Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Pietro Calandra is active.

Publication


Featured researches published by Pietro Calandra.


Journal of Colloid and Interface Science | 2010

Self-assembly in surfactant-based liquid mixtures: bis(2-ethylhexyl)phosphoric acid/bis(2-ethylhexyl)amine systems.

Pietro Calandra; Angela Ruggirello; Andrea Mele; Vincenzo Turco Liveri

Surfactant-based liquid mixtures constitute an interesting class of nanostructured materials with promising potential in specialized applications. Here, structural and conductometric properties of liquid mixtures composed of bis(2-ethylhexyl)amine (BEEA) and bis(2-ethylhexyl)phosphoric acid (HDEHP) have been thoroughly investigated with the aim to correlate structural features with system charge transport capability. The evolution of self-assembled local nanostructures with system composition has been investigated by FT-IR and XRD while the conductometric properties were probed by conventional AC complex impedance. Both pure components exhibit nano-segregation due to their amphiphilic nature but with only very low proton conductivities. However their mixtures, characterized by local organization of polar and apolar domains driven by acid-base interactions between HDEHP PO(4)H and BEEA NH groups, show enhanced structural order and proton conductivity.


Journal of Colloid and Interface Science | 2009

Physico-chemical investigation of nanostructures in liquid phases: Nickel chloride ionic clusters confined in sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles

Pietro Calandra; Gaetano Di Marco; Angela Ruggirello; Vincenzo Turco Liveri

The confinement of finite amounts of nickel chloride in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles dispersed in n-heptane has been investigated by FT-IR, UV-vis-NIR and fluorescence spectroscopies. The analysis of experimental data consistently leads to hypothesize that NiCl(2) forms small size ionic clusters stabilized by a monolayer of oriented surfactant molecules. Due to confinement and interfacial effects, these ionic clusters show peculiar photophysical properties, which are different from those possessed by the bulk material. From NiCl(2)/AOT/n-heptane solutions, by evaporation of the organic solvent, interesting salt/surfactant nanocomposites at various salt concentrations have been prepared and characterised by WAXS. On the other hand, after mix with Na(2)S-containing dry micellar systems, the formation of NiS nanoparticles have been ascertained by UV-vis spectroscopy.


Journal of Colloid and Interface Science | 2010

Fast proton conduction in hydrogen bonded microheterogeneous systems: bis(2-ethylhexyl)phosphoric acid/N-methyl formamide liquid mixtures.

Pietro Calandra; Marco Passarello; Angela Ruggirello; Vincenzo Turco Liveri

Structural and dynamical properties of bis(2-ethylhexyl)phosphoric acid (HDEHP)/N-methyl formamide (NMF) liquid mixtures in the whole composition range have been investigated by Fourier Transform Infrared spectroscopy (FT-IR), X-rays Diffraction (XRD), and AC complex impedance spectroscopy. Driven by hydrogen bond interactions among HDEHP PO(4)H group and NMF CO and NH groups, and also by steric effects among the HDEHP alkyl chains, the system microstructure is mainly characterized by the coexistence of spatially separated hydrophilic and hydrophobic nanodomains showing local organization and short-range order. The evolution of this structural feature with system composition has been highlighted by FT-IR and XRD. On the other hand, the thermally activated proton mobility within these hydrophilic domains, as pointed out by AC complex impedance measurements, emphasizes the occurrence of a percolating behaviour characterized by percolation threshold at zero. Due to fast proton conduction across the interconnected network formed by the polar groups, some samples showed very high room-temperature conductivity up to 10(-3) S cm(-1).


Journal of Colloid and Interface Science | 2009

Complex permittivity of FeCl3/AOT/CCl4 microemulsions probed by AC impedance spectroscopy

Pietro Calandra; Angela Ruggirello; Vincenzo Turco Liveri

The complex permittivity of FeCl(3)/AOT/CCl(4) microemulsions in the 1-10(5) Hz frequency range has been measured by the conventional AC complex impedance technique. Measurements as a function of the volume fraction of the dispersed phase (FeCl(3)+AOT) and temperature at fixed salt-to-AOT molar ratio (R, R = 0.5) show that the entrapment of FeCl(3) clusters significantly enhances the local permittivity of the AOT reverse micelles and the number density of charge carriers resulting from the peculiar state of the confined inorganic salt. An estimate of the apparent static permittivity of the FeCl(3) ionic clusters entrapped in the core of AOT reverse micelles gives the very high and quite surprisingly value of about 237. Moreover, a thorough analysis of conductivity data and of their temperature dependence strongly supports the hypothesis that the charge transport in these systems is mainly sustained by a mechanism of hopping consisting in the continuous jumping of charged species within supra-micellar aggregates of AOT reverse micelles whose aggregation is driven by fluctuating opposite charges on contacting micelles.


Atti della Accademia Peloritana dei Pericolanti : Classe di Scienze Fisiche, Matematiche e Naturali | 2011

Modeling of the particle scattering structure factor for branched bio-polymers in solution: A X-ray scattering study

Pietro Calandra; M. A. Kiselev; Domenico Lombardo

We present a study which illustrates the modeling of the Particle Scattering Structure Factor from Small Angle X-ray Scattering (SAXS) data. The studied sample was a poly(amidoamine) Pamam dendrimers in water solution. The intra-particle form factor P(q) has been analyzed employing an inverse Fourier transformation which allows to obtain the particle pair distance distribution function and to gain information about dendrimer shape. The experimental inter-dendrimer structure factor S(q) has been analysed in the framework of liquid integral equation theory for charged systems in solution. From that, we derive an effective interparticle interaction composed of a screened Coulombic plus hard-sphere repulsion potential, which allow the estimation of the dendrimer effective surface charge Z eff . The present analysis, applied to a Pamam dendrimers in water solution, strongly supports the finding that structures and interaction of dendrimer is strongly influenced by charge effects. As a result, this quantity can be considered as a crucial parameters for the modulation of the degree of structural organization in solution, suitable for a number of potential applications.


Journal of Physical Chemistry B | 2003

Synthesis of Ultra-small ZnS Nanoparticles by Solid−Solid Reaction in the Confined Space of AOT Reversed Micelles

Pietro Calandra; and Alessandro Longo; Vincenzo Turco Liveri


Journal of Physical Chemistry B | 2003

Physicochemical Investigation of Lightfast AgCl and AgBr Nanoparticles Synthesized by a Novel Solid−Solid Reaction

Pietro Calandra; Alessandro Longo; and Vito Marcianò; Vincenzo Turco Liveri


Journal of Cluster Science | 2010

Structural and Optical Properties of Novel Surfactant Coated TiO2–Ag Based Nanoparticles

Pietro Calandra; Angela Ruggirello; Alessandro Pistone; Vincenzo Turco Liveri


Colloids and Surfaces A: Physicochemical and Engineering Aspects | 2011

Synthesis and physico-chemical characterization of Au/TiO2 nanostructures formed by novel “cold” and “hot” nanosoldering of Au and TiO2 nanoparticles dispersed in water

E. Fazio; Pietro Calandra; Vincenzo Turco Liveri; Nadia Santo; Sebastiano Trusso


Materials Letters | 2010

Synthesis of Yb nanoparticles by laser ablation of ytterbium target in sodium bis(2-ethylhexyl)sulfosuccinate reverse micellar solution

Pietro Calandra; Domenico Lombardo; F. Neri; Angela Ruggirello; Sebastiano Trusso; Vincenzo Turco Liveri

Collaboration


Dive into the Pietro Calandra's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

E. Fazio

University of Messina

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

F. Neri

University of Messina

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge