Papers by Keyword: Polyhedral Oligomeric Silsesquioxane (POSS)

Abstract: The present study aimed to characterize the structure of nanocomposites obtained from the incorporation of three different polyhedral oligomeric silsesquioxane (POSS) in an epoxy resin. glycidylisobutyl-POSS, triglycidylisobutyl-POSS and glycidyl-POSS were added (5% by weight) in an epoxy matrix, diglycidyl ether of bisphenol-A (DGEBA), through a sonication process. The nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and dynamic mechanical analysis (DMA). The XRD analysis presented a characteristic peak of POSS. The incorporation of glycidylisobutyl-POSS showed a significant increase in the value of glass transition temperature (T_g), being also the most effective in terms of dispersion. It should also be noted that glycidyl-POSS presented a greater influence on the thermal stability.

Abstract: This paper reports polyamide 11 (PA11)/layered silicate (clay) nanocomposite using polyhedral oligomeric silsesquioxane (POSS) surfactants. POSS functionalized with amino, ammonium and guanidinium groups were synthesized and used to facilitate the intercalation of polymer chains between silicate layers thereby to improve the dispersion of clay in polymer matrix. Nanocomposites from the blends of POSS-modified clay and PA11 were thus formulated via melting compounding and their mechanical and physical properties were characterized.

Abstract: Two kinds of proton exchange membranes (PEMs) containing POSS are designed and prepared, one is sulfonated poly (ether ether ketone) (SPEEK)/bisphenol S diglycidyl ether (DEBS)/POSS hybrids with the semi-interpenetrating polymer networks (IPNs) structure and the other is sulfonated polyimides (SPI)/POSS hybrids with cross-link structure. IPNs should be more contributed to improve the proton conductivities of PEMs than cross-link structure.

Abstract: Liquid crystalline polymer (LCP) and the copolymer of LCOand Pendant Polyhedral Oligomeric Silsequioxanes (LCP-POSS) showed the first-order photoisomerization reaction. As compared with LCP, the photoisomerization rate constant of LCP-POSS decreased a little. With a higher thermal stability and more stable LC behavior as well as a little decreased photoisomerization rate constant, the incorporation of POSS to azobenzene liquid crystalline polymers may have significant sense and will definitely play a key role in developing novel high-performance optic and photonic nanodevices.

Abstract: A series of poly(methyl methacrylate) (PMMA) composites containing polyhedral oligomeric silsesquioxane (POSS) were produced by bulk polymerization. The morphology, thermal and mechanical properties of the composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analyses (TGA) and dynamic mechanical analyses (DMA). Results show that the octa(3-chloropropyl)-POSS (ocp-POSS) and trisilanolphenyl-POSS (triol-POSS) have high compatibility with PMMA and can be uniformly dispersed into PMMA matrix. The separate incorporation of these two types of POSS contributes to the improvement of thermal stability of PMMA composites. When the content of POSS was 7.5 wt%, the thermal decomposition temperatures (5% mass loss) of PMMA composites with ocp-POSS and triol-POSS were increased by about 104 °C and 130 °C, respectively. The increase of triol-POSS content in the PMMA matrix gave slight enhanced storage modulus before glass transition.

Abstract: Five different multifunctional nitro octaphenyl silsesquioxane (NPS) were Synthesised and reduction was carried out to obtain amino octaphenyl silsesquioxane(APS). These compounds were characterized with elementary analysis, fourier transform infrared(FTIR), nuclear magnetic resonance (NMR, ²⁹Si), wide-angle X-ray diffraction(XRD) and thermogravimetry (TG). Experiental results showed that the longer the nitration time, the more nitro connected to the OPS, but not positively, nitro number remained unchanged after five hours. NPS has good thermal stability than corresponding APS under 450°C, and the thermal stability of APS are decrease with the increase of amino number.

Abstract: The sulfonated poly(ether ether ketone) (SPEEK)/bisphenol S diglycidyl ether (DEBS)/POSS ternary hybrids is designed and prepared to incorporate POSS into SPEEK to form a new cross-linked proton exchange membrane (PEM). Compared with the SPEEK, the ternary hybrids possesses lower water uptake (WU) and linear expansion (LE), but higher proton conductivity. The proton conductivity of SPEEK/DEBS/POSS can reach to 1.1×10^-1 S/cm.

Abstract: Cyanate ester resin (CE)/epoxy functionalized polyhedral oligomeric silsesquioxane (POSS-Ep) organic-inorganic hybrids were prepared by casting and curing. The hybrid resin systems were studied by gel time test to evaluate the effect of POSS-Ep on curing reactivity of CE. Impact and flexural strengths of the hybrids were investigated. The thermal properties of the hybrids were studied by thermogravimetric analysis (TGA). TGA results show that CE10 also possesses the best thermal stability. The initial temperature of decomposition (Ti) of CE10 is 426 oC, 44 oC higher than that of the pristine CE.

Abstract: A series of cyanate ester resin (CE) based organic-inorganic hybrids containing different content (0, 5, 10, 15 and 20 wt%) of epoxy functionalized polyhedral oligomeric silsesquioxane (POSS-Ep) were prepared by casting and curing. Impact and flexural strengths of the hybrids were investigated. Results showed that CE10 containing 10wt% of POSS-Ep displayed not only the optimum impact strength but the optimum flexural strength.

Abstract: Different contents of epoxy functionalized polyhedral oligomeric silsesquioxane (POSS-Ep) were used to modify cyanate ester resin. The dynamic mechanical properties of the hybrids were studied dynamic mechanical analysis (DMA). DMA results showed that POSS-Ep tended to decrease E’ of the hybrids at the glassy state but to increase E’ of the hybrids at the rubbery state.