at room temperature. The structures of the hydrolyzed and dihydroxyphosphino‐functionalized copolymers were confirmed by Fourier transform infrared spectroscopy and elemental analysis. The complexation behavior of these functionalized copolymers toward metal ions in 25 ppm aqueous solutions was observed over time periods of up to 7 h. The adsorption toward Pb(+2) was highest, followed by those of Cu(+2), Cr(+3), and Ni(+2). On the dihydroxyphosphino‐functionalized St–MA (20% divinylbenzene) copolymer, the adsorption of Pb(+2) showed a linear relationship with the concentrations and fit the Langmuir isotherm. The kinetics of Pb(+2) adsorption on this dihydroxyphosphino‐functionalized copolymer also fit the rate equation of the moving boundary model, t = [1 − 3(1 − X)2/3 + 2(1 − X)], where X is the fractional conversion. The metal‐ion adsorption kinetics of this copolymer appeared to be particle diffusion control, in which the moving boundary advanced from the surface toward the center. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 92–101, 2004
Free‐radical copolymerization of styrene with butyl acrylate. II. Elemental kinetic copolymerization step predictions from homopolymerization data
Authors: Fernández‐García M. , Fernández‐Sanz M. , Madruga E. L. 
Published: December 2003

AbstractThe free‐radical copolymerization of styrene and butyl acrylate has been carried out in benzene at 50 °C. The lumped kp/k parameter (where kp and kt are the average copolymerization propagation and termination rate constants, respectively) has been determined. Applying the implicit penultimate unit model for the overall copolymerization propagation rate coefficient and the terminal unit effect for the overall copolymerization termination rate coefficient and using the homopolymerization kinetic coefficients, we have found good qualitative agreement between the experimental and theoretical kp/k values. The variation of the copolymerization rate in solution with respect to the values previously found in bulk has been ascribed to a chain length effect on the copolymerization termination rate coefficient. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 130–136, 2004
Transetherification polycondensation: The roles of the catalyst, monomer structure, and polymerization conditions
Authors: Ch. Behera Girish , Ramakrishnan S. 
Published: December 2003

AbstractA detailed study of the novel melt transetherification polycondensation process, which was recently developed in our laboratory, is presented. The efficacy of different catalysts, such as p‐toluenesulfonic acid (PTSA), camphorsulfonic acid, and their pyridinium salts, was examined. The pyridinium salts, especially pyridinium camphorsulfonate (PCS), outperformed PTSA both in terms of the polymer molecular weights (the polydispersity) and the extent of discoloration of the polymer. The evolution of the molecular weight with the polymerization time was monitored with two different catalysts, PTSA and PCS, and these studies demonstrated that, while PTSA yielded polymers with a broad molecular weight distribution, the use of PCS curtailed possible side reactions that led to this broadening. Model reactions suggested that one possible reason for this broadening could be the formation of macrocyclics facilitated by an ether–ether exchange reaction, which was shown to occur much more rapidly when PTSA was used. A further interesting and rather unprecedented feature, which became apparent while the effect of the acid–catalyst concentration was being examined, was the dual role played by the acid, which acted both beneficially as a catalyst and detrimentally, defunctionalizing the chain end and terminating polymer growth. This conclusion was based on the observed decrease in the molecular weight of the polymer at very high catalyst concentrations, which suggested that there existed an optimum catalyst concentration at which a balance was struck between the molecular weight of the polymer formed and the polymerization time. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 102–111, 2004
Z. Guan, Control of polymer topology through late‐transition‐metal catalysis, J Polym Sci Part A: Polym Chem (2003), 41(22), 3680–3692
Authors: Guan Zhibin 
Published: December 2003

AbstractThe original article to which this Erratum refers was published in
J Polym Sci Part A: Polym Chem (2003) 41(22) 3680–3692No abstratct.
Combined Uvulopalatopharyngoplasty and Radiofrequency Tongue Base Reduction for Treatment of Obstructive Sleep Apnea/Hypopnea Syndrome
Authors: Friedman Michael , Ibrahim Hani , Lee George , Joseph Ninos J. 
Published: December 2003

OBJECTIVEIn this study, we compare the objective results of uvulopalatopharyngoplasty (UPPP) combined with tongue base radiofrequency reduction (TBRF) with standard UPPP treatment of obstructive sleep apnea/hypopnea syndrome (OSAHS).STUDYDESIGNWe conducted a retrospective study of 277 patients who had stage I, II, or III OSAHS based on the Friedman staging system previously presented.METHODSOne hundred thirty‐four patients who had treatment with UPPP only were used as a control group. This included 31 patients with stage I, 29 patients with stage II, and 74 patients with stage III OSAHS. An additional 143 patients with Stage II (n = 52) and III (n = 91) OSAHS were treated with combined UPPP and TBRF, initially and followed by additional TBRF treatments (up to 9000 J) as necessary. Subjective results were collected based on questionnaires and the Epworth Sleepiness Scale score for the experimental group, but these subjective measures were not available for the control group. Objective results were compared based on the polysomnographic findings before and after surgery.RESULTSSubjectively, the study group did extremely well. Based on objective measures of successful treatment, UPPP plus TBRF resulted in a significantly higher percentage of patients who were “cured” of OSAHS compared with the control group.CONCLUSIONSStage I patients were usually successfully treated with UPPP only. However, patients allocated to stage II or III will benefit from the addition of TBRF to standard UPPP. Many UPPP‐plus‐TBRF patients in this study aborted further recommended TBRF treatments after subjective improvement and therefore objective results for this group, although improved in comparison to stage II and III patients treated with UPPP only, may not represent maximal potential improvement.
Comparison of Computed Tomography and Magnetic Resonance Imaging in the Diagnosis of Parotid Tumors
Authors: Koyuncu Mehmet , ŞeŞen Teoman , Akan HÜseyin , Ismailoglu Ahmet A. , Tanyeri YÜcel , Tekat Atilla , Ünal Recep , Incesu LÜtfi 
Published: December 2003

OBJECTIVEThe role of computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis of parotid tumors was investigated.METHODSForty patients with the clinical suspicion of a parotid mass underwent both CT and MRI of the parotid region. Two radiologists independently assessed the CT and MRI results with respect to tumor localization, tumor margin characteristics, and infiltration of surrounding tissue. Histopathologic specimens were obtained in all cases and correlated with the radiologic findings.RESULTSThe sensitivity and specificity of CT and MRI were nearly the same for tumor location, tumor margin, and tumor infiltration.CONCLUSIONThe 2 imaging techniques provided the same information with respect to the presurgical planning and contribute to the diagnosis and therapy planning of parotid tumors. (Otolaryngol Head Neck Surg 2003;129:726‐32.)
The Endoscopic Modified Lothrop Procedure for Salvage of Chronic Frontal Sinusitis after Osteoplastic Flap Failure
Authors: Stankiewicz James A. , Wachter Bryan 
Published: December 2003

OBJECTIVEWhile reported results utilizing the osteoplastic flap procedure are very good, some patients fail the surgery due to recurrent or persistent frontal sinus disease. This study was performed to evaluate the utility of the endoscopic modified Lothrop sinus surgery for osteoplastic flap failure.STUDY DESIGN AND SETTINGA retrospective chart analysis and telephone survey of 10 patients from outside our institution for whom an osteoplastic flap with fat obliteration failed were salvaged using a computerized endoscopic modified Lothrop procedure.RESULTSThe main complaints were headache/pressure and recurrent infection. The usual pathology was chronic sinusitis and/or mucocele. The frontal recess and floor of the frontal sinus were the most common areas of persistent disease. Symptomatic clinical improvement was noted in more than 90% of patients.CONCLUSIONSalvage endoscopic modified Lothrop sinus surgery is recommended for a limited number of traditional osteoplastic flap failures. Computerized surgical navigation may help avoid complications in situations with abnormal anatomy and previous dissection.SIGNIFICANCEThe endoscopic modified Lothrop procedure should be considered to salvage failed osteoplastic flap sinus obliteration. (Otolaryngol Head Neck Surg 2003;129:678‐83.)
Long‐Term Hearing Preservation after Middle Fossa Removal of Vestibular Schwannoma
Authors: Friedman Rick A. , Kesser Bradley , Brackmann Derald E. , Fisher Laurel M. , Slattery William H. , Hitselberger William E. 
Published: December 2003

OBJECTIVEWe sought to determine long‐term hearing preservation in vestibular schwannoma patients after undergoing middle fossa resection.STUDY DESIGN, SETTING, AND OUTCOME MEASURESWe conducted a retrospective chart review of patients undergoing middle fossa resection from 1990 to 1995 at a tertiary care center. Pure‐tone thresholds, before resection and at least 5 years after resection, and speech discrimination scores are reported.RESULTSSeventy percent of patients with immediate postoperative hearing maintained serviceable hearing at more than 5 years after surgery. Pure‐tone average in the operative ear changed at the same rate as hearing in the unoperated ear during this follow‐up period.CONCLUSIONSMore than two thirds of patients who underwent middle fossa resection of a vestibular schwannoma with some hearing postoperatively maintain that hearing at greater than 5 years of follow‐up. Surgery alone does not have a negative impact on long‐term hearing preservation. (Otolaryngol Head Neck Surg 2003;129:660‐5.)