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Superhydrophobic and wear abrasion resistant high impact polystyrene (HIPS)/silica nanocomposite coatings for metal surfaces have been produced by spray. An environmentally friendly perfluorinated acrylic copolymer (PFAC) primer coating layer was applied first, in order to enhance adhesion with the substrate and prolong abrasion resistance. The best nanocomposite composition was found to be 50% silica nanoparticles with respect to HIPS by weight. This coating displayed the lowest friction coefficient compared to other nanocomposites with lower or higher silica concentrations. Tribological experiments on the best performing nanocomposites indicated that wear tracks or marks had no debris, cracks or complete material removal. Furthermore, Taber® abrasion tests confirmed tribological findings and showed that the best nanocomposites resisted superhydrophobic degradation up to 35 continuous linear abrasion cycles (15 kPa). Nanocomposites made with general purpose polystyrene instead of HIPS could only resist up to 15 Taber® abrasion cycles. The reason was attributed to the mechanical energy dissipation capability of rubber domains in HIPS. Thermal annealing of the coatings had a deterministic effect on the durability of the coatings against wear induced loss of superhydrophobicity. Annealed and non-annealed coatings were characterized by Fourier transform infrared and X-ray photoelectron spectroscopy. Due to ease of fabrication, resultant mechanical robustness, use of non-toxic materials, and low-cost industrial scale availability of HIPS, nanoparticles and the primer polymer, these coatings can be effortlessly transformed into larger scale non-wettable protective treatments for metals. [ABSTRACT FROM AUTHOR]

Microcrystalline cellulose (MCC) and polyamide 66 (PA66) have been separately dissolved in solutions containing trifluoroacetic acid (TFA) as a common solvent, mixed after their dissolution and cast. After solvent evaporation, self-organized membranes have been formed with three dimensional (3D) porous, interconnected morphology, the porosity of which depends on the relative ratio of cellulose and PA66, and is lost when the initial MCC content exceeds 50% by weight. Thermal and chemical analysis and X-ray diffraction results indicate that the addition of cellulose induces the amorphisation of PA66, while possible chemical interaction exists between the amorphous parts of PA66 and the cellulose. The various membranes produced with different 3D porosities have been characterized in terms of dielectric constant and salt permeability and their relation to cellulose-PA66 ratio has been determined. [ABSTRACT FROM AUTHOR]

In this study, active biocomposite films of low-density polyethylene (LDPE) containing 5% wt. of curcumin, a natural chemical produced by some plants, are developed by melt extrusion and hot pressing. The detailed study of the physicochemical properties of the formed films demonstrates that the curcumin molecules, homogeneously dispersed in the whole volume of the LDPE matrix, cause a notable increase in the thermal stability of the LDPE polymer, without altering its thermal processability. At the same time the LDPE's water vapor barrier properties are significantly improved, while an effective antioxidant scavenging activity is observed against the 2,2-diphenyl-1-picrylhydrazyl free radicals (DPPH•). These results indicate that the developed active films based on the combination of LDPE and curcumin, following industrially applied preparation methods, are ideal candidates for active food packaging applications. Image 1 • Highly antioxidant food packaging films from low-density polyethylene (LDPE) and curcumin. • Excellent water vapor barrier properties. • High thermal stability without altering thermal processability. • Fabrication through industrially applicable methods. [ABSTRACT FROM AUTHOR]

Amorphous cellulose and poly(methyl methacrylate) (PMMA) blends in the form of free standing transparent hybrid films were prepared by dissolving both polymers in trifluoroacetic acid (TFA). Ultraviolet–visible (UV–vis) measurements indicated that the transparency of the films was always maintained regardless of cellulose-PMMA proportions. In addition, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) measurements were carried out in order to characterize the chemical composition, intermolecular interactions and the crystallinity of the hybrid films. Thermo-gravimetric analysis (TGA), differential scanning calorimeter (DSC) and tensile test measurements demonstrated that amorphous cellulose improved the thermal and mechanical properties of PMMA considerably. Scanning electron microscope (SEM) and atomic force microscopy (AFM) measurements showed that hybrid films had no micron scale phase separation or segregation, resulting in highly uniform and homogenous miscibility between amorphous cellulose and PMMA. The wetting characteristics of the hybrid films were also studied by water contact angle measurements. Hybrid films showed better water barrier properties in comparison to commercial paper packaging. Furthermore, the hybrid films exhibited relative high dissolution resistance to common organic solvents, which dissolve PMMA completely. Considering the recent interest in polymer blends based on natural and synthetic macromolecules, these new transparent hybrids can have various potential applications particularly in general packaging and biomedical technologies. [ABSTRACT FROM AUTHOR]

• Graphene has a stimulatory effect on neuronal differentiation of N2a cells. • The adhesion factor polylysine enhances the stimulatory effect. • The physicochemical features of polylysine on graphene act as cues for N2a cells. • Polylysine–coated graphene is promising for regenerative medicine. We compared the proliferation and differentiation of mouse neuroblastoma Neuro 2A cell line on single layer graphene and glass substrates. Quantitative and qualitative analysis of the cell proliferation and differentiation were performed, considering also the effect of a common adhesion factor, namely polylysine. We observed that on graphene substrates the cells proliferate faster with respect to glass; additionally, the presence of the adhesion factor enhances the difference and, remarkably, boosts the cell differentiation on the graphene-based interface. To understand the mechanism underlying a different cell behavior on the same adhesion coating, we carried out a physicochemical investigation of the studied interfaces (glass and graphene, bare and polylysine coated) by several techniques. In particular, we employed infrared spectroscopy to gain information on polylysine conformation, and atomic force microscopy force-distance curves to study adhesion properties at the surface. The results indicate that polylysine has an enhanced binding affinity for graphene, as well as a different molecular arrangement on graphene with respect to glass. These properties act as surface cues to trigger the cell response. [ABSTRACT FROM AUTHOR]

All -PLA blends have been fabricated by an easily scalable and green melt-blending of linear-PLLA and 3-armed star-shaped PDLLA at different proportions (100:0, 95:5, 90:10, 80:20, and 50:50, w:w). The fabrication process, carried out in a hot-press, consisted of three steps: an initial heating of the thoroughly blended polymer mixtures at 170 °C for 5 min, a second heating at 170 °C for 5 min with a pressure of 200 Pa, and a final cooling at room temperature during 20 min keeping the same pressure. This methodology resulted in very homogenous amorphous samples, as revealed by XRD and DSC. The incorporation of star-PDLLA toughened the polylactide matrix by a clear ductilization, opening opportunities for the expanded use of the developed blends in different applications, due to their increased processability. DSC analysis revealed indeed that by increasing star-PDLLA content it is possible to gradually reduce the T g , as well as the capability of crystallization of the linear-PLLA component. Such properties determine a plasticizing effect on the final blends. The increased content of the star component turned the films from transparent to translucent and decreases the thermal decomposition temperatures, which remain in any case very well above room temperature. The water vapor transmission rates varied with the star-PDLLA content between values characteristic for isolating to breathable films, thus allowing the use of these blends in different applications such as food packaging and biomedical devices. Finally, no important changes of water contact angle and water uptake were observed between the different blends. Despite the negligible effect of seawater on the biodegradation of commercial PLA, star-PDLLA-containing blends showed high biodegradation rates at short-times in marine environments, reinforcing the environmentally friendly character of polylactide. Image 1 • All -PLA blends have been fabricated by melt-blending of linear and star PLA. • The incorporation of star PLA toughened the polylactide matrix. • These blends showed high biodegradation rates at short-times in marine environments. [ABSTRACT FROM AUTHOR]