Nanocellulose enriched mortars: Evaluation of nanocellulose properties affecting microstructure, strength and development of mixing protocols

In this work, four different nanocellulose (NCs) aqueous suspensions (two Cellulose Nano-Fibrils-CNF and a pair of Cellulose Nano-Crystals-CNC) were selected for the evaluation of key aspects that potentially affect the final performance of mortars. The main objective was the development of appropriate mixing protocols that will allow the incorporation of cellulose nanoadditives into cementitious blends. Inclusion of two different NC species into mortars will provide a side-by-side performance comparison between CNCs and CNFs leading to a better understanding of particle morphology impact on the properties of cementitious composites. Moreover, preliminary structural and physicochemical NC characterization tests were performed to enlighten the effects of NC intrinsic features on the final efficiency of the materials. Strength tests of as-obtained NC enriched specimens revealed an enhanced performance when compared to respective reference samples. In particular the presence of CNFs – and specifically AVAP® CNFs– in the mortar mixture resulted in an increase up to 43% in flexural strength values, whereas CNCs were more effective in raising compressive strength values (up to 21%). Supposing that this improvement, emanates from evolving interactions between NCs and defects existing in the matrix at the onset of their formation a more detailed study is on-going aiming at the in depth comprehension of all synoptic parameters that will enable a straight correlation between mortars and nanocellulose properties and will facilitate the use of NCs to upgrade cementitious materials into tailored made composites

A Green Route to Copper Loaded Silica Nanoparticles Using Hyperbranched Poly(Ethylene Imine) as a Biomimetic Template: Application in Heterogeneous Catalysis

Copper containing silica nanostructures are easily produced through a low cost versatile approach by means of hyperbranched polyethyleneimine (PEI), a water soluble dendritic polymer. This dendritic molecule enables the formation of hybrid organic/inorganic silica nanoparticles in buffered aqueous media, at room temperature and neutral pH, through a biomimetic silicification process. Furthermore, the derived hybrid organic/inorganic materials dispersed in water can be easily loaded with various copper amounts, due to the presence of PEI, which, despite having been integrated in the silica network, retains its strong copper chelating ability. Following calcination, the obtained copper loaded nanopowders are characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), N2 adsorption, Temperature programmed reduction (TPR) and UV-Vis diffuse reflectance (UV-Vis-DR) techniques and evaluated for automotive exhaust purification under simulated conditions at the stoichiometric point. Effective control over final materials’ pore structural and morphological characteristics is provided by employing different buffer solutions, i.e., tris(hydroxymethyl)aminomethane (Tris) or phosphate buffer. It was found that the enhancement of the nanopowders textural features, obtained in the presence of Tris buffer, had a great impact on the material’s catalytic behavior, improving significantly its activity towards pollutants oxidation

A green route to copper loaded silica nanoparticles using hyperbranched poly(ethylene imine) as a biomimetic template : application in heterogeneous catalysis

Copper containing silica nanostructures are easily produced through a low cost versatile approach by means of hyperbranched polyethyleneimine (PEI), a water soluble dendritic polymer. This dendritic molecule enables the formation of hybrid organic/inorganic silica nanoparticles in buffered aqueous media, at room temperature and neutral pH, through a biomimetic silicification process. Furthermore, the derived hybrid organic/inorganic materials dispersed in water can be easily loaded with various copper amounts, due to the presence of PEI, which, despite having been integrated in the silica network, retains its strong copper chelating ability. Following calcination, the obtained copper loaded nanopowders are characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), N2 adsorption, Temperature programmed reduction (TPR) and UV-Vis diffuse reflectance (UV-Vis-DR) techniques and evaluated for automotive exhaust purification under simulated conditions at the stoichiometric point. Effective control over final materials’ pore structural and morphological characteristics is provided by employing different buffer solutions, i.e., tris(hydroxymethyl)aminomethane (Tris) or phosphate buffer. It was found that the enhancement of the nanopowders textural features, obtained in the presence of Tris buffer, had a great impact on the material’s catalytic behavior, improving significantly its activity towards pollutants oxidation