摘要:

AbstractThe introduction of cyclicansa‐substituents allows for the synthesis of soluble poly‐(para‐phenylene)s PPP's possessing main chain chirality. The novel chiral PPP's represent an attractive combination of π‐conjugated character and chirality. We have synthesized open chain (single‐stranded) as well as ladder‐type chiral PPP's. The single‐stranded chiral PPP's exhibit temperature‐dependent changes of chiroptical properties. The behaviour should be assigned to conformational changes. The chiral ladder polymers contain the cyclophane loops exclusively on one side of the molecular board and are characterized by an unexpectedly high chiroptical activity of the π‐π*‐transition. They are potential candidates to study non‐linear chiroptical properties and to investigate circulary polarized luminescence (photo‐ and el

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980901

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA new pentafunctional monomer (3a) was prepared by acylation of silylated 3,5‐diaminobenzoic acid (DABA) with 3,5‐bisacetoxybenzoyl chloride. The polycondensation of this monomer or its trimethylsilyl ester yielded a hyperbranched poly(ester‐amide) having a nearly alternating sequence of one DABA and two 3,5‐dihydroxybenzoic acid (DHBA) units. However, due to ester‐amide interchange reactions, ca. 15–25% of the DABA units lose their role as branching units. When 3,5‐bisacetoxybenzoic acid and 3,5‐bisacetamidobenzoic acid were copolycondensed in a 2:1 ratio, the resulting polymer and endgroup structures were different. Furthermore, hyperbranched copoly(ester‐amide)s with a variable DHBA/DABA ratio from 10:0 down to 3:7 were prepared. The glass transition temperature (Tg) increased by approx. 90°C (up to 250°C) at higher molar fractions of DABA. Furthermore, monomer3awas copolycondensed with 3‐acetoxybenzoic acid or its trimethylsilyl ester. The resulting copoly(ester‐amide)s were again amorphous, showing a continuous decrease of theTgdown to the value of the poly(3‐hydroxybenzoic acid) (poly

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980902

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe synthesis and characterization of fluorescence‐labelled, phase segregating block polyesterurethanes based on the known biocompatible and degradable materials poly[(R)‐3‐hydroxybutyric acid] (PHB), poly(ϵ‐caprolactone) (PCL), and poly[(ϵ‐caprolactone)‐co‐glycolide] (PCL/PGA) is described. To introduce fluorescence labels in the amorphous domains of the polymers, phenacyl 10,11‐dihydroxyundecanoate (PDUA) was synthesized and copolymerized with a PHB diol, a PCL diol, and aliphatic diisocyanates. After cleavage of the protecting group (without degradation of the polymer backbone), the carboxyl group was reacted with a fluorescent amine (dansylcadaverine) in the presence of 4,6‐diphenylthieno[3,4‐d]‐1,3‐dioxol‐2‐one 5,5‐dioxide (Steglich reagent). Also a polymer containing13C‐labelled carboxy groups was synthesized and the labelling reaction monitored by13C NMR spectroscopy. To introduce fluorescence labels in the hard segment of the polymers, a new low‐molecular‐weight diol based on poly[(R)‐hydroxybutyric acid] and containing protected carboxy groups was synthesized. After the deprotection, the carboxy groups were reacted with a fluorescent amine (dansylcadaverine) in the presence of an activating system based on dicyclohexylcarbodiimide. The labelled PHB diol was then copolymerized with a poly[(ϵ‐caprolactone)‐co‐glycolide] diol and an aliphatic diisocyanate. The so obtained fluorescence‐labelled block polyesterurethanes are promissing materials for the investigation of the biocompatibility and degradation of the corresponding, non‐labelled materials (DegraPol®) by means of fluoresc

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980903

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractIsopiestic vapor sorption measurements were carried out for concentrated solutions of poly(styrene‐co‐butadiene) (SBR) and poly(styrene‐co‐acrylonitrile) (SAN) in a number of aromatic solvents in the temperature range of 343 to 398 K. Henry constants were determined by means of inverse gas‐liquid chromatography in the temperature range of 373 K (SBR) or 423 K (SAN) to 473 K, to obtain additional data at infinite dilution for the solvents, and for two of the monomers, styrene and 1,3‐butadiene, in SBR.The chain‐of‐rotators (COR) equation of state model was used to calculate the thermodynamic quantities applying a group‐contribution approach. In general, good agreement is observed between experimental and c

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980904

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe course of the 2,4,6‐trimethylbenzoyldiphenylphosphine oxide initiated free‐radical photopolymerization of an oligo(ethylene glycol) dimethacrylate ((EG)23DMA) in two oligo(ethylene glycol) dimethyl ethers ((EG)3DME and (EG)11DME) in the presence of LiCF3SO3has been studied by means of differential scanning calorimetry (DSC), FT‐Raman spectroscopy and sol‐gel analysis. In order to obtain the kinetical data of the fast photopolymerization, the photo‐DSC curves were corrected numerically. Both, the initial and the maximum polymerization rates were found to depend on the concentration of the monomer and the photo‐initiator with the order 2,5 and 0,2, respectively. Upon addition of LiCF3SO3, the polymerization rate is increased. Grafting reactions from (EG)11DME were observed resulting in its partially linking to the poly(methacryla

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980905

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractInhomogeneous heating of carbon‐black filled SBR (styrene‐co‐butadiene rubber) cylinders was mapped by NMR imaging in situ during dynamic mechanical load. The linear relationship betweenT2and temperature was used for direct imaging of temperature profiles. Experiments were performed as a function of shear frequency between 0 and 10 Hz and of carbon black contents between 10 and 70 phr (parts per hundred rubber). For a composite cylinder with a hard core and a soft shell an unexpected heat distribution was obs

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980906

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractDetailed synthetic aspects of new aromatic polyethers containing oxadiazole units are described. They are obtained by the nucleophilic displacement reaction of 2,2‐bis(4‐hydroxyphenyl)hexafluoropropane with 2,5‐bis(4‐fluorophenyl)‐1,3,4‐oxadiazole and 2,5‐bis(4‐fluoronaphthyl)‐1,3,4‐oxadiazole. The purity of the polyethers strongly depends on the reaction solvent. Best results were achieved with Ph2SO2as compared toN‐methyl‐2‐pyrrolidone (NMP) and 1,3‐dimethyltetrahydro‐2(1H)‐pyrimidinone (DMPU) in the temperature range from 190–200°C. All polyethers are fully soluble in common organic solvents and excellent films are obtained by spin‐coating. High molecular weight polyethers without oligomers were only achieved, when Ph2SO2was used as solvent. All polyethers are characterized by high thermal stability and high glass transition temperatures. The substitution of bisphenyloxadiazole by bisnaphthyloxadiazole units in the polyethers leads to a bathochromic shift of the absorption from 299 nm to 345 nm. Polyethers with bisnaphthyloxadiazole units show a blue fluorescence with a maximum at 427 nm. The application of these novel polyethers as efficient electron transport and injection layer in bilayer light emitting diodes based on poly(1,4‐phenylenevinylene) is shown. The best results were obtained with oxadiazole polyethers

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980907

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe synthesis of a benzo‐15‐crown‐5 functionalized α‐olefin (4′‐(undec‐10‐enylcarboxylate)benzo‐15‐crown‐5,5) and its terpolymerization with carbon monoxide and various α‐olefins are described. A decline of the glass transition temperatures (Tg) of the corresponding terpolymers was observed upon incorporating compound5into the polymer main chain. Ion‐selective membranes were prepared by encapsulating the benzo‐15‐crown‐5 functionalized α‐olefin/CO terpolymers in a microporous polyethylene support. Preliminary ion‐transport experiments demonstrate the ability of these novel crown ether substituted polyketones to transport NaClO4across the membranes. Adjusting the polarity of the polyketones via the length of the olefinic side chain offers a mea

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980908

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractGas permeability coefficients of a series of aromatic polyimides, which were prepared from oxydiphthalic dianhydride (ODPA) with various aromatic diamines, with respect to H2, CO2, O2, N2, and CH4were measured under 10 atm and in the temperature range from 30 to 150°C. A significant change in gas permeability and permselectivity resulting from systematic variation of the chemical structure of the polyimides was found. Among the polyimides which were prepared from phenylenediamine and its derivatives as well as bridged diamines without side groups on the benzene rings of the diamine residues, the increase of the gas permeability is accompanied by a decrease of the permselectivity. However, both the gas permeability and the permselectivity of the polyimides which were prepared from bridged diamines with methyl or methoxy groups on the benzene rings of the diamine residues simultaneously increase

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980909

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA supported version of zirconocene catalysts on siloxane copolymers having 1,2,3,4‐tetramethylcyclopentadienyl (Cp″)‐fluorenyl (Flu) (I) or cyclopentadienyl (Cp)‐fluorenyl (II) groups as substituents was prepared and applied to propene polymerization using methylalumoxane (MAO) or [Ph3C][B(C6F5)4] as cocatalyst. Catalyst (I), which was soluble in toluene, exhibited very low activity, whereas catalyst (II), which was composed of a toluene soluble (Cat‐A) and an insoluble fraction (Cat‐B), displayed a fairly high activity. Both catalysts (A and B) give a mixture of syndiotactic, atactic and a small quantity of isotactic polypropene, with a fraction of syndiotactic pentads ranging from about 50–75%. In contrast, the corresponding non‐supported catalyst gives almost completely atac

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980910

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY