Wood Surface Modification with Hybrid Materials Based on Multi-Walled Carbon Nanotubes.

In this work, new treatments based on multi-walled carbon nanotubes (MWCNTs), MWCNTs decorated with zinc oxide (ZnO), MWCNTs decorated with hydroxyapatite (HAp) and MWCNTs decorated with silver (Ag) nanoparticles dispersed in PHBHV solution are proposed for improving sound oak wood properties. We hypothesize that the solutions containing decorated MWCNTs will be more efficient as wood consolidants, not only because of the improved mechanical properties of the treated wood but also because of the hydrophobic layer created on the wood surface. In order to test these hypotheses, the treatments' potential was investigated by a number of complex methods, such as colorimetric parameter measurements, water absorption tests, mechanical tests, artificial aging and antifungal tests. The data confirm that the treated wood materials have moderate stability, and the color differences are not perceived with the naked eye. A significant improvement of the treated samples was observed by water absorption, humidity and mechanical tests compared to untreated wood. The best results were obtained for samples treated by brushing with solutions based on decorated CNTs, which confirms that a uniform and thicker layer is needed on the surface to ensure better protection. The wood behavior with accelerated aging revealed that the control sample degraded faster compared to the other treated samples. Antifungal tests showed that higher growth inhibition was obtained for samples treated with 0.2% MWCNTs_ZnO + PHBHV. Considering all of the obtained results, it can be concluded that the most effective treatment was MWCNTs_ZnO + PHBHV at a nanocomposite concentration of 0.2%, applied by brushing. Thus, wood protection against mold and fungi will be achieved, simultaneously ensuring improved mechanical strength and water barrier properties and therefore maintaining the structural integrity of sound oak wood over time.

Biocompatible and Antimicrobial Cellulose Acetate-Collagen Films Containing MWCNTs Decorated with TiO2 Nanoparticles for Potential Biomedical Applications.

This research focuses on the synthesis of multi-walled carbon nanotubes (MWCNTs) decorated with TiO2 nanoparticles (NPs) and incorporated in cellulose acetate-collagen film in order to obtain a new biomaterial with potential biomedical applications and improved antimicrobial activity. The successful decoration of the MWCNTs with TiO2 NPs was confirmed by several structural and morphological analysis, such as Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction and transmission electron microscopy. The obtained nanocomposites were further incorporated into cellulose acetate-collagen films, at different concentrations and absorption kinetics, antimicrobial activity and in vitro biocompatibility of the obtained films was investigated. The antimicrobial tests sustained that the presence of the nanocomposites into the polymeric matrix is an important aspect in increasing and maintaining the antimicrobial activity of the polymeric wound dressings over time. The biocompatibility and cytotoxicity of the obtained films was evaluated using cellular viability/proliferation assay and fluorescent microscopy which revealed the ability of the obtained materials as potential wound dressing biomaterial.

Hybrid Materials Based on Multi-Walled Carbon Nanotubes and Nanoparticles with Antimicrobial Properties.

In this study, multi-walled carbon nanotubes (MWCNTs) were decorated with different types of nanoparticles (NPs) in order to obtain hybrid materials with improved antimicrobial activity. Structural and morphological analysis, such as Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy, environmental scanning electron microscopy/energy-dispersive X-ray spectroscopy and the Brunauer-Emmett-Teller technique were used in order to investigate the decoration of the nanotubes with NPs. Analysis of the decorated nanotubes showed a narrow size distribution of NPs, 7-13 nm for the nanotubes decorated with zinc oxide (ZnO) NPs, 15-33 nm for the nanotubes decorated with silver (Ag) NPs and 20-35 nm for the nanotubes decorated with hydroxyapatite (HAp) NPs, respectively. The dispersion in water of the obtained nanomaterials was improved for all the decorated MWCNTs, as revealed by the relative absorbance variation in time of the water-dispersed nanomaterials. The obtained nanomaterials showed a good antimicrobial activity; however, the presence of the NPs on the surface of MWCNTs improved the nanocomposites' activity. The presence of ZnO and Ag nanoparticles enhanced the antimicrobial properties of the material, in clinically relevant microbial strains. Our data proves that such composite nanomaterials are efficient antimicrobial agents, suitable for the therapy of severe infection and biofilms.

Development of thermoplastic composites based on recycled polypropylene and waste printed circuit boards.

In the last several years, the electronic waste, especially printed circuit boards have significantly increased over the world, generating one of the highest rates of solid waste. The recycling process of the printed circuit boards implies mainly the recovery of metals and glass fibers, while the reuse of the polymeric support has remained largely in the phase of research. In this paper, the non-metallic part of printed circuit boards was used as filler (up to 30%), but also to improve the fire resistance of thermoplastic composites based on recycled polypropylene and diene block-copolymers. The synergy between the elastic effect of elastomers and the reinforcing effect of the waste powder into the thermoplastic matrix was studied by mechanical and dynamo-mechanical analysis, X-ray diffraction, optical microscopy, micro-calorimetry and thermo-gravimetrical analysis. Improved mechanical properties, especially impact strength was observed. The compatibization of components considering the interactions between the ethylene-butylene blocks from the hydrogenated and maleinized styrene-butadiene block-copolymer and recycled polypropylene, respectively between the MA groups and the functionalities of the waste powder, evidenced by FTIR, was highlighted by changes in the X-ray pattern and an increased fire resistance and thermal stability.

Nanomaterials Used in Conservation and Restoration of Cultural Heritage: An Up-to-Date Overview.

In the last few years, the preservation of cultural heritage has become an important issue globally, due to the fact that artifacts and monuments are continually threatened by degradation. It is thus very important to find adequate consolidators that are capable of saving and maintaining the natural aspect of these objects. This study aims to provide an updated survey of the main nanomaterials used for the conservation and restoration of cultural heritage. In the last few years, besides the classic nanomaterials used in this field, such as metal nanoparticles (copper and silver) and metal oxides (zinc and aluminum), hydroxyapatite and carbonated derivatives, tubular nanomaterials (such as carbon nanotubes) have been used as a potential consolidate material of cultural heritage. Tubular nanomaterials have attracted attention for use in different fields due to their structures, as well as their ability to present multiple walls. These nanotubes have the necessary properties in preserving cultural heritage, such as superior mechanical and elastic strength (even higher than steel), high hydrophobicity (with a contact angle up to 140°), optical properties (high photodegradation protection), large specific surface area (from 50 to 1315 m2/g, depending on the number of walls) for absorption of other nanomaterials and relatively good biocompatibility.