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  • 1
    Electronic Resource
    Electronic Resource
    Cyanophenoxy-containing microbial polyesters: Structural analysis, thermal properties, second harmonic generation and in-vivo biodegradability (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 39 (1996), S. 205-213 
    Details
    ISSN: 0959-8103
    Keywords: Pseudomonas putida ; poly(β-hydroxyalkanoate) ; microbial polyesters ; poly[3-hydroxy-6(4-cyanophenoxy)hexanoate] ; non-linear optics ; in-vivo biodegradation ; 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 , Physics
    Notes: Pseudomonas putida KT 2442 was utilized as biocatalyst to form optoactive poly(β-hydroxyalkanoate)s (PHAs) from a cosubstrate mixture of octanoate and the achiral polarizable carbon source 6(4-cyanophenoxy)hexanoate, CPH. COSY and heteronuclear multiplet quantum correlation experiments were used to assign 1H and 13C NMR signals of 3-hydroxy-6(4-cyanophenoxy)hexanoate (3HCPH) repeat units. The methine carbon of 3HCPH repeat units was sensitive to repeat unit sequence effects, indicating that a substantial fraction of 3HCPH centered triad sequences in the product contain neighboring 3-hydroxyoctanoate and 3-hydroxhexanoate repeat units. Comparing the thermal properties of 0 and 19.6 mol% 3HCPH samples by differential scanning calorimetry shows that 3HCPH incorporation results in melting at temperatures 〉64°C (not seen for the 0 mol% sample), more rapid crystallization and a new Tg transition at ∼ -21°C. These characteristics indicate that chains and/or chain segments are formed that are enriched in 3HCPH which phaseseparate and form a unique crystal structure. Measurements of second harmonic generation (SHG) intensities carried out using in-situ corona-poled samples showed weak SHG signals that increased by a factor of 8 for an increase in the 3HCPH content from 26 to 34 mol%. Comparatively higher SHG intensities (5 times) were found for PHAs which contained 5.1 mol% 3-hydroxy-6(4-nitrophenoxy)hexanoate (3HNPH) repeat units relative to a PHA with 17 mol% 3HCPH. In-vivo biodegradation studies of microbial polyesters prepared with and without 3HCPH repeat units showed that PHA chains with 3HCPH degraded to lesser extents (weight loss of ∼ 20 and 50% over 72 h incubations). The large increase in polydispersity from 1.9 to 4.3 observed during in-vivo biodegradation of microbial polyesters containing 3HCPH repeat units was attributed to the existence of chains with highly variable contents of 3HCPH repeat units.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of polarity of the medium on the stereospecific polymerization of propylene by ansa-zirconocene catalyst (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2049-2056 
    Details
    ISSN: 0887-624X
    Keywords: metallocenes ; olefin polymerizations ; Ziegler-Natta catalysts ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Propylene was polymerized with rac-ethylene-bis (1-η5-indenyl)dichlorozirconium/methylaluminoxane in solvents of different polarity. The poly (propylene) formed was separated by solvent extraction; 13C-NMR and DSC measurements were made on the polymer fractions. The poly(propylene) in each solvent fraction has its characteristic molecular weight steric pentad distributions, melting transition temperature, and enthalpy for fusion irrespective of the polymerization medium. The results suggest that the medium dielectric constant does not affect the polymerization rate or the intrinsic stereoselectivity, propagation and chain transfer rates a given catalytic species but can alter the occurrence of steric insertion errors through shifting of distributions of the propagating species producing poly(propylenes) of different stereoregularities. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321106
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  • 3
    Electronic Resource
    Electronic Resource
    Poly(p-Phenylenebenzobisoxazole) fiber with polyphenylene sulfide pendent groups (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 159-164 
    Details
    ISSN: 0887-624X
    Keywords: poly(p-phenylenebenzobisoxazole) ; polyphenylene sulfide ; pendent group ; crosslinking ; heat treatment ; compressive strength ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(p-phenylenebenzobisoxazole) (PBO) fiber with polyphenylene sulfide (PPS) pendent groups was made to improve PBO fiber compressive strength by crosslinking. PPS moieties allowed the polymeric network to crosslink at heat-treatment temperatures at which PBO does not thermally degrade. PBO-PPS fiber heat-treated for 30 s at 600°C did not dissolve or break up in methanesulfonic acid. Compressive strength of crosslinked fiber was about 20% better than that of unmodified PBO fiber. In another experiment, 10 mol % of 2,5-diphenylsulfideterephthalic acid was incorporated into PBO fiber. The side chain of one phenyl sulfide unit was too short to enhance crosslinking, and the fiber had about the same compressive strength as unmodified PBO fiber. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330118
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  • 4
    Electronic Resource
    Electronic Resource
    13C-NMR spectra of cis-polymyrcene and cis-polyfarnesene (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 71-77 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homopolymers of myrcene and farnesene were prepared anionically in pure cyclohexane. The microstructure, determined from an analysis of the 13C-NMR spectrum and spin-lattice relaxation times, indicates the polymers are at least 85% cis-1,4, 10% cis-3,4, and under 3% trans-1,4.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260107
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  • 5
    Electronic Resource
    Electronic Resource
    Retardation of dibenzo polyether-formaldehyde resin formation by alkali-metal cations (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 2267-2274 
    Details
    ISSN: 0887-624X
    Keywords: dibenzo polyether ; formaldehyde condensation polymerization ; alkali-metal cation sorption ; template polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Macrocyclic polyethers are well-known complexing agents for alkali-metal and alkaline earth-metal cations. The influence of alkali-metal cations upon the polycondensation rate of acyclic and cyclic dibenzo polyethers with formaldehyde in formic acid and alkali-metal cation sorption by some of the resultant resins have been investigated. For certain dibenzo polyether and alkali-metal cation combinations, polymer formation is markedly reduced. The alkali-metal cation that provides the best fit for the macrocyclic polyether cavity produces the greatest retardation of polymer formation. It is proposed that metal ion complexation renders the dibenzo polyether monomer inert to polymerization under the reaction conditions. No template effect for alkali-metal cation sorption by dibenzo polyether carboxylic acid resins was observed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080331321
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  • 6
    Electronic Resource
    Electronic Resource
    Excited states of CF4 plasma for polymerization of TMPTA monomer (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 323-328 
    Details
    ISSN: 0887-624X
    Keywords: CF4 plasma ; trimethylolpropane triacrylate ; excited states ; plasma induced polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The F and CF2-CF2+ excited states have been detected by emission spectroscopy in CF4RF plasmas used for TMPTA polymerization. These excited states are related through electron collision to F and CF2 ground states. The temporal variation of the F and CF2-CF2+ radiative states near the substrate reveals that the F atoms disappear first by incorporation in the monomer during the polymerization phase and, then, by a third body recombination process enhanced by the polymer surface. The CF2-CF2+ radiative states are varying as the inverse of the F states indicating a strong destruction mechanism of CF2 radicals by F atoms.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300217
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  • 7
    Electronic Resource
    Electronic Resource
    Polymer drying. VII. 1H-NMR studies of evaporation from liquid saturated poly(styrene-co-divinylbenzene) (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1155-1161 
    Details
    ISSN: 0887-624X
    Keywords: adsorption ; desorption ; association ; polystyrene ; NMR ; polymer transitions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Composition-studies were carried out in which samples of films composed of poly(styrene-co-divinylbenzene) particles enmeshed by poly(tetrafluoroethylene) fibers were saturated with dichloromethane and then allowed to evaporate at 23°C to virtual dryness as the 1H-NMR signals and residual weight of sorbed liquid were monitored. The correlations, of 1H-NMR line-widths with the corresponding log of the number, αt of residual sorbed molecules per monomer unit show that sharp changes occur as αt passes through αG the composition that exists when all the liquid not sorbed (i.e., not present within the liquid-saturated particles), has been eliminated, and again as αt passes through αg the composition that exists when the particles attain the rigidity characteristic of the glassy state. Correlation of the corresponding T1 relaxation times with log αt show that sharp changes occur when αt becomes equal first to α′s and then to α′g the compositions that exist respectively when, firstly, all the sorbed liquid not immobilized by adsorption to the polymer chains within the particles has been eliminated, and then when the desorption of immobilized liquid from the chains causes the composition to begin to undergo transition from its rubbery state to its glassy state.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300622
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and characterisation of polyamides and polyimides from methylene bis[benzenamine] styryl pyridines (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 34 (1994), S. 35-39 
    Details
    ISSN: 0959-8103
    Keywords: polyamides ; polyimides ; styryl pyridines ; synthesis ; characterisation ; 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 , Physics
    Notes: Two diamines with potential non-linear optical characteristics, (E)-4, 4′-[[[2-(4-pyridinyl)ethenyl]phenyl]methylene]bis[benzenamine] (2a) and (E)-4, 4′-[[[2-(4-pyridinyl)ethenyl]phenyl]methylene]bis [N-ethylbenzenamine] (2b), were condensed with dianhydrides, benzophenone tetracarboxylic dianhydride and pyromellitic dianhydride, to obtain polyamic acids. These polyamic acids were soluble in polar aprotic solvents such as dimethyl formamide and dimethyl acetamide, and could be cast into transparent, tough and flexible films, which on cyclodehydration yield amorphous thermally stable polyimides. Characterisation using IR spectroscopy, X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry are reported.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210340106
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  • 9
    Electronic Resource
    Electronic Resource
    Customized neonatal incubator for measurement of platelet-artificial microvascular graft interactions under controlled flow, temperature, and transmural pressure (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 1-7 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A neonatal incubator has been custom modified to enable measurement of initial platelet retention on biomaterials in vitro under clinically relevant hemodynamic conditions. To calibrate this device, platelet retention on several materials having microconduit geometry (0.7-1.0 mm i.d.) has been measured after perfusion with citrated whole blood (containing 111 Indium-labelled platelets) at a shear rate of 312 s-1, 37°C, and 80 cm H2O transmural pressure. The relative reactivity of these materials toward platelets was: glass 〈 Fibrinogen(Fg)-coatedglass 〈 Fg-coated polyethylene 〈 polyethylene ∼ = Expanded polytetrafluoroethylene. Interindividual variation is relatively large (coefficient of variation = 35.5 ± 9.3%), but comparison to intraindividual controls reduces the variability to 14.8 ± 10.3%, a level which is suitable for economical testing of platelet retention to biomaterials in the presence or absence of drugs. This approach may have particular value in the study of the mechanism of platelet interactions with artificial microvascular grafts under perfusion conditions which are relevant to the first moments of flow, when initial platelet deposition occurs.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030102
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  • 10
    Electronic Resource
    Electronic Resource
    Development of lithographic techniques for metallisation of organic substrates (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 1 (1992), S. 197-201 
    Details
    ISSN: 1057-9257
    Keywords: Lithography ; SAW device ; Methylbenzylamino-5-nitropyridine ; Gold/titanium bilayer ; Shadow masking ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: A wide range of applications which involve organic crystalline materials require the metallisation of low-molecular-weight compounds. Conventional lithographic techniques used in silicon fabrication technology use high-temperature processing methods which are unsuitable for organic materials. Gold/titanium bilayer and shadow-masking techniques were found to provide suitable solutions to the problem of metallisation of these materials and allowed fabrication of a surface acoustic wave (SAW) device with (-)-2-α-methylbenzylamino-5-nitropyridine (MBANP) as substrate.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/amo.860010406
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