摘要:

AbstractRelationships between the ratios of the mean‐square radii of gyrationgsand the second virial coefficientsgA2of ring‐shaped and linear polymers with the degree of polymerizationPof the polymer and its Peterlin exponent ε in dilute solution were derived theoretically and numerical values calculated. The second virial coefficients of ring‐shaped and of linear polystyrene at 25°C in toluene were determined using light scattering. By verifying the theoretical calculation based on the experimental determination of this polymer‐solvent system with light scattering and other methods reported in the literature, the agreement between theoretical calculation and experimental results is shown. The correlation equations for linear (l) and ring‐shaped (r) polystyrene in toluene at 25°CA2, 1= 8,06 · 10−3·M0,224andA2,r= 6,68 · 10−3·M0,218were obtained us

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920601

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractIn order to explain the difference in theta temperatures between ring‐shaped polymers and their corresponding linear polymers, the Huggins parameters χ of ring‐shaped polymers is assumed to obey the dependence χ = χ1(1 + σ ϕ2) on local segment concentration as expressed by the volume fraction of the polymer ϕ2, and σ being a constant. A comparison between theoretical results and light scattering measurements of Roovers and ourselves is sa

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920602

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe photosensitivity incis‐polyphenylacetylene (cis‐PPA, polymerized with rare‐earth catalysts) can be significantly enhanced by doping the PPA with I2or FeCl3and sensitizing with 4‐isothiocyanatofluorescein (F‐II) or 2,4,7‐trinitro‐9‐fluorenone (TNF), which are powerful sensitizers. The electrophotographic photoreceptor (P/R) device withcis‐PPA + F‐II (on Al substrate) appeared preferable in photosensitivity enhancement and showed good photosensitivity: dark decay 1,8 V/s; maximum rate of discharge 321 V/s; residual surface potential 22 V; discharge 89, 1%; photosensitivity 2,96 s−1. This is a new “family” of photosensitive materials which ca

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920603

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractPyrrole was found to polymerize electrochemically in a smooth and facile way when the immediate vincinity of the anode is at a pH of 3 ([H+] = 10−3mol/dm3). The polymerization is inhibited by the presence of a H+scavenger, di‐tert‐butylpyridine. Polymerization of pyrrole in a buffered solution of pH 4 gives a polypyrrole (PPy) film of slightly different chemical structure from that obtained in a buffered solution of pH 3, as shown by their IR spectra. No polymerization takes place in the buffered solution at pH>7. These facts show the important role of H+ions played in the electrochemical polymerization of pyrrole. Pyrrole might go through a protonated structure before it transfers an electron to the electrode, to form a cation radical which starts the polymerization. A new mechanism of polymerization is proposed in conformity with observed facts about the structure o

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920604

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractPolyesters containing 3,3′‐substituted azobenzene and benzanilide moieties as a part of conformationally mobile aromatic blocks were synthesized. Polymers based on 3,3′‐substituted azobenzene residues exhibit liquid‐crystalline properties and unusual thermal properties such as opposite odd‐even effect and unexpectedcis‐transisomeric ratio of azo group. Similar polymers with an amide group between the 1,3‐substituted benzene rings cannot form

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920605

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractInitiation constant 2kd·f, dissociation constantkd, and efficiency factorfof AIBN were measured at 60°C for two model homopolymerization systems: methyl methacrylate (MMA) inN‐methyl‐2‐pyrrolidone (NMP) andN‐vinyl‐2‐pyrrolidone (NVP) in methyl isobutyrate (MiB) as the solvent. The stable Banfield radical was used as inhibitor. A pronounced solvent effect was observed on the side reaction of the inhibitor with the monomers. Particular solvent sensitivity of monomers in this reaction was identified, whereby opposite solvent properties of NMP and MiB as well as of MMA and NVP were found. The initiation constant 2kd·fdepends mainly on the dissociation constant of the initiatorkdin regard to its solvent dependence. The efficiency factorfis influenced by monomer concentration, stability (reactivity) of primary radicals and by viscosity of the reaction medium (solven

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920606

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractBinary systems of methyl methacrylate (MMA)/N‐vinyl‐2‐pyrrolidone (NVP) and MMA/N‐methyl‐2‐pyrrolidone (NMP) with NMP as saturated model of NVP and of NVP/methyl isobutyrate (MiB) with MiB as saturated model of MMA were investigated by means of IR and NMR spectroscopy. Investigations were carried out at room temperature or at 60°C in CHCl3(IR) or CDCl3and C6H12/C6D12(NMR). It can be concluded from IR and NMR spectra that the polarity of MMA increases in the presence of NVP and the polarity of NVP decreases in the presence of MMA. Equilibrium constantsKof complex formation were determined to:K= 0,169 ± 0,037 L · mol−1for MMA/NVP at 30°C, 0,112 ± 0,024 L · mol−1for NVP/MiB at 60°C and 0,125 ± 0,030 L ·

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920607

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractA study was conducted of the excited states of the combination eosine/amine/iodonium salt through time‐resolved laser spectroscopy, of the photolysis products formed under light exposure, and of the rates of polymerization. It allows the process to be precised and discussed. It is apparent that the iodonium salt has no effect on the initiation step of the polymerization reaction but sharply decreases the termination reactions. The formation of a complex between eosine and the iodonium salt is suggested; this complex is destroyed in the presence of amin

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920608

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractA liquid‐crystalline side‐chain polymer with laterally incorporated naphthalene groups in the mesogenic moiety is investigated in binary mixtures with an optical uniaxial low‐molar‐mass liquid crystal. Mixtures with up to 50 mol‐% content of the monomeric liquid crystal show a biaxial nematic phase. At lower temperatures a new biaxial smectic phase is observed, which corresponds to the smectic A phase. The angles between the optical axes are measured in dependence of temperature and mixture composition. Starting from the neat polymer, the angles decrease in the nematic as well as in the smectic phase with increasing mole fraction of the uniaxial liquid crystal. From the results a phase transformation uniaxial nematic to biaxial nematic can be

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920609

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractNew types of macroporous polymers containing chiral cavities were prepared for the racemic resolution of free sugars. As template monomers 6‐O‐methyl‐ and 6‐O‐benzyl‐αD‐galactopyranose 1,2;3,4‐tetra‐O‐bis(4‐vinylphenylboronate) (3candb) as well as 1‐O‐methyl‐ and 1‐O‐benzyl‐βD‐fructopyranose 2,3;4,5‐tetra‐O‐bis(4‐vinylphenylboronate) (4candb) were copolymerized with a large amount of ethylene dimethacrylate. After splitting off the respective templates, these polymers were used for the racemic resolution of the racemates ofD,L‐galactose andD,L‐fructose, and also the racemates, of 1‐O‐methyl‐ and 1‐O‐benzyl‐D,L‐fructose. The polymer prepared from3byielded the highest selectivity for the racemic resolution ofD,L‐galactose. In the case of fructose the benzyl‐ether‐imprinted polymers yielded the highest selectivity, especially for 1‐O‐methyl‐D,L‐fructose separation. Polymers imprinted withD‐galactose derivatives showed inverse selectivity by preferably absorbingL‐fructose from the racem

ISSN:0025-116X    

DOI:10.1002/macp.1991.021920610

出版商:Hüthig&Wepf Verlag    

年代:1991

数据来源: WILEY