摘要:

AbstractThe present article describes the synthesis and magnetic properties of poly(phenylacetylene) (3) with pi‐toporegulated pendant stable 4,4,5,5‐tetramethylimidazolin‐3‐oxide‐1‐yloxyl radicals topologically participating in the pi‐conjugated system of poly(phenylacetylene). Polyradical3was prepared by the condensation reaction of poly(p‐ethynylbenzaldehyde) with 2,3‐bis(hydroxylamino)‐2,3‐dimethylbutane followed by oxidation with lead dioxide. The spin concentration of3determined by the ESR spectroscopic method was 1.1 × 1021spins/g. This value approximately corresponds to 0.5 unpaired electron spin per the repeating unit. A powder ESR spectrum of3gave a 100% Lorentzian single line showing spin‐exchange narrowing. The vibrating sample magnetometer (VSM) measurement of3afforded a straight line with a positive slope, suggesting that3has predominant paramagnetic properties with

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300601

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractPoly(1,3‐cyclohexadiene‐alt‐α‐fluoroacrylonitrile) [poly(1,3‐CHD/α‐FAN)], an alternating copolymer of α‐fluoroacrylonitrile and 1,3‐cyclohexadiene has been prepared in bulk using varied monomer feed ratios and AIBN as initiator at 65°C. Elemental and1H‐NMR analyses indicate that the copolymer contains an equimolar composition of α‐FAN and 1,3‐CHD as observed for alternating copolymers with donor‐acceptor polymerizations. A 2‐D1H‐COSY NMR experiment indicates that the copolymer contains 1,4‐linkages across the cyclohexene unit while more reliable13C‐NMR spectra suggests the copolymer to contain both 1,2‐ and 1,4‐linkages. Poly(1,3‐CHD/α‐FAN) exhibits improved thermal stability relative to the alternating copolymer of 1,3‐CHD and α‐chloroacrylonitrile due to a higher resist

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300602

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

Abstract1,4‐Phenylenebis(methylene) sulfonium salts were polymerized under different conditions to yieldp‐xylylene sulfonium salt polyelectrolytes in a broad range of molecular weights. The aqueous reaction mixture formed a reversible gel at initial monomer concentrations higher than 1.0M, but at lower concentrations it remained as an emulsion until reaction completion. The effect of reaction time on intrinsic viscosities and polymer yields for both the emulsion and the gel state is discussed. The higher yields obtained when the reaction was carried out in the presence of a water‐immiscible organic solvent were apparently due to the effect of this solvent on increasing the concentration of the reactive intermediate that led to the polyelectrolyte. Both the addition of an organic solvent and the variation of the initial monomer concentrations allowed some control over the molecular weight of the polyelectrolyte f

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300603

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractCopolymers of 2,2,6,6‐tetramethylpiperidinyl methacrylate (TPMA) with styrene (S) and with methyl methacrylate (MMA) were synthesized using AIBN as initiator. S–TPMA copolymers from feed ranging from 0.10–0.80 mole fractions TPMA and MMA‐TPMA copolymers from feed of 0.04–0.85 mole fractions TPMA were used in the determination of monomer reactivity ratiosr1,r2. Four different methods were employed in the calculations ofr1andr2and all calculated results were in good agreement with each other. The structure of S–TPMA copolymers was inferred to be of an alternating nature while that of MMA–TPMA copolymers was random. Both copolymers are potential hindered amine light stabilizers (HALS) and are expected to be less extractable from, and more compatible with, polystyrene and poly(methyl methacrylate)

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300604

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractLiquid crystalline ionomers containing sulfonate groups on the terminal unit of the chain were synthesized by an interfacial condensation reaction of 4,4′‐dihydroxy‐α,α′‐dimethyl benzalazine, the monofunctional dyefast yellow(FY), and a 50/50 mixture of sebacoyl and dodecanedioyl dichlorides. The weight‐average molecular weights were estimated from inherent viscosity measurements to be between 6000–11,000 and the sodium sulfonate concentrations ranged from 0–18.4 meq/100 g polymer. Elemental analyses, however, indicated much higher molecular weights, which suggested that there was a distribution of chains with one, two, or no FY endgroups. The polymers were semicrystalline and melted at ca. 140°C to form nematic mesophases that were stable over a temperature range of ca. 80°C. They were thermally stable to about 350°C. The ionomeric nature of the polymers was confirmed by the presence of intermolecular associations in nonpolar solvents, as demonstrated by dilute solution vi

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300605

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe synthesis of 1‐(4‐hydroxyphenyl)‐2‐(2‐fluoro‐4‐hydroxyphenyl)ethane (FBPE), 1‐(4‐hydroxyphenyl)‐2‐(2‐chloro‐4‐hydroxyphenyl)ethane (CIBPE), 1‐(4‐hydroxyphenyl)‐2‐(2‐bromo‐4‐hydroxyphenyl)ethane (BrBPE), and 1‐(4‐hydroxyphenyl)‐2‐(2‐trifluoromethyl‐4‐hydroxyphenyl)ethane (CF3BPE), of the corresponding polymers based on 1,5‐dibromopentane (RBPE‐5), 1,8‐dibromooctane (RBPE‐8), and of the copolymers based on various ratios of 1,5‐dibromopentane and 1,8‐dibromooctane [RBPE‐5/8(A/B)] is described. The phase transition temperatures and thermodynamic parameters ofRBPE‐5andRBPE‐8polymers were compared to those of the corresponding polyethers based on 1,2‐bis(4‐hydroxyphenyl)ethane (BPE) and 1‐(4‐hydroxyphenyl)‐2‐(2‐methyl‐4‐hydroxyphenyl)ethane (MBPE) which were reported previously. Both isotropic‐nematic transition temperatures and corresponding thermodynamic parameters (i.e., enthalpy and entropy changes) decrease in the following order of the substituent R: H>F>CH3>Cl>Br>CF3. This order corresponds to the increase of the breadth of th

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300606

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe kinetic parameters have been measured for octene‐1 solution polymerization at 120°C catalyzed by zirconocene with the cocatalyst methylaluminoxane. The polymerizations were performed in an attenuated total reflectance (ATR) reaction cell. The progress of the reactions were followed by observing the disappearance of octene‐1 using the 910 cm−1band measured by FT‐IR spectroscopy. The dependence of the reaction rate,Rp, on catalyst concentration and cocatalyst/catalyst ratio was examined. The catalyst deactivation mechanism was studied by fitting the experimental data to mathematical models involving second‐order propagation and either first or second order catalyst deactivation. Second‐order catalyst deactivation provided a much better fit. The calculated deactivation rate constant,kd, is 21 (Ms)−1. This model is used to determine the propagation rate constant for Al/Zr = 4 × 103askp= 19.9 (Ms)−1. A decrease in Al/Zr = 3 × 102lowered the propagation rate constant,kp, to 9.6 (Ms)−1indicating that less than 50% of the initial Zr is active

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300607

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractNew aromatic polyimides containing triphenylamine unit were prepared by two different methods, i.e., a conventional two‐step method starting from 4,4′‐diaminotriphenylamine and aromatic tetracarboxylic dianhydrides and the one‐step thioanhydride method starting from the aromatic diamine and aromatic tetracarboxylic dithioanhydrides. Both procedures yielded high‐molecular‐weight polyimides with inherent viscosities of 0.47–1.17 dL/g. Some of these polymers were soluble in organic solvents such asN,N‐dimethylacetamide,N‐methyl‐2‐pyrrolidone,m‐cresol, and pyridine. All the polyimides afforded transparent, flexible, and tough films, and the color varied from pale yellow to dark red, depending markedly on the tetracarboxylic acid components. The glass transition temperatures (Tgs) of these polyimides were in the range of 287–331°C and the 10% weight loss temperatures were above 520°C in air. The polyimides prepared by the one‐step method exhibited better solubility in organic solvents and had somewhat lowerTgs than the polymers prepared by a

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300608

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThis article describes the synthesis of a novel series of soluble polyarylenes containing alternating binapthylene and biphenylene structural units. They were obtained by the cation‐radical polymerization of bis(1‐naphthyl) biphenyls. The following monomers were synthesized and polymerized : 4,4′‐bis(1‐naphthyl) biphenyl (9), 3,3′‐bis(1‐naphthyl) biphenyl (10), 2,2′‐bis(1‐naphthyl)biphenyl (11), and 2,5‐bis(1‐naphthyl)biphenyl (14). All polymerizations were performed in nitrobenzene using FeCl3as oxidant. Polymers with number average molecular weights of up to

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300609

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractA number of polyamides and model amides based on 3,3′‐dimethylnaphthidine and various dicarboxylic acids were synthesized inN‐methylpyrrolidone containing lithium chloride either by low temperature solution or by direct polycondensation using triphenyl phosphite and pyridine. The polyamides had inherent viscosities of 0.36−5.42 dL g−1and were, in general, readily soluble inN‐methylpyrrolidone. Amorphous members exhibited relatively high glass transition temperatures in the range of 340–380 and 200–230°C for aromatic and aliphatic polymers, respectively. All polyamides showed good thermal stability in nit

ISSN:0887-624X    

DOI:10.1002/pola.1992.080300610

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY