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  • 1
    Electronic Resource
    Electronic Resource
    Photochemistry and photophysics of poly(organophosphazenes) and related compounds: A review. II. Bimolecular reactions (1994)
    Springer
    Journal of inorganic and organometallic polymers and materials 4 (1994), S. 95-142 
    Details
    ISSN: 1572-8870
    Keywords: Poly(organophosphazenes) ; bimolecular reactions ; photochemistry ; photophysics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the second part of this review we highlight the bimolecular reactions (hydrogen abstraction, and energy or electron transfer) that take place in the photochemistry of poly(organophosphazenes). Both inter-molecular interactions (i.e. between excited free chromophores and ground state groups attached to the phosphazenes, or between excited phosphazene substituents and external quenchers) and intra-molecular processes (i.e. between excited and ground state groups geminally attached to the same phosphorus or supported to different phosphorus along the polyphosphazene skeleton) are exploited. Suggestions are given on the possible practical application of these reactions in different photochemical domains, e.g. heterogeneous-phase photosensitization, photocrosslinking, photoconductivity, microelectronics, light-induced radical polymerization of vinyl monomers, etc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01036538
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  • 2
    Electronic Resource
    Electronic Resource
    Photochemical Behavior of Poly(Organophosphazenes). 15. Light-Induced Cross-Linking of [(4-Benzoylphenoxy) x (Methoxyethoxyethoxy)2 − x ] Phosphazene Copolymers (1998)
    Springer
    Journal of inorganic and organometallic polymers and materials 8 (1998), S. 67-88 
    Details
    ISSN: 1572-8870
    Keywords: Poly(organophosphazenes) ; photochemical behavior ; light-induced cross-linking ; poly[bis(methoxyethoxyethoxy)phoshazene] ; benezophenone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis of a new, highly photosensitive, phosphazene copolymer containing an almost-equimolecular quantity of benzophenone and methoxyethoxyethoxy substituents is reported in this paper, together with the photochemical behavior of this material when irradiated in film both in oxygen and in an argon atmosphere. It has been detected that the photoreactivity of the phosphazene material strongly depends on the light absorption process by the benzophenone moieties, whose selective excitation predominantly brings about an intramolecular hydrogen abstraction reaction from the ethylene oxide units, thus producing highly reactive phosphazene macroradicals. The coupling reactions of these species results in the complete cross-linking of the polyphosphazene substrate and in its total insolubilization. Moreover, the influence of molecular oxygen on the overall photochemical process of the benzophenone/ethyleneoxide-substituted phosphazene copolymer is investigated. The implications of the light-induced reticulation process in the controlled insolubilization of poly[ bis (methoxyethoxyethoxy)phosphazene] are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022411205861
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Phosphazene-bound Rose Bengal: A novel photosensitizer for singlet oxygen generation (1991)
    Springer
    Journal of inorganic and organometallic polymers and materials 1 (1991), S. 389-395 
    Details
    ISSN: 1572-8870
    Keywords: Poly(organophosphazenes) ; cyclophosphazenes ; Rose Bengal ; photosensitization ; singlet oxygen ; oxidation ; heterogeneous phase photosensitizer ; 1,3-diphenyl-isobenzofuran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this paper we report the synthesis and the characterization of cyclo- and polyphosphazenes supporting Rose Bengal. These substrates are suitable for the photosensitized generation of singlet oxygen, both in homogeneous and in heterogeneous phase. The efficiency of1O2 production has been measured in homogeneous solution using, as photosensitizer, the cyclophosphazene-bound Rose Bengal and considering, as testing reaction, the oxidation of 1,3-diphenylisobenzofuran; it was found comparable to that of free Rose Bengal in the same experimental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702501
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  • 4
    Electronic Resource
    Electronic Resource
    Photochemistry and photophysics of poly(organophosphazenes) and related compounds: A review. I. Monomolecular processes (1994)
    Springer
    Journal of inorganic and organometallic polymers and materials 4 (1994), S. 1-29 
    Details
    ISSN: 1572-8870
    Keywords: Poly(organophosphazenes) ; monomolecular processes ; photochemistry ; photophysics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this review we report an outline of the synthesis, UV-Vis spectral characterization, and light-induced reactivity in monomolecular processes of poly(organophosphazenes). The photoreactivity of phosphazene polymers, both in solution and in solid state, strongly depends on the nature of the chromophore attached to the phosphorus atoms of the inorganic −P=N − backbone. In fact, polyphosphazenes not bearing mobile hydrogen atoms in the side moieties undergo, in the first excited singlet state, homolytic eleavage of the bonds connecting the substituents to the inorganic backbone: free radicals of the substituents and phosphazene macroradicals are formed. Moreover, for polyphosphazenes containing labile hydrogens in the side groups, C–H bond scission takes place with the formation of free hydrogens and radicals located in the phosphazene substituents. From these species degradation or crosslinking of the macromolecules will follow according to the experimental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00684025
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  • 5
    Electronic Resource
    Electronic Resource
    Photochemistry and photophysics of poly(organophosphazenes) and related compounds: A review. III. Applicative aspects (1994)
    Springer
    Journal of inorganic and organometallic polymers and materials 4 (1994), S. 205-236 
    Details
    ISSN: 1572-8870
    Keywords: Poly(organophosphazenes) ; photochemistry ; photophysics ; photochromism ; azobenzene ; spiropyran ; light-induced grafting ; photo-stabilizers ; photoinitiators
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the third part of this review we report some applicative aspects of poly(organophosphazenes) in photochemical fields. In particular, the possible application of phosphazene polymers that contain azobenzene or spiropyran residues as photochromic macromolecules is outlined; the light-induced grafting of organic, carbon-backboned polymers onto polyphosphazene matrices, as a method of modifying both surface and bulk properties of these materials, is highlighted; and the potential application of cyclophosphazenes as photo-stabilizers for commercial organic polymers or as photoinitiators for radical polymerization of vinyl monomers is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00683716
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Photochemical behaviour of poly(organophosphazenes). 14. Photooxidation of poly[bis(4-isopropylphenoxy) phosphazene] under accelerated conditions (1996)
    Springer
    Journal of inorganic and organometallic polymers and materials 6 (1996), S. 325-340 
    Details
    ISSN: 1572-8870
    Keywords: Poly(organophosphazenes) ; photooxidation ; poly[bis(4-isopropylphenoxy)-phosphazene] ; photodegradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The photooxidation of poly[bis(4-isopropylphenoxy)phosphazene] under accelerated conditions has been followed by FTIR and UV visible spectroscopic techniques. The main photooxidation products are acetophenone and phenol groups. In addition, acetone vapors have been detected by GC MS combined techniques concomitant with the IR spectral changes in the CH stretching region, suggesting a significant decrease in the isopropyl moieties. The presence of polymeric sequences having phenol groups under our conditions gives origin to further oxidation reactions due to electron transfer or radical recombination or to hydrogen abstraction reactions promoted by unhindered phenoxyl radicals. In addition, the absence of UV visible light, i.e., under thermooxidation reaction at 60° C has demonstrated that phenol groups are the main responsible of secondary oxidation products. The complexity of the photooxidation mechanism in the solid state for this polymer makes it difficult to determine a definitive degradation mechanism under both thermo- and photooxidative conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062513
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