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Dive into the research topics where Guido Soliveri is active.

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Featured researches published by Guido Soliveri.


Journal of Colloid and Interface Science | 2013

Wettability of bare and fluorinated silanes: A combined approach based on surface free energy evaluations and dipole moment calculations

Giuseppe Cappelletti; S. Ardizzone; Daniela Meroni; Guido Soliveri; Michele Ceotto; Cinzia Biaggi; Maurizio Benaglia; Laura Raimondi

The assessment of the surface free energy (SFE) of a material permits to control and predict a large number of physicochemical properties of a solid surface and its reactivity. Here, the surface energies of a series of bare and fluorinated silanes are determined by means of different semi-empirical models on the grounds of contact angle determinations for different solvents. Literature data are also considered in order to produce a series of films with increasing SFE. Wetting envelopes (WE) are obtained for the various surfaces in order to predict the wettability of the films by numerous commonly employed solvents. The polar and disperse components of the surface energies are obtained by the Owens-Wendt-Rabel-Kaelbe (OWRK) method; the values of the polar components are compared with gas-phase dipole moments obtained by theoretical calculations employing semi-empirical Hamiltonians. The sequences of the polar components of the SFE and of the calculated dipole moments for the different molecules are strictly the same. The interplay between theoretical and experimental approaches proves efficient in predicting the behavior of different systems and it could be employed in tuning the SFE of a solid surface with respect to its final applications.


Journal of Nanoparticle Research | 2013

Electrochemically assisted deposition of transparent, mechanically robust TiO2 films for advanced applications

Giulia Maino; Daniela Meroni; Valentina Pifferi; Luigi Falciola; Guido Soliveri; Giuseppe Cappelletti; S. Ardizzone

In recent years, titanium dioxide has received ever growing interest, thanks to its promising applications in numerous fields such as environmental remediation, H2 generation and photovoltaics. Here, transparent and mechanically robust TiO2 films are deposited by a simple and inexpensive electrochemically assisted procedure on various kinds of substrates, both conductive and nonconductive (e.g., glass slides or different metal laminas with variable surface roughness). The obtained films are uniform, crack-free and exhibit excellent chemical, mechanical, and electrochemical robustness. The obtained layers are compared to films prepared by a routine preparation technique, such as dip coating, showing much better morphological, optical, and conductive properties. The photo-activity of TiO2 can be exploited to obtain transparent spectroelectrochemical systems and to control the wetting features of the surface. Applications concerning the modulation of the wettability are presented with respect to both the antifogging and antistain properties. The photoelectrochemical properties of TiO2 films are exploited to activate a photoelectrochemical polymerization of polypyrrole onto an unconductive support. These materials are promising for numerous applications such as smart windows, antifogging mirrors, solar cells, and optically transparent electrodes.


Nanotechnology | 2016

Positron annihilation spectroscopy: a new frontier for understanding nanoparticle-loaded polymer brushes

Guido Panzarasa; S. Aghion; Guido Soliveri; G. Consolati; R. Ferragut

Nanoparticle-loaded polymer brushes are powerful tools for the development of innovative devices. However, their characterization is challenging and arrays of different techniques are typically required to gain sufficient insight. Here we demonstrate for the first time the suitability of positron annihilation spectroscopy (PAS) to investigate, with unprecedented detail and without making the least damage to samples, the physico-chemical changes experienced by pH-responsive polymer brushes after protonation and after loading of silver nanoparticles. One of the most important findings is the depth profiling of silver nanoparticles inside the brushes. These results open up a completely new way to understand the structure and behavior of such complex systems.


Journal of Physical Chemistry C | 2017

A Close Look at the Structure of the TiO2-APTES Interface in Hybrid Nanomaterials and Its Degradation Pathway: An Experimental and Theoretical Study

Daniela Meroni; Leonardo Lo Presti; Giovanni Di Liberto; Michele Ceotto; Robert G. Acres; Kevin C. Prince; Roberto Bellani; Guido Soliveri; S. Ardizzone

The surface functionalization of TiO2-based materials with alkylsilanes is attractive in several cutting-edge applications, such as photovoltaics, sensors, and nanocarriers for the controlled release of bioactive molecules. (3-Aminopropyl)triethoxysilane (APTES) is able to self-assemble to form monolayers on TiO2 surfaces, but its adsorption geometry and solar-induced photodegradation pathways are not well understood. We here employ advanced experimental (XPS, NEXAFS, AFM, HR-TEM, and FT-IR) and theoretical (plane-wave DFT) tools to investigate the preferential interaction mode of APTES on anatase TiO2. We demonstrate that monomeric APTES chemisorption should proceed through covalent Si–O–Ti bonds. Although dimerization of the silane through Si–O–Si bonds is possible, further polymerization on the surface is scarcely probable. Terminal amino groups are expected to be partially involved in strong charge-assisted hydrogen bonds with surface hydroxyl groups of TiO2, resulting in a reduced propensity to react with other species. Solar-induced mineralization proceeds through preferential cleavage of the alkyl groups, leading to the rapid loss of the terminal NH2 moieties, whereas the Si-bearing head of APTES undergoes slower oxidation and remains bound to the surface. The suitability of employing the silane as a linker with other chemical species is discussed in the context of controlled degradation of APTES monolayers for drug release and surface patterning.


Journal of Materials Science | 2014

Engineered organic/inorganic hybrids for superhydrophobic coatings by wet and vapour procedures

Guido Soliveri; Daniela Meroni; Giuseppe Cappelletti; Rita Annunziata; Valentina Aina; G. Cerrato; S. Ardizzone

Siloxane/oxide hybrids have attracted growing attention thanks to their ability to modulate the surface energy, wettability, or self-lubricity of a material. Here, we compare two functionalisation procedures (chemical vapour deposition and wet impregnation) on substrate films composed by preformed oxide particles. Three kinds of particles, characterised by different natures (SiO2 and TiO2) and average particle size, were studied to highlight possible effects related to the chemical and morphological state of the substrate surface. Morphological characterisations were carried out using dynamic light scattering and scanning electron microscopy, while the structure of the hydrophobing layer was studied by combining Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance. The degree of functionalisation and the features of the siloxane layer vary significantly among the adopted oxides and functionalisation methods. The wettability features of the different hybrids closely mirror the results of the spectroscopic characterisations, giving rise to either Lotus leaf or patch-wise hydrophobic systems depending on the adopted conditions.


Journal of Materials Chemistry C | 2016

Tuning the electrochemical properties of silicon wafer by grafted-from micropatterned polymer brushes

G. Panzarasa; Guido Soliveri; Valentina Pifferi

Silicon wafer is the material of choice for microfabrication. However, the development of innovative on-chip electrochemical sensors using silicon is hampered by its poor electrochemical properties. In this article we demonstrate how grafted-from micropatterned polymer brushes dramatically enhance the electrochemical response of silicon electrodes. Our results are relevant not only for a deeper understanding of the structure and behavior of polymer brushes, but also for the combination of the versatility of surface-initiated polymerization and an innovative patterning technique (remote photocatalytic lithography) which paves the way for the fabrication of integrated devices.


RSC Advances | 2015

Electrochemical sensors cleaned by light: a proof of concept for on site applications towards integrated monitoring systems

Valentina Pifferi; Guido Soliveri; G. Panzarasa; S. Ardizzone; Giuseppe Cappelletti; Daniela Meroni; Luigi Falciola

The potential for on site applications of a SiO2–Ag NPs–TiO2 self-cleaning electrode was demonstrated. Dopamine was used both as the analyte and the fouling agent. Three different UV lamps (a powerful lamp (45 mW cm−2) for photocatalysis, a TLC lamp and a commercial LED torch) were studied. After fouling, total recovery of the electroanalytical performances was achieved upon a short irradiation performed directly in the solution of interest.


Journal of Materials Chemistry C | 2016

ON/OFF switching of silicon wafer electrochemistry by pH-responsive polymer brushes

G. Panzarasa; Matthias Dübner; Valentina Pifferi; Guido Soliveri; C. Padeste

pH-Switchable electrochemical properties are demonstrated for the first time for native oxide-coated silicon wafer electrodes. Ultrathin and ultrathick pH-responsive poly(methacrylic acid) (PMAA) brushes, obtained by surface-initiated atom transfer radical polymerization, were used to achieve redox gating. PMAA brushes are reversibly switched between their protonated and deprotonated states by alternating acidic and basic pH, which corresponds to a swelling/collapsing behavior. As a result, the electrochemical properties of the PMAA brush-modified silicon electrode are switched “ON” and “OFF” simply by changing pH. The electrochemical properties of the modified electrode were examined by means of cyclic voltammetry and electrochemical impedance spectroscopy both in the absence and presence of ruthenium(III) hexamine, a well-known cationic redox probe.


Nanomaterials | 2018

Preparation of a Sepia Melanin and Poly(ethylene-alt-maleic Anhydride) Hybrid Material as an Adsorbent for Water Purification

Guido Panzarasa; Alina Osypova; G. Consolati; F. Quasso; Guido Soliveri; Javier Ribera; Francis W. M. R. Schwarze

Meeting the increasing demand of clean water requires the development of novel efficient adsorbent materials for the removal of organic pollutants. In this context the use of natural, renewable sources is of special relevance and sepia melanin, thanks to its ability to bind a variety of organic and inorganic species, has already attracted interest for water purification. Here we describe the synthesis of a material obtained by the combination of sepia melanin and poly(ethylene-alt-maleic anhydride) (P(E-alt-MA)). Compared to sepia melanin, the resulting hybrid displays a high and fast adsorption efficiency towards methylene blue (a common industrial dye) for a wide pH range (from pH 2 to 12) and under high ionic strength conditions. It is easily recovered after use and can be reused up to three times. Given the wide availability of sepia melanin and P(E-alt-MA), the synthesis of our hybrid is simple and affordable, making it suitable for industrial water purification purposes.


Nanotechnology | 2017

Branched poly(ethyleneimine): a versatile scaffold for patterning polymer brushes by means of remote photocatalytic lithography

Guido Panzarasa; Matthias Dübner; Guido Soliveri; Matthias Edler; Thomas Griesser

Patterning of functional surfaces is one of the cornerstones of nanotechnology as it allows the fabrication of sensors and lab-on-a-chip devices. Here, the patterning of self-assembled monolayers of branched poly(ethyleneimine) (bPEI) on silica was achieved by means of remote photocatalytic lithography. Moreover, when 2-bromoisobutyryl-modified bPEI was used, the resulting pattern could be amplified by grafting polymer brushes by means of surface-initiated atom transfer radical polymerization. In contrast to previous reports for the patterning of bPEI, the present approach can be conducted in minutes instead of hours, reducing the exposure time to UV radiation and enhancing the overall efficiency. Furthermore, our approach is much more user-friendly, allowing a facile fabrication of patterned initiator-modified surfaces and the use of inexpensive instrumentation such as a low-power UV source and a simple photomask. Considering the versatility of bPEI as a scaffold for the development of biosensors, patterning by means of remote photocatalytic lithography will open new opportunities in a broad field of applications.

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Guido Panzarasa

Swiss Federal Laboratories for Materials Science and Technology

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