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• 1
Electronic Resource
s.l. : American Chemical Society
Journal of medicinal chemistry 38 (1995), S. 2176-2187
ISSN: 1520-4804
Source: ACS Legacy Archives
Topics: Chemistry and Pharmacology
Type of Medium: Electronic Resource
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• 2
Electronic Resource
Bognor Regis [u.a.] : Wiley-Blackwell
ISSN: 0887-624X
Keywords: polyaddition ; phosphorus-containing polymer ; saturated polymer ; phenylphosphine ; 1,4-divinylbenzene ; 1,4-diisopropenylbenzene ; flame resistance ; thermal stability ; DSC ; TG ; Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: A polyaddition of phenylphosphine (PH) to 1,4-divinylbenzene (DVB) or 1,4-diisopropenylbenzene (DIPB) was carried out by radical initiations or UV irradiation at 60-80°C in toluene under a nitrogen atmosphere. The soluble polymer with higher molecular weight ($$\bar M_w = 2 \times 10^4$$) was obtained in a high yield with AIBN initiator for 95 h in the presence of 5% excess of PH to DVB (monomer feed ratio [DVB]0/[PH]0 = 1/1.05). On the other hand, a polyaddition of PH to DIPB proceeded much slower than the case of DVB, but the high polymer was obtained in a high yield by choosing polyaddition conditions such as polyaddition temperature and initiator concentration. From 1H-NMR, IR analyses, and phosphorus content of the polymers, it was characterized that both polymers have the alternating structure consisting of PH and DVB or DIPB units in 1 : 1 ratio. The glass transition and decomposition temperatures of both polymers under a nitrogen atmosphere were almost similar: 15-30°C and 380-385°C, respectively; but, the polymers were oxidized by heating under an atmosphere of air. The polymers had a self-extinguishing property and the polymer blend of the flammable polymers such as polystyrene and polyethylene with the phosphorus-containing polymers exhibited an excellent flame resistance. © 1994 John Wiley & Sons, Inc.
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• 3
Electronic Resource
Bognor Regis [u.a.] : Wiley-Blackwell
ISSN: 0887-624X
Keywords: cis polymerization of butadiene ; copolymerization of butadiene and styrene ; gadolinium tricarboxylate ; effect of pKa of ligand ; polymerization mechanism ; Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Type of Medium: Electronic Resource
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• 4
Electronic Resource
Bognor Regis [u.a.] : Wiley-Blackwell
ISSN: 0887-624X
Keywords: living cationic polymerization ; isobutyl vinyl ether ; cyclic ether additives ; cyclic formal additives ; acyclic ether additives with oxyethylene units ; EtAlCl2 ; Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The living cationic polymerization of isobutyl vinyl ether (IBVE) was investigated in the presence of various cyclic and acyclic ethers with 1-(isobutoxy)ethyl acetate [CH3CH(OiBu)OCOCH3, 1]/EtAlCl2 initiating system in hexane at 0°C. In particular, the effect of the basicity and steric hindrance of the ethers on the living nature and the polymerization rate was studied. The polymerization in the presence of a wide variety of cyclic ethers [tetrahydrofuran (THF), tetrahydropyran (THP), oxepane, 1,4-dioxane] and cyclic formals (1,3-dioxolane, 1,3-dioxane) gave living polymers with a very narrow molecular weight distribution (MWD) (M̄ω/M̄n ≤ 1.1). On the other hand, propylene oxide and oxetane additives resulted in no polymerization, whereas 1,3,5-trioxane gave the nonliving polymer with a broader MWD. The polymerization rates were dependent on the number of oxygen and ring sizes, which were related to the basicity and the steric hindrance. The order of the apparent polymerization rates in the presence of cyclic ether and formal additives was as follows: nonadditive ∼ 1,3,5-trioxane ≫ 1,3-dioxane 〉 1,3-dioxolane ≫ 1,4-dioxane ≫ THP 〉 oxepane ≫ THF ≫ oxetane, propylene oxide ≫ 0. The polymerization in the presence of the cyclic formals was much faster than that of the cyclic ethers: for example, the apparent propagation rate constant k in the presence of 1,3-dioxolane was 103 times larger than that in the presence of THF. Another series of experiments showed that acyclic ethers with oxyethylene units were effective as additives for the living polymerization with 1/EtAlCl2 initiating system in hexane at 0°C. The polymers obtained in the presence of ethylene glycol diethyl ether and diethylene glycol diethyle ether had very narrow molecular weight distribution (M̄ω/M̄n ≤ 1.1), and the M̄n was directly proportional to the monomer conversion. The polymerization behavior was quite different in the polymerization rates and the MWD of the obtained polymers from that in the presence of diethyl ether. These results suggested the polydentate-type interaction or the alternate interaction of two or three ether oxygens in oxyethylene units with the propagating carbocation, to permit the living polymerization of IBVE. © 1994 John Wiley & Sons, Inc.
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• 5
Electronic Resource
Bognor Regis [u.a.] : Wiley-Blackwell
ISSN: 0887-624X
Keywords: conjugated polymer ; addition polymerization ; 2-cyano-1,4-benzenedithiol ; 1,4-diethynylbenzene ; electrical conductivity ; Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: A novel addition polymerization of 2-cyano-1,4-benzenedithiol to 1,4-diethynylbenzene was carried out by UV irradiation in toluene at 50°C under nitrogen atmosphere. The polymerization proceeded readily, and a pale-yellowish conjugated polymer contain-ing sulfur atoms and cyano groups (M̄n = 20,400-80,800) was obtained in a 60-80% yield for 120-250 min. The polymer was found to be 1 : 1 alternating structure of anti-Markownikoff's type and was insolu-ble in conventional organic solvents. Since the polymer having molecular weight of the order of 104 had a softening point at 115°C, a thin polymer film was obtained by heat press. TG analysis of the polymer indicated its decomposition point at about 620°C under argon atmosphere. The electrical conductivity of the polymer pellet was 10-10 S/cm at 300 K without doping and on the order of 10-5 S/cm on I2 doping. Fur-thermore, the electrical conductivity of the undoped polymer pellet reversibly changed from the order of 10-10 S/cm at 300 K to 10-7 S/cm at 435 K with temperature variation, accompanying with increasing carrier density and mobility. The polymer pellet (M̄n = 80,800) aged at 250°C for 5 min under nitrogen atmosphere exhibited the order of 10-7 S/cm at 300 K. Thermal treatment of the polymers was thought to cause spreading of conjugated system through molecular rearrangement supported by x-ray diagrams. An absorption edge of diffuse reflectance spectra of the polymer (M̄n = 80,800) was 635 nm and shifted to 880 nm by heat treatment of the polymer. © 1995 John Wiley & Sons, Inc.
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• 6
Electronic Resource
Bognor Regis [u.a.] : Wiley-Blackwell
ISSN: 0887-624X
Keywords: ziegler type catalyst ; rare earth metal catalyst ; 4f electrons ; Ln(OCOCCl3)3 ; cis-polymerization of butadiene ; copolymerization of butadiene and styrene ; Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: No abstract.
Type of Medium: Electronic Resource
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• 7
Electronic Resource
Bognor Regis [u.a.] : Wiley-Blackwell
ISSN: 0887-624X
Keywords: 1,4-benzenedithiol ; 1,4-diethynylbenzene ; crystal structure ; solid-state polymerization ; layer structure ; Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: The crystal structure of 1,4-benzenedithiol (BDT) was determined by the Rietveld method based on the calculation of the atomic coordinates of the BDT molecule using the Molecular Mechanics Program (MMP2). The refined crystal structure of BDT was monoclinic P21/c with dimensions, a = 7.795, b = 7.290, c = 5.955 Å, β = 92.16°, z = 2. The R factor of the refined structure was 0.038. Using above results, the mechanism of solid-state addition polymerization of BDT to 1,4-diethynylbenzene (DEB) was studied. Sublimed BDT piles up onto glass plate substrate and forms the layer structure along with the a axis. An inclination angle of the piled BDT column was 60° toward the substrate surface. DEB crystal structure was also monoclinic P21/c with a = 4.007, b = 6.018; c = 15.340 Å, β = 91.42°, z = 2. Sublimation of equimolar mixture of BDT and DEB gave a crystal having 1 : 1 composition, in which DEB column is situated between the columns of BDT. Relative arrangement of both monomers was suitable for the addition of —SH and —C=CH groups, since the distance between the two groups is 3.3 Å by CERIUS II calculation. Therefore, the addition polymerization of BDT to DEB easily proceeded by UV irradiation and the resulting polymer had a highly layer structure along with the a axis of BDT crystal. Tentatively estimated crystal structure of polymer obtained is monoclinic with a = 7.73, b = 7.30, c = 5.95 Å, β = 92.16°. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1621-1625, 1997
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• 8
Electronic Resource
New York, NY : Wiley-Blackwell
Polymers for Advanced Technologies 3 (1992), S. 81-85
ISSN: 1042-7147
Keywords: p-Benzenedithiol ; p-Diethynylbenzene ; Layer structure ; Amorphous state ; Phase transition ; Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes: Phase transition of the layer structure of poly(p-benzenedithiol-co-p-diethylbenzene) obtained in solid state polymerization was studied by a thermal treatment or UV irradiation under a nitrogen atmosphere. The peak intensities in the X-ray diffraction diagram of polymers gradually decreased with the thermal treatment time above 55°C. Below 50°C the layer structure of polymers hardly changed. The apparent activation energy for the phase transition was about 15 Kcal/mol [63 KJ/mol] at the initial stage and gradually decreased to a few Kcal/mol [ca. 2 KJ/mol]. UV light from a high-pressure mercury lamp also gradually induced the phase transition from the layer structure to an amorphous one. The pristine polymer possesses phase transition points at 75, 95 and 130°C. The exothermic transition at 75°C can be understood as the thermal destruction of the semistable layer structure. The exothermic transition at 95°C may be correspond to the cis → trans thermal isomerization of the C=°C bond in the polymer main chain.The diffuse reflectance spectrum of the pristine polymer differed from that of the amorphous polymer obtained by the thermal treatment of the pristine polymer. SEM photographs of the pristine polymer showed a particular surface structure, i.e. entangled fibrous material. TEM photographs of the pristine polymer exhibited a bright valley-and-hill structure, whereas that of the amorphous polymer obtained by thermal treatment exhibited a plain surface.
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• 9
Electronic Resource
New York, NY : Wiley-Blackwell
Polymers for Advanced Technologies 6 (1995), S. 394-401
ISSN: 1042-7147
Keywords: 1,4-divinylbenzene ; 1,4-benzenedithiol ; polyadditionl pseudo liquid crystalline polymer ; reversible phase transition ; Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes: Polyaddition of 1,4-benzenedithiol (BDT) to 1,4-divinylbenzene (DVB) was carried out with 2,2′-azobisisobutyronitrile initiator in toluene at 75°C under a nitrogen atmosphere. The polymerization proceeded without an induction period, to give a white polymer with a high molecular weight (M̄w = 110,000) in ca. 90% yield for 2 hr. It was confirmed by 1H-NMR (nuclear magnetic resonance), IR (infrared) and sulfur contents that the polymer had an alternating structure of DVB and BDT units. The end-capping reaction of the polymer was also achieved by addition of thiophenol and/or styrene to the polymerization solution at a final stage of the polymerization. The polymer film exhibited a reversible phase transition between a transparent state and an opaque one by thermal mode. The thermal property of the polymer was studied by differential scanning calorimetry (DSC) analysis and polarized optical microscope observation with the polymer film. The detailed DSC analysis showed that the end-capped polymer with a relatively low molecular weight (M̄W = 4400-9600) exhibited similar to liquid crystalline behavior. A diffuse reflectance spectrum of the polymer coated on an aluminum plate showed a marked difference in reflective light intensity in the ultraviolet and visible regions: the reversible phase transition between an opaque and a transparent polymer layers was induced by thermal mode. The light transmittance of the polymer film, which was measured by depolarized light intensity method, was very sensitive toward the temperature variation.
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• 10
Electronic Resource
Bognor Regis [u.a.] : Wiley-Blackwell
ISSN: 0887-624X
Keywords: Chemistry ; Polymer and Materials Science
Source: Wiley InterScience Backfile Collection 1832-2000
Topics: Chemistry and Pharmacology
Notes: 9,10-Diethynylanthracene was prepared by the alkaline hydrolysis of 9,10-bis (trimethylsilylethynyl) anthracene. Another new monomer of 9, 10-anthracenedithiol was prepared by the reduction of anthracene polydisulfide. A crystalline conjugated polymer of 9,10-diethynylanthracene with 9,10-anthracenedithiol was synthesized in a THF solution at 50°C by UV irradiation or by using radical initiators. The molecular weight (M̄n) of the insoluble polymer in THF is about 20000-30000 and the soluble is about 4000. From the sulfur content and IR spectrum of the insoluble polymer, it is realized that the obtained polymer has the alternating structure consisting of 9,10-diethynylanthracene and 9,10-anthracenedithiol units. X-ray pattern indicated that the polymer has a layer structure. The conductivity of the undoped polymer was about 10-11S/cm, but enhanced up to 10-6 S/cm by doping with iodine. The enhancement of the conductivity seems to be the existence of the CT complex among the polymer backbone and iodine or iodine anion.