Synthesis of 3D Dendritic Gold Nanostructures Assisted by a Templated Growth Process: Application to the Detection of Traces of Molecules.

Complex architectures like 3D gold dendritic nanostructures were synthesized by an in situ templated growth method using a thin film of a block copolymer [polystyrene-b-poly(4-vinylpyridine)] deposited onto silicon substrates. The overall study has demonstrated the strong link between the morphology, size, and distribution of the structures and the synthetic physicochemical parameters, such as pH, reaction temperature, concentration, and nature of reactants. A nonequilibirum state of the medium has been required to create a fractal growth of the gold structures onto a prepatterned gold-seeded surface and has led to a better control of the structures' surface coverage rate. Those as-prepared nanodendrites have also exhibited high electrocatalytic activity toward a significant enhancement factor, as well as important sensitivity, thanks to tip effects. The electrochemical experiment results have demonstrated efficient adsorption and quantification of very low traces of specific molecules like glutathione or hexadecanethiol.

Efficient Removal of Volatile Organic Compounds by FAU-Type Zeolite Coatings.

Silicone and pure organic binders were used to develop FAU-type zeolite coatings applied on pre-treated aluminum substrates by using a spraying method and then cured under specific conditions. The influence of the amount of binder on adhesion properties of zeolite coatings was first investigated to determine the optimum ratio between zeolite and binder. Zeolite coatings were then elaborated with a high zeolite content (between 70 and 80 wt.%) to ensure high adsorption capacities. The amount of binders involved in different zeolite coatings was sufficient to achieve interesting adhesion and cohesion properties. The accessibility of zeolite microporosity was studied by nitrogen adsorption-desorption measurements, which revealed a very small or no loss of the micropore volume for the optimized coatings. Volatile Organic Compounds (VOCs) adsorption measurements were carried out using n-hexane as probe molecule. FAU-type zeolite in powder form adsorbs 180 mg/ganhydrous zeolite, whereas the amounts of n-hexane adsorbed by zeolite coatings ranged from 131 to 175 mg/ganhydrous zeolite.

Prediction of the mechanical properties of zeolite pellets for aerospace molecular decontamination applications.

Zeolite pellets containing 5 wt % of binder (methylcellulose or sodium metasilicate) were formed with a hydraulic press. This paper describes a mathematical model to predict the mechanical properties (uniaxial and diametric compression) of these pellets for arbitrary dimensions (height and diameter) using a design of experiments (DOE) methodology. A second-degree polynomial equation including interactions was used to approximate the experimental results. This leads to an empirical model for the estimation of the mechanical properties of zeolite pellets with 5 wt % of binder. The model was verified by additional experimental tests including pellets of different dimensions created with different applied pressures. The optimum dimensions were found to be a diameter of 10-23 mm, a height of 1-3.5 mm and an applied pressure higher than 200 MPa. These pellets are promising for technological uses in molecular decontamination for aerospace-based applications.