Influence of Anodic Conditions on Self-ordered Growth of Highly Aligned Titanium Oxide Nanopores

Self-aligned nanoporous TiO2templates synthesized via dc current electrochemical anodization have been carefully analyzed. The influence of environmental temperature during the anodization, ranging from 2 °C to ambient, on the structure and morphology of the nanoporous oxide formation has been investigated, as well as that of the HF electrolyte chemical composition, its concentration and their mixtures with other acids employed for the anodization. Arrays of self-assembled titania nanopores with inner pores diameter ranging between 50 and 100 nm, wall thickness around 20–60 nm and 300 nm in length, are grown in amorphous phase, vertical to the Ti substrate, parallel aligned to each other and uniformly disordering distributed over all the sample surface. Additional remarks about the photoluminiscence properties of the titania nanoporous templates and the magnetic behavior of the Ni filled nanoporous semiconductor Ti oxide template are also included

Biocomposite films based on κ-carrageenan/locust bean gum blends and clays : physical and antimicrobial properties

The aims of this work were to evaluate the physical and antimicrobial properties of biodegradable films composed of mixtures of κ-carrageenan (κ-car) and locust bean gum (LBG) when organically modified clay Cloisite 30B (C30B) was dispersed in the biopolymer matrix. Film-forming solutions were prepared by adding C30B (ranging from 0 to 16 wt.%) into the κ-car/LBG solution (40/60 wt.%) with 0.3 % (w/v) of glycerol. Barrier properties (water vapour permeability, P vapour; CO2 and O2 permeabilities), mechanical properties (tensile strength, TS, and elongation-at-break, EB) and thermal stability of the resulting films were determined and related with the incorporation of C30B. Also, X-ray diffraction (XRD) was done in order to investigate the effect of C30B in film structure. Antimicrobial effects of these films against Listeria monocytogenes, Escherichia coli and Salmonella enterica were also evaluated. The increase of clay concentration causes a decrease of P vapour (from 5.34 × 10−11 to 3.19 × 10−11 g (m s Pa)−1) and an increase of the CO2 permeability (from 2.26 × 10−14 to 2.91 × 10−14 g (m s Pa)−1) and did not changed significantly the O2 permeability for films with 0 and 16 wt.% C30B, respectively. Films with 16 wt.% clay exhibited the highest values of TS (33.82 MPa) and EB (29.82 %). XRD patterns of the films indicated that a degree of exfoliation is attained depending on clay concentration. κ-car/LBG–C30B films exhibited an inhibitory effect only against L. monocytogenes. κ-car/LBG–C30B composite films are a promising alternative to synthetic films in order to improve the shelf life and safety of food products.J. T. Martins, A. I. Bourbon, A. C. Pinheiro and M. A. Cerqueira gratefully acknowledge the Fundacao para a Ciencia e Tecnologia (FCT, Portugal) for their fellowships (SFRH/BD/32566/2006, SFRH/BD/73178/2010, SFRH/BD/48120/2008 and SFRH/BPD/72753/2010, respectively), and B. W. S. Souza acknowledges the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil)

Clay-based bionanocomposite foams: morphology and porosity characterization by X-ray microtomography technique

Poster presented at the XV Brazil MRS Meeting, held in Campinas (Brazil) on September 25-29th, 2016.X-ray microtomography is an useful technique increasingly applied to characterize the textural properties of cellular solids allowing to determine morphology, texture, variable density elements, surface area, interconnectivity, structure thickness, pore volume, mean pore diameter and porosity (closed and open). This technique has been here applied characterization of bionanocomposite foams. This type of biohybrid nanomaterials produced by the assembly of biopolymers and inorganic particles, can be conformed as low-density macroporous solids (foams), deserving advanced applications such as acoustic insulation, fire retardant materials, removal of pollutants from water, biocatalysis, biomedicine, sensing and energy storage [1-2]. This work introduces results on X-ray microtomography of bionanocomposite foams formed from the association of polysaccharides such as chitosan, starch and alginate, with clay nanoparticles of lamellar (vermiculite) or fibrous (sepiolite) morphology and produced by freeze- drying of the bionanocomposite hydrogels. The resulting foams show interconnected elongated macropores highly porous (e.g., 90% porosity) with appropriate mechanical properties for diverse applications. In the case of functional bionanocomposites based on the intercalation of the cationic biopolymer chitosan in natural or in organically modified vermiculite samples, these foams have the ability to remove Cd(II) ions from aqueous solution [3]. On the other hand, the bionanocomposite foams prepared by mixing starch, alginate and sepiolite show excellent fire retardant properties