Epoxy-clay nanocomposites were prepared by the dispersion of an organically modified layered clay in an epoxy resin (diglycidyl ether of bisphenol A) and curing in the presence of methyl tetrahydro acid anhydride at 80 -160°C. The nanometer-scale dispersion of layered clay within the crosslinked epoxy-resin matrix was confirmed by X-ray diffraction and transmission electron microscopy, and the basal spacing of the silicate layer was greater than 100 -150 Å. Experiments indicated that the hydroxyethyl groups of the alkyl ammonium ions, which were located in the galleries of organically modified clay, participated in the curing reaction and were directly linked to the epoxy-resin matrix network. Experimental results showed that the properties of epoxy were improved, evidently because of the loading of organically modified clay. The impact strength and tensile strength of the nanocomposites increased by 87.8 and 20.9%, respectively, when 3 wt % organic clay was loaded, and this demonstrated that the composites were toughened and strengthened. The thermal-decomposition and heat-distortion temperatures were heightened in comparison with those of pure epoxy resin, and so were the dynamic mechanical properties, including the storage modulus and glass-transition temperature. Moreover, experiments showed that most properties of the composites were ameliorated with low clay contents.

A series of organo-soluble polyimides based on a new fluorinated diamine, 4,4′-bis(3-amino-5-trifluoromethylphenoxy)-3,3′,5,5′-tetramethyl biphenyl (3,5-TFMDA) and various aromatic dianhydrides, were synthesized and characterized. The structures of the obtained polyimides were affirmed by Fourier transform infrared measurement and the properties were evaluated by wide-angle X-ray diffraction measurement, ultraviolet-visible analysis, thermogravimetry (TG), differential scanning calorimetry (DSC), tensile and electrical tests, and solubility tests. It was shown that the polyimides have good solubility not only in polar aprotic solvents, but in many common solvents, such as cyclopentanone, chloroform, and even in toluene for PI-4, derived from TFMDA and 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). The polyimide solutions could be cast into flexible and tough films, which exhibited good thermal stability up to 500° C and showed glass transition temperatures in the range of 250–280° C. The films also showed acceptable tensile properties and good electrical insulating properties. Furthermore, the polyimide films exhibited good transparency in the visible light region with transmittance higher than 80% at 450 nm and a cut-off wavelength lower than 360 nm.

SYNOPSISA photosensitive polysiloxaneimide precursor was synthesized from oxydianiline, bis(paminophenoxy)dimethylsilane, and a diacid chloride. This diacid chloride was prepared by the reaction of thionyl chloride with a diacid, which resulted from the reaction of pyromellitic dianhydride with hydroxyethylacrylate in N-methylpyrrolidone (NMP). The adhesion properties between polyimide and substrates such as SiOe wafer were improved with introduction of siloxane moiety into the polyimide chain. The dielectric constant decreased with increasing siloxane moiety content. The photocrosslinking reaction results show that an 88-90% gel fraction was reached under the irradiation of a high-pressure mercury lamp.

This article describes the preparation of a kind of auto-photosensitive polyimide (PSPI) that contains organo-silicone moiety in its main chain. A group of novel auto-photosensitive polyimides were prepared based on the aromatic diamine monomers and 3,3Ј,5,5Ј-benzophenontetracarboxylic dianhydride (BTDA) by the method of solution polycondensation at room temperature and imidized at a high temperature. The properties of PSPIs, such as ultraviolet (UV) absorption, electric and adhesion properties, and moisture absorption, were characterized by UV analysis, a dielectric constant detector, and so on. The relationship between the structure and properties of PSPIs is discussed.

SYNOPSISIn this article, a polyimide precursor was synthesized from oxydianiline and a diacid chloride. This diacid chloride was prepared by the reaction of thionyl chloride with a diacid, which resulted from the reaction of pyromellitic dianhydride with cinnamyl alcohol in N-methylpyrrolidone (NMP) . The photoresist, made from the above polyimide precursor, was spincoated onto silicon wafers, prebaked, and then exposed to UV light with a high pressure Hg lamp. The pattern generation process was also investigated. The appropriate conditions of the photolithographic procedures, involving photoresist compounding, spin coating, prebaking, exposure, development, rinse, postbaking, etc., were determined. The experimental results show that the photoresist exhibited excellent thermal stability and adequate photosensitivity.