The possibility to impart surface properties to any polymeric substrate using a fast, reproducible, and industrially friendly procedure, without the need for surface pretreatment, is highly sought after. This is in particular true in the frame of antibacterial surfaces to hinder the threat of biofilm formation. In this study, the potential of aryl‐azide polymers for photofunctionalization and the importance of the polymer structure for an efficient grafting are demonstrated. The strategy is illustrated with a UV‐reactive hydrophilic poly(2‐oxazoline) based copolymer, which can be photografted onto any polymer substrate that contains carbon–hydrogen bonds to introduce antifouling properties. Through detailed characterization it is demonstrated that the controlled spatial distribution of the UV‐reactive aryl‐azide moieties within the poly(2‐oxazline) structure, in the form of pseudogradient copolymers, ensures higher grafting efficacy than other copolymer structures including block copolymers. Furthermore, it is found that the photografting results in a covalently bound layer, which is thermally stable and causes a significant antiadherence effect and biofilm reduction against Escherichia coli and Staphylococcus epidermidis strains while remaining noncytotoxic against mouse fibroblasts.

A novel and simple method for the measurement of cloud point temperatures of solutions is presented. Cloud point determination , which is currently used to establish the phase diagrams of protein solutions, is indicative of proteins interactions and constitutes a useful tool for food products engineering. We describe a novel experimental setup that allows screening of a large number of physical-chemical conditions in one measurement and the determination of cloud point temperatures both above and below ambient temperature. We use a simple method to avoid solvent evaporation and condensation, so that the setup can be used for solutions prepared with a volatile solvent. We present the operating parameter range and the precision of the measurement. The optical properties of the system are calibrated with solutions of known transmittance, and the determination of cloud point temperatures is validated on a standard non-ionic surfactant solution. Finally, we demonstrate the efficiency of the method by determining the phase diagram of a wheat protein extract, soluble in a water/ethanol mixture. Complemented with differential scanning calorimetry measurements, the liquid-liquid phase transition can be determined up to a protein concentration of 250 g/L, a range inaccessible with conventional methods for this protein extract.

The paper will discuss the possibility for light spectroscopies, e.g. Brillouin Light Scat- tering or Raman Scattering, to locally monitor the densification of amorphous silica. It is indeed well-known that silica significantly densifies under high stresses, either elastically as for example during a high-pressure experiment in a diamond-anvil cell below about 10 GPa or plastically above that limit. Further, this elastic limit strongly depends on the temperature. Irradiation-induced density changes are also observed using ultra-short laser pulses, neutrons or other particles. All these different routes lead to substantial structural modifications which in turn alter the response of silica to light spectroscopy in a complex manner.

High-pressure Brillouin [1] and polarized Raman spectra [2] of vitreous silica are measured up to 8 GPa in diamond-anvil cell at room temperature. On one hand, Brillouin frequencies show that the well-known anomalous maximum in the pressure dependence of the compressibility is suppressed by He incorporation into the silica network. This shows that the elastic anomaly relates to the collapse of the largest interstitial voids in the structure. On the other hand, the combined use of either a nonpenetrating pressurizing medium-argon-or a penetrating one-helium and Neon, allows one to separate density from stress effects on the Raman frequencies.[1]C. Weigel, A. Polian, M. Kint, B. Ruffl ́e, M. Foret, and R. Vacher, Phys. Rev. Lett. 109, 245504 , 2012[2]C. Weigel, M. Foret, B. Hehlen, M. Kint, S. Cl ́ement, A. Polian, R. Vacher, and B. Ruffl ́e, Phys. Rev. B 93, 224303 , 2016

We report measurements and theoretical predictions on the effect of an aligning magnetic field on the orientational disorder of a nematic liquid crystal in contact with isotropic solid substrates. Different types of substrates present a similar disorder and a similar dependency on the magnetic field amplitude, i.e. a decreasing of the angular distribution widths and spatial correlation lengths. Measurements are in qualitative agreement with a theory where the orientational disorder emerges from the competition between the aligning magnetic torque and the disorienting thermal fluctuations during the adsorption of the liquid crystal molecules on the substrate.

Fracture propagation is inherently a multiscale problem, involving the coupling of many length scales from sample dimension to molecular level. Fracture mechanics provides a valuable link between the macroscopic scale of the structural loading of the samples and the scale of the process zone for brittle materials. Modeling the toughness of materials requires yet an investigation at scales smaller than this process zone, which is nanometric in oxide glasses and micrometric in polymer glasses.We present here the important insights that have been obtained through an in situ experimental investigation of the strain fields in the micrometric neighborhood of a propagating crack. We show the richness of atomic force microscopy combined with digital image correlation although it limits the observations to the external surface of the sample and to very slow crack propagation (below nm/s). For oxide glasses, this novel technique provided enlightening information on the nanoscale mechanisms of stress corrosion during subcritical crack propagation (Ciccotti, J Phys D Appl Phys 42:214006, 2009; Pallares et al., Corros Rev 33(6):501–514, 2015), including the relevance of crack tip plasticity (Han et al., EPL 89:66003, 2010), stress-induced ion exchange processes (Célarié et al., J Non-Cryst Solids 353:51–68, 2007), and capillary condensation in the crack tip cavity (Grimaldi et al., Phys Rev Lett 100:165505, 2008; Pallares et al., J Am Ceram Soc 94:2613–2618, 2011). An extension of this technique has recently been developed for glassy polymers (George et al., J Mech Phys Solids 112:109–125, 2018), leading to novel insights on the transition between crazing and shear yielding mechanisms and to promising new ways to link the toughness properties to the time-dependent large strain material properties of these nominally brittle materials.