1,721,149 research outputs found
Nanostructured Surfactant-Based Systems for the Removal of Polymers from Wall Paintings: A Small-Angle Neutron Scattering Study
No full textNanostructured soft matter systems represent effective and long-lasting solutions with respect to traditional and often obsolete methodologies for the conservation of works of art. In particular, complex fluids such as micelles and microemulsions are the most performing media for the removal of organic materials from porous supports, like wall paintings or stones. In this Article, we report on the characterization of two systems, EAPC and XYL, which have shown good to optimal performances in the removal of organic polymers from wall paintings. EAPC is a five-components fluid composed of water, sodium dodecylsulfate (SDS), 1-pentanol (PeOH), propylene carbonate (PC), and ethyl acetate (EA), while XYL is a “classical” o/w microemulsion, where p-xylene droplets are stabilized in water by SDS and PeOH. Small-angle neutron scattering (SANS) with contrast variation is used to infer a detailed picture of the structure of these complex fluids, with a particular focus on the partition of the components between the bulk phase and the nanocompartments. We found that, differently from XYL, the EAPC system is neither a microemulsion nor a simple micellar solution, with the cosolvents partitioned between the dispersing phase and the disperse droplets. These different structural features play a key role in defining the cleaning effectiveness and specifically the kinetics of interaction between the nanofluid and the polymeric coating to be removed, which is of paramount importance for the application in the field. Both of these nanofluids are effective in polymer removal, but EAPC is considerably more efficient and versatile. The composition and the structure at the nanoscale determine the capability of removing a broad range of different polymer coatings from porous materials. A representative case study is here described, addressing a particularly challenging conservative issue, which is the removal of a multilayered aged coating that was irreversibly damaging the pictorial layer of the Annunciation Basilica in Nazareth
New Methodologies for the Conservation of Cultural Heritage: Micellar Solutions, Microemulsions, and Hydroxide Nanoparticles
No full textModern civilization’s inherited artworks have a powerful impact on society, from political, sociological, and anthropological points of view, so the conservation of our Cultural Heritage is fundamental for conveying to future generations our culture, traditions, and ways of thinking and behaving. In the conservation of cultural artifacts, scientists intervene in the degradation of often unique handcrafts, resulting from a delicate balance of aging, unpredicted events, environmental conditions, and sometimes incorrect previous restoration treatments, the details of which are often not precisely known.
Nanoscience and nanotechnology are revolutionizing materials science in a pervasive way, in a manner similar to polymer chemistry’s revolution of materials science over the preceding century. The continuous development of novel nanoparticle-based materials and the study of physicochemical phenomena at the nanoscale are creating new approaches to conservation science, leading to new methodologies that can “revert” the degradation processes of the works of art, in most cases “restoring” them to their original magnificent appearance.
Until recently, serendipity and experiment have been the most frequent design principles of formulations for either cleaning or consolidation of works of art. Accordingly, the past has witnessed a number of actively detrimental treatments, such as the application of acrylic and vinyl resins to wall paintings, which can irreversibly jeopardize the appearance (or even the continued existence) of irreplaceable works of art. Current research activity in conservation science is largely based on the paradigm that compatibility of materials is the most important prerequisite for obtaining excellent and durable results.
The most advanced current methodologies are (i) the use of water-based micelles and microemulsions (neat or combined with gels) for the removal of accidental contaminants and polymers used in past restorations and (ii) the application of calcium hydroxide nanoparticles for the consolidation of works of art. In this Account, we highlight how conservation science can benefit from the conceptual and the methodological background derived from both soft (micro- emulsions and micelles for cleaning) and hard (nanoparticles for consolidation) nanoscience.
A combination of different nanotechnologies allows today’s conservators to provide, in each restoration step, interventions respectful of the physicochemical characteristics of the materials used by artists. The “palette” of methods provided by nanoscience is continuously enriching the field, and the development of novel nanomaterials and the study of nanoscale physicochemical phenomena will further improve the performance of restoration formulations and our comprehension of degradation mechanism
Nanofluids and chemical highly retentive hydrogels for controlled and selective removal of overpaintings and undesired graffiti from street art
Full text linkOne of the main problems connected to the conservation of street art is the selective removal of overlying undesired
graffiti, i.e., drawings and tags. Unfortunately, selective and controlled removal of graffiti and overpaintings from street
art is almost unachievable using traditional methodologies. Recently, the use of nanofluids confined in highly retentive
pHEMA/PVP semi-interpenetrated polymer networks was proposed. Here, we report on the selective removal of acrylic
overpaintings from a layer of acrylic paint on mortar mockups in laboratory tests. The results of the cleaning tests were
characterized by visual and photographic observation, optical microscopy, and FT-IR microreflectance investigation. It was
shown that this methodology represents a major advancement with respect to the use of nonconfined neat solvent
Smart cleaning of cultural heritage: a new challenge for soft nanoscience
No full textThe search for innovative, smart and performing cleaning agents is one of the main issues of modern
conservation science. Nanosciences do not only provide solutions to this scientific field in terms of new
materials but also change radically the approach to problems and challenges. In this feature article we
review the most innovative nanostructured systems developed in the last decade for the cleaning of
artworks together with some noteworthy case studies. Micelles, microemulsions, thickened complex
fluids, and responsive gels that constitute the new ‘‘cleaning palette’’ for modern conservators are here
presented and critically analyzed. The development of these smart nanostructured systems requires the
comprehension of their behavior and interactions with other materials down to the nanoscale. In the
last section of this manuscript we report on the most recent results from a study about the mechanism of
polymer removal from porous artifacts using nanofluids, such as micelles or microemulsions. The rules
of classical detergency do not fully address the polymer removal mechanism and a schematic model of
the process is proposed
Chapitre : On the Nature of the Pigments of the General History of the Things of New Spain: The Florentine Codex
No full textBaglioni, Piero Giorgi, Rodorico Arroyo, Marcia Carolina Chelazzi, David Ridi, Francesca Magaloni Kerpel, Diana Baglioni, Piero ; Giorgi, Rodorico ; Arroyo, Marcia Carolina ; Chelazzi, David ; Ridi, Francesca ; Magaloni Kerpel, Diana, "On the Nature of the Pigments of the General History of the Things of New Spain: The Florentine Codex», en Colors between Two Worlds. The Florentine Codex of Bernardino de Sahagún", dans Wolf, Gerhard (éd.) ; Connors, Joseph (éd.) ; Waldman, Louis A. (éd..
Calcium hydroxide nanoparticles from solvothermal reaction for the deacidification of degraded waterlogged wood
Full text linkHypothesis
A combination of acid and iron ions inside the wood has been corroding the cellulose matrix of the Swedish warship Vasa, imposing its deacidification. Past deacidification treatments displayed poor penetration inside the wood matrix with limited efficacy. A vacuum assisted treatment of wood using newly developed calcium hydroxide nanoparticle dispersions represents a possible candidate for the treatment of acidic waterlogged wood objects such as sculptures and decorative artifacts.
Experiments
A solvothermal process was used for the synthesis of calcium hydroxide nanoparticle dispersions. Before the application on waterlogged wood, the physico-chemical characterization of these systems was carried out using several techniques. The efficacy of the deacidification treatment of wood samples from the Vasa was assessed by determination of pH and Differential Thermal Gravimetric (DTG) measurements.
Findings
The proposed solvothermal reactions can be used to produce stable and highly concentrated calcium hydroxide nanoparticle dispersions in alcohols, needing no further purification before the application. This process has also the advantage to be upscalable to industrial level. Both pH and DTG measurements showed that the newly developed dispersions can homogenously penetrate inside the wood up to 20 cm, neutralizing acidity and creating an alkaline buffer inside the wooden matrix, to hinder the degradation of residual cellulose
Nonaqueous Microemulsion in the Bmim Tf2N/Brij 30/ n-Nonane System: Structural Investigation and Application as Gold Nanoparticle Microreactor
Full text linkMicroemulsions based on ionic liquids (ILs) are being increasingly studied in many different areas of physical chemistry because of the attractive properties of ILs. In particular, waterless microemulsions where the IL represents the polar phase can be of interest for those applications that demand the nanosegregation of polar substances, but in which the absence of water is a strict requirement. In this work, we prepared a reverse, nonaqueous microemulsion based on the low-viscosity room-temperature IL, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, the surfactant Brij 30, and n-nonane. The systems were characterized by dynamic light scattering and small-angle X-ray scattering; the IL/oil microemulsion was further employed as a templating system for the synthesis of gold nanoparticles from hydrogen tetrachloroaurate(III), HAuCl4, by UV-photoreduction technique.Fil: Mamusa, Marianna. Università degli Studi di Firenze; ItaliaFil: Arroyo, Marcia Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina. Università degli Studi di Firenze; ItaliaFil: Fratini, Emiliano. Università degli Studi di Firenze; ItaliaFil: Giorgi, Rodorico. Università degli Studi di Firenze; ItaliaFil: Baglioni, Piero. Università degli Studi di Firenze; Itali
Morpho-chemical characterization and surface properties of carcinogenic zeolite fibers
Full text linkZeolites belonging to erionite family were recently discovered to be very dangerous for the human health since demonstrated to be carcinogenic. Conversely, offretite family zeolites were suspected carcinogenic. Mineralogical, morphological, chemical, and surface characterizations were performed on two erionites (GF1, MD8) and one offretite (BV12) fibrous samples and, for comparison, one scolecite (SC1) sample. The specific surface area analysis indicated a larger availability of surface sites for the adsorption onto GF1, while SC1 shows the lowest one and the presence of large pores in the poorly fibrous zeolite aggregates. Selected spin probes revealed a high adsorption capacity of GF1 compared to the other zeolites, but the polar/charged interacting sites were well distributed, intercalated by less polar sites (Si-O-Si). MD8 surface is less homogeneous and the polar/charged sites are more interacting and closer to each other compared to GF1. The interacting ability of BV12 surface is much lower than that found for GF1 and MD8 and the probes are trapped in small pores into the fibrous aggregates. In comparison with the other zeolites, the non-carcinogenic SC1 shows a poor interacting ability and a lower surface polarity. These results helped to clarify the chemical properties and the surface interacting ability of these zeolite fibers which may be related to their carcinogenicity
Polymer Film Dewetting by Water/Surfactant/Good-Solvent Mixtures: A Mechanistic Insight and Its Implications for the Conservation of Cultural Heritage
Full text linkAqueous nanostructured fluids (NSFs) have been proposed to remove polymer coatings from the surface of works of art; this process usually involves film dewetting. The NSF cleaning mechanism was studied using several techniques that were employed to obtain mechanistic insight on the interaction of a methacrylic/acrylic copolymer (Paraloid B72) film laid on glass surfaces and several NSFs, based on two solvents and two surfactants. The experimental results provide a detailed picture of the dewetting process. The gyration radius and the reduction of the Tg of Paraloid B72 fully swollen in the two solvents is larger for propylene carbonate than for methyl ethyl ketone, suggesting higher mobility of polymer chains for the former, while a nonionic alcohol ethoxylate surfactant was more effective than sodium dodecylsulfate in favoring the dewetting process. FTIR 2D imaging showed that the dewetting patterns observed on model samples are also present on polymer-coated mortar tiles when exposed to NSF
Laser‐Induced Graphene from Commercial Inks and Dyes
Full text linkLaser-induced graphene (LIG) has been so far obtained from polymer precursors and proposed for numerous applications, including various types of sensors and energy storage solutions. This study examines a radically different class of new precursors for LIG, distinct from polymers: inks and dyes. The identification of specific organic dyes present in commercial markers demonstrates that the aromatic structure, in conjunction with high thermal stability (residual weight > 20% at 800°C), are key factors for laser-induced pyrolysis. Eosin Y is identified as an excellent LIG precursor, comparable with well-known polyimide. The unique properties of dyes allow for dispersion in various media, such as acrylic binder. A dye concentration of 0.75 mol L−1 in acrylic binder results in a conductivity of 34 ± 20 S cm−1 for LIG. The composition and microstructure of LIG from dyes are thoroughly characterized, revealing peculiar features. A versatile “Paint & Scribe” methodology is introduced, enabling to integrate LIG tracks onto any wettable surface, and in particular onto printed and flexible electronics. A process for obtaining freestanding and transferrable LIG is demonstrated by dissolving acrylic paint in acetone and floating LIG in water. This advancement offers novel avenues for diverse applications that necessitate a transfer process of LIG
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