Nour F. Attia

Polyaniline as a Material for Hydrogen Storage Applications

The main challenge of commercialization of the hydrogen economy is the lack of convenient and safe hydrogen storage materials, which can adsorb and release a significant amount of hydrogen at ambient conditions. Finding and designing suitable cost-effective materials are vital requirements to overcome the drawbacks of investigated materials. Because of its outstanding electronic, thermal, and chemical properties, the electrically conducting polyaniline (PANI) has a high potential in hydrogen storage applications. In this review, the progress in the use of different structures of conducting PANI, its nanocomposites as well as activated porous materials based on PANI as hydrogen storage materials is presented and discussed. The effect of the unique electronic properties based on the π-electron system in the backbone of these materials in view of the hydrogen uptake and the relevant mechanisms are highlighted.

Polyaniline-Polypyrrole Composites with Enhanced Hydrogen Storage Capacities

A facile method for the synthesis of polyaniline-polypyrrole composite materials with network morphology is developed based on polyaniline nanofibers covered by a thin layer of polypyrrole via vapor phase polymerization. The hydrogen storage capacity of the composites is evaluated at room temperature exhibits a twofold increase in hydrogen storage capacity. The HCl-doped polyaniline nanofibers exhibit a storage capacity of 0.46 wt%, whereas the polyaniline-polypyrrole composites could store 0.91 wt% of hydrogen gas. In addition, the effect of the dopant type, counteranion size, and the doping with palladium nanoparticles on the storage properties are also investigated.

Exfoliated graphene nanosheets: pH-sensitive drug carrier and anti-cancer activity

A straightforward and facile method for the exfoliation of graphene sheets using poly(vinylpyrrolidone) nanoparticles of an average size of 42nm was developed and their dual role as pH-sensitive drug carrier and anti-cancer agent was evaluated. The cytotoxic impact of the exfoliated nanosheets (GRP-PVP-NP) was examined on various cells (HCT-116, HeLa, SCC-9, NIH-3T3 and HEK-293cells) by a series of assays. Their cytotoxic nature was attributed to affecting the mitochondrial enzyme activity, proliferation capability, and the formation of tight junctions in cancer cells. The endocytosis was found to be internalization mechanism for the cellular uptake of nanosheets. The generation of reactive oxygen species and elicitation of caspase-3 activity which was undoubtedly associated with triggering of oxidative stress speculated to be the dominant cause of the cytotoxic pattern of nanosheets against cancer cells. Additionally, the results also showed the role of the nanosheets as a pH-sensitive drug carrier through drug loading by supramolecular interaction. The efficient release of doxorubicin was seen at low pH and in an environment with a low oxygen concentration, thus under conditions mimicking the typical tumor microenvironment. Therefore, these findings provide the first evidence for a dual function of exfoliated graphene sheets and also elucidate the cytotoxic mechanism responsible for the cancer cell death.

Novel synthesis of nanoparticles-based back coating flame-retardant materials for historic textile fabrics conservation

Novel flame-retardant back coating layer for historic textile fabrics was developed. Silica nanoparticles originated from agriculture waste rice husk were prepared through one pot thermal method. The morphological and structure properties of nanoparticles were studied. The silica nanoparticles were further impregnated with organic borate producing flame-retardant composite. The obtained composite incorporated with the binder by mechanical mixing providing flame-retardant coating paste. The coating paste spread on the back surface of textile fabrics. Varied compositions of nanoparticles, binder and organic borate were studied in the back coating layer. The flammability, thermal stability and mechanical properties of the blank and treated samples of linen fabrics as an inner support to the historical textiles were investigated. Flame retardancy of the back-coated linen samples has improved achieved high class of flame-retardant textile fabrics of zero rate of burning compared to 80.3 mm/min for blank. The synergistic effect of flame retardancy between nanoparticles and organic borate was investigated. The tensile strength of the flame retardant fabrics was enhanced by 27% and elongation was improved. The effect of industrial aging on the flame retardancy and mechanical properties of flame-retardant back coating textiles was studied.