Analytical pyrolysis to study microplastics and other polymers in the environment

Synthetic polymers constitute a wide class of materials which has enhanced the quality of human life, providing comforts and innovations. Anyway, the increasing production and the incorrect waste management, are leading to the occurrence of polymers in the environment, generating concern. To understand the extent of this issue, analytical investigation holds an essential position. Standardised methods have not established yet, and additional studies are required to improve the present knowledge. The main aim of this thesis was to provide comprehensive information about the potential of pyrolysis coupled with gas-chromatography and mass spectrometry (Py-GC-MS) for polymers investigation, from their characterisation to their identification and quantification in complex matrices. Water-soluble (poly(dimethylsiloxanes), PDMS bearing poly(ethylene glycol), PEG, side chains) and water-insoluble polymers (microplastics, MPs, and bioplastics) were studied. The different studies revealed the possibility to identify heterogeneous classes of polymers, fingerprinting the presence of PDMS copolymers and distinguishing chemically different polyurethanes (PURs). The occurrence of secondary reactions in pyrolysis of polymer mixtures was observed as possible drawback. Pyrolysis products indicative of secondary reactions and their reaction mechanisms were identified. Py-GC-MS also revealed its fundamental role for the identification of polymers composing commercial bioplastics items based. The results aided to identify chemicals that have the potential to migrate in sea waters. Investigations of environmental samples demonstrated the capability of Py-GC-MS to provide reliable, reproducible and comparable results about polymers in complex matrices (PEG-PDMS in sewage sludges and PURs and other MPs in road dusts and spider webs). Criticisms were especially found in quantitation, such as the retrieval reference materials, the construction of reliable calibration protocols and the occurrence of bias due to interferences between pyrolysis products. This thesis pursues the greater purpose to develop harmonised and standardised methods for environmental investigations of polymers, that is fundamental to assess the real state of the environment.

Design, synthesis and photovoltaic properties of some thiophene-based conjugated polymers for organic solar cells

The current issue of the resource of energy combined with the tendency to give a green footprint to our lifestyle have prompted the research to focus the attention on alternative sources with great strides in the optimization of polymeric photovoltaic devices. The research work described in this dissertation consists in the study of different semiconducting π-conjugated materials based on polythiophenes (Chapter I). In detail, the GRIM polymerization was deepened defining the synthetic conditions to obtain regioregular poly(3-alkylthiophene) (Chapter II). Since the use of symmetrical monomers functionalized with oxygen atom(s) allows to adopt easy synthesis leading to performing materials, disubstituted poly(3,4-dialkoxythiophene)s were successfully prepared, characterized and tested as photoactive materials in solar cells (Chapter III). A “green” resource of energy should be employed through sustainable devices and, for this purpose, the research work was continued on the synthesis of thiophene derivatives soluble in eco-friendly solvents. To make this possible, the photoactive layer was completely tailored starting from the electron-acceptor material. A fullerene derivative soluble in alcohols was successfully synthetized and adopted for the realization of the new devices (Chapter IV). New water/alcohol soluble electron-donor materials with different functional groups were prepared and their properties were compared (Chapter V). Once found the best ionic functional group, a new double-cable material was synthetized optimizing the surface area between the different materials (Chapter VI). Finally, other water/alcohol soluble materials were synthetized, characterized and used as cathode interlayers in eco-friendly devices (Chapter VII). In this work, all prepared materials were characterized by spectroscopy analyses, gel permeation chromatography and thermal analyses. Cyclic voltammetry, X-ray diffraction, atomic force microscopy and external quantum efficiency were used to investigate some peculiar aspects.

A comprehensive experimental and numerical approach for assessing the hydro-mechanical behaviour of river embankments

In this doctoral dissertation, a comprehensive methodological approach for the assessment of river embankments safety conditions, based on the integrated use of laboratory testing, physical modelling and finite element (FE) numerical simulations, is proposed, with the aim of contributing to a better understanding of the effect of time-dependent hydraulic boundary conditions on the hydro-mechanical response of river embankments. The case study and materials selected for the present research project are representative for the riverbank systems of Alpine and Apennine tributaries of the main river Po (Northern Italy), which have recently experienced various sudden overall collapses. The outcomes of a centrifuge test carried out under the enhanced gravity field of 50-g, on a riverbank model, made of a compacted silty sand mixture, overlying a homogeneous clayey silt foundation layer and subjected to a simulated flood event, have been considered for the definition of a robust and realistic experimental benchmark. In order to reproduce the observed experimental behaviour, a first set of numerical simulations has been carried out by assuming, for both the embankments and the foundation unit, rigid soil porous media, under partially saturated conditions. Mechanical and hydraulic soil properties adopted in the numerical analyses have been carefully estimated based on standard saturated triaxial, oedometer and constant head permeability tests. Afterwards, advanced suction-controlled laboratory tests, have been carried out to investigate the effect of suction and confining stresses on the shear strength and compressibility characteristics of the filling material and a second set of numerical simulations has been run, taking into account the soil parameters updated based on the most recent tests. The final aim of the study is the quantitative estimation of the predictive capabilities of the calibrated numerical tools, by systematically comparing the results of the FE simulations to the experimental benchmark.

Valorization and recycling of waste biomass and bioplastics into molecules, polymers and catalysts

The enormous amount of goods that world societies consume every day, derives from an immense consumption of energy and raw materials, and leads to an unthinkable amount of wastes. The abuse of fossil-based resources and the mismanaged waste is leading to big environmental pollution and climate change, with consequences on all living beings. To solve this issue and start living in equilibrium with nature, modern societies must stop using fossil fuels massively in favor to clean renewable energies, recycling, and biomass and waste utilization for materials and chemical production. Moreover, bioplastic recycling must be prioritized over their biodegrading and composting. This work is dedicated to the study of new synthetic strategies that fall into these fields.

Mainstreaming of Nature-Based Solutions for the mitigation of hydro-meteorological hazard: governance analysis of a socio- technical change

The Nature-Based Solutions (NBS) concept and approach were developed to simultaneously face challenges such as risk mitigation and biodiversity conservation and restoration. NBSs have been endorsed by major International Organizations such as the EU, the FAO and World Bank that are pushing to enable a mainstreaming process. However, a shift from traditional engineering “grey” solutions to wider and standard adoption of NBS encounters technical, social, cultural, and normative barriers that have been identified with a qualitative content analysis of policy documents, reports and expert interviews. The case of the region Emilia-Romagna was studied by developing an analytical framework that brought together the social-ecological context, the governance system and the characteristics of specific NBSs.

Enhancing predictive capability of models for solubility and permeability in polymers and composites

The interpretation of phase equilibrium and mass transport phenomena in gas/solvent - polymer system at molten or glassy state is relevant in many industrial applications. Among tools available for the prediction of thermodynamics properties in these systems, at molten/rubbery state, is the group contribution lattice-fluid equation of state (GCLF-EoS), developed by Lee and Danner and ultimately based on Panayiotou and Vera LF theory. On the other side, a thermodynamic approach namely non-equilibrium lattice-fluid (NELF) was proposed by Doghieri and Sarti to consistently extend the description of thermodynamic properties of solute polymer systems obtained through a suitable equilibrium model to the case of non-equilibrium conditions below the glass transition temperature. The first objective of this work is to investigate the phase behaviour in solvent/polymer at glassy state by using NELF model and to develop a predictive tool for gas or vapor solubility that could be applied in several different applications: membrane gas separation, barrier materials for food packaging, polymer-based gas sensors and drug delivery devices. Within the efforts to develop a predictive tool of this kind, a revision of the group contribution method developed by High and Danner for the application of LF model by Panayiotou and Vera is considered, with reference to possible alternatives for the mixing rule for characteristic interaction energy between segments. The work also devotes efforts to the analysis of gas permeability in polymer composite materials as formed by a polymer matrix in which domains are dispersed of a second phase and attention is focused on relation for deviation from Maxwell law as function of arrangement, shape of dispersed domains and loading.

Investigation on the role of polymeric ligands in heterogeneous nanocatalysis towards the development of hybrid metal-polymer catalysts

The relationship between catalytic properties and the nature of the active phase is well-established, with increased presence typically leading to enhanced catalysis. However, the costs associated with acquiring and processing these metals can become economically and environmentally unsustainable for global industries. Thus, there is potential for a paradigm shift towards utilizing polymeric ligands or other polymeric systems to modulate and enhance catalytic performance. This alternative approach has the potential to reduce the requisite amount of active phase while preserving effective catalytic activity. Such a strategy could yield substantial benefits from both economic and environmental perspectives. The primary objective of this research is to examine the influence of polymeric hydro-soluble ligands on the final properties, such as size and dispersion of the active phase, as well as the catalytic activity, encompassing conversion, selectivity towards desired products, and stability, of colloidal gold nanoparticles supported on active carbon. The goal is to elucidate the impact of polymers systematically, offering a toolbox for fine-tuning catalytic performances from the initial stages of catalyst design. Moreover, investigating the potential to augment conversion and selectivity in specific reactions through tailored polymeric ligands holds promise for reshaping catalyst preparation methodologies, thereby fostering the development of more economically sustainable materials.

Polymerization of isatin towards polymers for anion exchange membranes and gas separation applications

In a world where the problem of energy resources, pollution and all aspects related to these issues become more and more dominant, a greater commitment is needed in the search for solutions. The goal of this project is to make a contribution to the research and development of new materials to reduce the environmental impact in some fields. First of all, we tried to synthesize and prepare an isatin-based membrane which has the potential for use in separating industrial gases. Furthermore, ion exchange membranes, specifically hydroxide exchange membranes (HEMs) derived from the same product can be developed for fuel cells (HEMFC) applications. These materials are essential for energy conversion and storage. The most difficult challenge is to guarantee their thermal stability and stability in corrosive environments such as alkali without losing efficiency. In recent years the poly- hydroxyalkylation catalysed with superacids, e.g. TFSA, has become increasingly studied. This reaction is exploited for the synthesis of the compounds of this thesis. After a preliminary optimization of the reaction conditions it was concluded that due to the rigidity and excessive reactivity of the system, it was not possible to obtain the isatin-based membrane to evaluate the gas separation properties. The synthesis of precursor materials for HEMs was successful by using 1-(4-bromobutyl)indoline-2,3-dione (BID) instead of isatin. A characterization of the obtained polymers was carried out using NMR, TGA and DSC analyses, and subsequently the membranes were functionalized with different ammonium-based cations. Unfortunately, this last step was not successful due to the appearance of side reactions. Future studies on the mechanism and kinetics of the reaction solve this obstacle.

Study Of The Homogeneity Of Drug Loaded In Polymeric Films Using Near-infrared Chemical Imaging And Split-plot Design.

Split-plot design (SPD) and near-infrared chemical imaging were used to study the homogeneity of the drug paracetamol loaded in films and prepared from mixtures of the biocompatible polymers hydroxypropyl methylcellulose, polyvinylpyrrolidone, and polyethyleneglycol. The study was split into two parts: a partial least-squares (PLS) model was developed for a pixel-to-pixel quantification of the drug loaded into films. Afterwards, a SPD was developed to study the influence of the polymeric composition of films and the two process conditions related to their preparation (percentage of the drug in the formulations and curing temperature) on the homogeneity of the drug dispersed in the polymeric matrix. Chemical images of each formulation of the SPD were obtained by pixel-to-pixel predictions of the drug using the PLS model of the first part, and macropixel analyses were performed for each image to obtain the y-responses (homogeneity parameter). The design was modeled using PLS regression, allowing only the most relevant factors to remain in the final model. The interpretation of the SPD was enhanced by utilizing the orthogonal PLS algorithm, where the y-orthogonal variations in the design were separated from the y-correlated variation.

Fine Needle Aspiration Cytology In The Diagnosis Of Perioral Adverse Reactions To Cosmetic Dermal Fillers.

Facial cosmetic procedures are increasingly requested, and dermal filler materials have been widely used as a nonsurgical option since the 1980s. However, injectable fillers have been implicated in local adverse reactions. Therefore, the aim of this article was to describe the use of fine needle aspiration cytology (FNAC) in the diagnosis of foreign-body reactions to the perioral injection of dermal fillers. A 69-year-old woman presented with a painful nodule on her right nasolabial fold. Intraoral FNAC was performed, and cytologic smears were examined under optical and polarized light microscopy, showing birefringent microspheres, confirming the diagnosis of an adverse reaction caused by polymethyl methacrylate filler. FNAC is a less invasive method to confirm the diagnosis of adverse reactions caused by perioral cosmetic dermal fillers.

Sargassum Filipendula Alginate From Brazil: Seasonal Influence And Characteristics.

The aim of this work is focused on the extraction and characterization of the Brazilian seaweed Sargassum filipendula alginate. Alginates obtained at different seasons were characterized by liquid state nuclear magnetic resonance spectroscopy and scanning electron microscopy. The alginate extraction efficiency was about 20%. Different seasons of the year and different stages in the life cycle of Sargassum sp. in southeastern Brazil influenced the M/G and, consequently, the technological properties of extracted alginates.

Improved Selective Cholesterol Adsorption By Molecularly Imprinted Poly(methacrylic Acid)/silica (pmaa-sio₂) Hybrid Material Synthesized With Different Molar Ratios.

The present paper describes the synthesis of molecularly imprinted polymer - poly(methacrylic acid)/silica and reports its performance feasibility with desired adsorption capacity and selectivity for cholesterol extraction. Two imprinted hybrid materials were synthesized at different methacrylic acid (MAA)/tetraethoxysilane (TEOS) molar ratios (6:1 and 1:5) and characterized by FT-IR, TGA, SEM and textural data. Cholesterol adsorption on hybrid materials took place preferably in apolar solvent medium, especially in chloroform. From the kinetic data, the equilibrium time was reached quickly, being 12 and 20 min for the polymers synthesized at MAA/TEOS molar ratio of 6:1 and 1:5, respectively. The pseudo-second-order model provided the best fit for cholesterol adsorption on polymers, confirming the chemical nature of the adsorption process, while the dual-site Langmuir-Freundlich equation presented the best fit to the experimental data, suggesting the existence of two kinds of adsorption sites on both polymers. The maximum adsorption capacities obtained for the polymers synthesized at MAA/TEOS molar ratios of 6:1 and 1:5 were found to be 214.8 and 166.4 mg g(-1), respectively. The results from isotherm data also indicated higher adsorption capacity for both imprinted polymers regarding to corresponding non-imprinted polymers. Nevertheless, taking into account the retention parameters and selectivity of cholesterol in the presence of structurally analogue compounds (5-α-cholestane and 7-dehydrocholesterol), it was observed that the polymer synthesized at the MAA/TEOS molar ratio of 6:1 was much more selective for cholesterol than the one prepared at the ratio of 1:5, thus suggesting that selective binding sites ascribed to the carboxyl group from MAA play a central role in the imprinting effect created on MIP.

Preparation, Characterization And In Vitro Digestibility Of Gellan And Chitosan-gellan Microgels.

Gellan microgels with potential application in delivery systems were obtained by physically cross-linked gellan gum. The microgels were produced by atomization followed by ionotropic gelation using CaCl2 (gellan/Ca) or KCl (gellan/K) as hardening agent and part of them were coated with chitosan in order to improve their resistance to gastric digestion. Size distribution, morphology and zeta potential of microgels were evaluated before and after in vitro digestion process. The long term stability was also evaluated. Spherical microparticles were obtained at gellan concentration above 0.6% w/w, showing average size among 70-120 μm. Most of the coated and uncoated microgels showed stability in aqueous media, except the uncoated gellan/K microgel. The in vitro digestion evaluation showed that all particles maintained their size and shape after the gastric digestion step. However, the enteric digestion caused disintegration of microgels indicating their potential application for enteric delivery systems. The chitosan-coated microgels showed lower degree of fragmentation when compared to the uncoated microgels, indicating that the coating process enable a better control of microgels releasing properties during the enteric digestion.

Solid Lipid Nanoparticles As Nucleic Acid Delivery System: Properties And Molecular Mechanisms.

Solid lipid nanoparticles (SLNs) have been proposed in the 1990s as appropriate drug delivery systems, and ever since they have been applied in a wide variety of cosmetic and pharmaceutical applications. In addition, SLNs are considered suitable alternatives as carriers in gene delivery. Although important advances have been made in this particular field, fundamental knowledge of the underlying mechanisms of SLN-mediated gene delivery is conspicuously lacking, an imperative requirement in efforts aimed at further improving their efficiency. Here, we address recent advances in the use of SLNs as platform for delivery of nucleic acids as therapeutic agents. In addition, we will discuss available technology for conveniently producing SLNs. In particular, we will focus on underlying molecular mechanisms by which SLNs and nucleic acids assemble into complexes and how the nucleic acid cargo may be released intracellularly. In discussing underlying mechanisms, we will, when appropriate, refer to analogous studies carried out with systems based on cationic lipids and polymers, that have proven useful in the assessment of structure-function relationships. Finally, we will give suggestions for improving SLN-based gene delivery systems, by pointing to alternative methods for SLNplex assembly, focusing on the realization of a sustained nucleic acid release.

Production Of Microparticles With Gelatin And Chitosan.

In the past few decades, the textile industry has significantly increased investment in research to develop functional fabrics, with a special focus on those aggregating values. Such fabrics can exploit microparticles inferior to 100 μm, such as those made by complex coacervation in their creation. The antimicrobial properties of chitosan can be attributed to these microparticles. Developing particles with uniform structure and properties would facilitate the control for the eventual release of the core material. Thus, a complex coacervation between gelatin and chitosan was studied, and the optimal conditions were replicated in the encapsulation of limonene. Spherical particles formed had an average diameter (D3,2) of 30 μm and were prepared with 89.7% efficiency. Cross-linking of these microparticles using glutaraldehyde and tripolyphosphate was carried out before spray drying. After drying, microparticles cross-linked with glutaraldehyde were oxidized and clustered and those that were cross-linked with tripolyphosphate resisted drying and presented a high yield.