Electrospun polymeric nanohybrids with outstanding pollutants adsorption and electroactivity for water treatment and sensing devices

Graphene oxide (GO) and carbon nanotubes (CNTs) were loaded at different mutual ratios into poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) matrix and electrospun to construct mats that were assessed as smart sorbents for decontaminating water from methylene blue (MB) pollutant, while ensuring the additional possibility of detecting the dye amounts. The results revealed that sorption capacity enhances upon increasing GO content, which is beneficial to wettability and active area. Equilibrium adsorption of these materials is precisely predicted by the Langmuir isotherm model and the maximum capacities herein achieved, ranging from 120 to 555 mg/g depending on the formulation, are higher than those reported for similar systems. The evolution of the structure and properties of such materials as a function of dye adsorption was studied. The results reveal that MB molecules prompted the increase of electrical conductivity of the samples in a dose-dependent manner. Mats containing solely CNTs, while displaying the worst sorption performance, showed the highest electrical performances, displaying interesting changes in their electrical response as a function of the dye amount adsorbed, with a linear response and high sensitivity (309.4 mu S cm-1 mg-1) in the range 0-235 mu g of dye adsorbed. Beyond the possibility to monitor the presence of small amounts of MB in contaminated water and the saturation state of sorbents, this feature could even be exploited to transform waste sorbents into high-added value products, including flexible sensors for detecting low values of pressure, human motion, and so on

Two-dimensional and three-dimensional multifunctional polymeric systems

La ricerca della multifunzionalità e il miglioramento dell'efficienza a livello di sistema sono emersi come temi centrali nella scienza e nell'ingegneria contemporanea, catalizzando un cambiamento di paradigma nella progettazione e nelle prestazioni di prodotti e componenti. La crescente importanza della multifunzionalità nel panorama scientifico e ingegneristico sottolinea la necessità di una profonda comprensione e un'esplorazione rigorosa di questi materiali, strutture e processi strumentali nella loro realizzazione. Questa tesi di dottorato mira a condurre un esame approfondito dei benefici derivanti dall'adozione di processi di produzione innovativi, come l'elettrofilatura a umido e il processo di fusione reattiva, per stabilire correlazioni tra struttura, processo e proprietà. Ciò comporta il confronto tra vari processi e materiali per ottenere strutture multifunzionali in vari settori dell'ingegneria. L'obiettivo principale di questo studio è lo sviluppo di strutture multifunzionali gerarchiche 2D e 3D utilizzando diverse matrici polimeriche, esplorando la loro sinergia potenziale con vari riempitivi carboniosi e naturali utilizzati come catalizzatori per ottenere la multifunzionalità. Le molteplici caratteristiche di questi materiali multifunzionali includono funzionalità meccaniche, termiche, morfologiche e chimiche, che vengono esaminate come vie promettenti per l'innovazione e lo sviluppo sostenibile. Lo studio si addentra anche nell'impatto dei parametri di controllo del processo, ponendo attenzione al miglioramento dei tempi di produzione e all'ottimizzazione dei protocolli e delle condizioni dei processi utilizzati. È stato evidenziato il ruolo cruciale di queste strutture gerarchiche multifunzionali, con applicazioni nella purificazione dell'acqua da vari inquinanti e nello sviluppo potenziale di sensori per il loro monitoraggio. Inoltre, è stata indagata la potenzialità dei materiali compositi polimerici multifunzionali attraverso riempitivi alternativi, come i rifiuti naturali e la lignina. L'obiettivo è confrontare particelle carboniose e naturali nei campi di applicazione scelti. Da questa prospettiva, la valorizzazione dei rifiuti naturali per la produzione di materiali eco-compatibili con proprietà multifunzionali potrebbe consentire la produzione di strutture complesse e sostenibili in piena conformità con i principi dell'economia circolare. Attraverso una revisione completa dello stato dell'arte e una delineazione delle future direzioni di ricerca, l'obiettivo è contribuire ad aprire nuovi percorsi di ricerca e innovazione nei campi scientifico e ingegneristico, immaginando un futuro in cui materiali e strutture multifunzionali ci guideranno verso una maggiore sostenibilità ed efficienza in vari settori.Pursuing multifunctionality and enhancing system-level efficiency have emerged as central themes in contemporary science and engineering, catalysing a paradigm shift in the design and performance of products and components. The growing significance of multifunctionality in the scientific and engineering landscape underscores the need for a deep understanding and rigorous exploration of these materials, structures, and instrumental processes in their realization. This doctoral thesis aims to conduct an in-depth examination of the benefits arising from the adoption of innovative production processes, such as wet-electrospinning and reactive melt processing, to establish correlations between structure, process, and properties. This involves comparing various processes and materials to achieve multifunctional structures in various engineering sectors. This study's primary focus is the development of hierarchical 2D and 3D multifunctional structures using different polymeric matrices, exploring their potential synergy with various carbonaceous and natural fillers used as catalysts to achieve multifunctionality. The multiple features of these multifunctional materials include mechanical, thermal, morphological, and chemical functionalities, which are examined as promising avenues for innovation and sustainable development. The study also delves into the impact of process control parameters, paying attention to improving production times and optimizing the protocols and conditions of the processes used. The crucial role of these multifunctional hierarchical structures has been highlighted, with applications in water purification from various pollutants and the potential development of sensors for monitoring them. Additionally, the potential of multifunctional polymeric composite materials has been investigated through alternative fillers, such as natural waste and lignin. The aim is to compare carbonaceous and natural particles in the chosen application fields. From this perspective, the natural waste’s valorisation for producing eco-friendly materials with multifunctional properties could allow the production of complex and sustainable structures in full compliance with the circular economy principles. Through a comprehensive review of the state of the art and an outline of future research directions, the aim is to contribute to opening new paths of research and innovation in the scientific and engineering fields, envisioning a future where multifunctional materials and structures will drive us towards greater sustainability and efficiency across various sectors

Attrezzature per la formazione come attivatori di processi rigenerativi transcalari: i Patti Educativi Territoriali e il caso triestino

Il contributo proposto intende indagare alcune dinamiche che legano le attrezzature a standard per la formazione e l’innesco di processi rigenerativi spaziali transcalari, con particolare riferimento al ruolo ricoperto dalla didattica e dai processi di progettazione partecipata. Le metodologie di ricerca adottate sono la literature review, lo studio di caso comparato e la ricerca-azione. Il contributo si inserisce all’interno di un percorso di dottorato di ricerca presso l’Università degli Studi di Trieste

Hierarchically Structured Hybrid Membranes for Continuous Wastewater Treatment via the Integration of Adsorption and Membrane Ultrafiltration Mechanisms

Growing environmental concerns are stimulating researchers to develop more and more efficient materials for environmental remediation. Among them, polymer-based hierarchical structures, attained by properly combining certain starting components and processing techniques, represent an emerging trend in materials science and technology. In this work, graphene oxide (GO) and/or carbon nanotubes (CNTs) were integrated at different loading levels into poly (vinyl fluoride-co-hexafluoropropylene) (PVDF-co-HFP) and then electrospun to construct mats capable of treating water that is contaminated by methylene blue (MB). The materials, fully characterized from a morphological, physicochemical, and mechanical point of view, were proved to serve as membranes for vacuum-assisted dead-end membrane processes, relying on the synergy of two mechanisms, namely, pore sieving and adsorption. In particular, the nanocomposites containing 2 wt % of GO and CNTs gave the best performance, showing high flux (800 L × m−2 h−1) and excellent rejection (99%) and flux recovery ratios (93.3%), along with antifouling properties (irreversible and reversible fouling below 6% and 25%, respectively), and reusability. These outstanding outcomes were ascribed to the particular microstructure employed, which endowed polymeric membranes with high roughness, wettability, and mechanical robustness, these capabilities being imparted by the peculiar self-assembled network of GO and CNTs

Wet electrospinning-aided self-assembly of multifunctional GO-CNT@PCL core-shell nanocomposites with spider leg bioinspired hierarchical architectures

We report a fast route enabling the multiscale design of nanohybrid structures comprising a 3D fibrous network of polycaprolactone (PCL) wrapped by graphene oxide (GO) sheets onto which carbon nanotube (CNT) brushes are anchored. The method relies on electrospinning PCL solutions onto a suspension of GO and CNTs in ethanol. Self-assembly is due to electrostatic wrapping of GO sheets around PCL fibers and 7C-7C stacking between GO and CNTs. Hierarchical architecture and nanopatterned surface allow gathering the starting properties of PCL, GO and CNTs into lightweight (99% porosity) yet robust (1575% stiffness improvement), amphiphilic monoliths that can remove methylene blue and/or methyl orange from stagnant water with ca.100% efficiency

Modelling the structure-property relationships of high performance PBAT-based biocomposites with natural fibers obtained from Chamaerops humilis dwarf palm

Two fibrous fillers were achieved from stalks and leaves of Chamaerops humilis dwarf palm and tested as reinforcing agents for poly(butylene adipate co-terephthalate) (PBAT)-based composites. The influence of filler type and content on the morphomechanical properties of the green composites was assessed. The outcomes of tensile tests pointed out that both fillers are strong candidates to overcome the two main limiting aspects of PBAT, that is, the lack of both stiffness and cost-effectiveness, while preserving its stretchability and environmental sustainability. The remarkable stiffness increments (up to 300%), combined with fair retention of stretchability (33%) and doubled resistance, led to the fabrication of biocomposites with toughness values as high as 20-25 MJ/m(3). These results could be ascribed to the combination of several factors, including the formation of an extensive and robust interphasic region. This latter, ascribed to the chemical affinity between aromatic parts of fillers and matrix, presented different features in the two types of fillers, thus endowing resulting biocomposites with a broad array of mechanical performance, which can be predicted by introducing opportune modifications to Halpin-Tsai model which allow considering the crucial role of interphase