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The integration of multifunctional elements directly embedded in three-dimensional (3D) printed parts is the cutting-edge of additive manufacturing (AM) and it is crucial for enlarging as well as for strengthening AM role in industrial applications. Here, a straightforward and low-cost method that synergically combines stereolithography (SLA) and selective electroless metallization (EM) is presented for the fabrication of 3D parts characterized by complex shapes and end-use multifunctionalities (conductive, magnetic, mechanical properties). To this end, a novel photocurable composite based on acrylate resin loaded with nickel (Ni) particles is developed for high-resolution SLA-printing of features with self-catalytic properties for EM. Ni particles are loaded in the resin to trigger metal deposition avoiding time consuming and expensive laser-based surface activation. The effect of Ni content on SLA behavior as well as on the efficiency of EM process is studied. Metallized SLA cured samples show good electrical and magnetic properties as well as improved robustness with respect to their non-loaded counterparts. Then, selective metallization of 3D printed parts is successfully achieved by implementing a multi-material SLA-printing where loaded and non-loaded resins are properly interchanged with strong adhesion at the interface, thus offering a cost-effective approach for rapid prototyping of functional free-form features on 3D structures.

Ultrasonic-Assisted Liquid Phase Exfoliation (UALPE) is considered one of the most promising approaches for the scale-up of graphene production. The process is based on the isolation and stabilization of layers of 2D materials, such as graphene: the selection of a proper stabilizing/exfoliating agent is crucial to achieve a stable Few-Layers-Graphene (FLG) dispersion. In the present work we propose the use of alkali lignin (AL) as a polymeric stabilizing agent for the rapid (≤ 3 hours) synthesis of FLG. Sonication time and graphite-to-lignin (Gr/AL) ratios were investigated as the primary operational parameters to identify the optimal working conditions. Spectroscopical characterization of the samples were employed to assess the quality of the synthesized material: the analysis of the Raman and XPS spectra provided insight on the number of layers and the nature of the limited defects introduced with the exfoliation procedure.Low-defectivity FLG was obtained at Gr/AL = 8 and a sonication time of 3 hours. Furthermore, Scanning Electron Microscopy and Dynamic Light Scattering were performed to investigate the size of the exfoliated flakes (∼ 400 nm). The procedure proposed represents a rapid route for the synthesis of FLG, which will be further explored for composites in chemiresistive devices.

The demand for robust engineering materials demonstrating good tribological performance under arduous service conditions has forged the development of novel coating materials and techniques. In the field of surface engineering, multilayer structures have attracted great interest. Electrodeposition offers a versatile and controlled route to engineering coatings in tribology. Electrodeposited coatings can provide tailored electronic, magnetic, mechanical, wear-resistant and corrosion-resistant characteristics as well as an improved load-bearing capability. The performance of multilayered electrodeposits can significantly exceed that of single layers. This paper critically reviews the fabrication, microstructure, engineering properties and potential applications of electrodeposited multilayer coatings. Such coatings can provide powerful, complementary additions to the toolkit for engineering electrodeposition, enabling future advances. Critical aspects requiring further R & D endeavors are identified.

Aerogels are commonly regarded as soft and versatile materials for multiple applications thanks to their features such as elastic behavior, swelling ability and responsive characteristics. In the last decades these qualities have ensured them multiple uses in biomedical field as controlled drug delivery systems and scaffolds for tissue engineering applications. Recently their employment as sensors has attracted great interest especially thanks to their tunability and the possibility to be used as soft material instead of conventional and many times unreliable sensors in multiple sensing applications. In this work we synthetized graphene oxide/polyaniline aerogels by in situ chemical polymerization of aniline monomer in aqueous dispersion of graphene oxide sheets. We characterized the system through chemical and mechanical analysis, and we its responsivity as gas sensing device was verified. Moreover, we investigated the influence of the encapsulation of graphene nanoplatelets on the responsive ability of the device. The addition of the graphene moieties improves the conductivity of the system, its compressive mechanical resistance and the applicability of these devices as gas sensors.

Ethylene glycol-based solutions containing metal precursor chloride salts were investigated for the electrodeposition of cobalt thin films and nanowires. The electrochemical behavior of 0.5 M Co(II) chloride solution at 70 °C was studied by means of cyclic voltammetry (CV) on a Pt substrate. The reduction process was shown to be irreversible, with high faradaic efficiencies (85–90 %). A diffusion coefficient (D0) of 2.29 × 10−6 cm2 s−1 for the Co species was estimated from the electrochemical behavior at different scan rates (from 25 to 125 mV s−1). The electrodeposition process was also studied on a copper substrate at different cathodic potentials (from −0.75 V vs Pt to −0.95 V vs Pt). Field-emission scanning electron microscopy (FE-SEM) and electron dispersive spectroscopy (EDS) revealed high-purity, compact films. Template-assisted electrodeposition resulted in ~16–18 μm long cobalt nanowires with an aspect ratio L/D > 100. X-ray diffraction (XRD) analysis of Co thin films showed a preferential orientation along the HCP [100] direction, which was even more marked for the nanowires. Vibrating sample magnetometry (VSM) highlighted that the fact that Co thin films were magnetized in-plane, while in nanowires a competition between shape and magnetocrystalline anisotropy led to similar magnetic behavior for the in-plane and out-of-plane directions. Keywords: Organic solvent, Magnetization, Non-aqueous, Electroplating, Alumina template

Targeted drug delivery is currently emerging as a promising approach to overcome the limits of currently employed administration techniques. The most convenient methodology to control drug delivery is the application of stimuli-responsive materials, which can release drugs only when required, to remotely controlled microdevices able to navigate human body. Thanks to this synergy, release can be controlled both spatially and temporally. Spatial control is guaranteed by the maneuverability of the devices, which can be precisely guided to release in targeted locations. Temporal control, conversely, is guaranteed by the functionalization introduced in the stimuli-responsive material. In this context, the present work describes the coating of magnetically controlled microdevices with functionalized alginate-based hydrogels able to release drugs at pH values lower than 4.5. Hydrogels are functionalized binding the drug with either an azidoethyl ester bond or an amidic bond, following an innovative synthesis route. After fabrication, release from hydrogel coated microdevices as a function of the environmental pH is characterized. Finally, devices are magnetically actuated and the possibility to achieve spatially and temporally controlled release is demonstrated. The functional microtransporters described in the present work are particularly promising for in-vivo applications in environments where pH differences are present, like the digestive apparatus.

A chloride-free solution based on ethylene glycol was shown to be suitable for the electrodeposition of copper onto zinc, allowing the fabrication of a Mo/Zn/Cu/Sn metallic precursor stack. The addition of diethanolamine (DEA) played an essential role in minimizing displacement reactions by shifting copper reduction towards a more negative potential. The electrochemical behavior of copper species with and without DEA was studied by cyclic voltammetry, and subsequently confirmed by displacement reaction assessment (OCV and ICP-OES measurements). The metallic stack was characterized by SEM and AFM, showing the effectiveness of the copper plating solution. Reactive annealing was carried out in a tubular furnace to obtain the CZTS kesterite semiconductor, as confirmed by XRD and Raman spectroscopy. Keywords: Organic solution, Ethylene glycol, Diethanolamine, Chloride-free, CZTS