摘要:

Europium triundecylenate, Eu(UA)3, and terbium triundecylenate, Tb(UA)3, were prepared by the method described in our previous paper. Either Eu(UA)3or Tb(UA)3was dissolved in methacrylic acid (<20%) and copolymerized as a crosslinker with methyl methacrylate (>80) by bulk polymerization in molds made of two glass plates. The fluorescence spectroscopy of these Eu- or Tb-containing polymers under ultraviolet/visible excitation light was investigated. The fluorescence spectroscopy of solutions of Eu(UA)3or Tb(UA)3in methacrylic acid was measured and compared with that of the solid-state Eu- or Tb-containing polymers. The fluorescence excitation and emission spectra of the solutions and polymers showed the characteristic features of free Eu3+or Tb3+. The lifetime fluorescence of the solutions and polymers with Eu3+are also included.

ISSN:0022-233X    

DOI:10.1080/00222339009349679

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Poly(p-phenylenesulfide) (PPS) is efficiently and conveniently produced by a cationic and oxidative polymerization. Diphenyldisulfide is polymerized to PPS through one electron transfer at room temperature. The polymer is isolated as a white powder whose 1,4-structure is confirmed by IR. Phenylbis(phenylthio)sulfonium ion acts as an active species which is formed by oxidation of the S-S bond of diphenyldisulfide, and electrophilically substitutes on the phenyl ring. This polymerization is applicable to the polymerization of alkyl-substituted diphenyldisulfides to give PPSs, such as poly(2-methylphenylenesulfide) and poly(3,5-dimethylphenylene-sulfide).

ISSN:0022-233X    

DOI:10.1080/00222339009349680

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An overview of catalysts based upon tetra(neophyl)zirconium and bis(arene)titanium complexes supported on partially hydroxylated alumina for olefin polymerization is presented. The chemistry of the surface species has been partially elucidated. When these catalysts are used to polymerize propylene, the resulting stereoblock homopolymer is a thermoplastic elastomer. Physical and mechanical characterization of the polymer indicates that the properties may be attributed to an ether-soluble, largely amorphous, but high molecular weight fraction. The isotactic blocks in this largely atactic fraction cocrystallize with the crystalline, isotactic fraction to provide crosslinks in a rubbery network.

ISSN:0022-233X    

DOI:10.1080/00222339009349681

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Reaction of FeCl3with poly(N-methyl-2,5-pyrrolylene) (PNMPy), poly(2,5-thienylene) (PTh), and poly(3-methyl-2,5-thienylene) (P3MeTh) caused reduction of FeCl3to afford Fe2+species. Variable temperature Mössbauer spectra of the reaction systems indicated formation of FeCl2and FeCl−4. The latter is regarded as a counter-anion for the cation delocalized along the π-conjugated polymer chain.

ISSN:0022-233X    

DOI:10.1080/00222339009349682

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Synthetic bilayer membranes are two-dimensional arrays of am-phiphilic molecules. A large number of bilayer-forming am-phiphiles are designed by combinations of the structural elements (hydrophilic head, hydrophobic tail, connector, rigid segment, etc.). Metal chelate units have been incorporated into bilayer membranes as part of the bilayer component or as guest molecules. In the former example, a positively charged Cu(II)/polyamine complex and a Cu(II)/diketone unit are used as the hydrophilic head and rigid segment, respectively. The anisotropic orientation of these Cu(II) chelates is confirmed on the basis of the anisotropic ESR patterns observed for cast films of aqueous bilayer dispersions. Anionic planar Cu(II) complexes are incorporated noncovalently into cast films of ammonium bilayer membranes. These Cu(II) complexes are placed either horizontally or vertically, depending on the distribution of negative charges within each molecule. Strong antiferromagnetic interaction is observed when Cu(II) chelates are arranged two-dimensionally on bilayer membranes.

ISSN:0022-233X    

DOI:10.1080/00222339009349683

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Three different systems of glyceryl monooleate (GMO) bilayer lipid membrane (BLM) supported semiconductor particles have been prepared and characterized. A single composition of particulate semiconductor deposited on only one side of the BLM constituted System A, two different compositions of particulate semiconductors sequentially deposited on the same side of the BLM represented System B, and two different compositions of particulate semiconductors deposited on the opposite sides of the BLM made up System C. Effective refractive indices and optical thicknesses of GMO-BLM-supported In2S3and ZnS particles (System A), determined by Brewster-angle and reflection measurements, allowed the assessment of the maximum sizes and the volume fractions of semiconductor particles to be on the order of 1200 Å and 0.3, respectively. Since semiconductor particles are highly porous structures, only the first layer of particulates penetrated into the BLM and were considered in the proposed equivalent circuit and band models. The presence of semiconductors on the BLM surface has been established by voltage-dependent capacitance measurements, absorption spectroscopy, and optical microscopy. Subsequent to the injection of H2S, the first observable change was the appearance of fairly uniform white dots on the black film. These dots rapidly moved around and grew in size, forming islands which then merged with themselves and with a second generation of dots, which ultimately led to a continuous film which continued to grow in thickness. Cyclic voltammetry established the current rectifying behavior for the semiconductor-particle-coated BLMs. CdS, ZnS, and In2S3(System A) formed an n-type, while Cu2-(x+y)S (System A) behaved like a p-type, electrolyte-semiconductor (ES) junction. Semiconductor-semiconductor heterojunction (SS') formation was established for System C. Transfer of conduction-band electrons to dissolved oxygen (for the n-type ES junction) and across the membrane was considered to be responsible for the observed dark currents. Steady-state illumination of a CdS-containing BLM resulted in the prompt development of -150 to -200 mV (cisside negative) potential difference in an open circuit across the GMO BLM. This initial photovoltage,V1, quickly decayed to a steady value,Vs(- 100 to -150 mV). When the illumination was turned off, the potential difference across the GMO BLM decreased to its dark value in 3-4 minutes.

ISSN:0022-233X    

DOI:10.1080/00222339009349684

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Highly resolved refractive index patterns or patterns of iron oxide are obtained by photolysis of (CH3)3SnI or Fe(CO)5absorbed onto Coming's code 7930 porous Vycor glass followed by consolidation to a nonporous glass. The photochemistries of the molecules on the glass surface, as well as the distribution and relative sizes of the photodeposited metal oxides, are described. Rutherford backscattering, small-angle x-ray scattering, and scanning electron microscopy show that the glass consolidates about the iron oxide particle but not about the tin oxide particle. Tin oxide chemically modifies the glass surface so that it does not consolidate at temperatures as high as 1200°C.

ISSN:0022-233X    

DOI:10.1080/00222339009349685

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The immobilized enzyme chemically modified solid-state electrodes based on bilayer-film coating for amperometric determination of glucose have been fabricated and their sensor characteristics have been examined. The electrode substrate was coated with two kinds of polymeric films in a bilayer state, that is, System I: first with the cobalt tetrakis(o-aminophenyl)porphyrin polymer (poly-CoTAPP) film and then with an enzyme film consisting of bovine serum albumin and glucose oxidase (GOx), and System II: first with the Ru(NH3)3+6-containing montmorillonite clay film and then with the GOx enzyme film. The glucose concentration could be monitored by measuring the currents corresponding to the O2reduction and the H2O2reduction which are electrocatalyzed by the poly-CoTAPP film (System I) and the clay film (System II), respectively. The reproducible relationship between glucose concentration and sensor output was obtained for both systems with a dynamic range of ∼ 1-100 mM(for System I as an electrochemical detector for a flow injection analysis) and ∼0.4-4 mM(for System II). In addition, the sensors showed long-term stability (more than 1 and 2 months in System I and System II, respectively) and relatively rapid response (response times of System I and System II are − 5-10 and 40-60 s, respectively).

ISSN:0022-233X    

DOI:10.1080/00222339009349686

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Poly(ethylene oxide) (PEO)/LiClO4/poly(vinyl acetate) (PVAc) and PEO/LiClO4/poly(vinyl pyrrolidone) (PVP) complexes were prepared with various weight ratios of PVAc and PVP to PEO. The conductivity (σ) of the PEO/LiClO4complex was increased in a nonlinear fashion by the presence of up to 60 wt% PVAc. PEO/LiClO4/PVAc complexes with weight percents of PVAc greater than 60 had σ's less than that of PEO/LiClO4. The σ of PEO/LiClO4was decreased by the presence of any PVP.

ISSN:0022-233X    

DOI:10.1080/00222339009349687

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Colloidal dispersions of polymer-protected Pd/Pt and Pd/Au bimetallic clusters were prepared by reduction of an alcoholic solution of PdCl2and H2PtCl6or HAuCl4in the presence of poly(N-vinyl-2-pyrrolidone). The reduction can be carried out by refluxing in alcohol or by irradiation with visible light. The dispersions of the bimetallic clusters obtained are stable for months at room temperature and have from dark brown to brownish red color. Transmission electron micrographs show that the bimetallic clusters are composed of well-dispersed ultrafine particles of uniform size, about 1.5 nm for Pd-Pd and 3.4 nm for Pd-Au in diameter. The catalytic activity of the bimetallic clusters depends on the metal composition. In the case of the partial hydrogenation of 1, 3-cyclooctadiene, the activity went through a maximum when the alloy composition reached about 80% Pd and 20% Pt, or 60% Pd and 40% Au.

ISSN:0022-233X    

DOI:10.1080/00222339009349688

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor