Textile with Durable Janus Wetting Properties Produced by Plasma Polymerization

The development of coating methods that enable us to combine antagonist properties on a single material is a real challenge. This active research topic can impact, for instance, the textile field to engineer fabrics with liquid-repellent properties on one side and superhydrophilic properties on the opposite side. In this context, we have developed an easy surface functionalization process that provides durable Janus wetting properties to fabrics. On the basis of plasma-enhanced chemical vapor deposition (PECVD), we report a simple and reproducible three-step functionalization method that led to a coating with superhydrophobic and superoleophobic properties on one side of the porous substrate and superhydrophilic properties on the opposite side. A thin, fluorinated polymer film was deposited on one side, while the other side was functionalized with a polymer coating made of maleic anhydride, subsequently hydrolyzed to provide carboxylic acid groups to the surface. Static contact angles up to 169° with water and 162° with hexadecane were obtained on the fluorinated side of the fabric thanks to an appropriate combination of surface chemistry with dual-scale surface roughness. In addition, roll-off angles of 6 and 14° with water and hexadecane, respectively, were measured on this side of the sample. As for the opposite side, the hydrolyzed plasma polymer made of maleic anhydride enables us to obtain a surface that fully absorbs water and hexadecane. In addition, these tremendous properties were durable because no significant change was observed after aging and washing cycles. This simple surface functionalization process based on plasma polymerization is an innovative solution for the fabrication of textile with durable waterproof and breathable properties. Besides, the described concept can be adapted to numerous other applications that require Janus properties to porous substrates

Laser Ablation of Silver in Liquid Organic Monomer: Influence of Experimental Parameters on the Synthesized Silver Nanoparticles/Graphite Colloids

During the past decade, synthesizing silver nanoparticles (Ag NPs) by liquid phase-pulsed laser ablation (LP-PLA) has attracted a lot of attention. Basically, this technique allows producing various metallic nanoparticles with controlled size, shape, composition, or surroundings in several liquids (i.e., water, ethanol, acetone, toluene, and so forth). Recently, such processes have been studied in liquid organic monomer such as methyl methacrylate (MMA). However, the influence of the laser parameters on the materials synthesized in such reactive liquid and their features were not fully investigated so far. Here we investigate the LP-PLA of silver in two different but rather similar acrylate monomers: dodecyl acrylate (DOCA) and 1H,1H,2H,2H perfluorodecyl acrylate (PFDA). The influence of the fluence and the number of pulses on the production, size, and morphology of the materials has been examined. First, factorial design experiments have been achieved in order to determine the weight of the laser parameters in each precursor. This study shows two highly different behaviors in function of the monomer where the process took place. This has been explained by the plasma plume confinement and/or the “interpulses” self-absorption of the particles by the laser beam. The formation of graphite around the synthesized AgNPs has been highlighted by Raman spectroscopy at low number of pulses. Nevertheless, increasing the number of pulses could lead to three phenomenon depending on the fluence and the used monomer: degradation of the matrix, conservation of the matrix with changes in AgNPs size and distribution, or sustainment of the matrix with any changes in the particles properties. So the surrounding, the size, and stability could be triggered by adjusting these parameters. This paper does highlight that LP-PLA is a powerful technique to provide AgNPs in acrylate monomer with a good control of their features

Abnormal Enhancement of the Photoisomerization Process in a <i>trans</i>-Nitroalkoxystilbene Dimer Sequestered in β‑Cyclodextrin Cavities

We report on the synthesis and the photophysical properties of a <i>trans</i>-nitroalkoxystilbene dimer (DPNS). The fluorescence quantum yield (Φ_f), the Stokes shift, and the quantum yield for the <i>trans</i>-to-<i>cis</i> photoisomerization (Φ_<i>t→c</i>) are strongly dependent on the nature of the solvent. Upon increasing solvent polarity, Φ_f increases together with the decrease of Φ_<i>t→c</i>. This solvent-induced reverse behavior mainly stems from the progressive stabilization of a highly polar twisted internal charge transfer state (TICT) at excited singlet level which opens a competing channel to photoisomerization. In the presence of hydroxylic substrates (i.e., alcohols or water), fluorescence of DPNS is strongly quenched due to a hydrogen bonding interaction at excited state. The efficiency of the process is clearly correlated to the H-bond donor ability of the quencher. In aqueous solution, the major formation of a 2:1 host–guest complex with β-cyclodextrins (β-CD) prevents the quenching by H₂O and leads to a 50-fold increase of the fluorescence signal together with a strong band blue-shift with respect to that of the free chromophore. This latter effect was rationalized in terms of a severe reduction of the solvent-induced stabilization of the TICT state. As a consequence, the <i>trans</i>-to-<i>cis</i> photoisomerization reaction is reactivated and leads to a paradoxical 14-fold increase of Φ_<i>t→c</i> even though DPNS is sequestered in β-CD cavities

Biomimetic Cryptic Site Surfaces for Reversible Chemo- and Cyto-Mechanoresponsive Substrates

Chemo-mechanotransduction, the way by which mechanical forces are transformed into chemical signals, plays a fundamental role in many biological processes. The first step of mechanotransduction often relies on exposure, under stretching, of cryptic sites buried in adhesion proteins. Likewise, here we report the first example of synthetic surfaces allowing for specific and fully reversible adhesion of proteins or cells promoted by mechanical action. Silicone sheets are first plasma treated and then functionalized by grafting sequentially under stretching poly(ethylene glycol) (PEG) chains and biotin or arginine-glycine-aspartic acid (RGD) peptides. At unstretched position, these ligands are not accessible for their receptors. Under a mechanical deformation, the surface becomes specifically interactive to streptavidin, biotin antibodies, or adherent for cells, the interactions both for proteins and cells being fully reversible by stretching/unstretching, revealing a reversible exposure process of the ligands. By varying the degree of stretching, the amount of interacting proteins can be varied continuously