Analytical Characterization of the Intercalation of Neutral Molecules into Saponite.

Organo-modified layered materials characterization poses challenges due to their complexity and how other aspects such as contamination, preparation methods and degree of intercalation influence the properties of these materials. Consequently, a deep understanding of their interlayer organization is of utmost importance to optimize their applications. These materials can in fact improve the stability of photoactive molecules through intercalation, avoiding the quenching of their emission at the solid state, to facilitate their use in sensors or other devices. Two synthetic methods for the preparation of saponites with a cationic surfactant (CTABr) and a neutral chromophore (Fluorene) were tested and the obtained products were initially characterized with several complementary techniques (XRPD, SEM, TGA, IR, UV-Vis, Fluorescence and Raman spectroscopy), but a clear understanding of the organization of the guest molecules in the material could not be obtained by these techniques alone. This information was obtained only by thermogravimetry coupled with gas chromatography and mass spectroscopy (TGA-GC-MS) which allowed identifying the species present in the sample and the kind of interaction with the host by distinguishing between intercalated and adsorbed on the surface.

Impulse excitation technique data set collected on different materials for data analysis methods and quality control procedures development.

Mechanical properties such as the Young modulus, shear modulus and Poisson's coefficient are very important to define different materials applications, for basic research and for quality control procedures. Impulse excitation technique (IET) is a non-destructive, easy and fast method for characterization of elastic and acoustic properties of materials. The technique consists in sending a mechanical impulse in a sample and measuring the output sound wave. Commercial instruments are widely spread in metal industry, but they are not diffused in academic research centres. Such instruments can be easily self-built at low cost, allowing a much wider diffusion and exploitation in many fields involving materials characterization, since they guarantee high precision and high data reproducibility. For a proper acoustic characterization, necessary to obtain reliable mechanical data, a calibration of the instrument must be performed, for a proper association of the acoustic response to the features of each specific material. In this data article, a data set of impulses, collected on different materials by a self-built instrument for IET, named IETeasy, is provided for mechanical properties characterization by a self-built IET tool, and multivariate statistical analysis purposes. The aim is double in the short term: on one hand, providing a verified data set useful to develop, test and verify methods of analysis and tailor the IETeasy instrument on the needs of each specific user; on the other hand, giving a benchmark for any one designing, building and testing his IET home-made instrument. In the long term, since the data base is open, any contribution consisting in data collected by similar self-made or commercial instruments can be added to the data base, with the aim of building a large collection of data, useful for automatic recognition of sound outputs by machine learning or other multivariate or monovariate data analysis approaches, and for instrument performance comparison and alignment.

Adsorption Features of Various Inorganic Materials for the Drug Removal from Water and Synthetic Urine Medium: A Multi-Technique Time-Resolved In Situ Investigation.

Pharmaceutical active compounds, including hundreds of different substances, are counted among the emerging contaminants in waterbodies, whose presence raises a growing concern for the ecosystem. Drugs are metabolized and excreted mainly through urine as an unchanged active ingredient or in the form of metabolites. These emerging contaminants are not effectively removed with the technologies currently in use, making them a relevant environmental problem. This study proposes the treatment of urine and water at the source that can allow an easier removal of dissolved drugs and metabolites. The treatment of synthetic urine, with dissolved ibuprofen as a model compound, by adsorption, using various classes of inorganic materials, such as clays, hierarchical zeolites and ordered mesoporous silica (MCM-41), is presented. A multi-technique approach involving X-ray powder diffraction, solid-state NMR, UV-Vis and Raman spectroscopies was employed to investigate the adsorption process in inorganic adsorbents. Moreover, the uptake, the ensuing competition, the efficiency and selectivity as well as the packing of the model compound in ordered mesoporous silica during the incipient wetness impregnation process were all thoroughly monitored by a novel approach, involving combined complementary time-resolved in situ 1H and 13C MAS NMR spectroscopy as well as X-ray powder diffraction.

IETeasy: An open source and low-cost instrument for impulse excitation technique, applied to materials classification by acoustical and mechanical properties assessment.

In the past twenty years, impulse excitation technique (IET) has become a widely diffused non-destructive technique in metal industry field. This success resides in its capability to determine with high precision and accuracy some elastic properties of materials, such as Young's modulus, shear modulus and Poisson's ratio. The technique, which is very fast and non-destructive, consists in exciting a sample by a mechanical input and registering the acoustic output that, once analyzed by Fast Fourier-Transformation (FFT), provides the resonant frequencies of the sample, with a fast data analysis procedure. The approach is thus very easy to be applied to most materials and cost and time effective. Despite these many advantages, IET is still an under exploited technique in academic research centres, that mainly rely on traditional destructive methods for the evaluation of such properties, for instance by the measurement of strain-stress curves. Commercial IET instruments, similarly to traditional ones, have costs spanning from many hundreds to thousands of dollars, limiting their diffusion in academic world but also in small companies with limited R&D or quality control expenses. Non-professional instruments can also give very precise results and can be successfully used in basic research and in quality control even if not certified as commercial ones. Moreover they can be easily customized according to specific user needs and sample features. Since no examples of low cost IET designs can still be found in the scientific literature, we fill the gap in this paper, giving instructions for a self-assembled instrument for IET analysis, with a cost in the range of 70-85 USD. Moreover, the collected calibration data are analyzed to prove that the instrument can be used for other purposes than the common elastic properties determination, but also for a fast and cheap material characterization exploiting a multivariate analysis approach. Calibration results show that IETeasy can be used in both academic and industrial field for quality control purposes as a low-cost, fast and efficient alternative to tensometers. Principal component analysis, applied in this paper for the first time to IET data analysis, was able to distinguish and classify steel from Al or Cu alloys from polymers, but also different steel grades, demonstrating its potential in massive and eventually automatic IET data analysis. Calculated mechanical properties fitted with good approximation the ranges expected for each sample.

Selective bacterial colonization processes on polyethylene waste samples in an abandoned landfill site.

The microbial colonization of plastic wastes has been extensively studied in marine environments, while studies on aged terrestrial wastes are scarce, and mostly limited to the isolation of plastic-degrading microorganisms. Here we have applied a multidisciplinary approach involving culturomics, next-generation sequencing analyses and fine-scale physico-chemical measurements to characterize plastic wastes retrieved in landfill abandoned for more than 35 years, and to assess the composition of bacterial communities thriving as biofilms on the films' surfaces. All samples were characterized by different colors but were all of polyethylene; IR and DSC analyses identified different level of degradation, while FT-Raman spectroscopy and X-ray fluorescence further assessed the degradation level and the presence of pigments. Each plastic type harbored distinct bacterial communities from the others, in agreement with the differences highlighted by the physico-chemical analyses. Furthermore, the most degraded polyethylene films were found to host a bacterial community more similar to the surrounding soil as revealed by both α- and ß-diversity NGS analyses. This work confirms the novel hypothesis that different polyethylene terrestrial waste samples select for different bacterial communities, and that structure of these communities can be correlated with physico-chemical properties of the plastics, including the degradation degree.

The Use of POSS-Based Nanoadditives for Cable-Grade PVC: Effects on its Thermal Stability.

Plasticized-Poly(vinyl chloride) (P-PVC) for cables and insulation requires performances related to outdoor, indoor and submarine contexts and reduction of noxious release of HCl-containing fumes in case of thermal degradation or fire. Introducing suitable nanomaterials in polymer-based nanocomposites can be an answer to this clue. In this work, an industry-compliant cable-grade P-PVC formulation was added with nanostructured materials belonging to the family of Polyhedral Oligomeric Silsesquioxane (POSS). The effects of the nanomaterials, alone and in synergy with HCl scavenging agents as zeolites and hydrotalcites, on the thermal stability and HCl evolution of P-PVC were deeply investigated by thermogravimetric analysis and reference ASTM methods. Moreover, hardness and mechanical properties were studied in order to highlight the effects of these additives in the perspective of final industrial uses. The data demonstrated relevant improvements in the thermal stability of the samples added with nanomaterials, already with concentrations of POSS down to 0.31 phr and interesting additive effects of POSS with zeolites and hydrotalcites for HCl release reduction without losing mechanical performances.

New Hints on the Maya Blue Formation Process by PCA-Assisted In Situ XRPD/PDF and Optical Spectroscopy.

The exact recipe to prepare the ancient Maya Blue (MB), an incredibly resistant and brilliant pigment prepared from indigo (dye) and Palygorskite (clay), is lost to the ages. To unravel the key features of the MB formation process, several inorganic-dye couples were heated to 200 °C and cooled to RT, to investigate their reactivity and the diffusion and degree of sequestration of the dye into the inorganic host. In situ XRPD/PDF and fiber optic reflectance spectroscopy (FORS) data, along with TGA, provided a comprehensive overview on MB formation mechanism. XRPD/PDF gave information on long/short range behaviors of water desorption/adsorption and indigo sequestration, while TGA and in situ FORS gave information on mass and optical changes within temperature. Ex situ dye removal was used to understand the sample stability after the thermal treatment. A statistical approach based on principal component analysis was exploited to efficiently and jointly analyze the ≈3000 collected patterns. MB formation starts below 110 °C with disordered distribution of indigo within the channels, reaching maximum reaction speed and higher ordering at 150 °C. Above 175 °C, color changes and a stronger sequestration of indigo into framework channels are observed, whereas the affinity for water is dramatically reduced. The origin of different colors, hues, and stability in historical MB samples can then be explained in terms of different thermal histories of the starting mechanical indigo/palygorskite mixtures.

Luminescent Mesoporous Silica Built through Self-Assembly of Polyhedral Oligomeric Silsesquioxane and Europium(III) Ions.

The chemical combination of completely condensed polyhedral oligomeric silsequioxanes and Eu3+ ions has allowed the preparation of a novel robust mesoporous silica (Eu-MesoPOSS) with interesting luminescent properties and good hydrothermal and photobleaching stability. These properties make Eu-MesoPOSS a potential candidate for the fabrication of stable and efficient luminescent devices, and a multifunctional platform for bio-imaging applications.

POSS as building-blocks for the preparation of polysilsesquioxanes through an innovative synthetic approach.

A novel solvent-free solid-state synthesis was used to prepare a non-crystalline polysilsesquioxane sample, with a peculiar viscous form. The material was synthesized through direct self-condensation of a partially condensed polyhedral oligomeric silsesquioxane (POSS) and its physico-chemical properties, in terms of composition/structure, thermal stability and hydrophobicity, were investigated.

Rationalization of dye uptake on titania slides for dye-sensitized solar cells by a combined chemometric and structural approach.

A model photosensitizer (D5) for application in dye-sensitized solar cells has been studied by a combination of XRD, theoretical calculations, and spectroscopic/chemometric methods. The conformational stability and flexibility of D5 and molecular interactions between adjacent molecules were characterized to obtain the driving forces that govern D5 uptake and grafting and to infer the most likely arrangement of the molecules on the surface of TiO2. A spectroscopic/chemometric approach was then used to yield information about the correlations between three variables that govern the uptake itself: D5 concentration, dispersant (chenodeoxycholic acid; CDCA) concentration, and contact time. The obtained regression model shows that large uptakes can be obtained at high D5 concentrations in the presence of CDCA with a long contact time, or in absence of CDCA if the contact time is short, which suggests how dye uptake and photovoltaic device preparation can be optimized.

Structural characterization and thermal and chemical stability of bioactive molecule-hydrotalcite (LDH) nanocomposites.

Layered double hydroxides (LDH) are versatile materials used for intercalating bioactive molecules, both in pharmaceutical and cosmetic fields, with the purpose of protecting them from degradation, enhancing their water solubility to increase bioavailability, and/or obtaining modified release properties. The properties of the intercalation compounds of Mg/Al_LDH and Zn/Al_LDH with different drugs and sunscreens, namely diclofenac, ketoprofen, gliclazide, retinoic acid, furosemide, para-aminobenzoic acid and 2-phenylbenzimidazolsulfonic (Eusolex) acid, have been studied by crystallographic, spectroscopic and thermogravimetric techniques and by solid state NMR, to shed light on their structure, their molecular interactions and their stability from the thermal and chemical viewpoint. The structural features were described with particular attention to the interaction between the organic and inorganic components and to the stability of the intercalation products. For the first time two synchrotron radiation powder diffraction patterns of organic-containing LDH were solved and refined by Rietveld methods to obtain an experimental crystal structure.

One-pot synthesis and physicochemical properties of an organo-modified saponite clay.

An organo-saponite clay containing intercalated cetyltrimethylammonium (CTA(+)) cations was synthesized by an efficient one-step hydrothermal method and was compared with a CTA-exchanged saponite prepared by a classical postsynthesis intercalation route. In both hybrid samples, surfactant loading up to 10% was achieved. A comparative investigation of the physicochemical properties of both solids was carried out by a multidisciplinary approach, by using a combination of spectroscopic, structural, and thermal characterization tools. Powder X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) data indicated that the one-pot-prepared solid showed that the presence of CTA(+) molecules in the synthesis gel did not affect the clay structure. In addition, thermal analysis suggested that the inorganic layers play an active role in stabilizing and protecting the surfactant molecules by increasing their thermal stability. A different arrangement of intercalated CTA(+) ions in the two hybrid clays was observed by solid state NMR in combination with Fourier transform infrared (FTIR) spectroscopy and assigned to a different all-trans/gauche conformation ratio of the surfactant depending on the synthetic method used to prepare the two final materials. The surfactant organization is also influenced by the lamellae charge density, which is different in the two organo-modified materials as found by (27)Al and (29)Si MAS NMR experiments.

Understanding the physico-chemical properties of polyhedral oligomeric silsesquioxanes: a variable temperature multidisciplinary study.

This work is focused on a multidisciplinary study of a completely condensed octaisobutyl-silsesquioxane (IBUPOSS) as a model of the alkyl POSS family. IBUPOSS is characterized by the presence of eight isobutyl groups bonded to the corners of the siliceous framework. Differential scanning calorimetric measurements and an innovative simultaneous in situ Raman/XRPD experiment suggested that IBUPOSS undergoes a solid phase transition around 330 K, and indicated that this transition is related to a change in the conformational freedom of the isobutyl chains. The X-ray powder diffraction (XRPD) pattern of the high temperature phase was indexed in the high symmetry [R3m] space group. The Raman data indicated a larger mobility of the aliphatic side chains at high temperature, thus inducing a disorder in the IBUPOSS moiety. Multidimensional heteronuclear solid-state NMR experiments were employed to probe the structural and motional features of the observed phase transition. The various conformations can be accounted for by a pseudo-D(3h) symmetry able to obey to the [R3m] space group. Simulations on molecular mechanics and dynamics, together with quantum-chemical calculations, confirmed this hypothesis and gave some hints on the conformational mobility and the energetic features of IBUPOSS, a base material with relevant applications in catalysis and polymer science.

Carbon coated microshells containing nanosized Gd(III) oxidic phases for multiple bio-medical applications.

Novel sub-microsized graphitic carbon shells embedding nanometric Gd(III) oxidic phases feature thermal and chemical inertness with enhanced T2 relaxation in aqueous dispersions, thus representing potential candidates for dual diagnostic (magnetic resonance imaging) and therapeutic (neutron capture therapy) applications.

A versatile route to bifunctionalized silsesquioxane (POSS): synthesis and characterisation of Ti-containing aminopropylisobutyl-POSS.

A facile synthetic pathway leading to significant yields of bifunctional polyhedral oligomeric silsesquioxanes (POSS) with two different functionalities on the same cage structure, namely Ti-NH2POSS, is proposed in this manuscript.

Polypropylene containing Ti- and Al-polyhedral oligomeric silsesquioxanes: crystallization process and thermal properties.

This paper deals with the preparation and characterization of isotactic polypropylene (PP) containing different metal-polyhedral oligomeric silsesquioxanes (M-POSS). Two M-POSS, Ti(IV)- and Al(III)-isobutyl-POSS, defined by a monomeric structure, were selected for dispersion, and particular attention was paid to the assessment of the morphology, crystallization process and thermal behavior of M-POSS/PP composites, using SEM and TEM microscopy, x-ray diffraction (XRD), FTIR and Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and gas chromatography/mass spectrometry. The study of M-POSS/PP thermal degradation showed that Ti-POSS and Al-POSS induce different effects on the thermoxidative behavior of the polypropylene matrix, showing a clear specificity of the metal center on the PP degradation pathway. In particular, Ti-POSS showed a significant stabilization of PP when heating under air, whereas limited effects were observed with Al-POSS. Moreover, Ti-POSS was also found to affect PP crystallization, driving the crystallization process along specific crystallographic directions.

The vibrational spectra of the cyanide ligand revisited. Bridging cyanides.

The nu(CN) vibrational spectra of cyanide groups bridging two metal atoms present a confused picture. Factors relevant to the interpretation of the available data are reviewed. Some mechanisms for frequency change, relative to the corresponding terminal species, are made more quantitative than previously described, and others are highlighted for the first time. The kinematic effect is much less important than previously assumed. It seems that an effect responsible for the major part of the frequency increase upon bridging commonly observed is the cation electric field, together with concomitant relaxation (the IVSE model). However, a contribution may well come from the change in the sigma bonding in the CN unit.

Vibrational study of some layered structures based on titanium and zirconium phosphates.

A Raman and infrared study was carried out on layered zirconium and titanium acid phosphates of alpha- and gamma-type, alpha-M[O(3)POH](2).H(2)O and gamma-M[PO(4)][O(2)P(OH)(2)].2H(2)O, respectively. The spectra were initially approached by means of the classical correlation method in the solid state, which accounts for the complexity of the infrared spectra of both species. However, the number of bands and their relative intensity in the Raman spectra suggest a quite total absence of quadrupolar coupling between the vibrating units. So, if interunit coupling is neglected, a molecular approach considering the vibrations of isolated tetrahedral [PO(4)] and octahedral [MO(6)] building blocks can allow an affordable spectroscopic description of the title compounds. Interesting insights on the relationships between spectral properties and structure can be drawn by comparison with the spectra of alkali phosphates and of MO(6) oxoanions. A significant high-energy shift of the nu(P-O) modes is observed in the layered phosphates with respect to the corresponding salts, which parallels the low-energy shift of the nu(M-O) modes. Surprisingly, an increase of the M-OP interaction can reinforce the P-O bond. A simple theoretical model, based on the interaction between the [PO(4)] unit and four Li(+) in similar geometrical arrangement found in the structures of the layered phosphates, offers a reasonable explanation of this phenomenon.