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  • Polymer and Materials Science  (8)
Publikationsart
Schlagwörter
Verlag/Herausgeber
Erscheinungszeitraum
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 2 (1991), S. 67-72 
    ISSN: 1045-4861
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Poly(vinyl alcohol) (PVA) microspheres impregnated with barium sulphate and methyl iothalamate, having diameters raning from 100 to 1500 μm were prepared by the glutaraldehyde cross-linking of an aqueous dispersion of PVA containing the radiopaques in paraffin oil using dioctyl sulfosuccinate (DOS) as the stabilizing agent and thionyl chloride as the catalyst. while the use of thionyl chloride allowed the formation of spherical, nonaggregatory beads, other catalysts such as magnesium chloride and hydrochloric acid gave rise to an agglomerated product. The radiopaques were found to be firmly trapped inside the microspheres as they did not leach out on prolonged standing in water, on sonication, or on steam sterilization. Microspheres with pores and channels were also made by incorporating a fine powder of methyl methacrylate along with barium sulphate during their preparation and washing out the polymer after the microspheres were formed. The porous nature of such microspheres was confirmed by transmission electron microscopy (TEM). Microspheres containing the radiopaques exhibited hydrophilicity, swelling ability, and compressibility to a significant extent. the radiopaque nature of the microspheres was confirmed by their x-ray images. In vitro tests using heparinized calf blood showed that the microspheres were nonhaemolytic in nature. These microspheres may find application as radiopaque emboli in particulate embolization.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 743-748 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Triiodophenol and iothalamic acid (5-acetamido-2,4,6-triio-N-methyl isophthalamic acid) were converted to their acrylic derivatives by esterfication with methacryloyl chloride and 2-hydroxyethyl methacrylate (HEMA), respectively. The monomers due to presence of heavy iodine atoms were expected to be radiopaque in nature. The monomers were characterized using TLC, IR, and 1H-NMR spectroscopy. Both monomers were highly resistant to homopolymerization and copolymerization with other acrylic monomers such as methyl methacrylate (MMA) or HEMA by initiators such as 2,2′-azobis isobutyronitriie (AIBN) or benzoyl peroxide (BPO) yielding only polymers of low molecular weight. The polymers obtained were charactrized by gel permeation chromatography (GPC) and differential thermal analysis (DTA). The resistance to polymerization is presumably due to the presence of bulky iodine atoms in the monomers sterically hindering the propagation step. The decomposition temperatures of the homopolymers and copolymers were close to 300°. Copolymers of HEMA with both radiopaque monomers incorporated to the extent of 25 wt % in the feed, however, produced polymers with good radiopacity. Copolymers with HEMA were also prepared in the form of microspheres by a solvent evaporation method with the aim of using them as particles in therapeutic embolization. While the polymer based on triiodophenol was found to cause extensive blood haemolysis in in vitro tests, polymer based on iothalamic acid was found to be nonhemolytic in character suggesting that copolymers based on iothalamic acid would be suitable for implantation in the living tissue.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 1153-1161 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Poly(methyl methacrylate)/(PMMA) microspheres crosslinked with various concentrations of ethylene glycol dimethacrylate (EGDM) were prepared by a suspension polymerization procedure. They were subjected to alkaline hydrolysis in ethylene glycol at high temperature (〉 175°C), resulting in the rapid conversion of methacrylate ester functions to methacrylic acid, while retaining the spherical shape of the microspheres intact. The method provides a novel approach to obtain smooth, nearly perfect spherical, mechanically strong, high water-absorbing hydrogel beads from crosslinked PMMA. The reaction has been found to be considerably faster than many of the hydrolysis procedures reported previously. The effect of concentration of alkali, particle size, crosslinking density, and reaction time on the extent of hydrolysis has been investigated to a limited extent.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 56 (1995), S. 1187-1195 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The migration of phthalate esters which are commonly employed for plasticizing poly(vinyl chloride) (PVC) is a significant problem in PVC-based medical devices as well as in packaging used for food stuffs and pharmaceuticals. Medical-grade PVC resin was treated with sodium azide in dimethylformamide (DMF) to prepare the azide polymer. The polymeric azide was coated onto the surface of plasticized PVC sheets by dipping in a solution of the polymer in tetrahydrofuran (THF). Crosslinking of the azide polymer was accomplished by irradiating the surface using a 125 W UV lamp for various lengths of time. Migration of the plasticizer di 2-(ethylhexyl phthalate) (DEHP) from coated and uncoated samples was examined in n-hexane at 30°C. It was found that 50-80% reduction in migration of DEHP could be effected from plasticized PVC in comparison with the controls in 72 h by this technique depending on the concentration of the coating solution, coating thickness, azide concentration, and irradiation dose. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 2937-2940 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 993-1004 
    ISSN: 0021-9304
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin , Technik allgemein
    Notizen: Highly porous poly(2-hydroxyethyl methacrylate) (PHEMA) microspheres prepared by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) in presence of polymeric diluents such as poly(methyl methacrylate) (PMMA) in toluene and poly(tetramethylene glycol) (PTMG) were made radiopaque by esterification of the reactive hydroxyl groups with iothalamic acid and iopanoic acid, two radiopaque substances clinically used. Of the various solvents and catalysts examined, tetrahydrofuran (THF) and N,N′-dimethyl paratoluidine (DMPT) were found to be best for obtaining a high degree of conversion. More than 30 wt% iodine could be bound to the microspheres which made them sufficiently radiopaque to be imaged radiographically. Microspheres retained their porosity, swelling ability, hydrophilicity, and surface morphology to a significant extent after iodination. Preliminary implantation studies of such microspheres subcutaneously in rats have shown no adverse tissue reactions over a 6-month period. It is suggested that these microspheres would prove to be useful as particulate emboli in endovascular embolization.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 21 (1983), S. 3201-3208 
    ISSN: 0360-6376
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of phase-transfer-catalyzed free-radical polymerization of methyl methacrylate using the system ammonium peroxydisulfate/hexadecyl pyridinium chloride have been investigated in the temperature range of 50-60°C in ethyl acetate/water two-phase systems. The superior efficiency of the phase-transfer-catalyzed reaction in comparison with polymerization initiated by oil soluble initiators such as 2,2′-azobisisobutyronitrile and benzoylperoxide has been demonstrated. Rate of polymerization increased with increase in concentration of the quaternary salt but showed a tendency to level off at higher concentrations. Increase in the peroxydisulfate concentration also resulted in an increase in the rate at lower concentrations, but was found to decrease at higher concentrations. The order with respect to the monomer was found to be approximately unity. The title reaction has been found to be not truly phase-transfer catalyzed in character as claimed by previous workers. A suitable kinetic scheme has been proposed to account for the experimental data and its significance discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 22 (1984), S. 31-38 
    ISSN: 0360-6384
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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