John W. Fitch

Hexafluoroisopropylidene-Containing Polymers for High-Performance Applications

Abstract High-performance polymers are used in applications demanding service at enhanced temperature while maintaining their structural integrity and an excellent combination of chemical, physical, and mechanical properties. Some of the important polymers in this respect are polyimides, polyamides, and polybenzazoles. However, all of these polymers have a common problem of processing difficulty due to their infusibility and poor solubility in organic solvents. The reasons are strong interchain forces, inherent macromolecular rigidity, or semicrystallinity. A great amount of work has been directed to making polymers more tractable, soluble, and processable without sacrificing their high-performance characteristics. Thus, the last two decades have witnessed the spectacular growth of research in a new polymer type, the one containing hexafluoroisopropylidene (6F) groups. Incorporation of 6F units into the macromolecular chain increases the solubility, thermal stability, flame resistance, glass transition te...

Synthesis of novel fluorine‐containing poly(aryl ether ketone)s

The high-performance fluorinated polymers have been receiving considerable attention as interesting advanced materials. The incorporation of fluorine atoms into polymer chains leads to polymers with increased solubility, flame resistance, thermal stability and glass transition temperature while also leading to decreased color, crystallinity, dielectric constant and moisture absorption. 2,3,4,5,6-Pentafluorobenzoic acid (PFBA) is a valuable intermediate for pharmaceuticals, pesticides, perfumes, cosmetics and so on, and it is available as a commercial product. However, the polymers derived from PFBA have not been reported so far. In this paper, we report the synthesis and characterization of novel fluorinated poly(aryl ether ketone)s (PEKs) containing 2,3,5,6-tetrafluoro-1,4-phenylene moieties derived from PFBA. Novel fluorinated PEKs are prepared from PFBA by aromatic nucleophilic substitution reaction, of which Mn values range from 2.28 × 104 to 1.04 × 105. They have all para connected linear structures. The aromatic fluorine of the para position to the carbonyl groups of monomers is preferentially substituted by phenoxide and this para orientation is mainly attributed to the steric effect rather than π-electron density. The obtained PEKs except 8F-PEKEK (BP) show excellent solubilities in common solvents and can be cast into tough transparent films. They also exhibit high glass transition temperatures depending on the structures and outstanding thermal stabilities. Furthermore, these fluorine-containing PEKs exhibit low dielectric constants from 2.87 to 3.52 at 1 MHz. Copyright

Vinylmetallics as Ligands : I. The preparation of some alkylvinylsilane and alkylvinyltin complexes of copper(I) chloride

Abstract The compounds, (CH3)3SiCHCH2·CuCl,(CH3)3SnCHCH2·CuCl,(CH3)2Si(CHCH)2)2·2 CuCl, (CH3)2Sn(CHCH2)2·2 CuCl, and (C4H9)Sn(CHCH2)2·2 CuCl are prepared by allowing the neat vinylmetallic to react with copper(I) chloride. The new π-complexes are characterized by elemental analysis and by IR and NMR spectroscopy. A bonding schme is proposed to explain the unusual liability of these complexes.

Synthesis of poly-Schiff bases and some copper(II) and manganese(lI) polychelates

Abstract Four poly-Schiff bases derived from hydroxyketones and aromatic diamines have been synthesized, and their copper and manganese complexes were prepared and charactefized by elemental analyses, spectral, magnetic and thermal data. The polychelates are of 1:1 (metal-poly-Schiff base) stoichiometry and exhibit four and six-coordination for copper and manganese respectively. The chelation is through the nitrogen of the azomethine group and oxygen of hydroxy group in the poly-Schiff bases.

Organometalloidal derivatives of the transition metals : VI. The potential of 29Si NMR spectroscopy in analysis of π-organosilyl complexes of the transition metals [1]

Abstract The 29 Si FT NMR characteristics of a number of π organosilyl-transition metal complexes have been determined and their usefulness for characterizing the complexes investigated.

Vinylmetallics as ligands III. Synthesis and characterization of potassium trichloro(trimethylvinylsilane)platinate(II)

Abstract The preparation and some reactions of the compound potassium trichloro(trimethylvinylsilane)platinate(II) are reported.

Vinylmetallics as ligands. VI. Preparation and stabilities of a series of vinylsilane-platinum (0) complexes

Abstract A series of complexes of formula, [(Ph 3 P) 2 PtCH 2 CHSi (CH 3 ) n (OC 2 H 5 ) 3n ] (n  0,1,2,3), has been prepared and characterized. The all carbon compound, [(Ph 3 P) 2 PtCH 2 CHC (CH 3 ) 3 ], has also been prepared and found to decompose in solution much more readily than its silicon analogue.

Vinylmetallics as ligands : VII. Acetylacetonatobis(η2-vinylsilane)rhodium(I) complexes

Abstract Complexes of the type, [(acac)Rh(ViSiR 3 ) 2 ] and [(acac)Rh(Vi 2 SiR 2 )], are readily prepared by displacement of ethylene from [(acac)Rh(C 2 H 4 ) 2 ]. The compounds, which are less reactive to air than similar carbon analogues, have been characterized by 1 H and 13 C NMR. The 13 C NMR results suggest that the vinylsilane ligands function as better π-acceptors than do similar carbon analogues, and that d π p π interactions between the silicon atom and the double bond are decreased upon coordination of the vinylsilane.

Poly(aryl ether ketones) bearing alkylated side chains

Poly(aryl ether ketones) containing pendant alkyl side chains were prepared by the nucleophilic displacement reaction of 2,2-bis(4-hydroxphenyl)tridecane, 2-2,bis(4hydroxyphenyl)nonadecane and bisphenol AF with 2,2-bis-[4-(4-fluorobenzoyl)phenyl]propane and 2,2-bis[4-(4-fluorobenzoyl)phenyl]hexa-fluoropropane in the presence of potassium carbonate in N,N-dimethylacet-amide. The polymers had inherent viscosities up to 1.04 dl g−1 in chloroform, formed creaseable films and were soluble in common organic solvents. Their dielectric constants were below 2.60 (at 10 GHz). The inclusion of the alkyl side chains lowered the T g, thermal stability and char yield of fluorinated poly(ether ketone) as expected.

Fluorine- and silicon-containing polyoxadiazoles

Abstract Colourless polyoxadiazoles containing both hexafluoroisopropylidene and diphenylsilyl groups in the backbone have been synthesized. The new film-forming polymers are soluble in common solvents (tetrahydrofuran, CHCl 3 ) and are stable (by thermogravimetric analysis) to about 500°C in both nitrogen and air.