Roberto Lazzaroni - Academia.edu (original) (raw)

Uploads

Papers by Roberto Lazzaroni

Research paper thumbnail of Doping LiMnPO 4 with Cobalt and Nickel: A First Principle Study

A density functional theory (DFT) study has been carried out on transition metal phosphates with ... more A density functional theory (DFT) study has been carried out on transition metal phosphates with olivine structure and formula LiMPO4 (M = Fe, Mn, Co, Ni) to assess their potential as cathode materials in rechargeable Li-ion batteries based on their chemical and structural stability and high theoretical capacity. The investigation focuses on LiMnPO4 , which could offer an improved cell potential (4.1 V) with respect to the reference LiFePO4 compound, but it is characterized by poor lithium intercalation/de-intercalation kinetics. Substitution of cations like Co and Ni in the olivine structure of LiMnPO4 was recently reported in an attempt to improve the electrochemical performances. Here the electronic structure and lithium intercalation potential of Ni-and Co-doped LiMnPO4 were calculated in the framework of the Hubbard U density functional theory (DFT+U) method for highly correlated materials. Moreover, the diffusion process of lithium in the host structures was simulated, and the activation barriers in the doped and pristine structures were compared. Our calculation predicted that doping increases Li insertion potential while activation barriers for Li diffusion remain similar to the pristine material. Moreover, Ni and Co doping induces the formation of impurity states near the Fermi level and significantly reduces the band gap of LiMnPO4 .

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Direct visualization of microphase separation in block copoly(3-alkylthiophene)s

RSC Adv., 2014

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Functional polymers: scanning force microscopy insights

Physical Chemistry Chemical Physics, 2006

Scanning force microscopy (SFM) and related techniques make it possible to visualize polymer syst... more Scanning force microscopy (SFM) and related techniques make it possible to visualize polymer systems with a molecular resolution. Beyond imaging, they also enable the unveiling of a variety of (dynamic) physico-chemical properties of both isolated polymer chains and their supramolecular architectures, including structural, mechanical and electronic properties. This article reviews recent progress in the use of SFM on polymers, with a particular emphasis on the mechanical properties of copolymers and single polymer chains, as well as on the bottom-up fabrication of supramolecular polymeric (helical) nanostructures in particular based upon pi-conjugated macromolecules as building blocks for nanoelectronics. Through a detailed understanding of the polymer behavior, we propose solutions for the generation of organic functional (nano)systems.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Doping of poly(3-hexylthiophene) nanofibers: microscopic morphology and electrical properties

European Physical Journal-applied Physics, 2009

The microstructure of thin deposits of poly(3-hexylthiophene) on silicon surfaces is investigated... more The microstructure of thin deposits of poly(3-hexylthiophene) on silicon surfaces is investigated as a function of the solution concentration, the maturation time and the solvent nature, with the aim of generating one monolayer of P3HT nanofibers on the surface. These films are then exposed to a NOPF{6} solution, in order to oxidize the conjugated system and to produce conducting nanostructures.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Relationship between the microscopic morphology and the charge transport properties in poly(3-hexylthiophene) field-effect transistors

Journal of Applied Physics, 2006

We fabricate field-effect transistors (FETs) by depositing a regioregular poly(3-hexylthiophene) ... more We fabricate field-effect transistors (FETs) by depositing a regioregular poly(3-hexylthiophene) (RR-P3HT) active layer via different preparation methods. The solvent used in the polymer film deposition and the deposition technique determine the film microstructure, which ranges from amorphous or granular films to a well-defined fibrillar texture. The crystalline ordering of RR-P3HT into fibrillar structures appears to lead to optimal FET performances,

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Oxidizing Ru(II) Complexes as Irreversible and Specific Photo-Cross-Linking Agents of Oligonucleotide Duplexes

Inorganic Chemistry, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The chemical and electronic structure of the interface between aluminum and conjugated polymers or molecules

Synthetic Metals, 1993

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Regioregular poly(3-hexylthiophene)-poly(ε-caprolactone) block copolymers: Controlled synthesis, microscopic morphology, and charge transport properties

Organic Electronics, 2010

In this paper, we describe the design and characterization of regioregular poly(3-hexylthiophene)... more In this paper, we describe the design and characterization of regioregular poly(3-hexylthiophene)-poly(ε-caprolactone) di- and tri-block copolymers (RRP3HT-b-PCL and PCL-b-RRP3HT-b-PCL). The well-controlled synthesis of (di)hydroxyl-terminated RRP3HT makes possible to design block copolymer structures with a narrow molecular weight distribution. The microscopic morphology is investigated by atomic force microscopy, which reveals self-assembled fibrillar structures with the RRP3HT nanoribbons separated by narrow domains

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Synthesis and Characterization of Water-Soluble Amphipatic Polystyrene-Based Dendrigrafts

Macromolecules, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Electrochemical synthesis and characterization of the electronic structure of new conjugated polymers from dithienylene vinylene derivatives

Synthetic Metals, 1996

Highly conjugated thiophene derivatives, based on thienylene vinylene and thienylene vinylene phe... more Highly conjugated thiophene derivatives, based on thienylene vinylene and thienylene vinylene phenylene units, have been synthesized in order to examine: (i) the effect of such regular conjugated monomer structures on polymer formation; and (ii) the optical and electrochemical properties of the corresponding macromolecules. The all-trans monomers have been prepared by a Wittig reaction. The polymers have then been synthesized electrochemically.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optical Absorption Spectra of Aromatic Isothianaphthene Oligomers: Theory and Experiment

The Journal of Physical Chemistry, 1995

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Multiphase coatings from complex radiation curable polyurethane dispersions

Progress in Organic Coatings, 2012

ABSTRACT The waterborne nature of radiation curable polyurethane dispersions largely respond to t... more ABSTRACT The waterborne nature of radiation curable polyurethane dispersions largely respond to the current environmental concerns and do not require any additional coalescent since the film formation (drying) and hardening (photo-curing) take place in distinct steps. It is possible to design aqueous dispersions with distinct polymer particle populations resulting in micro-structured coatings with optimized properties over a wide range of curing conditions. Mixed dispersions based on hard and soft acrylated polyurethane particles were used as model systems for the present study. The minimum film formation temperature has been investigated as a function of the hard:soft polymer ratio. The elastic modulus of the dry coatings shows a reinforcing effect consistent with the inclusion of hard domains in a soft continuous matrix. However, the level of reinforcement is not properly predicted by the usual mechanical models and it is qualitatively accounted for by assuming a composition gradient (interphase) between the hard domains and the matrix. The multiple-phase structure was clearly established by Atomic Force Microscopy in agreement with thermal analysis data. Furthermore the local nanoscale mechanical properties were mapped using a new imaging mode based on real-time force-distance curve analysis. Finally, the coatings prepared using this multiple-phase pattern present a clear benefit over conventional homogeneous coatings by offering an improved balance of chemical and mechanical resistance in pigmented systems applied on melamine-coated MDF panels. (C) 2012 Elsevier B.V. All rights reserved.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Control of the Morphology of Linear and Cyclic PS- b -PI Block Copolymer Micelles via PS Addition

Langmuir, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Structuration of Semiconducting Polymer Thin Films by Nanorubbing

IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Structural and Charge-Transport Properties of a Liquid-Crystalline α,ω-Disubstituted Thiophene Derivative: A Joint Experimental and Theoretical Study

The Journal of Physical Chemistry C, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Structure and Dynamics of a Bisurea-Based Supramolecular Polymer in n -Dodecane

The Journal of Physical Chemistry B, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Liquid Crystalline Metal-free Phthalocyanines Designed for Charge and Exciton Transport

The Journal of Physical Chemistry B, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Mechanism of the Antioxidant Action of Silybin and 2,3-Dehydrosilybin Flavonolignans: A Joint Experimental and Theoretical Study

The Journal of Physical Chemistry A, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Synthesis, characterization and comparative OFET behaviour of indenofluorene–bithiophene and terthiophene alternating copolymers

Synthetic Metals, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Electrochemical synthesis of new electroactive polymers from dithienvlene-vinylene derivatives

Synthetic Metals, 1997

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Doping LiMnPO 4 with Cobalt and Nickel: A First Principle Study

A density functional theory (DFT) study has been carried out on transition metal phosphates with ... more A density functional theory (DFT) study has been carried out on transition metal phosphates with olivine structure and formula LiMPO4 (M = Fe, Mn, Co, Ni) to assess their potential as cathode materials in rechargeable Li-ion batteries based on their chemical and structural stability and high theoretical capacity. The investigation focuses on LiMnPO4 , which could offer an improved cell potential (4.1 V) with respect to the reference LiFePO4 compound, but it is characterized by poor lithium intercalation/de-intercalation kinetics. Substitution of cations like Co and Ni in the olivine structure of LiMnPO4 was recently reported in an attempt to improve the electrochemical performances. Here the electronic structure and lithium intercalation potential of Ni-and Co-doped LiMnPO4 were calculated in the framework of the Hubbard U density functional theory (DFT+U) method for highly correlated materials. Moreover, the diffusion process of lithium in the host structures was simulated, and the activation barriers in the doped and pristine structures were compared. Our calculation predicted that doping increases Li insertion potential while activation barriers for Li diffusion remain similar to the pristine material. Moreover, Ni and Co doping induces the formation of impurity states near the Fermi level and significantly reduces the band gap of LiMnPO4 .

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Direct visualization of microphase separation in block copoly(3-alkylthiophene)s

RSC Adv., 2014

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Functional polymers: scanning force microscopy insights

Physical Chemistry Chemical Physics, 2006

Scanning force microscopy (SFM) and related techniques make it possible to visualize polymer syst... more Scanning force microscopy (SFM) and related techniques make it possible to visualize polymer systems with a molecular resolution. Beyond imaging, they also enable the unveiling of a variety of (dynamic) physico-chemical properties of both isolated polymer chains and their supramolecular architectures, including structural, mechanical and electronic properties. This article reviews recent progress in the use of SFM on polymers, with a particular emphasis on the mechanical properties of copolymers and single polymer chains, as well as on the bottom-up fabrication of supramolecular polymeric (helical) nanostructures in particular based upon pi-conjugated macromolecules as building blocks for nanoelectronics. Through a detailed understanding of the polymer behavior, we propose solutions for the generation of organic functional (nano)systems.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Doping of poly(3-hexylthiophene) nanofibers: microscopic morphology and electrical properties

European Physical Journal-applied Physics, 2009

The microstructure of thin deposits of poly(3-hexylthiophene) on silicon surfaces is investigated... more The microstructure of thin deposits of poly(3-hexylthiophene) on silicon surfaces is investigated as a function of the solution concentration, the maturation time and the solvent nature, with the aim of generating one monolayer of P3HT nanofibers on the surface. These films are then exposed to a NOPF{6} solution, in order to oxidize the conjugated system and to produce conducting nanostructures.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Relationship between the microscopic morphology and the charge transport properties in poly(3-hexylthiophene) field-effect transistors

Journal of Applied Physics, 2006

We fabricate field-effect transistors (FETs) by depositing a regioregular poly(3-hexylthiophene) ... more We fabricate field-effect transistors (FETs) by depositing a regioregular poly(3-hexylthiophene) (RR-P3HT) active layer via different preparation methods. The solvent used in the polymer film deposition and the deposition technique determine the film microstructure, which ranges from amorphous or granular films to a well-defined fibrillar texture. The crystalline ordering of RR-P3HT into fibrillar structures appears to lead to optimal FET performances,

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Oxidizing Ru(II) Complexes as Irreversible and Specific Photo-Cross-Linking Agents of Oligonucleotide Duplexes

Inorganic Chemistry, 2009

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The chemical and electronic structure of the interface between aluminum and conjugated polymers or molecules

Synthetic Metals, 1993

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Regioregular poly(3-hexylthiophene)-poly(ε-caprolactone) block copolymers: Controlled synthesis, microscopic morphology, and charge transport properties

Organic Electronics, 2010

In this paper, we describe the design and characterization of regioregular poly(3-hexylthiophene)... more In this paper, we describe the design and characterization of regioregular poly(3-hexylthiophene)-poly(ε-caprolactone) di- and tri-block copolymers (RRP3HT-b-PCL and PCL-b-RRP3HT-b-PCL). The well-controlled synthesis of (di)hydroxyl-terminated RRP3HT makes possible to design block copolymer structures with a narrow molecular weight distribution. The microscopic morphology is investigated by atomic force microscopy, which reveals self-assembled fibrillar structures with the RRP3HT nanoribbons separated by narrow domains

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Synthesis and Characterization of Water-Soluble Amphipatic Polystyrene-Based Dendrigrafts

Macromolecules, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Electrochemical synthesis and characterization of the electronic structure of new conjugated polymers from dithienylene vinylene derivatives

Synthetic Metals, 1996

Highly conjugated thiophene derivatives, based on thienylene vinylene and thienylene vinylene phe... more Highly conjugated thiophene derivatives, based on thienylene vinylene and thienylene vinylene phenylene units, have been synthesized in order to examine: (i) the effect of such regular conjugated monomer structures on polymer formation; and (ii) the optical and electrochemical properties of the corresponding macromolecules. The all-trans monomers have been prepared by a Wittig reaction. The polymers have then been synthesized electrochemically.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Optical Absorption Spectra of Aromatic Isothianaphthene Oligomers: Theory and Experiment

The Journal of Physical Chemistry, 1995

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Multiphase coatings from complex radiation curable polyurethane dispersions

Progress in Organic Coatings, 2012

ABSTRACT The waterborne nature of radiation curable polyurethane dispersions largely respond to t... more ABSTRACT The waterborne nature of radiation curable polyurethane dispersions largely respond to the current environmental concerns and do not require any additional coalescent since the film formation (drying) and hardening (photo-curing) take place in distinct steps. It is possible to design aqueous dispersions with distinct polymer particle populations resulting in micro-structured coatings with optimized properties over a wide range of curing conditions. Mixed dispersions based on hard and soft acrylated polyurethane particles were used as model systems for the present study. The minimum film formation temperature has been investigated as a function of the hard:soft polymer ratio. The elastic modulus of the dry coatings shows a reinforcing effect consistent with the inclusion of hard domains in a soft continuous matrix. However, the level of reinforcement is not properly predicted by the usual mechanical models and it is qualitatively accounted for by assuming a composition gradient (interphase) between the hard domains and the matrix. The multiple-phase structure was clearly established by Atomic Force Microscopy in agreement with thermal analysis data. Furthermore the local nanoscale mechanical properties were mapped using a new imaging mode based on real-time force-distance curve analysis. Finally, the coatings prepared using this multiple-phase pattern present a clear benefit over conventional homogeneous coatings by offering an improved balance of chemical and mechanical resistance in pigmented systems applied on melamine-coated MDF panels. (C) 2012 Elsevier B.V. All rights reserved.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Control of the Morphology of Linear and Cyclic PS- b -PI Block Copolymer Micelles via PS Addition

Langmuir, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Structuration of Semiconducting Polymer Thin Films by Nanorubbing

IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Structural and Charge-Transport Properties of a Liquid-Crystalline α,ω-Disubstituted Thiophene Derivative: A Joint Experimental and Theoretical Study

The Journal of Physical Chemistry C, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Structure and Dynamics of a Bisurea-Based Supramolecular Polymer in n -Dodecane

The Journal of Physical Chemistry B, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Liquid Crystalline Metal-free Phthalocyanines Designed for Charge and Exciton Transport

The Journal of Physical Chemistry B, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Mechanism of the Antioxidant Action of Silybin and 2,3-Dehydrosilybin Flavonolignans: A Joint Experimental and Theoretical Study

The Journal of Physical Chemistry A, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Synthesis, characterization and comparative OFET behaviour of indenofluorene–bithiophene and terthiophene alternating copolymers

Synthetic Metals, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Electrochemical synthesis of new electroactive polymers from dithienvlene-vinylene derivatives

Synthetic Metals, 1997

Bookmarks Related papers MentionsView impact