Chemical approach for controlling nadimide cure temperature and rate with maleimide

Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl endcapped monomers and oligomers. The copolymers can be cured at temperatures under about 300 C by controlling the available concentration of the maleic end-capped reactant. Control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymers, so as to either increase Diels-Alder retrogression of the norbornenyl capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic-capped reactant

Phosphorus-containing imide resins

Bis- and tris-imides derived from tris (m-aminophenyl) phosphine oxides by reaction with maleic anhydride or its derivatives, and addition polymers of such imides, including a variant in which a mono-imide is condensed with a dianhydride and the product is treated with a further quantity of maleic anhydride. Such monomers or their oligomes may be used to impregnate fibers and fabrics which when cured, are flame resistant. Also an improved method of producing tris (m-aminophenyl) phosphine oxides from the nitro analogues by reduction with hydrazine hydrate using palladized charcoal or Raney nickel as the catalyst is described

Synthesis and Characterization of Three-Coordinate Ni(III)-Imide Complexes

A new family of low-coordinate nickel imides supported by 1,2-bis(di-tert-butylphosphino)ethane was synthesized. Oxidation of nickel(II) complexes led to the formation of both aryl- and alkyl-substituted nickel(III)-imides, and examples of both types have been isolated and fully characterized. The aryl substituent that proved most useful in stabilizing the Ni(III)-imide moiety was the bulky 2,6-dimesitylphenyl. The two Ni(III)-imide compounds showed different variable-temperature magnetic properties but analogous EPR spectra at low temperatures. To account for this discrepancy, a low-spin/high-spin equilibrium was proposed to take place for the alkyl-substituted Ni(III)-imide complex. This proposal was supported by DFT calculations. DFT calculations also indicated that the unpaired electron is mostly localized on the imide nitrogen for the Ni(III) complexes. The results of reactions carried out in the presence of hydrogen donors supported the findings from DFT calculations that the adamantyl substituent was a significantly more reactive hydrogen-atom abstractor. Interestingly, the steric properties of the 2,6-dimesitylphenyl substituent are important not only in protecting the Ni═N core but also in favoring one rotamer of the resulting Ni(III)-imide, by locking the phenyl ring in a perpendicular orientation with respect to the NiPP plane

Molecular and macromolecular structure changes in polyamide 11 during thermal oxidation

The present article reports a study of thermal oxidation of unstabilized polyamide 11 films at several temperatures (90–165 °C) under atmospheric pressure and under various oxygen pressures (up to 1.6 MPa) at 110 °C. The chemical structure changes are monitored by IR spectroscopy (carbonyl groups) and UV–visible spectrophotometry (yellowing). Molar mass changes are determined by size exclusion chromatography (SEC). By investigating the influence of oxygen pressure it is clearly shown that reactions involving P° radicals other than O2 addition cannot be neglected under atmospheric pressure. Under the conditions of this study limited to relatively low oxidation levels, IR and UV measurements indicate that carbonyl groups and chromophores responsible for yellowing have the same relative yield whatever the temperature and oxygen pressure. SEC measurements highlight the significant predominance of random chain scissions over crosslinking events. Crosslinking only appears after an induction time, presumably because it involves reactions between primary oxidation products. The ratio of carbonyl groups over chain scissions is about 7.5 at low conversion and about 2.5 at high conversion, showing that α amino alkoxy radicals are mainly transformed into imides without chain scission

The synthesis and characterization of polypeptide-adriamycin conjugates and its complexes with adriamycin. Part I

Poly(α-l-glutamic acid) (PGA) was grafted with amino acid and oligopeptide spacers up to 5 amino acids with the use of N,N'-carbonyldiimidazole and 2,3-dihydro-1,2-benz-isothiazole-3-on-1, 1-dioxide (saccharin) as an additive, and these polypeptides were characterized. The antitumor antibiotic adriamycin was covalently coupled via an amide bond onto PGA and onto the grafted polymers with the use of N-ethoxycarbonyl-2-ethoxy-1, 2-dihydroquinoline (EEDQ); these conjugates were characterized. The conjugates containing Gly—Gly—l-Leu spacer arms did yield free adriamycin upon digestion with papain. Adriamycin gave fairly stable complexes with PGA—adriamycin and branched poly peptide—adriamycin conjugates; these complexes were characterized

Chemical approach for controlling nadimide cure temperature and rate

Polyimide resins suitable for use as composite matrix materials are formed by copolymerization of maleic and norbornenyl endcapped monomers and oligomers. The copolymers can be cured at temperatures under about 300 C by controlling the available concentration of the maleic capped reactant. This control can be achieved by adding sufficient amounts of said maleic reactant, or by chemical modification of either copolymer, so as to either increase Diels-Alder retrogression of the norbornenyl capped reactant and/or holding initiation and polymerization to a rate compatible with the availability of the maleic capped reactant

Fully Chlorinated N-Silyl Amides of Titanium and Tungsten

The reaction of hexachlorodisilazanyllithium (Cl3Si)2NLi (1), with TiCl4 leads selectively to the novel fully chlorinated amides (Cl3Si)2NTiCl3 (2) or [(Cl3Si)2N]2 TiCl2 (3), respectively, depending on the molar ratio of the starting materials. The analogous reaction of 1 with WCl6 yielded the amide imide Cl3SiNW(Cl3)N(SiCl3)2 (5) by elimination of SiCl4. The relative amounts of the starting materials had no effect on the formation of 5. 14/15N- and 29Si-NMR data on the starting materials and products show significantly different effects, when compared with those of analogous N-trimethylsilyl derivatives, due to the lower energy of the electrons in the NSi and NM ß bonds. The crystal structure of 5 (triclinic, space group P1) was determined by X-ray structure analysis

Fused Quinoidal Oligothiophenes Imides with High Electrical Conductivity

Organic diradicals are molecules containing two unpaired electrons, which are usually highly reactive.1-2 Although these organic diradicals present a wide range of potential applications, their air stability still remains as a major obstacle.3 In order to overcome this, new organic diradicals based on quinoidal oligothiophenes-derivatives (QOT) have been synthesized, i.e. BTICN, ISOCN and QTICN (see Figure 1). These new molecules present high stability and electrical conductivity, which have been achieved by employing imide-bridged fused molecular frameworks. The combination of strong electron-withdrawing imide with tetracyano groups in the conjugated skeletons also enabled extremely deeply aligned LUMO levels and large diradical character assisted by cross-conjugation.4 Here we use different experimental techniques and DFT calculations to provide new insights into the electron conduction mechanism of QOT diradicaloids, in order to demonstrate the great potential of fused quinoidal oligothiophene imides in developing stable organic diradicals and high-performance doping-free n-type conductive materials.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

7-Azabicyclo[2.2.1]heptane N-Imide as an Intermediate in the Thermal Decomposition of N-Amino-7-Azabicyclo[2.2.1]heptane and the Corresponding Benzenesulphonamide

An intermediate in the thermal decomposition of N-amino-7-azabicyclo[2.2.1]heptane and the corresponding benzenesulphonamide derivative, whose structure is consistent with the formulation 7-azabicyclo[2.2.1]heptane N-imide, affords on thermal fragmentation the hydrocarbon products hexa-1,5-diene, bicyclo[2.2.0]hexane, and cyclohexene and does not rearrange to the corresponding stable 2,3-diazabicyclo[2.2.2]oct-2-ene isomer