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232 results on '"Malafronte, Anna"'

13. Molecular View of Properties of Random Copolymers of Isotactic Polypropylene

Author

Auriemma, Finizia, De Rosa, Claudio, Di Girolamo, Rocco, Malafronte, Anna, Scoti, Miriam, Cioce, Claudia, Abe, Akihiro, Series editor, Albertsson, Ann-Christine, Series editor, Coates, Geoffrey W, Series editor, Genzer, Jan, Series editor, Kobayashi, Shiro, Series editor, Lee, Kwang-Sup, Series editor, Leibler, Ludwik, Series editor, Long, Timothy E., Series editor, Möller, Martin, Series editor, Okay, Oguz, Series editor, Percec, Virgil, Series editor, Tang, Ben Zhong, Series editor, Terentjev, Eugene M., Series editor, Theato, Patrick, Series editor, Vicent, Maria J., Series editor, Voit, Brigitte, Series editor, Wiesner, Ulrich, Series editor, Zhang, Xi, Series editor, Auriemma, Finizia, editor, Alfonso, Giovanni Carlo, editor, and de Rosa, Claudio, editor

Published
2017
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17. Crystal Structure of Poly(7-heptalactone)

Author

Malafronte, Anna, primary, Scoti, Miriam, additional, Caputo, Maria Rosaria, additional, Li, Bo, additional, O’ Reilly, Rachel K., additional, Dove, Andrew P., additional, Müller, Alejandro J., additional, and De Rosa, Claudio, additional

Published
2023
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29. Model of Crystallization Behavior of Isotactic Polypropylene: The Role of Defects.

Author

Scoti, Miriam, De Stefano, Fabio, Di Girolamo, Rocco, Malafronte, Anna, Talarico, Giovanni, and De Rosa, Claudio

Subjects
POLYPROPYLENE, DISTRIBUTION (Probability theory), CRYSTAL defects, PROPENE, COPOLYMERS
Abstract

The crystallization behavior of propene–ethylene (iPPC2), propene–butene (iPPC4), propene–pentene (iPPC5), and propene–hexene (iPPC6) isotactic copolymers, prepared with single center metallocene catalysis, is described. Thanks to the perfectly random distribution of comonomers along the macromolecules, these copolymers can be considered as model for the crystallization behavior of isotactic polypropylene (iPP) that is mainly defined by the average length of the regular propene sequences. A model of the crystallization behavior of iPP is described based on the definition of a double effect of defects (stereodefects and comonomers), the interruption effect of defects excluded from the crystals that shortens the length of the crystallizable propene sequences inducing crystallization of the γ form, and the effect of inclusion of defects in the crystals of α form, γ form or δ form that induces the crystallization of the form whose lattice is less disturbed by the defect. [ABSTRACT FROM AUTHOR]

Published
2023
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38. Exploiting Self-Assembly of Block Copolymers to Fabricate Nanocomposite Thin Films with Controlled Morphology at Nanoscale.

Author

Malafronte, Anna, Emendato, Alessandro, Auriemma, Finizia, Di Girolamo, Rocco, Laus, Michele, Lupi, Federico Ferrarese, and De Rosa, Claudio

Subjects
COPOLYMERS, NANOCOMPOSITE materials, THIN films, MOLECULAR self-assembly, FABRICATION (Manufacturing)
Abstract

As the advantageous properties of nanoparticles (NPs) often emerge only when appropriate coupling and exchange phenomena between the NPs can take place, the control of the inter-particle distance, regular ordering, and location of the nanoparticles onto solid supports is a critical issue. A robust method to control the spatial organization of NPs onto solid supports, based on the use of self-assembling di-block copolymers (BCPs) as structure-guiding material, is reported. Two different polystyrene-b-poly(methyl methacrylate) (PSb- PMMA) BCPs, characterized by a different PS volume fraction, were used as matrices for the fabrication of nanocomposite thin films with cylindrical and lamellar morphologies controlled at the nanoscale. Selective inclusion of surface functionalized gold (Au) and zinc oxide (ZnO) NPs of appropriate size in the PS nanodomains was achieved from dispersions of the BCPs and NPs in a common solvent. The orientation of the BCPs cylinder and lamellar nanodomains in spin-coated thin films was controlled by solvent and thermal annealing protocols, coupled with techniques of surface neutralization. [ABSTRACT FROM AUTHOR]

Published
2021
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39. Crystallization Behavior of Copolymers of Isotactic Poly(1-butene) with Ethylene from Ziegler–Natta Catalyst: Evidence of the Blocky Molecular Structure

Author

De Rosa, Claudio, primary, Ruiz de Ballesteros, Odda, additional, Auriemma, Finizia, additional, Talarico, Giovanni, additional, Scoti, Miriam, additional, Di Girolamo, Rocco, additional, Malafronte, Anna, additional, Piemontesi, Fabrizio, additional, Liguori, Dario, additional, Camurati, Isabella, additional, and Morini, Giampiero, additional

Published
2019
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45. Deformation across length scales in polyolefines: effect of the chain microstructure on the polymorphism, phase transitions and morphological changes

Author

AURIEMMA, FINIZIA, DE ROSA, CLAUDIO, DI GIROLAMO, ROCCO, MALAFRONTE, ANNA, SCOTI, MIRIAM, AA.VV., Auriemma, Finizia, DE ROSA, Claudio, DI GIROLAMO, Rocco, Malafronte, Anna, and Scoti, Miriam

Abstract

The transformations related to phase changes of the crystals, and at lamellar length scales by effect of tensile deformation are studied in the case of some isotactic polypropylene samples having high molecular mass, polydispersity index ≈2, and stereodefects at different concentrations and with a uniform distribution, The stress induced transformations are followed in real time during stretching through wide and small angle X-ray scattering measurements. The data analysis evidences that during the transformations of the spherulitic into the fibrillar morphology, stress-induced phase transitions occurring during plastic deformation are regulated by the same factors that govern the textural and morphological changes, that is the ability of the entangled amorphous chains to transmit the stress and the intrinsic stability of the lamellar crystals. Since the relative stability of the different polymorphic forms involved in the structural transformations and the intrinsic flexibility of the chains depend on the stereoregularity, precise correlations between the stereoregularity of the chains, and the deformation behavior are outlined, paving the way for understanding the material properties at molecular level

Published
2016

46. Fabrication of ordered arrays of Pd nanoclusters and PdO nanoparticles by using self-assembled block copolymers as templates

Author

MALAFRONTE, ANNA, DE ROSA, CLAUDIO, AURIEMMA, FINIZIA, DI GIROLAMO, ROCCO, Massimo Lazzari, AA.VV., Malafronte, Anna, DE ROSA, Claudio, Auriemma, Finizia, DI GIROLAMO, Rocco, and Massimo, Lazzari

Subjects
block copolymers, nanoparticles, self-assembly
Abstract

Palladium (Pd) and palladium oxide (PdO) nanoparticles (NPs) synthesis has gained considerable interest in the last few decades due to their numerous potential utilizations [1-3]. Systems based on Pd show high activity and selectivity in numerous catalytic processes [2, 3], like the catalytic formation of C-C bonds, one of the most useful transformations in organic synthesis [2]. Because sustainable development involves the utilization of reusable catalysts, the search for new catalytic systems to replace existing homogeneous ones is one important issue [4]. In this context, the immobilization of NPs on a solid support is an interesting alternative since the catalyst can be recycled by simple filtration and the atom/ion leaching from the particles can be minimized. Also, many electronic devices, such as resistors, use compositions containing palladium. All these applications may be more suitable with NPs in a patterned form and, since the majority of unique NPs properties are highly microstructure-dependent, to form Pd and PdO arrays on solid supports with a precise control of nanoparticles dimensions and spacing is a an important issue. Here, we report a simple method to fabricate arrays of palladium (Pd) nanoclusters and palladium oxide (PdO) nanoparticles with tunable dimensions and lateral spacing by using polystyrene-block-poly(ethylene oxide) copolymers (PS-b-PEO) as both stabilizers for Pd NPs and templates controlling the distribution of them. The cylindrical self-assembled nanostructure formed from PS-b-PEO has been used as host for selectively sequestering a nanoparticles precursor (palladium(II) acetate) in cylindrical domains of PEO. Then, Pd NPs have been obtained by reduction of the precursor in presence of the BCPs. In this way, nanocomposite thin films of well-defined morphology based on PS-b-PEO matrices and Pd NPs have been obtained. Furthermore, PdO NPs of improved stability against aggregation have been obtained on a solid and conductive support (silicon wafer) by treating the Pd containing films in air at elevated temperatures. We were able to modulate the dimensions of Pd nanoclusters and PdO NPs and their inter-distance by using as template two different PS-b-PEO copolymers having different molecular weights of both PS and PEO blocks.

Published
2015

47. Block Copolymers‐Based Nanoporous Thin Films with Tailored Morphology for Biomolecules Adsorption.

Author

Malafronte, Anna, Auriemma, Finizia, Santillo, Chiara, Di Girolamo, Rocco, Barker, Robert, Gerelli, Yuri, and De Rosa, Claudio

Subjects
BLOCK copolymers, THIN films, QUARTZ crystal microbalances, ADSORPTION (Chemistry), MYOGLOBIN, ETHYLENE oxide, NANOPOROUS materials, BIOMOLECULES
Abstract

The adsorption of myoglobin (Mb) onto nanoporous thin films build up using block‐copolymers (BCPs) is analyzed. The nanoporous thin films, fabricated by exploiting self‐assembly of lamellar BCPs and the concept of sacrificial block, are characterized by a well‐defined morphology containing nanochannels of width ≈20 nm delimited by polystyrene (PS) domains, decorated with pendant poly(ethylene oxide) (PEO) chains. The adsorption of Mb onto the nanoporous material is studied by means of UV–visible spectroscopy, quartz crystal microbalance, and neutron reflectometry measurements. In order to determine the role of nanopores, experiments are also conducted by using supports made of nonporous PS thin films and nude glass slides. The results indicate that the BCP‐nanoporous material exhibits a remarkably higher adsorption capability than PS and glass. As PEO exhibits a low degree of protein adsorption, this result may be essentially attributed to the presence of the nanopores. The large surface area, the opened pore structure, and the trapping effect of the pores are the main factors determining the increased Mb adsorption capability of the BCP‐based support. Yet, the presence of PEO chains decorating the PS walls at porous surface does not prevent Mb biomolecules to establish good interactions with the support. [ABSTRACT FROM AUTHOR]

Published
2020
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