CNR Institute for Macromolecular Studies

Genova, Italy

CNR Institute for Macromolecular Studies

Genova, Italy
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Ruzicka B.,University of Rome La Sapienza | Zaccarelli E.,University of Rome La Sapienza | Zulian L.,CNR Institute for Macromolecular Studies | Angelini R.,University of Rome La Sapienza | And 4 more authors.
Nature Materials | Year: 2011

The relevance of anisotropic interactions in colloidal systems has recently emerged in the context of the rational design of new soft materials. Patchy colloids of different shapes, patterns and functionalities are considered the new building blocks of a bottom-up approach toward the realization of self-assembled bulk materials with predefined properties. The ability to tune the interaction anisotropy will make it possible to recreate molecular structures at the nano- and micro-scales (a case with tremendous technological applications), as well as to generate new unconventional phases, both ordered and disordered. Recent theoretical studies suggest that the phase diagram of patchy colloids can be significantly altered by limiting the particle coordination number (that is, valence). New concepts such as empty liquids-liquid states with vanishing density-and equilibrium gels-arrested networks of bonded particles, which do not require an underlying phase separation to form-have been formulated. Yet no experimental evidence of these predictions has been provided. Here we report the first observation of empty liquids and equilibrium gels in a complex colloidal clay, and support the experimental findings with numerical simulations. © 2011 Macmillan Publishers Limited. All rights reserved.

La Penna G.,CNR Institute of Chemistry of organometallic Compounds | Perico A.,CNR Institute for Macromolecular Studies
Biophysical Journal | Year: 2010

The protein-DNA complex, involved in the lac operon of enteric bacteria, is paradigmatic in understanding the extent of DNA bending and plasticity due to interactions with protein assemblies acting as DNA regulators. For the lac operan, two classes of structures have been proposed: 1 ), with the protein tetramer lying away from the DNA loop (wrapped-away model); and 2), with the protein tetramer lying inside the DNA loop (wrapped-around model). A recently developed electrostatic analytical model shows that the size and net charge of the Lac protein tetramer allow the bending of DNA, which is consistent with another wrapped-around model from the literature. Coarse-grained models, designed based on this observation, are extensively investigated and show three kinds of wrapped-around arrangements of DNA and a lower propensity for wrapped-away configurations. Molecular dynamics simulations of an all-atom model, built on the basis of the most tightly collapsed coarse-grained model, show that most of the DNA double-helical architecture is maintained in the region between O3 and O1 DNA operators, that the DNA distortion is concentrated in the chain beyond the O1 operator, and that the protein tetramer can adapt the N-terminal domains to the DNA tension. © 2010 by the Biophysical Society.

Periolatto M.,Polytechnic University of Turin | Ferrero F.,Polytechnic University of Turin | Vineis C.,CNR Institute for Macromolecular Studies
Carbohydrate Polymers | Year: 2012

The purpose of this work was to develop a textile finish based on radical UV-curing of chitosan on cotton and silk to confer antimicrobial properties. Fabrics were impregnated with a solution of 2% w chitosan in aqueous acetic acid (2% v/v) added of 2-hydroxy-2-methylphenylpropane-1-one (2% w/w with respect to chitosan) as photoinitiator and cured at room temperature by exposure to UV lamp for 60 s on both the sides. The antimicrobial activity of finished fabrics was tested according to ASTM standard test performed with Escherichia coli. Obtained results showed a strong antimicrobial activity conferred by the treatment, homogeneous on fabric surface, without affecting the hand properties of fabrics due to the low chitosan weight on (about 2%). The treatment durability to domestic laundering was tested after 5 cycles using either anionic or nonionic detergents. The antimicrobial activity resulted completely maintained after washing with a nonionic surfactant, while with anionic detergents the treatment durability was better for samples prepared with a deeper penetration of chitosan inside the fibers. The fabrics were characterized by dyeing tests, SEM and FTIR-ATR analyzes. © 2011 Elsevier Ltd All rights reserved.

Boggioni L.,CNR Institute for Macromolecular Studies | Tritto I.,CNR Institute for Macromolecular Studies
MRS Bulletin | Year: 2013

Highly active metallocenes and other single site catalysts as well as Grubbs and Schrock metathesis catalytic systems have opened up the possibility to polymerize cycloolefins or to copolymerize them with ethene or propene. The polymers obtained show exciting structures and properties. Cycloolefins such as cyclopentene, cyclooctene, norbornene, and their substituted derivatives are incorporated into the polymer chain either by double bonds or by ring-opening metathesis polymerization. Materials with elastomeric properties or tactic polymers with high glass transition temperatures and melting points are obtained with a wide range of microstructures. For example, cycloolefin copolymers and other homo-and copolymers of norbornene are of great academic and industrial interest because of their properties and applications in optoelectronics, lenses, and coatings. © 2013 Materials Research Society.

Botta C.,CNR Institute for Macromolecular Studies | Betti P.,CNR Institute for Macromolecular Studies | Pasini M.,CNR Institute for Macromolecular Studies
Journal of Materials Chemistry A | Year: 2013

Organic host-guest based materials, obtained with a low cost self-assembly technology, show an efficient energy downshift from the UV-visible to the deep red, thanks to cascade resonant energy transfer processes among three different dyes inserted in the nanochannels of the host, opening for the design of fully organic luminescent solar concentrators. This journal is © 2013 The Royal Society of Chemistry.

Ciferri A.,Duke University | Ciferri A.,CNR Institute for Macromolecular Studies
Chemistry - A European Journal | Year: 2010

Purely ionic interactions in natural and synthetic macromolecules involve the mutual interaction of fixed charges and their interaction with mobile ions. Such charge-dependent interactions lead to well-documented effects, including chain expansion of polyelectrolytes, globularization of polyampholytes, distributions of mobile ions according to charge screening, or ion condensation models. A variety of structural features, functions, and applications of these systems is amplified by the superimposition of charge-independent effects associated with the occurrence of less polar or hydrophobic groups, special salts, surfactants, or complementary protein assemblies. For instance, ionic and hydrophobic attractive interactions stabilize pearls (or rings)-on-a-string conformations, possibly a model for the formation of the chromatin assembly. The attractive interactions due to hydrophobic fatty acid groups attached to polysaccharides promote the formation of vesicles that entrap and slowly release water-soluble drugs. Intra- and intermolecular associations based on ion-pairing mixed interactions also control the formation of host-guest compounds, protein conformation, and the assembly of layered polyelectrolytes. Metallo-supramolecular polymers and networks are formed due to the coordination of multivalent cations with bi- and trifunctional organic ligands. The association of lithium salts to polymers in the absence of water allows the formation of highly efficient energy sources. It also allows the identification of the ionic species that control charge-independent contributions to Hofmeister effects. This critical review presents a synthetic classification of systems displaying ionic mixed interactions, and a discussion of underlying molecular mechanisms. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Consonni R.,CNR Institute for Macromolecular Studies | Cagliani L.R.,CNR Institute for Macromolecular Studies | Cogliati C.,CNR Institute for Macromolecular Studies
Journal of Agricultural and Food Chemistry | Year: 2012

The saccharide profiles of 5 different botanical species in 86 Italian honey samples were investigated by 1H and 1H- 13C NMR spectroscopy. Nineteen saccharides were identified in the aqueous extracts, namely, fructose, glucose, gentiobiose, isomaltose, kojibiose, maltose, maltulose, melibiose, nigerose, palatinose, sucrose, turanose, erlose, isomaltotriose, kestose, maltotriose, melezitose, raffinose, and maltotetraose. PCA performed on NMR spectral regions, in particular between 4.400 and 5.700 ppm and the fructose signal at 4.050 ppm, revealed a partial sample grouping. The score contribution plots derived from PCA performed using the mean values for the buckets of the anomeric region for each floral source allowed the identification of saccharides characterizing different honeys. OPLS-DA models were further evaluated to confirm the previous findings. OPLS-DA models were also built to highlight differences between polyfloral and high mountain polyfloral honeys and between high mountain polyfloral and rhododendron honeys, both collected at high altitude; S-plots highlighted the characteristic saccharides. © 2012 American Chemical Society.

Ravasio A.,CNR Institute for Macromolecular Studies | Boggioni L.,CNR Institute for Macromolecular Studies | Tritto I.,CNR Institute for Macromolecular Studies
Macromolecules | Year: 2011

Complex [Pd(κ2-P,O-{2-(2-MeOC6H 4)2P}C6H4SO3)Me(dmso)] (1) was investigated as a single component catalyst for the copolymerization of ethylene with norbornene affording P(E-co-N) in excellent yields and molar masses significantly higher than those of polyethylene. Copolymer molar masses increased with N concentration. Determination of microstructure and reactivity ratios revealed a strong inherent tendency to form alternating copolymers. The ability of palladium complex 1 to effectively copolymerize ethylene with functionalized norbornene derivatives was also demonstrated. © 2011 American Chemical Society.

Kozma E.,CNR Institute for Macromolecular Studies | Catellani M.,CNR Institute for Macromolecular Studies
Dyes and Pigments | Year: 2013

Perylene-3,4,9,10-tetracarboxylic acid diimides (PDIs) and their derivatives represent one of the most promising class of electron accepting materials, due to their outstanding chemical and physical properties, including high electron mobility and high molar absorption coefficients. Their rigid, fused aromatic core favours pep intermolecular interactions imparting n-type semiconducting properties useful for optoelectronic applications. The PDIs have attracted interest as photovoltaic functional materials for their strong electron-accepting character and significant charge transport properties. This feature article describes the application of PDI based molecules and polymers in organic photovoltaic solar cells. © 2013 Elsevier Ltd.

Canetti M.,CNR Institute for Macromolecular Studies | Bertini F.,CNR Institute for Macromolecular Studies
European Polymer Journal | Year: 2010

Small-angle X-ray scattering, wide-angle X-ray diffraction and differential scanning calorimetry analysis were carried out to evaluate the evolution of the supermolecular structure of poly(ethylene terephthalate) (PET) during isothermal crystallization and annealing process. PET was crystallized from the melt by isothermal treatments at 226 °C. Partially crystallized samples were prepared interrupting the crystallization by quenching, while prolonged treatments were performed to prepare annealed samples. The adopted crystallization procedures allowed to form crystals which developed during primary and secondary crystallization, and the annealing process. On the basis of X-ray data, the lamellar and amorphous phases were unambiguously attributed. The lamellar thickness and the crystallinity progressively enhance with increasing the time of thermal treatment; on the contrary, the long period decreases and this effect is mainly due to the contraction of the amorphous phase. The melting behaviour of the annealed samples indicates that the heating-induced crystal reorganization phenomena are inconsistent. The interdependency between the melting temperature and the crystal thickness allowed to extrapolate the equilibrium melting temperature. © 2009 Elsevier Ltd. All rights reserved.

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