Michele Galizia - Academia.edu (original) (raw)

Papers by Michele Galizia

Research paper thumbnail of Methanol diffusion in polyimides: A molecular description

Polymer, 2014

ABSTRACT In this contribution the diffusion of methanol in two commercial polyimides (6FDA-ODA an... more ABSTRACT In this contribution the diffusion of methanol in two commercial polyimides (6FDA-ODA and Ultem® 1000) is investigated in detail by gravimetric analysis and in-situ, time-resolved FTIR spectroscopy. Two methods of spectral data analysis are employed, namely difference spectroscopy (DS) and least-squares curve fitting (LSCF). These approaches provided complementary information about the overall diffusivity, the interactions and the dynamics of the molecular species present in the investigated systems. Spectroscopic measurements on thin film samples (2 – 4 μm) allowed us to identify the interaction site(s) on the polymer backbone and to propose likely structures for the H-bonding molecular aggregates.By coupling gravimetric and spectroscopic data collected in the same experimental conditions it was possible to evaluate the molar absorptivities of the different molecular species, and hence their populations, in both polyimides. The results highlighted the relevance of the H-bonding interaction and of the substrate molecular structure on the final transport properties of the systems.

Research paper thumbnail of Solubility and diffusivity of low molecular weight compounds in semi-crystalline poly-(2,6-dimethyl-1,4-phenylene)oxide: The role of the crystalline phase

Journal of Membrane Science, 2013

Research paper thumbnail of Dispersing hydrophilic nanoparticles in hydrophobic polymers: hdpe/zno nanocomposites by a novel template-based approach

Express Polymer Letters, Dec 29, 2013

Research paper thumbnail of Dispersing hydrophilic nanoparticles in hydrophobic polymers: HDPE/ZnO nanocomposites by a novel template-based approach

Express Polymer Letters, 2014

Research paper thumbnail of Gas and Vapor Transport in Mixed Matrix Membranes Based on Amorphous Teflon AF1600 and AF2400 and Fumed Silica

Ind Eng Chem Res, 2010

... MC Ferrari, M. Galizia, MG De Angelis, and GC Sarti*. Dipartimento di Ingegneria Chimica, Min... more ... MC Ferrari, M. Galizia, MG De Angelis, and GC Sarti*. Dipartimento di Ingegneria Chimica, Mineraria e delle Tecnologie Ambientali (DICMA), Alma Mater Studiorum-Universita di Bologna, via Terracini 28, 40131 Bologna, Italy. Ind. Eng. Chem. Res. ...

Research paper thumbnail of Modelling the Solubility of Gases in High Free Volume Glassy Polymers with the Nelf Model

ABSTRACT High free volume glassy polymers such as polyimides, substituted polyacetylenes, polynor... more ABSTRACT High free volume glassy polymers such as polyimides, substituted polyacetylenes, polynorbornenes are very promising for the gas separation or sensor field, due to extremely high gas/vapour solubility and permeability. In this work we present an experimental characterization of sorption and diffusion of organic n-alkane vapours in poly (trimethyl-silyl norbornene), as well as the volume dilation isotherm associated to the polymer swelling during sorption. The polymer examined is endowed with a high fractional free volume and exhibits a very high vapour uptake. The experimental data have then been modelled with the Non Equilibrium Lattice Fluid (NELF) approach. The model provides an extension of the Lattice Fluid equation of state, valid above the glass transition, to the non equilibrium state typical of glassy polymers below Tg. The gas or vapour solubility isotherm can be reliably predicted by the model on the basis of the knowledge of the polymer density in the glass and of the pure component parameters, typically obtained from information on the volumetric behaviour of the pure penetrant, e.g. along the Liquid-Vapour saturation curve, and of the pure polymer, in terms of Pressure-Volume-Temperature data above Tg. In the case of polynorbornenes, however, there is no experimental access to the equilibrium volumetric behavior above the glass transition, since due to their rigid structure they do not exhibit a glass transition before degradation, and thus the determination of the pure polymer parameters cannot be obtained through the usual procedure. To overcome this difficulty we have adjusted the polymer parameters on experimental gas solubility data at infinite dilution, obtained by inverse gas chromatography. The results have been compared successfully to the experimental vapour solubility and dilation isotherms of normal pentane and hexane; the same parameters have been used to evaluate a priori the solubility of other penetrants.

Research paper thumbnail of Gas and vapour transport in mixed matrix membranes based on amorphous Teflon® AF1600 and AF2400 and fumed silica

The enhancement of gas and vapor transport rates induced by the addition of fumed silica nanopart... more The enhancement of gas and vapor transport rates induced by the addition of fumed silica nanoparticles to fluorinated glassy polymers is interpreted and quantitatively modeled considering the additional free volume created by incorporation of filler. That effect can be evaluated accurately from gas solubility data, using the NELF model. The solubility of CH 4 and CO 2 in matrices of Teflon AF1600 and AF2400, filled with variable amounts of fumed silica nanoparticles, was measured at 35°C; the solubility of n-C 4 and n-C 5 vapors, as well as their diffusivity and the dilation induced in the same polymer matrices, was also measured at 25°C. The fractional free volume (FFV) values, estimated on the basis of CH 4 solubility data, were used to predict the solubility of the other penetrants inspected, with excellent agreement with experimental data. In addition, a single empirical correlation can be drawn, for both AF1600 and AF2400-based mixed matrices, between the infinite dilution diffusivity of vapors and the FFV value calculated from solubility data. Similarly, a simple correlation valid for both matrices is obtained as well for the dependence of diffusivity on penetrant concentration. Finally, use of the NELF model also allows an estimate of the swelling induced by the sorption process on the basis of virtually one simple data point of gas solubility.

Research paper thumbnail of Vapor Transport in Silica-Based Hybrid and Mixed Matrix Glassy Membranes

Nanocomposite materials obtained combining inorganic fillers with high free volume glassy polymer... more Nanocomposite materials obtained combining inorganic fillers with high free volume glassy polymers have been investigated in the last decade with the aim to improve the permselectivity of polymeric membranes for gas and vapor separation. The glassy matrix chosen for the present study is poly[1-(trimethylsilyl)-1-propyne] (PTMSP), for which relatively large information about the gas and vapour transport and the microscopic morphology is available in the literature. The object of this study is an experimental analysis of n-pentane sorption and diffusion into: i) mixed matrices formed by PTMSP and hydrophobic nanometric silica added in solution (mass fractions ranging from 10 to 50wt %); ii) hybrid matrices formed by PTMSP and Si-SiO2 obtained from tetraethoxysilane (TEOS) via sol-gel reaction, with silica content ranging from 10 to 30%. The first aim of the study is to compare the transport behaviour of the two types of matrices at similar silica content and to understand the role of ...

Research paper thumbnail of Predictive calculation of hydrogen and helium solubility in glassy and rubbery polymers

Journal of Membrane Science, 2015

Research paper thumbnail of Addition-type polynorbornene with trimethylsilyl side groups: study of organic vapors sorption, transport and swelling

... M. Galizia 1 , MG De Angelis 1 , GC Sarti 1 , Y. Yampolskii 2 1 Alma Mater Studiorum – Univer... more ... M. Galizia 1 , MG De Angelis 1 , GC Sarti 1 , Y. Yampolskii 2 1 Alma Mater Studiorum – Università di Bologna, Dipartimento di Ingegneria Chimica, Mineraria e delle Tecnologie Ambientali, via U. Terracini 34, 40131 Bologna. ...

Research paper thumbnail of Modelling the Solubility of Gases in High Free Volume Glassy Polymers with the Nelf Model

ABSTRACT High free volume glassy polymers such as polyimides, substituted polyacetylenes, polynor... more ABSTRACT High free volume glassy polymers such as polyimides, substituted polyacetylenes, polynorbornenes are very promising for the gas separation or sensor field, due to extremely high gas/vapour solubility and permeability. In this work we present an experimental characterization of sorption and diffusion of organic n-alkane vapours in poly (trimethyl-silyl norbornene), as well as the volume dilation isotherm associated to the polymer swelling during sorption. The polymer examined is endowed with a high fractional free volume and exhibits a very high vapour uptake. The experimental data have then been modelled with the Non Equilibrium Lattice Fluid (NELF) approach. The model provides an extension of the Lattice Fluid equation of state, valid above the glass transition, to the non equilibrium state typical of glassy polymers below Tg. The gas or vapour solubility isotherm can be reliably predicted by the model on the basis of the knowledge of the polymer density in the glass and of the pure component parameters, typically obtained from information on the volumetric behaviour of the pure penetrant, e.g. along the Liquid-Vapour saturation curve, and of the pure polymer, in terms of Pressure-Volume-Temperature data above Tg. In the case of polynorbornenes, however, there is no experimental access to the equilibrium volumetric behavior above the glass transition, since due to their rigid structure they do not exhibit a glass transition before degradation, and thus the determination of the pure polymer parameters cannot be obtained through the usual procedure. To overcome this difficulty we have adjusted the polymer parameters on experimental gas solubility data at infinite dilution, obtained by inverse gas chromatography. The results have been compared successfully to the experimental vapour solubility and dilation isotherms of normal pentane and hexane; the same parameters have been used to evaluate a priori the solubility of other penetrants.

Research paper thumbnail of POLY 150-Experimental data and model description for the solubility and diffusivity of organic vapors in mixed matrix membranes

Research paper thumbnail of Characterization and modeling of the organic vapour transport in addition-type poly (trimethylsilyl norbornene)

Research paper thumbnail of Organic vapours sorption, diffusion and swelling in Poly (trimethyl silyl norbornene)

Poly(trimethyl silyl norbornene) (PTMSN) obtained via addition is an high free volume glassy poly... more Poly(trimethyl silyl norbornene) (PTMSN) obtained via addition is an high free volume glassy polymer whose vapor sorption properties are very similar to those of poly(trimethyl silyl propyne) (PTMSP): both materials can be exploited in several membrane-based separation processes. Sorption, diffusion and swelling experiments were performed on PTMSN, using three different n-alkane vapors (n-C 4 , n-C 5 , n-C 6 ). The solubility data were successfully compared with the Nonequilibrium Lattice Fluid Model previsions, whose characteristic parameter were determined from a collection of infinite dilution solubility data.

Research paper thumbnail of Thermodynamics of water sorption in high performance glassy thermoplastic polymers

Frontiers in Chemistry, 2014

Sorption thermodynamics of water in two glassy polymers, polyetherimide (PEI) and polyetheretherk... more Sorption thermodynamics of water in two glassy polymers, polyetherimide (PEI) and polyetheretherketone (PEEK), is investigated by coupling gravimetry and on line FTIR spectroscopy in order to gather information on the total amount of sorbed water as well as on the different species of water molecules absorbed within the polymers, addressing the issue of cross-and self-interactions occurring in the polymer/water systems. Water sorption isotherms have been determined at temperatures ranging from 30 to 70 • C while FTIR spectroscopy has been performed only at 30 • C. The experimental analysis provided information on the groups present on the polymer backbones involved in hydrogen bonding interactions with absorbed water molecules. Moreover, it also supplied qualitative indications about the different "populations" of water molecules present within the PEEK and a quantitative assessment of these "populations" in the case of PEI. The results of the experimental analysis have been interpreted using an equation of state theory based on a compressible lattice fluid model for the Gibbs energy of the polymer-water mixture, developed by extending to the case of out of equilibrium glassy polymers a previous model intended for equilibrium rubbery polymers. The model accounts for the non-equilibrium nature of glassy polymers as well as for mean field and for hydrogen bonding interactions, providing a satisfactory quantitative interpretation of the experimental data.

Research paper thumbnail of Diffusion and molecular interactions in a methanol/polyimide system probed by coupling time-resolved FTIR spectroscopy with gravimetric measurements

Frontiers in Chemistry, 2014

In this contribution the diffusion of methanol in a commercial polyimide (PMDA-ODA) is studied by... more In this contribution the diffusion of methanol in a commercial polyimide (PMDA-ODA) is studied by coupling gravimetric measurements with in-situ, time-resolved FTIR spectroscopy. The spectroscopic data have been treated with two complementary techniques, i.e., difference spectroscopy (DS) and least-squares curve fitting (LSCF). These approaches provided information about the overall diffusivity, the nature of the molecular interactions among the system components and the dynamics of the various molecular species. Additional spectroscopic measurements on thin film samples (about 2 μm) allowed us to identify the interaction site on the polymer backbone and to propose likely structures for the H-bonding aggregates. Molar absorptivity values from a previous literature report allowed us to estimate the population of first-shell and second-shell layers of methanol in the polymer matrix. In terms of diffusion kinetics, the gravimetric and spectroscopic estimates of the diffusion coefficients were found to be in good agreement with each other and with previous literature reports. A Fickian behavior was observed throughout, with diffusivity values markedly affected by the total concentration of sorbed methanol. Citation: Musto P, Galizia M, La Manna P, Pannico M and Mensitieri G (2014) Diffusion and molecular interactions in a methanol/polyimide system probed by coupling time-resolved FTIR spectroscopy with gravimetric measurements. Front. Chem.

Research paper thumbnail of Water Sorption Thermodynamics in Polymer Matrices

Solid Mechanics and Its Applications, 2013

Research paper thumbnail of Vapor Sorption and Diffusion in Mixed Matrices Based on Teflon® AF 2400

Freeman/Membrane Gas Separation, 2010

Polymers are currently the dominant materials for gas separation membranes because of their proce... more Polymers are currently the dominant materials for gas separation membranes because of their processability that allows the economic production of modules for large scale separation. Their separation ability, however, may be low in comparison with more rigid molecular sieving ...

Research paper thumbnail of Gas sorption in poly-(2,6-dimethyl-1,4-phenylene)oxide containing nanoporous crystalline phases

ABSTRACT In this contribution is presented an analysis of mass transport properties of low molecu... more ABSTRACT In this contribution is presented an analysis of mass transport properties of low molecular weight compounds in amorphous PPO and in semi-crystalline PPO obtained by treating with benzene and carbon tetrachloride the amorphous sample. It is found that semi-crystalline samples are endowed with larger gas sorption capacity and diffusivity as compared to the amorphous ones: this behaviour has been attributed to the nanoporous nature of the crystalline phases induced by treatment with solvents. In particular, sorption experiments, carried out at 30°C with methane, carbon dioxide, propane and propylene, have shown that both semi-crystalline PPOs display rather interesting features which make them suitable for use as membrane materials in gas separation processes, in view of the relatively high values of solubility and diffusivity. Moreover, these peculiar sorption and mass transport properties have been found to be virtually unaffected by thermal ageing: in fact, sorption experiments conducted on amorphous and semi-crystalline PPO after treatment at 65°C for three months showed that sorption properties of aged samples are the same as for the untreated samples. This is an important feature to assure the stability of performances in membrane applications.

Research paper thumbnail of Improving surface and transport properties of macroporous hydrogels for bone regeneration

Journal of Biomedical Materials Research Part A, 2014

Hydrogels have been frequently considered as suitable materials for hard tissue engineering as mi... more Hydrogels have been frequently considered as suitable materials for hard tissue engineering as mineralized extracellular matrix analogue. However, major lacks in bone-substitution still concern the mimicking of native microenvironment for promoting cell differentiation into osteogenic way. Here, we propose the study of mineralized macroporous hydrogels (mMHs) made of poly(ethylenglycol)diacrylate fabricated by the combination of ultraviolet photopolymerization/salt leaching technique and treated by osteopromotive medium. We demonstrate that peculiar morphological and chemical features of mMH are crucial to create a reservoir system able to efficiently recruit environmental signals to cells. In particular, mass transport mechanisms are regulated by the coupling of a Knudsen-type diffusion within the void space of the pores with a standard diffusion mechanism through the pores walls. Meanwhile, the deposition of hydrophilic mineral phases onto the pore surface further affects transport mechanisms, in view of their capability to establish interactions with water molecules and to exert mechanical constrains on the swelling of the hydrogel network, thus promoting slower diffusion kinetics. These properties concur to influence in vitro human mesenchymal stem cells activities: macropore architecture of the hydrogel-like network positively affects cell recognition as compared to nonporous scaffolds, while osteopromotive treatment mainly allows to guide differentiation in osteogenic way as proved by staining of in vitro formed Ca-rich mineral deposits (i.e., alizarin red) and expression via reverse transcription-polymerase chain reaction of main bone markers. Hence, mMH is promising to develop three-dimensional scaffolds as experimental model to study in vitro cell events during bone regeneration. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1095-1105, 2015.

Research paper thumbnail of Methanol diffusion in polyimides: A molecular description

Polymer, 2014

ABSTRACT In this contribution the diffusion of methanol in two commercial polyimides (6FDA-ODA an... more ABSTRACT In this contribution the diffusion of methanol in two commercial polyimides (6FDA-ODA and Ultem® 1000) is investigated in detail by gravimetric analysis and in-situ, time-resolved FTIR spectroscopy. Two methods of spectral data analysis are employed, namely difference spectroscopy (DS) and least-squares curve fitting (LSCF). These approaches provided complementary information about the overall diffusivity, the interactions and the dynamics of the molecular species present in the investigated systems. Spectroscopic measurements on thin film samples (2 – 4 μm) allowed us to identify the interaction site(s) on the polymer backbone and to propose likely structures for the H-bonding molecular aggregates.By coupling gravimetric and spectroscopic data collected in the same experimental conditions it was possible to evaluate the molar absorptivities of the different molecular species, and hence their populations, in both polyimides. The results highlighted the relevance of the H-bonding interaction and of the substrate molecular structure on the final transport properties of the systems.

Research paper thumbnail of Solubility and diffusivity of low molecular weight compounds in semi-crystalline poly-(2,6-dimethyl-1,4-phenylene)oxide: The role of the crystalline phase

Journal of Membrane Science, 2013

Research paper thumbnail of Dispersing hydrophilic nanoparticles in hydrophobic polymers: hdpe/zno nanocomposites by a novel template-based approach

Express Polymer Letters, Dec 29, 2013

Research paper thumbnail of Dispersing hydrophilic nanoparticles in hydrophobic polymers: HDPE/ZnO nanocomposites by a novel template-based approach

Express Polymer Letters, 2014

Research paper thumbnail of Gas and Vapor Transport in Mixed Matrix Membranes Based on Amorphous Teflon AF1600 and AF2400 and Fumed Silica

Ind Eng Chem Res, 2010

... MC Ferrari, M. Galizia, MG De Angelis, and GC Sarti*. Dipartimento di Ingegneria Chimica, Min... more ... MC Ferrari, M. Galizia, MG De Angelis, and GC Sarti*. Dipartimento di Ingegneria Chimica, Mineraria e delle Tecnologie Ambientali (DICMA), Alma Mater Studiorum-Universita di Bologna, via Terracini 28, 40131 Bologna, Italy. Ind. Eng. Chem. Res. ...

Research paper thumbnail of Modelling the Solubility of Gases in High Free Volume Glassy Polymers with the Nelf Model

ABSTRACT High free volume glassy polymers such as polyimides, substituted polyacetylenes, polynor... more ABSTRACT High free volume glassy polymers such as polyimides, substituted polyacetylenes, polynorbornenes are very promising for the gas separation or sensor field, due to extremely high gas/vapour solubility and permeability. In this work we present an experimental characterization of sorption and diffusion of organic n-alkane vapours in poly (trimethyl-silyl norbornene), as well as the volume dilation isotherm associated to the polymer swelling during sorption. The polymer examined is endowed with a high fractional free volume and exhibits a very high vapour uptake. The experimental data have then been modelled with the Non Equilibrium Lattice Fluid (NELF) approach. The model provides an extension of the Lattice Fluid equation of state, valid above the glass transition, to the non equilibrium state typical of glassy polymers below Tg. The gas or vapour solubility isotherm can be reliably predicted by the model on the basis of the knowledge of the polymer density in the glass and of the pure component parameters, typically obtained from information on the volumetric behaviour of the pure penetrant, e.g. along the Liquid-Vapour saturation curve, and of the pure polymer, in terms of Pressure-Volume-Temperature data above Tg. In the case of polynorbornenes, however, there is no experimental access to the equilibrium volumetric behavior above the glass transition, since due to their rigid structure they do not exhibit a glass transition before degradation, and thus the determination of the pure polymer parameters cannot be obtained through the usual procedure. To overcome this difficulty we have adjusted the polymer parameters on experimental gas solubility data at infinite dilution, obtained by inverse gas chromatography. The results have been compared successfully to the experimental vapour solubility and dilation isotherms of normal pentane and hexane; the same parameters have been used to evaluate a priori the solubility of other penetrants.

Research paper thumbnail of Gas and vapour transport in mixed matrix membranes based on amorphous Teflon® AF1600 and AF2400 and fumed silica

The enhancement of gas and vapor transport rates induced by the addition of fumed silica nanopart... more The enhancement of gas and vapor transport rates induced by the addition of fumed silica nanoparticles to fluorinated glassy polymers is interpreted and quantitatively modeled considering the additional free volume created by incorporation of filler. That effect can be evaluated accurately from gas solubility data, using the NELF model. The solubility of CH 4 and CO 2 in matrices of Teflon AF1600 and AF2400, filled with variable amounts of fumed silica nanoparticles, was measured at 35°C; the solubility of n-C 4 and n-C 5 vapors, as well as their diffusivity and the dilation induced in the same polymer matrices, was also measured at 25°C. The fractional free volume (FFV) values, estimated on the basis of CH 4 solubility data, were used to predict the solubility of the other penetrants inspected, with excellent agreement with experimental data. In addition, a single empirical correlation can be drawn, for both AF1600 and AF2400-based mixed matrices, between the infinite dilution diffusivity of vapors and the FFV value calculated from solubility data. Similarly, a simple correlation valid for both matrices is obtained as well for the dependence of diffusivity on penetrant concentration. Finally, use of the NELF model also allows an estimate of the swelling induced by the sorption process on the basis of virtually one simple data point of gas solubility.

Research paper thumbnail of Vapor Transport in Silica-Based Hybrid and Mixed Matrix Glassy Membranes

Nanocomposite materials obtained combining inorganic fillers with high free volume glassy polymer... more Nanocomposite materials obtained combining inorganic fillers with high free volume glassy polymers have been investigated in the last decade with the aim to improve the permselectivity of polymeric membranes for gas and vapor separation. The glassy matrix chosen for the present study is poly[1-(trimethylsilyl)-1-propyne] (PTMSP), for which relatively large information about the gas and vapour transport and the microscopic morphology is available in the literature. The object of this study is an experimental analysis of n-pentane sorption and diffusion into: i) mixed matrices formed by PTMSP and hydrophobic nanometric silica added in solution (mass fractions ranging from 10 to 50wt %); ii) hybrid matrices formed by PTMSP and Si-SiO2 obtained from tetraethoxysilane (TEOS) via sol-gel reaction, with silica content ranging from 10 to 30%. The first aim of the study is to compare the transport behaviour of the two types of matrices at similar silica content and to understand the role of ...

Research paper thumbnail of Predictive calculation of hydrogen and helium solubility in glassy and rubbery polymers

Journal of Membrane Science, 2015

Research paper thumbnail of Addition-type polynorbornene with trimethylsilyl side groups: study of organic vapors sorption, transport and swelling

... M. Galizia 1 , MG De Angelis 1 , GC Sarti 1 , Y. Yampolskii 2 1 Alma Mater Studiorum – Univer... more ... M. Galizia 1 , MG De Angelis 1 , GC Sarti 1 , Y. Yampolskii 2 1 Alma Mater Studiorum – Università di Bologna, Dipartimento di Ingegneria Chimica, Mineraria e delle Tecnologie Ambientali, via U. Terracini 34, 40131 Bologna. ...

Research paper thumbnail of Modelling the Solubility of Gases in High Free Volume Glassy Polymers with the Nelf Model

ABSTRACT High free volume glassy polymers such as polyimides, substituted polyacetylenes, polynor... more ABSTRACT High free volume glassy polymers such as polyimides, substituted polyacetylenes, polynorbornenes are very promising for the gas separation or sensor field, due to extremely high gas/vapour solubility and permeability. In this work we present an experimental characterization of sorption and diffusion of organic n-alkane vapours in poly (trimethyl-silyl norbornene), as well as the volume dilation isotherm associated to the polymer swelling during sorption. The polymer examined is endowed with a high fractional free volume and exhibits a very high vapour uptake. The experimental data have then been modelled with the Non Equilibrium Lattice Fluid (NELF) approach. The model provides an extension of the Lattice Fluid equation of state, valid above the glass transition, to the non equilibrium state typical of glassy polymers below Tg. The gas or vapour solubility isotherm can be reliably predicted by the model on the basis of the knowledge of the polymer density in the glass and of the pure component parameters, typically obtained from information on the volumetric behaviour of the pure penetrant, e.g. along the Liquid-Vapour saturation curve, and of the pure polymer, in terms of Pressure-Volume-Temperature data above Tg. In the case of polynorbornenes, however, there is no experimental access to the equilibrium volumetric behavior above the glass transition, since due to their rigid structure they do not exhibit a glass transition before degradation, and thus the determination of the pure polymer parameters cannot be obtained through the usual procedure. To overcome this difficulty we have adjusted the polymer parameters on experimental gas solubility data at infinite dilution, obtained by inverse gas chromatography. The results have been compared successfully to the experimental vapour solubility and dilation isotherms of normal pentane and hexane; the same parameters have been used to evaluate a priori the solubility of other penetrants.

Research paper thumbnail of POLY 150-Experimental data and model description for the solubility and diffusivity of organic vapors in mixed matrix membranes

Research paper thumbnail of Characterization and modeling of the organic vapour transport in addition-type poly (trimethylsilyl norbornene)

Research paper thumbnail of Organic vapours sorption, diffusion and swelling in Poly (trimethyl silyl norbornene)

Poly(trimethyl silyl norbornene) (PTMSN) obtained via addition is an high free volume glassy poly... more Poly(trimethyl silyl norbornene) (PTMSN) obtained via addition is an high free volume glassy polymer whose vapor sorption properties are very similar to those of poly(trimethyl silyl propyne) (PTMSP): both materials can be exploited in several membrane-based separation processes. Sorption, diffusion and swelling experiments were performed on PTMSN, using three different n-alkane vapors (n-C 4 , n-C 5 , n-C 6 ). The solubility data were successfully compared with the Nonequilibrium Lattice Fluid Model previsions, whose characteristic parameter were determined from a collection of infinite dilution solubility data.

Research paper thumbnail of Thermodynamics of water sorption in high performance glassy thermoplastic polymers

Frontiers in Chemistry, 2014

Sorption thermodynamics of water in two glassy polymers, polyetherimide (PEI) and polyetheretherk... more Sorption thermodynamics of water in two glassy polymers, polyetherimide (PEI) and polyetheretherketone (PEEK), is investigated by coupling gravimetry and on line FTIR spectroscopy in order to gather information on the total amount of sorbed water as well as on the different species of water molecules absorbed within the polymers, addressing the issue of cross-and self-interactions occurring in the polymer/water systems. Water sorption isotherms have been determined at temperatures ranging from 30 to 70 • C while FTIR spectroscopy has been performed only at 30 • C. The experimental analysis provided information on the groups present on the polymer backbones involved in hydrogen bonding interactions with absorbed water molecules. Moreover, it also supplied qualitative indications about the different "populations" of water molecules present within the PEEK and a quantitative assessment of these "populations" in the case of PEI. The results of the experimental analysis have been interpreted using an equation of state theory based on a compressible lattice fluid model for the Gibbs energy of the polymer-water mixture, developed by extending to the case of out of equilibrium glassy polymers a previous model intended for equilibrium rubbery polymers. The model accounts for the non-equilibrium nature of glassy polymers as well as for mean field and for hydrogen bonding interactions, providing a satisfactory quantitative interpretation of the experimental data.

Research paper thumbnail of Diffusion and molecular interactions in a methanol/polyimide system probed by coupling time-resolved FTIR spectroscopy with gravimetric measurements

Frontiers in Chemistry, 2014

In this contribution the diffusion of methanol in a commercial polyimide (PMDA-ODA) is studied by... more In this contribution the diffusion of methanol in a commercial polyimide (PMDA-ODA) is studied by coupling gravimetric measurements with in-situ, time-resolved FTIR spectroscopy. The spectroscopic data have been treated with two complementary techniques, i.e., difference spectroscopy (DS) and least-squares curve fitting (LSCF). These approaches provided information about the overall diffusivity, the nature of the molecular interactions among the system components and the dynamics of the various molecular species. Additional spectroscopic measurements on thin film samples (about 2 μm) allowed us to identify the interaction site on the polymer backbone and to propose likely structures for the H-bonding aggregates. Molar absorptivity values from a previous literature report allowed us to estimate the population of first-shell and second-shell layers of methanol in the polymer matrix. In terms of diffusion kinetics, the gravimetric and spectroscopic estimates of the diffusion coefficients were found to be in good agreement with each other and with previous literature reports. A Fickian behavior was observed throughout, with diffusivity values markedly affected by the total concentration of sorbed methanol. Citation: Musto P, Galizia M, La Manna P, Pannico M and Mensitieri G (2014) Diffusion and molecular interactions in a methanol/polyimide system probed by coupling time-resolved FTIR spectroscopy with gravimetric measurements. Front. Chem.

Research paper thumbnail of Water Sorption Thermodynamics in Polymer Matrices

Solid Mechanics and Its Applications, 2013

Research paper thumbnail of Vapor Sorption and Diffusion in Mixed Matrices Based on Teflon® AF 2400

Freeman/Membrane Gas Separation, 2010

Polymers are currently the dominant materials for gas separation membranes because of their proce... more Polymers are currently the dominant materials for gas separation membranes because of their processability that allows the economic production of modules for large scale separation. Their separation ability, however, may be low in comparison with more rigid molecular sieving ...

Research paper thumbnail of Gas sorption in poly-(2,6-dimethyl-1,4-phenylene)oxide containing nanoporous crystalline phases

ABSTRACT In this contribution is presented an analysis of mass transport properties of low molecu... more ABSTRACT In this contribution is presented an analysis of mass transport properties of low molecular weight compounds in amorphous PPO and in semi-crystalline PPO obtained by treating with benzene and carbon tetrachloride the amorphous sample. It is found that semi-crystalline samples are endowed with larger gas sorption capacity and diffusivity as compared to the amorphous ones: this behaviour has been attributed to the nanoporous nature of the crystalline phases induced by treatment with solvents. In particular, sorption experiments, carried out at 30°C with methane, carbon dioxide, propane and propylene, have shown that both semi-crystalline PPOs display rather interesting features which make them suitable for use as membrane materials in gas separation processes, in view of the relatively high values of solubility and diffusivity. Moreover, these peculiar sorption and mass transport properties have been found to be virtually unaffected by thermal ageing: in fact, sorption experiments conducted on amorphous and semi-crystalline PPO after treatment at 65°C for three months showed that sorption properties of aged samples are the same as for the untreated samples. This is an important feature to assure the stability of performances in membrane applications.

Research paper thumbnail of Improving surface and transport properties of macroporous hydrogels for bone regeneration

Journal of Biomedical Materials Research Part A, 2014

Hydrogels have been frequently considered as suitable materials for hard tissue engineering as mi... more Hydrogels have been frequently considered as suitable materials for hard tissue engineering as mineralized extracellular matrix analogue. However, major lacks in bone-substitution still concern the mimicking of native microenvironment for promoting cell differentiation into osteogenic way. Here, we propose the study of mineralized macroporous hydrogels (mMHs) made of poly(ethylenglycol)diacrylate fabricated by the combination of ultraviolet photopolymerization/salt leaching technique and treated by osteopromotive medium. We demonstrate that peculiar morphological and chemical features of mMH are crucial to create a reservoir system able to efficiently recruit environmental signals to cells. In particular, mass transport mechanisms are regulated by the coupling of a Knudsen-type diffusion within the void space of the pores with a standard diffusion mechanism through the pores walls. Meanwhile, the deposition of hydrophilic mineral phases onto the pore surface further affects transport mechanisms, in view of their capability to establish interactions with water molecules and to exert mechanical constrains on the swelling of the hydrogel network, thus promoting slower diffusion kinetics. These properties concur to influence in vitro human mesenchymal stem cells activities: macropore architecture of the hydrogel-like network positively affects cell recognition as compared to nonporous scaffolds, while osteopromotive treatment mainly allows to guide differentiation in osteogenic way as proved by staining of in vitro formed Ca-rich mineral deposits (i.e., alizarin red) and expression via reverse transcription-polymerase chain reaction of main bone markers. Hence, mMH is promising to develop three-dimensional scaffolds as experimental model to study in vitro cell events during bone regeneration. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1095-1105, 2015.