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Papers by luciana sartore

Polymer, 2000

Polymers capable of responding to both temperature and pH changes were synthesised by radical cop... more Polymers capable of responding to both temperature and pH changes were synthesised by radical copolymerisation of N-isopropylacrylamide (NIPAAm) and N-methacryloyl-l-leucine (MALEU) in different NIPAAm/MALEU molar ratios (15:1, 10:1, 2:1 and 1:1). The polymers were characterised by Size Exclusion Chromatography, acid–base titrations, FT-IR and 1H-NMR analyses. Their solution behaviour was studied in 0.1 M NaCl and in citrate buffers (pH 4.0, 4.5, 5.0 and 6.0). At pH 4.0 and 4.5 the cloud point temperature (TCP) of copolymers was depressed proportionally to their MALEU content. In contrast, at pH 5.0 and 6.0 the phase transition temperature increased linearly. The behaviour of the copolymers with NIPAAm/MALEU ratios 15:1 and 10:1 was investigated also between pH 3 and 11 in 0.1 M NaCl. In both cases a sharp increase in TCP was observed around pH 4–5. The TCP vs. pH curve was linearised and the acidity constants were determined by the linearisation procedure. Furthermore, it was possible to demonstrate that the phase transition temperature increases linearly with the ionic content of the polymers.

J Appl Polym Sci, 2000

ABSTRACT

Macromolecules, Dec 4, 2006

... Filippo Samperi,* † Raniero Mendichi, ‡ Luciana Sartore, § Maurizio Penco, § and Concetto Pug... more ... Filippo Samperi,* † Raniero Mendichi, ‡ Luciana Sartore, § Maurizio Penco, § and Concetto Puglisi †. Institute of Chemistry and Technology of Polymers (CNR), Viale A. Doria 6, 95125 Catania, Italy, Istituto per lo Studio delle ...

Die Makromolekulare Chemie Macromolecular Symposia, Mar 1, 2002

Binary blends based on poly(vinyl chloride) (PVC) were prepared both by casting from tetrahydrofu... more Binary blends based on poly(vinyl chloride) (PVC) were prepared both by casting from tetrahydrofuran (THF) and by mixing in the melt form, in a discontinuous mixer, PVC and multi-block copolymers containing poly(ε-caprolactone) (PCDT) and poly(ethylene glycol) (PEG) segments. ...

J Biomol Struct Dyn, 1990

To assess the minimal peptide length required for the stabilization of the alpha-helix relative t... more To assess the minimal peptide length required for the stabilization of the alpha-helix relative to the 3(10)-helix in Aib-rich peptides, we have solved the X-ray diffraction structures of the terminally blocked sequential hexa- and octapeptides with the general formula-(Aib-L-Ala)n-(n = 3 and 4, respectively). The hexapeptide molecules are completely 3(10)-helical with four 1----4 intramolecular N-H . . . O = C H-bonds. On the other hand, the octapeptide molecules are essentially alpha-helical with four 1----5 H-bonds; however, the helix is elongated at the N-terminus, with two 1----4 H-bonds, giving these molecules a mixed alpha/3(10)-helical character. In both compounds the right-handed screw sense of the helix is dictated by the presence of the Ala residues of L-configuration. This study represents the first experimental proof for a 3(10)----alpha-helix conversion in the crystal state induced by peptide backbone lengthening only.

Polym Degrad Stabil, 2001

The thermogravimetric analysis (TGA) of two classes of multi-block copolymers based on poly(d,l-l... more The thermogravimetric analysis (TGA) of two classes of multi-block copolymers based on poly(d,l-lactic-glycolic acid) (PLGA) and diol-terminated poly(ε-caprolactone) (PCDT) or poly(ethylene glycol) (PEG) segments is reported. These materials, having the structure of poly(ester-carbonate)s, were synthesized by a chain extension reaction. The influence of the length of PCDT or PEG segments and of the molar ratio of d,l-lactic acid (LA) and glycolic acid (GA) residues on thermal stability in air and nitrogen atmosphere has been investigated. For comparison purposes the degradation behaviour of starting oligomers was also studied. TGA under nitrogen shows two degradation processes that can be ascribed to the PLGA and PCDT or PEG segments, respectively. In addition, the thermal stability increases with the LA content in the PLGA blocks. In the tests run under air two degradation steps have also been observed, though the former occurs in general at higher temperatures.

Polymer Engineering and Science, Nov 1, 2007

Polymer processing often activates material degradation, which affects to some extent the perform... more Polymer processing often activates material degradation, which affects to some extent the performance or the life cycle of the obtained products. Polymer degradation is usually evidenced by molecular weight variations as consequence of exposure to high processing temperature and to relevant mechanical stresses. The degrading effects of melt extrusion under different thermo-mechanical conditions on polymethyl-methacrylate and polystyrene are investigated. Materials were processed at different temperatures and rates in a single screw extruder and in a capillary rheometer. Processed and as-received materials were analysed by Gel permeation chromatography, solution viscosity, and melt rheology. Evaluations of molecular weight and rheological behavior changes after processing, as compared with as-received materials, evidenced the extent of degradation in the different conditions. Experimental analysis was accompanied by finite elements simulation of the polymer flow and heat transmission within the extruder. This allowed an estimation of the expected shear stresses and temperatures distributions, thus indicating potentially critical situations. It was found that the materials processed at the highest rates in extruder presented lowest molecular weight reductions. This was attributed to the shorter residence time in the extruder and to the possibility of wall slip phenomena, which likely reduce the actual shear stress and viscous dissipation in the fast processing conditions.

Appl Biochem Biotech, 1991

To overcome the uncertainty of the colorimetric or fluorimetric method so far employed for the ev... more To overcome the uncertainty of the colorimetric or fluorimetric method so far employed for the evaluation of monomethoxy(polyethylene glycol) (MPEG) covalently bound to protein, a direct method based on amino acid analysis is proposed. The method exploits the use of MPEG, which was bounded with the unnatural amino acid norleucine (MPEG-Nle). MPEG-Nle was activated at its carboxylic group to succinimidyl ester for the binding to the amino groups of protein.

Journal of Bioactive and Compatible Polymers

Acta Horticulturae, 2012

Keywords: sustainable agriculture, raw materials from renewable origin, waste products of the lea... more Keywords: sustainable agriculture, raw materials from renewable origin, waste products of the leather industry Abstract Low density polyethylene (LDPE) films are widespread used in agriculture for soil mulching. The use of LDPE mulching films causes the serious drawback of huge quantities of waste to be disposed of. Over the last years the growing environmental awareness has been prompting the research to develop a new generation of mulching products starting with raw materials from renewable origin. These materials have to retain their physical and mechanical properties while in use and have to be compostable or biodegradable at the end of their life, degrading via micro-organisms into carbon dioxide or methane, water and biomass. The research is focused on the development of novel biodegradable polymeric materials based on hydrolyzed proteins, derived from waste products of the leather industry. Biodegradable soil mulching coatings were realized with these biodegradable polymeric materials by means of spray techniques; the coatings were tested in a Ligustrum ovalifolium cultivation carried out inside a greenhouse. This paper describes the functionalities of the new bio-based mulching coatings, which were developed and tested in real scale greenhouse cultivation tests. During the trial, the biodegradable soil mulching materials showed suitable properties for an efficient and profitable use in agriculture. The innovative biodegradable spray coatings lasted up to 18 months. The biodegradable materials could be the environmentally friendly alternatives to synthetic petro-chemical polymers and could contribute to a sustainable agriculture.

Journal of the Balkan Tribological Association

in this work the electrical properties of vapour detectors, formed from composites of conductive ... more in this work the electrical properties of vapour detectors, formed from composites of conductive carbon-black and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. the new composites are tailored to produce increased sensitivity towards specific classes of analyte vapours. resonant frequency shift of a Quartz crystal Microbalance (QcM) and dc resistance measurements have been also performed simultaneously on polymercarbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVc) with di(2-ethylhexyl)phthalate (doP), a traditional low-molecular weight plasticiser, is used as representative of the behaviour of a traditional composite vapour detector.

In this work the electrical properties of vapor detectors, formed from composites of conductive c... more In this work the electrical properties of vapor detectors, formed from composites of conductive carbonblack and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. The new composites are tailored to produce increased sensitivity toward specific classes of analyte vapors. Resonant frequency shift of a Quartz Crystal Microbalance (QCM) and dc resistance measurements have been also performed simultaneously on polymer-carbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVC) with di(2-ethylhexyl)phthalate (DOP), a traditional low molecular weight plasticizer, is used as a representative of the behaviour of a traditional composite vapor detector. These new detectors showed an enhanced sensitivity upon exposure to acetic acid and amines vapors; the performances of our systems are 10 3 times higher than those of a traditional composite vapor detector. Moreover the extent of such responses is beyond that expected by mass uptake upon exposure to the same vapors and cannot be attributed solely to differences in polymer/gas partition coefficients. In this respect, several different chemical factors determine the dc electrical response of this system: in our opinion changes in polymer conformation during the adsorption process also play a significant role. The effects of the temperature on the electric resistance of the vapor detectors have also been studied. These materials showed a discontinuity in the temperature dependence of their resistance, and this discontinuity provided a simple method for determining the T g of the composites.

Polymer, 2000

Polymers capable of responding to both temperature and pH changes were synthesised by radical cop... more Polymers capable of responding to both temperature and pH changes were synthesised by radical copolymerisation of N-isopropylacrylamide (NIPAAm) and N-methacryloyl-l-leucine (MALEU) in different NIPAAm/MALEU molar ratios (15:1, 10:1, 2:1 and 1:1). The polymers were characterised by Size Exclusion Chromatography, acid–base titrations, FT-IR and 1H-NMR analyses. Their solution behaviour was studied in 0.1 M NaCl and in citrate buffers (pH 4.0, 4.5, 5.0 and 6.0). At pH 4.0 and 4.5 the cloud point temperature (TCP) of copolymers was depressed proportionally to their MALEU content. In contrast, at pH 5.0 and 6.0 the phase transition temperature increased linearly. The behaviour of the copolymers with NIPAAm/MALEU ratios 15:1 and 10:1 was investigated also between pH 3 and 11 in 0.1 M NaCl. In both cases a sharp increase in TCP was observed around pH 4–5. The TCP vs. pH curve was linearised and the acidity constants were determined by the linearisation procedure. Furthermore, it was possible to demonstrate that the phase transition temperature increases linearly with the ionic content of the polymers.

J Appl Polym Sci, 2000

ABSTRACT

Macromolecules, Dec 4, 2006

... Filippo Samperi,* † Raniero Mendichi, ‡ Luciana Sartore, § Maurizio Penco, § and Concetto Pug... more ... Filippo Samperi,* † Raniero Mendichi, ‡ Luciana Sartore, § Maurizio Penco, § and Concetto Puglisi †. Institute of Chemistry and Technology of Polymers (CNR), Viale A. Doria 6, 95125 Catania, Italy, Istituto per lo Studio delle ...

Die Makromolekulare Chemie Macromolecular Symposia, Mar 1, 2002

Binary blends based on poly(vinyl chloride) (PVC) were prepared both by casting from tetrahydrofu... more Binary blends based on poly(vinyl chloride) (PVC) were prepared both by casting from tetrahydrofuran (THF) and by mixing in the melt form, in a discontinuous mixer, PVC and multi-block copolymers containing poly(ε-caprolactone) (PCDT) and poly(ethylene glycol) (PEG) segments. ...

J Biomol Struct Dyn, 1990

To assess the minimal peptide length required for the stabilization of the alpha-helix relative t... more To assess the minimal peptide length required for the stabilization of the alpha-helix relative to the 3(10)-helix in Aib-rich peptides, we have solved the X-ray diffraction structures of the terminally blocked sequential hexa- and octapeptides with the general formula-(Aib-L-Ala)n-(n = 3 and 4, respectively). The hexapeptide molecules are completely 3(10)-helical with four 1----4 intramolecular N-H . . . O = C H-bonds. On the other hand, the octapeptide molecules are essentially alpha-helical with four 1----5 H-bonds; however, the helix is elongated at the N-terminus, with two 1----4 H-bonds, giving these molecules a mixed alpha/3(10)-helical character. In both compounds the right-handed screw sense of the helix is dictated by the presence of the Ala residues of L-configuration. This study represents the first experimental proof for a 3(10)----alpha-helix conversion in the crystal state induced by peptide backbone lengthening only.

Polym Degrad Stabil, 2001

The thermogravimetric analysis (TGA) of two classes of multi-block copolymers based on poly(d,l-l... more The thermogravimetric analysis (TGA) of two classes of multi-block copolymers based on poly(d,l-lactic-glycolic acid) (PLGA) and diol-terminated poly(ε-caprolactone) (PCDT) or poly(ethylene glycol) (PEG) segments is reported. These materials, having the structure of poly(ester-carbonate)s, were synthesized by a chain extension reaction. The influence of the length of PCDT or PEG segments and of the molar ratio of d,l-lactic acid (LA) and glycolic acid (GA) residues on thermal stability in air and nitrogen atmosphere has been investigated. For comparison purposes the degradation behaviour of starting oligomers was also studied. TGA under nitrogen shows two degradation processes that can be ascribed to the PLGA and PCDT or PEG segments, respectively. In addition, the thermal stability increases with the LA content in the PLGA blocks. In the tests run under air two degradation steps have also been observed, though the former occurs in general at higher temperatures.

Polymer Engineering and Science, Nov 1, 2007

Polymer processing often activates material degradation, which affects to some extent the perform... more Polymer processing often activates material degradation, which affects to some extent the performance or the life cycle of the obtained products. Polymer degradation is usually evidenced by molecular weight variations as consequence of exposure to high processing temperature and to relevant mechanical stresses. The degrading effects of melt extrusion under different thermo-mechanical conditions on polymethyl-methacrylate and polystyrene are investigated. Materials were processed at different temperatures and rates in a single screw extruder and in a capillary rheometer. Processed and as-received materials were analysed by Gel permeation chromatography, solution viscosity, and melt rheology. Evaluations of molecular weight and rheological behavior changes after processing, as compared with as-received materials, evidenced the extent of degradation in the different conditions. Experimental analysis was accompanied by finite elements simulation of the polymer flow and heat transmission within the extruder. This allowed an estimation of the expected shear stresses and temperatures distributions, thus indicating potentially critical situations. It was found that the materials processed at the highest rates in extruder presented lowest molecular weight reductions. This was attributed to the shorter residence time in the extruder and to the possibility of wall slip phenomena, which likely reduce the actual shear stress and viscous dissipation in the fast processing conditions.

Appl Biochem Biotech, 1991

To overcome the uncertainty of the colorimetric or fluorimetric method so far employed for the ev... more To overcome the uncertainty of the colorimetric or fluorimetric method so far employed for the evaluation of monomethoxy(polyethylene glycol) (MPEG) covalently bound to protein, a direct method based on amino acid analysis is proposed. The method exploits the use of MPEG, which was bounded with the unnatural amino acid norleucine (MPEG-Nle). MPEG-Nle was activated at its carboxylic group to succinimidyl ester for the binding to the amino groups of protein.

Journal of Bioactive and Compatible Polymers

Acta Horticulturae, 2012

Keywords: sustainable agriculture, raw materials from renewable origin, waste products of the lea... more Keywords: sustainable agriculture, raw materials from renewable origin, waste products of the leather industry Abstract Low density polyethylene (LDPE) films are widespread used in agriculture for soil mulching. The use of LDPE mulching films causes the serious drawback of huge quantities of waste to be disposed of. Over the last years the growing environmental awareness has been prompting the research to develop a new generation of mulching products starting with raw materials from renewable origin. These materials have to retain their physical and mechanical properties while in use and have to be compostable or biodegradable at the end of their life, degrading via micro-organisms into carbon dioxide or methane, water and biomass. The research is focused on the development of novel biodegradable polymeric materials based on hydrolyzed proteins, derived from waste products of the leather industry. Biodegradable soil mulching coatings were realized with these biodegradable polymeric materials by means of spray techniques; the coatings were tested in a Ligustrum ovalifolium cultivation carried out inside a greenhouse. This paper describes the functionalities of the new bio-based mulching coatings, which were developed and tested in real scale greenhouse cultivation tests. During the trial, the biodegradable soil mulching materials showed suitable properties for an efficient and profitable use in agriculture. The innovative biodegradable spray coatings lasted up to 18 months. The biodegradable materials could be the environmentally friendly alternatives to synthetic petro-chemical polymers and could contribute to a sustainable agriculture.

Journal of the Balkan Tribological Association

in this work the electrical properties of vapour detectors, formed from composites of conductive ... more in this work the electrical properties of vapour detectors, formed from composites of conductive carbon-black and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. the new composites are tailored to produce increased sensitivity towards specific classes of analyte vapours. resonant frequency shift of a Quartz crystal Microbalance (QcM) and dc resistance measurements have been also performed simultaneously on polymercarbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVc) with di(2-ethylhexyl)phthalate (doP), a traditional low-molecular weight plasticiser, is used as representative of the behaviour of a traditional composite vapour detector.

In this work the electrical properties of vapor detectors, formed from composites of conductive c... more In this work the electrical properties of vapor detectors, formed from composites of conductive carbonblack and insulating organic multifunctional polymers having metal ions complexing ability, were investigated. The new composites are tailored to produce increased sensitivity toward specific classes of analyte vapors. Resonant frequency shift of a Quartz Crystal Microbalance (QCM) and dc resistance measurements have been also performed simultaneously on polymer-carbon black composite materials. For comparison purpose, poly(vinyl chloride) (PVC) with di(2-ethylhexyl)phthalate (DOP), a traditional low molecular weight plasticizer, is used as a representative of the behaviour of a traditional composite vapor detector. These new detectors showed an enhanced sensitivity upon exposure to acetic acid and amines vapors; the performances of our systems are 10 3 times higher than those of a traditional composite vapor detector. Moreover the extent of such responses is beyond that expected by mass uptake upon exposure to the same vapors and cannot be attributed solely to differences in polymer/gas partition coefficients. In this respect, several different chemical factors determine the dc electrical response of this system: in our opinion changes in polymer conformation during the adsorption process also play a significant role. The effects of the temperature on the electric resistance of the vapor detectors have also been studied. These materials showed a discontinuity in the temperature dependence of their resistance, and this discontinuity provided a simple method for determining the T g of the composites.