In this work halloysite (Hal) nanotubes were used as nanocontainers for salycilic acid (SA) in a perspective of its use in active packaging for food industry. The system Hal/SA was investigated for ...its ability to stabilize Hal suspensions by turbidimetry, its release kinetics in water by UV spectroscopy and its antibacterial activity against Pseudomonas fluorescens IMA 19/5 by Isothermal Micro Calorimetry (IMC). IMC is a sensitive and non-destructive technique and allows the study of a wide range of relatively slow processes (hours and days) in solutions. The system Hal/SA resulted to stabilize Hal suspension in water and to release SA in a controlled way over 50h. Moreover the SA released by Hal/SA showed an antibacterial activity at lower concentrations than free SA, likely due to the close contact of bacteria and Hal in the reaction vessel.
Display omitted
•Study of salicylic acid (SA) loaded into halloysite (Hal) system in aqueous medium.•Hal/SA system stabilizes aqueous Hal suspensions.•Hal/SA system releases SA in a controlled way over 50h.•The antibacterial activity of Hal/SA system is tested by calorimetry.•Hal/SA system shows antibacterial activity at lower concentrations than free SA.
Aquazol poly (2-ethyl-oxazoline) is a tertiary aliphatic amide, with physical and chemical properties that are exploited in a variety of ways, from pharmaceutical applications to the conservation of ...cultural heritage. In this study, we evaluated the use of Aquazol as a new binder for retouching paint in the restoration of artworks.
Aquazol 500 admixed with various formulations of organic red pigments was used to prepare paint replicas which were artificially aged and investigated by a multi-analytical approach based on analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), and thermogravimetry (TG), complemented by FTIR and LIBS spectroscopy. This is the first study on the ageing phenomena of Aquazol 500 using analytical pyrolysis and thermogravimetric analysis. The influence of the pigments' components on the pyrolysis behavior of Aquazol was also investigated.
The paint replicas did not show significant modifications during artificial ageing. This thus highlights the optimal properties of Aquazol 500 as a binder for retouching, in addition to its already established suitability as a filler or consolidant in the restoration of artifacts. Interestingly, when Aquazol 500 is used in formulations containing organic pigments, Aquazol-pigment interactions are observed, strongly depending on the pigment used.
We studied ten alkyd artists' paints from the Griffin Alkyd, “fast drying oil colours” series (Winsor & Newton) in order to evaluate the effect of pigment–binder interactions on the stability of the ...alkyd resin. The literature on alkyd paints has focused above all on the characterization of the paints and their ageing processes using various techniques, however, to the best of our knowledge, research on pigment-resin interaction is still lacking.
We selected four alkyd colours (red, blue, yellow and green) in two formulations based on inorganic or organic pigments together with titanium white and black formulated with carbonized bones and we applied a combined differential scanning calorimetric (DSC) and thermogravimetric (TG) approach. The pure pigments and the whole paint replicas were analyzed, and the effect of natural ageing on the paints was monitored for eight months. Artificial ageing in an acetic acid atmosphere was also studied.
We found that organic and metallorganic pigments interacted the strongest with the alkyd resin, while the inorganic pigments appear to act more as dispersants. The chemical drying of the paint on the other hand, via auto-oxidation, is almost independent of the pigment and only depends on the alkyd content. The paint is fully dried after eight months. Paint samples from two hyper-realistic artworks, “Salto di qualità”, 2003, and “Senza nome”, 2007, by the Italian painter Patrizia Zara were investigated by DSC in order to evaluate the effects of several years of natural ageing on alkyd fast-drying oil colours. At the end of chemical drying, the alkyd colours seemed very stable. Artificial acid ageing visibly damaged the paint replicas, but appeared to act mostly on the pigment rather than on the resin network.
Two commercial organosilicons, Hydrophase.sup.®, a monomeric dispersion, and Disboxan 450.sup.®, an oligomeric dispersion, were studied in pure form and applied on acrylic paint replicas. Their ...physico-chemical characteristics, coating properties, and interaction with acrylic paint replicas were evaluated by TG, DSC, FTIR, and contact angle measurements. Hydrophase.sup.® showed a higher interaction when used on the top of acrylic paint replicas than Disboxan 450.sup.®. No appreciable modification was detected after two years of natural ageing.
Two commercial organosilicons, Hydrophase
®
, a monomeric dispersion, and Disboxan 450
®
, an oligomeric dispersion, were studied in pure form and applied on acrylic paint replicas. Their ...physico-chemical characteristics, coating properties, and interaction with acrylic paint replicas were evaluated by TG, DSC, FTIR, and contact angle measurements. Hydrophase
®
showed a higher interaction when used on the top of acrylic paint replicas than Disboxan 450
®
. No appreciable modification was detected after two years of natural ageing.
Urushi is the oldest and most precious lacquer used since antiquity in East Asia. For artistic purposes, in order to obtain suitable rheological properties, the lacquer is usually mixed with a ...vegetable oil. In this work we investigated the curing process of urushi/tung oil mixtures in order to highlight the chemical interactions at the molecular level between the two materials.
A multi-analytical approach was adopted, based on thermogravimetry (TG), differential scanning calorimetry (DSC), gas chromatography-mass spectrometry (GC-MS), evolved gas analysis-mass spectrometry (EGA-MS), analytical pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC-MS) and high performance liquid chromatography-mass spectrometry (HPLC-MS). Fresh and aged mixtures were analysed and the results were compared with those obtained from the analysis of the individual materials.
The data highlighted that different polymerisation and oxidation mechanisms take place in oil/urushi mixtures compared to the pure materials. Py-GC-MS and GC-MS showed that the profile of aliphatic mono- and di-carboxylic acids was drastically different for the aged film of pure tung oil compared to the mixtures. The ratio between the relative content of azelaic and palmitic acids was much lower in the mixtures than in the pure oil, highlighting a lower level of oxidation. On the other hand, the relative content of short chain carboxylic acids, which are produced by pyrolysis of the cross-linked oil network, increased as the concentration of urushi in the mixtures increased, thus indicating an increasing level of reticulation. HPLC-MS showed a relatively higher amount of triglycerides with hydroxylated fatty acids – the intermediate oxidation product of polyunsaturated fatty acids - in the mixtures with respect to pure tung oil.
A family of easily recoverable magnetic and thermally responsive composite materials, with nanoscale dimensions, were synthesized by a rapid and simple solvothermal approach. The synthesis was ...thermally activated, accelerated, and controlled using a coaxial antenna to directly apply the microwave energy inside the solvothermal reactor. The composite materials were made up by a confined phosphorylated nanoreactor, namely halloysite nanotubes grafted on the inner lumen with phosphoric acid (HNTs-(H+-PO4)), that promoted the urea hydrolysis thus favoring the formation of a local alkaline environment to catalyze the homogeneous in situ precipitation of superparamagnetic iron oxide nanoparticles (IONs) selectively on their inner or outer surface. Two new MW-assisted solvothermal methodologies were used: 1) in the first the solvent is directly loaded into the MW-assisted reactor together with HNTs-(H+-PO4) mechanically preloaded with iron chloride and urea in the lumen 2) in the second the synthesis is preceded by a further pre-functionalization step of the iron salt with clove essential oil (EO) as a green functionalization agent. Structural, morphological, textural, and magnetic properties were assessed by TEM, N2 physisorption, TG-FTIR, ICP, XRD, magnetic and magnetic hyperthermia measurements. The MW-assisted solvothermal deposition of IONs was fully controlled using the phosphorylated nanoreactor, in short synthesis times, by a simple methodology following the principles of sustainable chemistry. IONs were selectively deposited on the outer surface or in the inner lumen of HNTs yielding easily recoverable superparamagnetic and thermally responsive nanocarriers suitable for applications like targeted hyperthermia therapy.
Display omitted
•in-situ urea hydrolysis and IONs deposition were promoted by HNTs-(H+-PO4) nanoreactor.•Selective deposition of magnetic IONs in the inner or outer surfaces of HNTs-(H+-PO4).•Good heating response of magnetic nanocomposites under a remotely applied magnetic field.•Green, fast and simple MW-assisted solvothermal deposition methodologies.•Magnetic and thermally responsive nanocarriers suitable for applications like targeted hyperthermia.
The degradation of the proteinaceous binders, ovalbumin (OVA) and casein, and their interactions with azurite (Cu(3)(CO(3))(2)(OH)(2)), calcium carbonate (CaCO(3)), hematite (Fe(2)O(3)) and red lead ...(Pb(3)O(4)) pigments were studied. A multi-analytical approach based on Thermogravimetric Analysis (TG), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and Size Exclusion Chromatography (SEC) was used. The research was carried out on a set of paint reconstructions, which were analysed before and after artificial light ageing. We highlighted that in most cases the inorganic pigments interact with both proteins by decreasing their thermal stability and their intermolecular β-sheet content, and that ageing induces aggregation. We hypothesized that pigments intercalate between protein molecules, producing a partial disruption to the protein-protein intermolecular interaction. In the case of casein, these phenomena continued during ageing. In fact, we observed a complete disappearance of intermolecular β-sheets and an increase in intramolecular β-sheets and random coil during ageing. This result is in agreement with the structural properties of casein, whose aggregation is known to be induced by hydrophobic interactions. On the other hand, in aged OVA paint replicas, we observed the formation of new intermolecular β-sheets and an increase in thermostability. In addition FTIR showed oxidation of the side chains of the aged OVA/hematite sample and aged casein pigment samples, and SEC highlighted hydrolysis phenomena in aged carbonate, azurite and red lead/OVA complexes and in aged casein/calcium carbonate and casein/azurite samples.
PDF
