摘要:

AbstractThe electron transfer reaction from excited phenanthrene to acceptors was shown to be modified markedly when the phenanthrene unit was covalently linked to polyelectrolytes. (1) Such functionalized polyelectrolytes were shown to form hydrophobic microdomains in aqueous solution. (2) Uptake of amphiphilic acceptor substrates by the microdomain was demonstrated and was shown to accelerate the forward electron transfer reaction. (3) The electrostatic effect of microdomain was shown to effect the photoinduced charge separation. (4) The electrostatic potential of the microdomain was estimated to be comparable with that of surfactant micelles.

ISSN:0360-8905    

DOI:10.1002/polc.5070740104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThree copolymers of poly(acrylic acid‐co‐vinylamine) containing 12% (SP12). 30% (SP30), and 52% (SP52) amino groups were synthesized from poly(acrylic acid) by means of the Schmidt reaction. These copolymers were analyzed by C‐13 NMR and the results compared wiih the previously analyzed homopolymers. The various comonomer sequence distributions were identified by means of peak areas. It was determined thai (1) the reactivity was not significantly influenced by the triad taciicity of the parent poly(acrylic acid), (2) the final copolymer is characterized by an essentially alternating sequence, and (3) there is extensive lactam formation between neighboring carboxyl and amino groups. In terms of nearest neighbor effects, the relative rales of amine formation arek1/k0≈ 0.3 andk2/k0≈ 0. A C‐13 NMR pH titration of SPI2 showed that the carboxyl group with a neighboring amino group is more acidic man a carboxyl group flanked by two carb

ISSN:0360-8905    

DOI:10.1002/polc.5070740105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractRacemic or chiral bifunctional oligoethers of the type H—(O—CH(CH3)—CH2—)n—Cl,n= 4‐10, have been prepared by reacting racemic or optically active propylene oxide with teiraphenyl porphyrin (TPPH2)—AlEt2Cl initiator sysfem. The synthesized products were characterized by IR, elemental analysis, VPO, GPC, and1H and13CNMR techniques. The oligomers purified by fractional distillation exhibit narrowMWdistributions (M̄w/M̄n≈ 1.03). Chiroptical properties of the oligomers and their derivatives were examined and compared with those of high molecular weight polyfpropylene oxide). Different possibilities of applicadons of these oligomers are pres

ISSN:0360-8905    

DOI:10.1002/polc.5070740106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA single‐crysial polyethylene‐bound palladium catalys: was prepared and used in the synthesis of acelylene‐terminated mon

ISSN:0360-8905    

DOI:10.1002/polc.5070740107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe synthesis and characterization of uracil‐ and thy mine‐containing polynucleotide analogs with a linear polyethylenimine backbone is described. Hypochromicity is observed for these analogs in DMSO and in DMSO/H2O solutions and found lo increase as the percent water increases. The influence of water on the 240‐ to 280‐nm absorptions of the analogs and their monomer models is correlated with the mobiliiy of the nucleic‐acid‐base‐con tain ing pendant to the polymeric backbone. An impure 5‐fluorouracil analog has been prepared, and its increased solubility in water relative to the corresponding uracil analog has been noted. A thy mine‐containing analog with a PEI/PEOXZ backbone has been synthesized. The analog consists of water‐soluble and insoluble forms c

ISSN:0360-8905    

DOI:10.1002/polc.5070740108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractDDA measurements made over a wide frequency range with a novel sensor are used to determine the onset of reaction, variation in viscosity, onset of gel, and reaction completion in a series of peroxide‐initiated unsaturated polyester resins diluted in styrene monomer. The dielectric measurements provide detailed insights into (he the cure process not available by conventional thermographic technique

ISSN:0360-8905    

DOI:10.1002/polc.5070740109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of polyethylene terephthalale has been examined by healing isothermally in a high‐mass reaction chamber and collecting the evolved acetaldehyde on a GC column for quantization. Kinetics were determined at lime intervals up to 1 h for temperatures 225°C, 240°C, 250°C, 260°C, 265°C, 270°C, 280°C, and 300°C. The rate of acetaldehyde evolution was found to be directly proportional to time of reaction at each temperature, thus fitting a zero‐order reaction. The Arrhenius plot of the data yielded a straight line above the melting point with a slope different from the straight line for reaction rates below the melting point. The change in slopes occurred around the crystalline melting point. The following thermodynamic values were found above and below the melting point, respectively:EA, 37.5 and 8.2 kcal/mol; ΔSA, + 1.5 and −54 e.u.;A, 0.68 × 1014and 0.43 × 102sec−1. Possible mechanistic implicat

ISSN:0360-8905    

DOI:10.1002/polc.5070740110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe polymerization and characterization of the ether‐containing aromatic polyimides of the following general structure are presented.The polymerization was conducted in one step in homogeneous solution of m‐cresol at high temperatures. Typical polyeterimides (PEI) were noncrystalline and showed excellent thermal stability. Among 46 polymers synthesized, only two were crystalline. PEI had glass transition temperatures from 178° to 277°C and exhibited excellent processibility. Many PEI were also soluble in dipolar aprotic solvents and chlorinated hydroca

ISSN:0360-8905    

DOI:10.1002/polc.5070740111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractVarious halogen substituted poly (1,3‐phenylene‐isophthalamide)s have been prepared. Their glass transition temperatureTg(DSC), thermal decomposition courses (TGA), and flame resistance (oxygen index) are discussed.The polyamides substituted with halogen in the meta position to NH group showed higherTgand better thermal stability than those substituted with the same halogen in the ortho position. All halogenated polyamides studied had fairly good flame resistance characteristics: high oxygen indices and high char yields. Halogenated aromatic polyamides with nitrogen ortho to halogen showed the flammability characteristic: limiting oxygen index = 38 + 61 × (weight loss at initial plateau temperat

ISSN:0360-8905    

DOI:10.1002/polc.5070740112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractDipheny‐2‐pyridylmethyl methacrylate (D2PyMA) was anionically polymerized with several organolithium complexes of chiral ligands such as (‐)‐sparteine (Sp), (S,S)‐( + )‐ and (R,R)‐(‐)‐2,3‐dimethoxy‐1,4‐bis(dimethylamino)butane [(+)‐ and (‐ )‐DDB], (S)‐(‐)‐1 ‐ methyl‐2‐(piperi‐dinomethyl)pyrrolidine (MPP), (S,S)‐( + )‐3,4‐dimethoxy‐N‐(2‐(dimethylamino)ethyl)pyrrolidine (DDEP), and (S,S)‐(+ )‐N‐benzyl‐3,4‐dimethoxypyrrolidine (BDP) in toluene at low temperature. Sp complexes gave a polymer of low optical activity. DDB was a better chiral ligand, and its complex, particularly the complex withN,N'‐diphenylethylenediamine monolithium amide (DPEDA‐Li), was effective in preparing a polymer of high optical rotation. A THF‐soluble portion of the polymer obtained with (‐)‐DDB‐DPEDA‐Li showed [α]25/365about ‐ 1400°, which was comparable to that of poly(triphenylmethyl methacrylate) (PTrMA) with pure one‐handed helical structure. However, in the polymerization with DDB‐DPEDA‐Li, optical rotation of the polymer depended greatly on polymerization conditions, such as monomer and initiator concentrations, reaction temperature, and polar additives. Fractionation by THF and/or gel permeation chromatography of the obtained polymers revealed that poly(diphenyl‐2‐pyridylmethyl methacrylate) (PD2PyMA) consisted of a mixture of (+)‐ and (‐)‐ polymers which probably were not enantiomeric to each other. DDEP‐DPEDA‐Li and DDEP‐fluorenyllithium complexes were also efficient chiral initiators that gave polymer of the same or higher optical rotation in comparison with DDB complexes. The optical rotation of PD2PyMA in CHCl3‐2,2,2‐trifluoroethanol (90:10) slowly changed with time. Optically active PD2PyMA coated on macroporous silica

ISSN:0360-8905    

DOI:10.1002/polc.5070740113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY