摘要:

AbstractThe nitration of quinaldine by fuming nitric and sulfuric acid afforded nitroquinaldine. It was condensed with a half molar amount of 1,4‐benzenedicarbaldehyde in the presence of acetic anhydride to yield 2,2′‐(1,4‐phenylenedivinylene) bisnitroquinoline. The latter was catalytically hydrogenated to the corresponding diamine, PBAQ. The new polyamide and polymides bearing styrylpyridine segments were prepared utilizing PBAQ as starting material. In addition, a model diamide and diimide were synthesized and characterized IR and1H‐NMR spectroscopy. Inherent viscosities of polymers ranged from 0.31 to 0.60 dl/g. Certain polymer precursors such as a bismaleimide and bisnadimide were synthesized from the reactions of PBAQ with maleic and nadic anhydride, respectively. Their curing behavior was investigated by DTA. Curing of polyamide, polyimides, and polymer precursors at 240°C for 15 h yielded crosslinked polymers. They were stable up to 329–310°C in N2or air and afforded a char yield of 67–62% in N2at 800°C. © 1994 Joh

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321301

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractBromomethyl 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)3Br−. Published

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321302

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractLithium diisopropylamide is an efficient initiator for the anionic polymerization of methyl methacrylate in polar solvents at –78°C. Predictable molecular weights based on the initiator concentration were obtained, yields were quantitative, and molecular weight distributions were relatively narrow (2.0), and molecular weight control was not achieved. However, polymer yields were quantitative. In all cases, PMMA stereochemistry was indicative of a solvent‐separated lithium counterion, and triad compositions were identical to organolithium initiated homopolymers, i.e., 78% syndiotactic, 20% heterotactic, and 2% isotactic. © 1994 John Wiley&So

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321303

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractFive different polyaniline salts have been prepared by chemical polymerization of aniline in aqueous solution of different acids. Polyaniline samples have been heat treated at four different temperatures (150, 200, 275, and 375°C) and characterized by electron paramagnetic, electronic absorption, and infrared spectral measurements. Thermal stabilities of the chemically synthesized polyaniline salts have been studied by thermal analysis and spectral methods. Polyaniline salts undergo a three‐step weight‐loss process in the heating cycle. The first step (up to 110°C) corresponds to the loss of water molecules from the polymer chain. In the second step (110–275°C), a small amount of acid escapes as volatile gas, and after 275°C the polymer undergoes oxidative thermal degradation in the third step. It was found that thermal stability of polyaniline salts depends on the counteranion used and the polymer is apparently stable up to 250°C. No structural changes have taken place up to 200°C and this has been confirmed from infrared and electronic absorption spectra. No definite correlation exists between conductivity and spin concentration. © 1994 John Wil

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321304

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractPoly‐(2,4‐hexadiyn‐1,6‐diol) (PHDO), prepared by NbCl5/(n‐Bu)4Sn catalyzed metathesis of HDO, was pyrolyzed at various temperatures and electrical and structural properties of resulting polymers were investigated by FT‐IR, Laser Raman, CP/MAS13C‐NMR and X‐ray diffraction methods. The polymer obtained by pyrolysis of PHDO at 800°C showed a conductivity of about 10 S/cm at room temperature. The structure of the polymer seems to be a graphite‐like crystal consisting of condensed aromatic layers. © 1994 J

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321305

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractSince 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‐NH2poly (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. © 1

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321306

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe oxidation of hydroquinone catalyzed by pyridine‐Cu(II) complexes attached to polyorganosiloxane was investigated in the mixed solvent of methanol/water (vol. ratio 2/1). The catalytic oxidation followed Michaelis‐Menten‐like kinetics. The largek2term related to a turnover number indicated that the present polymeric catalysts have a remarkable effect on the activation process. The methylene number between the side‐chain acid amido and pyridyl groups of the polymeric ligand was shown to be closely related to the appearance of hydrophobic effects in both the substrate‐binding and the activation processes as deduced from the Michaelis constant and the thermodynamic and activation parameters. The binding parameters for 4‐methoxyphenol with pyridyl‐functionalized polyorganosiloxanes supported that the flexible backbone is also effective in the oxidation of hydroquinone. The Cu(II) complexes with pyridyl‐functionalized polyorganosiloxane would have the structures distorted from square planar formation, which would promote the reduction of Cu(II) to Cu(I), as concluded from ESR spectroscopy and electrochemical measurement. © 1994 John

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321307

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractAcyclic dience metathesis (ADMET) depolymerization of functionalized furan‐based polymers prepared via aqueous ring‐opening polymerization of 7‐oxanobornenes has been investigated. Results indicate that while very high molecular weight poly [exo‐N‐methyl‐7‐oxabicyclo [2.2.1] hept‐2,5‐diene‐2,3‐dicarboximide]can be depolymerized to oligomers with ease, poly [2,3‐dicarbomethoxy‐7‐oxabicyclo [2.2.1] hept‐2,5‐diene]is more resistant to depolymerization under similar conditions. This difference may be due to differential interaction of the carbonyls in the side chains with the metal atom of the catalyst in the proposed metallacyclobutane intermediate. ADMET depolymerization of poly [2,3‐bis (trifluoromethyl)‐7‐oxabicyclo [2.2.1] hept‐2,5‐diene]was feasible, however, the extent of depolymerization was decreased due to the use of a coordinating solvent (THF) used during the depolymeriza

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321308

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractDielectric barrier air discharge treatment of polyethylene, polypropylene, polyisobutylene, polystyrene, and polyisoprene substrates has been characterized by x‐ray photoelectron spectroscopy (XPS). The relative reactivities of these polymers towards silent discharge oxidation are rationalized in terms of ozone molecules interacting with an excited surface. © 1994 John Wiley&Sons, I

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321309

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractEffect of irradiation temperature on the main‐chain scission of poly (methyl methacrylate) (PMMA) caused by γ‐irradiation was studied by means of gel permeation chromatography and ESR spectroscopy. Although no temperature dependency was observed on the scission efficiency for purified PMMA, the efficiency for crude or monomer‐doped purified PMMA was decreased by decreasing the temperature below ca. 200 K. Above 200 K the efficiency was constant and did not depend on the purity of PMMA. ESR study of the irradiated PMMA revealed that the suppression of the scission below 200 K is induced by the addition of methyl methacrylate monomer to primary radical species, which otherwise cause the main‐chain scission by warming the polymer above 200 K. The primary radical generated above 200 K immediately converts to the scission‐type  CH2 Ċ(CH3) COOCH3radical through the β‐scission of the polymer main chain, so that the efficiency of the scission does not depend on both the impurity and the irradiation temperature. © 1994 J

ISSN:0887-624X    

DOI:10.1002/pola.1994.080321310

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY