Droplet Memory on Liquid-Infused Surfaces

The knowledge of droplet friction on liquid-infused surfaces (LIS) is of paramount importance for applications involving liquid manipulation. While the possible dissipation mechanisms are well-understood, the effect of surface texture has thus far been mainly investigated on LIS with highly regular solid topographies. In this work, we aim to address this experimental gap by studying the friction experienced by water droplets on LIS based on both random and regular polysilsesquioxane nanostructures. We show that the available models apply to the tested surfaces, but we observe a previously unreported droplet memory effect: as consecutive droplets travel along the same path, their velocity increases up to a plateau value before returning to the original state after a sufficiently long time. We study the features of this phenomenon by evaluating the motion of droplets when they cross the path of a previous sequence of droplets, discovering that moving droplets create a low-friction trace in their wake, whose size matches their base diameter. Finally, we attribute this to the temporary smoothing out of an initially conformal lubricant layer by means of a Landau–Levich–Derjaguin liquid film deposition behind the moving droplet. The proposed mechanism might apply to any LIS with a conformal lubricant layer

Silicon Oxycarbide Coatings Consisting of Defined Bottom–Up‐Grown Nanostructures

Silicon oxycarbide (SiOC) materials have arisen in the past few decades as a promising new class of glasses and glass-ceramics thanks to their advantageous chemical and thermal properties. Many applications, such as ion storage, sensing, filtering, or catalysis, require materials or coatings with high surface area and might benefit from the high thermal stability of SiOC. This work reports the first facile bottom–up approach to textured high surface area SiOC coatings obtained via direct pyrolysis of polysiloxane structures of well-defined shapes, such as nanofilaments or microrods. This work further investigates the thermal behavior of these structures by means of FT-IR, SEM, and EDX up to 1400 °C. The rods shrink in volume by ≈30% while their aspect ratio remains unaffected by pyrolysis until at least 1100 °C. The nano-sized filaments show signs of viscous flow already at a comparably low temperature of 900 °C which is very probably due to the nano-size effect. This might open a way to experimentally study the size-effect on the glass transition temperature of oxide glasses, an experimentally unexplored but very relevant topic. These structures have great potential, for example, as ion storage materials and supports in high temperature catalysis and CO2 conversion

Printable and Versatile Superhydrophobic Paper via Scalable Nonsolvent Armor Strategy

Despite great scientific and industrial interest in waterproof cellulosic paper, its real world application is hindered by complicated and costly fabrication processes, limitations in scale-up production, and use of organic solvents. Furthermore, simultaneously achieving nonwetting properties and printability on paper surfaces still remains a technical and chemical challenge. Herein, we demonstrate a nonsolvent strategy for scalable and fast fabrication of waterproofing paper through in situ surface engineering with polysilsesquioxane nanorods (PSNR). Excellent superhydrophobicity is attained on the functionalized paper surface with water contact angle above 160˚. Notably, the engineered paper features outstanding printability and writability, as well as greatly enhanced strength and integrity upon prolonged exposure to water (tensile strength ≈ 9.0 MPa). Additionally, the PSNR concurrently armors paper-based printed items and artwork with waterproofing, self-cleaning and antimicrobial functionalities without compromising their appearance, readability and mechanical properties. We also demonstrate that the engineered paper holds the additional advantages of easy processing, low cost and mechanochemical robustness, which makes it particularly promising for real world applications

Silicone nanofilaments grown on aircraft alloys for low ice adhesion

Many novel icephobic coatings have been shown to exhibit low adhesion strength to ice grown at null or low velocity. Of these, few have been shown to also exhibit low adhesion strength to ice grown by impacting high velocity supercooled water droplets. Even fewer of these have been shown to exhibit low adhesion strength to ice grown over a range of environmental conditions. Those that have shown such behavior have been held back by their susceptibility to certain bands of UV-exposure. Here, icephobic coatings made from Silicone Nanofilament (SNF) networks grown on anodic metal oxide surfaces are presented. They show low ice adhesion strength for a range of impact icing conditions and exhibit good durability against the tested conditions. Additionally, their nano-porous structure provides enhanced lubricant retention when infused with oil. The described coatings are a promising candidate for supporting hybrid ice protection systems on aircraft, thereby reducing the energy needed for anti−/de-icing

Droplet Memory on Liquid-Infused Surfaces

The knowledge of droplet friction on liquid-infused surfaces (LIS) is of paramount importance for applications involving liquid manipulation. While the possible dissipation mechanisms are well-understood, the effect of surface texture has thus far been mainly investigated on LIS with highly regular solid topographies. In this work, we aim to address this experimental gap by studying the friction experienced by water droplets on LIS based on both random and regular polysilsesquioxane nanostructures. We show that the available models apply to the tested surfaces, but we observe a previously unreported droplet memory effect: as consecutive droplets travel along the same path, their velocity increases up to a plateau value before returning to the original state after a sufficiently long time. We study the features of this phenomenon by evaluating the motion of droplets when they cross the path of a previous sequence of droplets, discovering that moving droplets create a low-friction trace in their wake, whose size matches their base diameter. Finally, we attribute this to the temporary smoothing out of an initially conformal lubricant layer by means of a Landau–Levich–Derjaguin liquid film deposition behind the moving droplet. The proposed mechanism might apply to any LIS with a conformal lubricant layer

Coral-like silicone nanofilament coatings with extremely low ice adhesion

Passive icephobic surfaces can provide a cost and energy efficient solution to many icing problems that are currently handled with expensive active strategies. Water-repellent surface treatments are promising candidates for this goal, but commonly studied systems, such as superhydrophobic surfaces and Slippery Liquid Infused Porous Surfaces (SLIPS), still face challenges in the stability and durability of their properties in icing environments. In this work, environmental icing conditions are simulated using an Icing Wind Tunnel, and ice adhesion is evaluated with a Centrifugal Adhesion Test. We show that superhydrophobic coral-like Silicone Nanofilament (SNF) coatings exhibit extremely low ice adhesion, to the point of spontaneous ice detachment, and good durability against successive icing cycles. Moreover, SNFs-based SLIPS show stably low ice adhesion for the whole duration of the icing test. Stability of surface properties in a cold environment is further investigated with water wettability at sub-zero surface temperature, highlighting the effect of surface chemistry on superhydrophobicity under icing conditions.publishedVersionPeer reviewe

Hydrophobic Coatings by Thiol-Ene Click Functionalization of Silsesquioxanes with Tunable Architecture

The hydrolysis-condensation of trialkoxysilanes under strictly controlled conditions allows the production of silsesquioxanes (SSQs) with tunable size and architecture ranging from ladder to cage-like structures. These nano-objects can serve as building blocks for the preparation of hybrid organic/inorganic materials with selected properties. The SSQs growth can be tuned by simply controlling the reaction duration in the in situ water production route (ISWP), where the kinetics of the esterification reaction between carboxylic acids and alcohols rules out the extent of organosilane hydrolysis-condensation. Tunable SSQs with thiol functionalities (SH-NBBs) are suitable for further modification by exploiting the simple thiol-ene click reaction, thus allowing for modifying the wettability properties of derived coatings. In this paper, coatings were prepared from SH-NBBs with different architecture onto cotton fabrics and paper, and further functionalized with long alkyl chains by means of initiator-free UV-induced thiol-ene coupling with 1-decene (C10) and 1-tetradecene (C14). The coatings appeared to homogeneously cover the natural fibers and imparted a multi-scale roughness that was not affected by the click functionalization step. The two-step functionalization of cotton and paper warrants a stable highly hydrophobic character to the surface of natural materials that, in perspective, suggests a possible application in filtration devices for oil-water separation. Furthermore, the purification of SH-NBBs from ISWP by-products was possible during the coating process, and this step allowed for the fast, initiator-free, click-coupling of purified NBBs with C10 and C14 in solution with a nearly quantitative yield. Therefore, this approach is an alternative route to get sol-gel-derived, ladder-like, and cage-like SSQs functionalized with long alkyl chains

Strategia, programmazione e valutazione delle performance alla luce del D. Lgs. 150/2009 nei servizi sanitari regionali: modello concettuale ed implicazioni operative

Al fine di supportare i processi di programmazione e valutazione dei risultati conseguiti dai sistemi sanitari nazionali e regionali risulta fondamentale introdurre, nella gestione aziendale, indicatori e strumenti in grado di misurare, valutare e valorizzare le dimensioni delle performance organizzative e individuali. Il modello logico-concettuale presentato in questo contributo, lungi dall’essere una panacea in grado di risolvere tutte le criticità legate alla gestione del ciclo della performance, si propone di essere un tentativo di porre chiarezza all’interno del contesto della riforma in atto, puntando sulle caratteristiche salienti di strumenti manageriali che sono noti e già ampiamente utilizzati in contesti for profit e not for profit. Tuttavia, se, da una parte, vi sono strumenti e metodologie ben noti, dall’altra non sempre i manager hanno la possibilità di utilizzarli al meglio. Occorre, quindi, prestare attenzione alle caratteristiche salienti del proprio modello organizzativo per far sì che vi sia un adattamento progressivo degli strumenti e delle logiche in questione.In order to support the processes of planning and assessment of achievements of national and regional health systems it is essential to introduce, in business management, indicators and tools able to measure, evaluate and enhance the organisational and individual performance. The logicalconceptual model presented in this paper, far from being a panacea able to solve all the problems related to the management of the performance cycle, is proposed to be an attempt to bring clarity to the internal context of the ongoing reform, focusing on the salient features of management tools that are known and already widely used in contexts of ‘for profit’ and ‘not for profit’. However, if, on the one hand, there are tools and methodologies well known by others, not always do managers have the opportunity to use them well. It is, therefore, necessary to pay attention to salient features of their organisational model to be sure that there is a progressive adaptation of the tools and logic in question