Solubilities thermogravimetric analysis

In most of the studies discussed above, except for the meta-linked diamines, when the aromatic content (dianhydride and diamine chain extender), of the copolymers were increased above a certain level, the materials became insoluble and infusible 153, i79, lsi) solution to this problem with minimum sacrifice in the thermal properties of the products has been the synthesis of siloxane-amide-imides183). In this approach pyromellitic acid chloride has been utilized instead of PMDA or BTDA and the copolymers were synthesized in two steps. The first step, which involved the formation of (siloxane-amide-amic acid) intermediate was conducted at low temperatures (0-25 °C) in THF/DMAC solution. After purification of this intermediate thin films were cast on stainless steel or glass plates and imidization was obtained in high temperature ovens between 100 and 300 °C following a similar procedure that was discussed for siloxane-imide copolymers. Copolymers obtained showed good solubility in various polar solvents. DSC studies indicated the formation of two-phase morphologies. Thermogravimetric analysis showed that the thermal stability of these siloxane-amide-imide systems were comparable to those of siloxane-imide copolymers 183>. 

Typical characterization of the thermal conversion process for a given molecular precursor involves the use of thermogravimetric analysis (TGA) to obtain ceramic yields, and solution NMR spectroscopy to identify soluble decomposition products. Analyses of the volatile species given off during solid phase decompositions have also been employed. The thermal conversions of complexes containing M - 0Si(0 Bu)3 and M - 02P(0 Bu)2 moieties invariably proceed via ehmination of isobutylene and the formation of M - O - Si - OH and M - O - P - OH linkages that immediately imdergo condensation processes (via ehmination of H2O), with subsequent formation of insoluble multi-component oxide materials. For example, thermolysis of Zr[OSi(O Bu)3]4 in toluene at 413 K results in ehmination of 12 equiv of isobutylene and formation of a transparent gel [67,68]. 

In this study, we extend the range of inorganic materials produced from polymeric precursors to include copper composites. Soluble complexes between poly(2-vinylpyridine) (P2VPy) and cupric chloride were prepared in a mixed solvent of 95% methanol 5% water. Pyrolysis of the isolated complexes results in the formation of carbonaceous composites of copper. The decomposition mechanism of the complexes was studied by optical, infrared, x-ray photoelectron and pyrolysis mass spectroscopy as well as thermogravimetric analysis and magnetic susceptibility measurements. 

Apart from the qualitative observations made previously about suitable solvents for study, the subject of solvates has two important bearings on the topics of thermochemistry which form the main body of this review. The first is that measured solubilities relate to the appropriate hydrate in equilibrium with the saturated solution, rather than to the anhydrous halide. Obviously, therefore, any estimate of enthalpy of solution from temperature dependence of solubility will refer to the appropriate solvate. The second area of relevance is to halide-solvent bonding strengths. These may be gauged to some extent from differential thermal analysis (DTA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) solvates of "aprotic solvents such as pyridine, tetrahydrofuran, and acetonitrile will give clearer pictures here than solvates of "protic solvents such as water or alcohols. 

A -sulfinylacetamide 297 in greater than 90% yield when a catalytic amount of methyltrioxorhenium is employed. Futhermore, the hetero-Diels-Alder adduct is highly soluble in both chlorinated and ethereal solvents. A detailed investigation of the retro-Diels-Alder reaction of 298 by thermogravimetric analysis revealed an onset temperature of 120 °C and complete conversion of bicycle 298 to pentacene 296 at 160 °C, which are temperatures compatible with the polymer supports typically used in electronics applications. The electronic properties of these newly prepared OTFTs are similar to those prepared by traditional methods. Later improvements to this chemistry included the use of A -sulfinyl-/< r/-butylcarbamate 299 as the dienophile <2004JA12740>. The retro-Diels-Alder reaction of substrate 300 proceeds at much lower temperatures (130 °C, 5 min with FlTcatalyst 150 °C, Ih with no catalyst). 

Kundu and Bhattacharya14 have isolated dioxouranium complexes of benzohydroxamic acid with the compositions M[U02(C7H602N)3] [where M = Li, Na, K, Cs, Tl, N4, pyH+ (pyridinium) or agH+ (aminoguanidinium)] and M [U02(C7H602N)3]2 [where M = enH2+ (ethylene-diammonium)]. All the complexes, with the exception of the sodium compound, are insoluble in common organic solvents but are soluble in DMSO and DMF. The complexes have been characterized on the basis of electronic, IR and molar conductance data in DMF. Their fairly stable character is indicated by thermogravimetric analysis and the stability order is NH4+ < Tl+ < Cs+ < Li+ w Na+ agH+ < K+ pyH+ < enHl+. 

Interesting comparisons have been made 17 between dendritic and the hyperbranched structures the thermal properties (glass transition temperature and thermogravimetric analysis) were independent of architecture and their solubilities were comparable, but greater than that shown for linear counterparts. 

The [Cr(H20)(0H) 0P(C H8)20 2]a polymer is a green solid which is readily soluble in chloroform, benzene, and tetrahydro-furan but is insoluble in water and diethyl ether. It does not melt before decomposing thermogravimetric analysis indicates decomposition starting at 365°C. A freshly prepared solution in chloroform has an intrinsic viscosity ranging from 0.03 to 0.04 dl./g. The intrinsic viscosity increases slowly when solutions in organic solvents (for example, 1 g./lOO ml. in chloroform) are allowed to stand at temperatures of approximately 55°C., and values of 0.6-0.8 dl./g. are common after a number of days. A sample with an intrinsic viscosity of 0.04 dl./g. 

Son and coworkers also reported the syntheses of hyperbranched poly(carbosilanes) via hydrosilylation. In one report, they prepared a series of AB3 carbosilarylene monomers (5, 6 and 7)173 which polymerized cleanly and rapidly to form soluble hyperbranched polymers in high yields. The polymers, ranging in appearance from sticky solids to oils, were characterized by NMR spectroscopy, thermogravimetric analysis, differential scanning calorimetry and vapor pressure osmometry. The polymers possessed subambient Tg... 

Although polar materials constitute the major portion of the pentane solubles, saturates and aromatics are also found in appreciable concentrations (Table V). The relatively low H/C ratio of the saturate fraction suggests a high concentration of saturated cyclics or olefins. Thermogravimetric analysis indicated that only about 40% of the pentane solubles is volatile under typical gas chromatographic conditions. 

Study of the solubility and solid phases encountered in the Zr02-H3P04-H20 system over the temperature range of 20 to 100°C. Techniques used include differential thermal calorimetry, thermogravimetric analysis, infrared spectroscopy and X-ray diffraction analysis. The paper discusses briefly the changes occurring in the solid phases over the temperature shift, but is poor in characterising the solution composition since the concentrations of the constituent ions were below the detectable concentrations. No chemical thermodynamics data are detailed in the paper. 

Infrared Spectrum Nuclear Magnetic Resonance Spectrum Mass Spectrum Ultraviolet Spectrum Differential Thermal Analysis Thermogravimetric Analysis Melting Range Solubility... 

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