The formation of supramolecular inclusion compounds (pseudopolyrotaxanes) produced by cyclodextri... more The formation of supramolecular inclusion compounds (pseudopolyrotaxanes) produced by cyclodextrins and polymers can be monitored through turbidimetry. In this paper, we studied the kinetics of the threading of linear poly(ethylene glycol) chains of different molecular weights and of a four-arm star-like polymer as a function of temperature. The main thermodynamic parameters are extracted. The aggregation and precipitation of pseudopolyrotaxanes are described in terms of the Avrami-Erofe'ev model, which provides relevant information on the mechanism of these processes. SAXS and TGA experiments confirm the structure and hydration of the final products obtained from the different polymers. A new hypothesis for the interaction between pseudopolyrotaxanes that leads to aggregation and precipitation, based on the spatial dielectric anisotropy, is proposed.
Abstract. High resolution quasi-elastic neutron scattering is used to investigate the slow dynami... more Abstract. High resolution quasi-elastic neutron scattering is used to investigate the slow dynamics of hydration water confined in calcium silicate hydrate gel in an aged cement paste at supercooled temperatures. A super-Arrhenius to Arrhenius dynamic crossover of the average translational relaxation time\ langle\ tau\ rangle as a function of the inverse temperature is observed at TL= 231±5 K, which coincides with a prominent peak in the differential scanning calorimetry cooling scan.
ABSTRACT A new family of oligotrehaluronamides was synthesized through the polycondensation of α,... more ABSTRACT A new family of oligotrehaluronamides was synthesized through the polycondensation of α,α-trehaluronic acid dimethyl ester and different diamines or polyamines. In particular, diamines with different molecular structure (1,n-alkylene diamines, aromatic diamine, and alkyleneoxydiamine) were used in order to modulate the molecular weights and the physical characteristics of the products, such as Tg, hydrophilic or hydrophobic properties, and solubility. α,α-Trehaluronic acid was obtained from a renewable source as α,α-trehalose. The syntheses of oligotrehaluronamides were carried out in different solvents such as ethanol, methanol, THF and DMSO, using triethylamine as catalyst. All the compounds obtained in this study were characterized through FT-IR and NMR spectroscopy. The molecular weights were evaluated by 1H-NMR and in some cases compared with those obtained from ESI-MS spectrometry. Glass transition temperatures and melting points were detected by differential scanning calorimetry. Low molecular weight oligoamides, containing several hydroxyl groups, are water-soluble and could be used in water-based formulations.
A Functional Bio-Interlayer Organic Field-Effect Transistor (FBI-OFET) sensor, embedding a strept... more A Functional Bio-Interlayer Organic Field-Effect Transistor (FBI-OFET) sensor, embedding a streptavidin protein capturing layer, capable of performing label-free selective electronic detection of biotin at 3 part per trillion (mass fraction) or 15 pM, is proposed here. The response shows a logarithmic dependence spanning over 5 orders of magnitude of analyte concentration. The optimization of the FBI analytical performances is achieved by depositing the capturing layer through a controllable Layer-by-Layer (LbL) assembly, while an easy processable spin-coating deposition is proposed for potential low-cost production of equally highly performing sensors. Furthermore, a Langmuirian adsorption based model allows rationalizing the analyte binding process to the capturing layer. The FBI-OFET device is shown to operate also with an antibody interlayer as well as with an ad hoc designed microfluidic system. These occurrences, along with the proven extremely high sensitivity and selectivity, open to FBI-OFETs consideration as disposable electronic strip-tests for assays in biological fluids requiring very low detection limits.
ABSTRACT The translational dynamics of the hydration water in tricalcium silicate, as well as the... more ABSTRACT The translational dynamics of the hydration water in tricalcium silicate, as well as the curing kinetics of the paste, have been investigated for the first time using neutron elastic backscattering measurements. A detailed analytical model has been formulated to extract the most important features of the calcium silicate curing process. As the curing time passes, water reacts with the tricalcium silicate, forming amorphous calcium silicate hydrate and crystalline calcium hydroxide. Concurrently, the water translational dynamics slows down due to the increased confinement in the developing matrix. The time evolution of the self-diffusion constant for the hydration water shows a decrease of 1 order of magnitude after two days of curing. The presented results agree with recent molecular dynamics simulations and 1H NMR results on similar systems.
A recently developed method based on Differential Scanning Calorimetry (DSC) has been used to stu... more A recently developed method based on Differential Scanning Calorimetry (DSC) has been used to study the hydration kinetics of tri-calcium silicate (C 3 S) in the presence of superplasticizers. We studied some of the most common additives employed in the ...
This paper reports on the analysis of the hydration kinetics of a tricalcium silicate paste cured... more This paper reports on the analysis of the hydration kinetics of a tricalcium silicate paste cured in presence of polymers industrially used in the extrusion process of mortars. In particular, we investigated the effect of a rheology-modifying additive (a methyl hydroxy ethyl cellulose) and a superplasticizer (a polyacrylic polymer). These polymers have been added to tricalcium silicate paste, both separately and together, to understand their distinct influence on the tricalcium silicate hydration and their possible synergies. The kinetic curves have been monitored from 10 to 40°C by means of Differential Scanning Calorimetry and fitted using the generalized Boundary Nucleation and Growth Model combined to a diffusion-limited model, to extract: induction times, reaction rates, activation energies and diffusion coefficients. As a main result, this paper contributes to the advancement of the knowledge in the field of the extrusion process of cementitious materials, providing a thermodynamic support to the empirical evaluations of the additives performances.
The formation of supramolecular inclusion compounds (pseudopolyrotaxanes) produced by cyclodextri... more The formation of supramolecular inclusion compounds (pseudopolyrotaxanes) produced by cyclodextrins and polymers can be monitored through turbidimetry. In this paper, we studied the kinetics of the threading of linear poly(ethylene glycol) chains of different molecular weights and of a four-arm star-like polymer as a function of temperature. The main thermodynamic parameters are extracted. The aggregation and precipitation of pseudopolyrotaxanes are described in terms of the Avrami-Erofe'ev model, which provides relevant information on the mechanism of these processes. SAXS and TGA experiments confirm the structure and hydration of the final products obtained from the different polymers. A new hypothesis for the interaction between pseudopolyrotaxanes that leads to aggregation and precipitation, based on the spatial dielectric anisotropy, is proposed.
Abstract. High resolution quasi-elastic neutron scattering is used to investigate the slow dynami... more Abstract. High resolution quasi-elastic neutron scattering is used to investigate the slow dynamics of hydration water confined in calcium silicate hydrate gel in an aged cement paste at supercooled temperatures. A super-Arrhenius to Arrhenius dynamic crossover of the average translational relaxation time\ langle\ tau\ rangle as a function of the inverse temperature is observed at TL= 231±5 K, which coincides with a prominent peak in the differential scanning calorimetry cooling scan.
ABSTRACT A new family of oligotrehaluronamides was synthesized through the polycondensation of α,... more ABSTRACT A new family of oligotrehaluronamides was synthesized through the polycondensation of α,α-trehaluronic acid dimethyl ester and different diamines or polyamines. In particular, diamines with different molecular structure (1,n-alkylene diamines, aromatic diamine, and alkyleneoxydiamine) were used in order to modulate the molecular weights and the physical characteristics of the products, such as Tg, hydrophilic or hydrophobic properties, and solubility. α,α-Trehaluronic acid was obtained from a renewable source as α,α-trehalose. The syntheses of oligotrehaluronamides were carried out in different solvents such as ethanol, methanol, THF and DMSO, using triethylamine as catalyst. All the compounds obtained in this study were characterized through FT-IR and NMR spectroscopy. The molecular weights were evaluated by 1H-NMR and in some cases compared with those obtained from ESI-MS spectrometry. Glass transition temperatures and melting points were detected by differential scanning calorimetry. Low molecular weight oligoamides, containing several hydroxyl groups, are water-soluble and could be used in water-based formulations.
A Functional Bio-Interlayer Organic Field-Effect Transistor (FBI-OFET) sensor, embedding a strept... more A Functional Bio-Interlayer Organic Field-Effect Transistor (FBI-OFET) sensor, embedding a streptavidin protein capturing layer, capable of performing label-free selective electronic detection of biotin at 3 part per trillion (mass fraction) or 15 pM, is proposed here. The response shows a logarithmic dependence spanning over 5 orders of magnitude of analyte concentration. The optimization of the FBI analytical performances is achieved by depositing the capturing layer through a controllable Layer-by-Layer (LbL) assembly, while an easy processable spin-coating deposition is proposed for potential low-cost production of equally highly performing sensors. Furthermore, a Langmuirian adsorption based model allows rationalizing the analyte binding process to the capturing layer. The FBI-OFET device is shown to operate also with an antibody interlayer as well as with an ad hoc designed microfluidic system. These occurrences, along with the proven extremely high sensitivity and selectivity, open to FBI-OFETs consideration as disposable electronic strip-tests for assays in biological fluids requiring very low detection limits.
ABSTRACT The translational dynamics of the hydration water in tricalcium silicate, as well as the... more ABSTRACT The translational dynamics of the hydration water in tricalcium silicate, as well as the curing kinetics of the paste, have been investigated for the first time using neutron elastic backscattering measurements. A detailed analytical model has been formulated to extract the most important features of the calcium silicate curing process. As the curing time passes, water reacts with the tricalcium silicate, forming amorphous calcium silicate hydrate and crystalline calcium hydroxide. Concurrently, the water translational dynamics slows down due to the increased confinement in the developing matrix. The time evolution of the self-diffusion constant for the hydration water shows a decrease of 1 order of magnitude after two days of curing. The presented results agree with recent molecular dynamics simulations and 1H NMR results on similar systems.
A recently developed method based on Differential Scanning Calorimetry (DSC) has been used to stu... more A recently developed method based on Differential Scanning Calorimetry (DSC) has been used to study the hydration kinetics of tri-calcium silicate (C 3 S) in the presence of superplasticizers. We studied some of the most common additives employed in the ...
This paper reports on the analysis of the hydration kinetics of a tricalcium silicate paste cured... more This paper reports on the analysis of the hydration kinetics of a tricalcium silicate paste cured in presence of polymers industrially used in the extrusion process of mortars. In particular, we investigated the effect of a rheology-modifying additive (a methyl hydroxy ethyl cellulose) and a superplasticizer (a polyacrylic polymer). These polymers have been added to tricalcium silicate paste, both separately and together, to understand their distinct influence on the tricalcium silicate hydration and their possible synergies. The kinetic curves have been monitored from 10 to 40°C by means of Differential Scanning Calorimetry and fitted using the generalized Boundary Nucleation and Growth Model combined to a diffusion-limited model, to extract: induction times, reaction rates, activation energies and diffusion coefficients. As a main result, this paper contributes to the advancement of the knowledge in the field of the extrusion process of cementitious materials, providing a thermodynamic support to the empirical evaluations of the additives performances.
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Papers by Francesca Ridi