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Understanding water drop impact on meshes is valuable to design passive systems for atmospheric water collection. By investigating water drop impact on hydrophobic and superhydrophobic surfaces, here, we identify the different drop impact outcomes and build outcome maps within the pertinent parameter spaces, based on Weber number and contact angles. Furthermore, we quantitatively evaluate critical factors such as the captured volume and spray characteristics of the penetrating liquid and also measure the drop rebound time, reporting that full rebound occurs on superhydrophobic meshes surfaces even at high We numbers, as the Cassie-Baxter wetting state is maintained.

Chitosan films have attracted increased attention in the field of sensors because of chitosan’s unique chemico-physical properties, including high adsorption capacity, filmability and transparency. A chitosan film sensor was developed through the dispersion of an ammonia specific reagent (Nessler’s reagent) into a chitosan film matrix. The chitosan film sensor was characterized to assess the film’s properties by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). A gas diffusion device was prepared with the chitosan film sensor, enabling the collection and detection of ammonia vapor from biological samples. The chitosan film sensor color change was correlated with the ammonia concentration in samples of human serum and artificial urine. This method enabled facile ammonia detection and concentration measurement, making the sensor useful not only in clinical laboratories, but also for point-of-care devices and wherever there is limited access to modern laboratory facilities.

Controlling water transport and management is crucial for continuous and reliable system operation in harsh weather conditions. Passive strategies based on nonwetting surfaces are desirable, but so far, the implementation of superhydrophobic coatings into real-world applications has been limited by durability issues and, in some cases, lack of compliance with environmental regulations. Inspired by surface patterning observed on living organisms, in this study we have developed durable surfaces based on contrast wettability for capillary-driven water transport and management. The surface fabrication process combines a hydrophobic coating with hard-anodized aluminum patterning, using a scalable femtosecond laser microtexturing technique. The concept targets heavy-duty engineering applications; particularly in aggressive weather conditions where corrosion is prevalent and typically the anodic aluminum oxide-based coating is used to protect the surface from corrosion, the concept has been validated on anodic aluminum oxide coated aluminum alloy substrates. Such substrates with contrast wettable characteristics show long-term durability in both natural and lab-based artificial UV and corrosion tests where superhydrophobic coatings tend to degrade.

Additive manufacturing technologies are developed and utilized to manufacture complex, lightweight, functional, and non-functional components with optimized material consumption. Among them, vat polymerization-based digital light processing (DLP) exploits the polymerization of photocurable resins in the layer-by-layer production of three-dimensional objects. With the rapid growth of the technology in the last few years, DLP requires a rational design framework for printing process optimization based on the specific material and printer characteristics. In this work, we investigate the curing of pure photopolymers, as well as ceramic and metal suspensions, to characterize the material properties relevant to the printing process, such as penetration depth and critical energy. Based on the theoretical framework offered by the Beer–Lambert law for absorption and on experimental results, we define a printing space that can be used to rationally design new materials and optimize the printing process using digital light processing. The proposed methodology enables printing optimization for any material and printer combination, based on simple preliminary material characterization tests to define the printing space. Also, this methodology can be generalized and applied to other vat polymerization technologies.

La additive manufacturing (AM) o stampa 3D è un processo, basato su diverse tecnologie, per la progettazione e la fabbricazione di oggetti tridimensionali, un'alternativa alla convinzionale subtractive manufacturing. La AM consente una produzione conveniente soprattutto per geometrie complesse, potenzialmente con impatti ambientali inferiori rispetto ai processi convenzionali, grazie alla flessibilità di progettazione e alla riduzione degli sprechi. Questi vantaggi hanno attirato l'attenzione di diversi settori industriali, per svariate applicazioni. Attualmente, diverse tecnologie AM vengono utilizzate per produrre parti leggere, funzionali e non funzionali. Tra questi, il Digital Light Processing (DLP) è una delle tecnologie più recenti e promettenti per la produzione di parti funzionali e non ad alta definizione. Rispetto alla stereolithography (SLA), che si basa su una sorgente laser per la polimerizzazione voxel per voxel, uno dei principali vantaggi del DLP è l'uso di una sorgente ad alta risoluzione, che polimerizza un intero strato con una proiezione ad ogni passaggio, riducendo così il tempo di stampa complessivo. Sviluppata inizialmente per la produzione di prototipi utilizzando fotopolimeri puri (resine), la tecnologia è stata recentemente testata per stampare sospensioni in ceramica e metallo. Attualmente, la tecnologia viene utilizzata per produrre parti 3D con materiali funzionali, come elastomeri, polimeri conduttivi, polimeri a memoria di forma, biopolimeri e materiali piezoelettrici. Questi materiali fotopolimerizzabili e sostenibili aggiungono un'altra dimensione alla parte stampata estendendo la stampa 3D alla stampa 4D. In questa tesi vengono evidenziate le novità e le caratteristiche speciali del DLP in contrasto con altre tecnologie AM. Inoltre, vengono affrontati vari aspetti del processo di stampa DLP, tra cui la preparazione del materiale, la comprensione dell'interazione tra materia leggera durante la stampa, le applicazioni e i pro, Additive Manufacturing (AM) or 3D printing is a process, based on different technologies, for the design and fabrication of three-dimensional objects, an alternative to conventional subtractive manufacturing. AM enables cost-effective manufacturing especially for complex geometries, potentially with lower environmental impacts compared to conventional processes, due to design flexibility and reduced waste. These advantages have drawn the attention of various industrial sectors, for a variety of applications. Currently, several AM technologies are being used to manufacture lightweight, functional, and non-functional parts. Among them, Digital Light Processing (DLP) is one of the most recent and promising technologies for producing high-definition functional and non-functional parts. When compared to stereolithography (SLA), which is based on a laser source for voxel-by-voxel polymerization, one of the major advantages of DLP is the use of a high-resolution source, curing an entire layer with one projection at each step, thus reducing the overall printing time. Initially developed for producing prototypes using pure photopolymers (resins), the technology has been recently tested to print ceramic and metal suspensions. Currently, the technology is being used to produce 3D parts using functional materials, such as elastomers, conductive polymers, shape memory polymers, biopolymers and piezoelectric materials. These photocurable, environmentally responsive materials add up another dimension to the printed part extending 3D printing to 4D printing. In this thesis, the novelties and peculiarities of DLP are highlighted in contrast to other AM technologies. Further, it covers various aspects of the DLP printing process including material preparation, insight into light-matter interaction during printing, and applications together with the advancements in DLP technology. The study also focuses on printing optimization for pure photopolymers, as well as ceramic and metal susp

One of the current greatest challenges in materials science and technology is the development of safe- and sustainable-by-design coatings with enhanced functionalities, e.g. to substitute fluorinated substances raising concerns for their potential hazard on human health. Bio-based polymeric coatings represent a promising route with a high potential. In this study, we propose an innovative sustainable method for fabricating coatings based on chitosan with modified functionality, with a fine-tuning of coating properties, namely transparency and superhydrophobicity. The process consists in two main steps: i) fluorine-free modification of chitosan functional groups with stearoyl chloride and freeze-drying to obtain a superhydrophobic powder, ii) coating deposition using a novel solvent-free approach through a thermal treatment. The modified chitosan is characterized to assess its chemico-physical properties and confirm the functionality modification with fatty acid tails. The deposition method enables tuning the coating properties of transparency and superhydrophobicity, maintaining good durability.

Additive manufacturing is a layer-by-layer strategy enabling the advanced design and fabrication of complex 3D objects and structures, overcoming geometry limitations and reducing waste production compared to conventional technologies. Among various additive manufacturing technologies, digital light processing (DLP), is an additive manufacturing technology used to print photopolymer parts, using a projected light source to cure an entire layer at once. Initially developed for pure resins, recent advances have demonstrated the potential of DLP in the polymerization of ceramic and metal-loaded suspensions, enabling the fabrication of ceramic and metal components after proper debinding and sintering. Such flexibility increases the potential of DLP for different applications, ranging from dental implants and bone scaffolds to smart biomaterials for soft robotics, smart wearables, and microfluidic devices. The review provides an overview of DLP technology and its recent advances; specifically, the review covers the photopolymer properties, the ceramic and metallic feedstock preparation, and the light-matter interaction mechanism underpinning the printing and post-processing steps. Finally, a description of the current application is provided and complemented with future perspectives.