摘要:

AbstractAn integrated chemical and physicochemical investigation of the cofacially joined metallomacrocyclic polymers [M(Pc)O]n(M = Si, Ge, Si) and the halogen‐doped, electrically conductive derivatives {[M(Pc)O]Xy}n(X = I; M = Si, Ge; X = Br; M = Si) is reported. The structures of these polymers have been studied by X‐ray diffraction, resonance Raman, transmission infrared, transmission optical,13C CP‐MAS NMR, and EPR spectroscopy. The picture which emerges is that of inhomogeneously doped, mixed‐valent arrays of predominantly ligand‐oxidized (π radical cation) metallomacrocycles. Magnetic susceptibility and optical reflectivity measurements reveal a progressive increase in tight‐binding bandwidths with decreasing interplanar (ring‐ring) spacing. Studies of dc electrical conductivity as a function of dopant level and temperature suggest that transport in these heterogeneously doped materials can be satisfactorily described with percolation theory and fluctuation‐induced carrier tunneling. The conductivity is a sensitive function of the ring‐ring stacking separations; evidence is presented for “metal‐like” (dσ/dt

ISSN:0360-8905    

DOI:10.1002/polc.5070700103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA review of an extensive study on the preparation and solid‐state reactivity of squareplanar NiX2L2complexes is presented, where X = Cl, Br, I, or NCS and L = P(CH2CH2CN)3. Physical, chemical, and crystallographic criteria have been evaluated for such complexes, from the viewpoints of the properties and reactivity of the squareplanar monomer and the analogous octahedral polymer. Factors such as nearest‐neighbor interactions, nucleation, temperature, doping, polymorphism, and crystal symmetry greatly influence the course of the thermal solid‐state reactions. The reactionsper seare characterized by chemical and crystallographic specificity, stereodirectionality, highly anisotropic front motion in single crystals, and reversibility. In a series of preliminary, related experiments, the radiation‐induced polymerization of salts and complexes of β‐acryloxypropionic acid and propiolic acid has been studied; there is a great variation in reactivity among these species. Many of the reactive phases have short contacts between neighboring molecules which would appear to satisfy topochemical criteria for reaction in the s

ISSN:0360-8905    

DOI:10.1002/polc.5070700104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractPolyacetylene was doped from solution with dihydrogen hexachloroiridate (H2IrCl6·6H2O), and also doped electrochemically with tetra‐n‐butylammonium hexachloroiridate(IV) (NBu4)2IrCl6·6H2O to form electrically conductive complexes. The doped polymer was characterized by ultraviolet, visible, and infrared spectroscopy, X‐ray diffraction, EPR spectroscopy, transmission electron microscopy, and electrical transport measurements. A hydrolyzed hexachloroiridate species was incorporated in the polymer during spontaneous doping with H2IrCl6·6H2O, whereas electrochemical doping with (NBu4)2IrCl6·6H2O resulted in the introduction of the expected hexachloroiridate species. Evidence suggests that, in the case of H2IrCl6·6H2O, doping occurs by a proton acid mechanism. TEM studies indicate that the hexachloroiridate dopant is not distributed homogeneously in the polymer. The stability of hexachloroiridate‐doped polyacetylene was examined in air, in an inert atmosphere, and at high temperatures. In air, the rate of decrease of the conductivity was about one order of magnitude per 28 days, whereas in an inert atmosphere, the conductivity dropped about one order of magnitude

ISSN:0360-8905    

DOI:10.1002/polc.5070700105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractPolyphosphazenes are prepared by a substitutive process that involves nucleophilic displacement reactions on poly(dihalophosphazenes). A variety of strategies are described for the utilization of this approach for the preparation of polymeric drugs and polymer‐bound transition metal system

ISSN:0360-8905    

DOI:10.1002/polc.5070700106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractRecent work has shown that the range of synthesis of new and useful phosphazene derivatives can be dramatically expanded by incorporation of an organofunctional substituent on the phosphazene ring. This substituent can serve as the site for various synthetic transformations leading to new monomeric and polymeric phosphazene moieties. Initial work on propenylphosphazenes and their copolymerization with organic monomers is briefly reviewed. The synthesis of new improved phosphazene monomers which lead to flame retardant copolymers is discussed. In addition to electron‐rich olefins such as alkoxylvinylphosphazenes, novel alkynlphosphazene/styrene copolymers were prepared. The vinyl alcohol derivative N3P3Cl5OCH=CH2and related compounds were prepared and characterized. Both homopolymerization and a broad range of copolymerization reactions of N3P3Cl5OCH=CH2are presented. The properties of these systems can be modified by reactions of the cyclophosphazene units in the polyme

ISSN:0360-8905    

DOI:10.1002/polc.5070700107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA series of exactly alternating silarylene‐siloxane homopolymers and copolymers was prepared by the step‐growth polymerization reaction of arylenedisilanols with bis(ureido)silanes. The polymers were obtained in high molecular weight and were found to have low glass transition temperatures and excellent thermal stabilities at high temperatures, particularly in an inert atmosphere. Copolymers containing vinylsiloxane units could be filled and crosslinked to form elastomers with useful mechanical properties and resistance to degradation in air at temperatures up to 25

ISSN:0360-8905    

DOI:10.1002/polc.5070700108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractTransition metal complexes, e.g., L2Pt(C2H4), L3RhCl, and L2Ir(CO)Cl (L = Ph3P), react with tetraalkyldisiloxanes, (HRR'Si)2O, to produce metallacycles featuring the transition metal, two silicons, and the oxygen in a four‐membered ring, MSiOSi. When R = Me and R' = Ph, stereoselectivity in the formation of the metallacycle from a mixture of stereoisomers of the starting disiloxane is observed. The catalytic activity of these complexes for the oligomerization of the disiloxanes has been investigated in the hope of obtaining stereoregular silicones. It has been found that extensive rearrangements occur which redistribute the groups on the silicon atoms. Increased selectivity for the desired exchange type (SiO groups for Si — H) was found when the catalysts were adsorbed on oxide supports. Although the goal of synthesizing stereoregular silicones has not yet been achieved, the results warrant further investigat

ISSN:0360-8905    

DOI:10.1002/polc.5070700109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThermoplastic polycarbosilane precursors for silicon carbide were prepared in high yield through potassium metal dechlorinations of mixtures of vinylic or chloromethyl (ClCH2—) methylchlorosilanes with other methylchlorosilanes in tetrahydrofuran solvent. Monomer mixtures are selected to maximize formation of backbone silicon‐carbon bonds and to maximize backbone branching at silicon, while retaining high synthetic yield and tractability and high yield of silicon carbide composition on pyrolysis. These precursor polymers are nonhazardous, relatively inert, i.e., stable to air and moisture, and have been spun to fiber form for ultimate conversion to silicon carbide fib

ISSN:0360-8905    

DOI:10.1002/polc.5070700110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractA new high‐performance amorphous thermoplastic, named polyetherimide, has been developed by the General Electric Company. This resin is characterized by high deflection temperature (200°C at 264 psi), high tensile strength and flexural modulus (480,000 psi), and very good retention of mechanical properties at elevated temperatures. In addition, the resin exhibits good electrical properties, which remain stable over a wide range of temperature and frequencies (including microwave). Polyetherimide is inherently flame resistant without the use of additives. It has a high limiting oxygen index of 47, combined with NBS smoke chamber results which show the lowest specific optical density of any unfilled thermoplastic (Dmax= 31). One synthetic method for the preparation of polyetherimides and a comprehensive property profile of the first member of this polymer family are present

ISSN:0360-8905    

DOI:10.1002/polc.5070700111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

ISSN:0360-8905    

DOI:10.1002/polc.5070700112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY