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This study is aimed at the synthesis of antimicrobial hydroxyapatite (HAP)‐based composites for dental application by stereolithography (SLA). A micron‐sized commercial HAP was modified by methacrylate and quaternary ammonium salt, and, then, it was used in different amounts (namely 2.5, 5, and 10 wt%) as filler for a photocurable custom made resin for SLA. Thermal stability, microstructure, and particles size of the pristine (HAP) and modified HAP (mHAP) were evaluated by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and particle size analyser (CILAS). The suitability of each formulation for stereolithography process was assessed by measuring viscosity, degree of conversion (DC%) by Fourier transform infrared spectroscopy (FTIR), glass transition temperature, and thermal stability. Photo‐cured specimens for physical, mechanical, and antimicrobial testing were built by SLA. The flexural strength of the samples was measured using a 3‐point bending test method, and the fractured surface was analysed by scanning electron microscopy (SEM). The antimicrobial activity of samples was investigated against some standard microorganisms (Staphylococcus aureus, Escherichia coli, and Candida albicans), as representative Gram positive and Gram negative bacteria and fungus, respectively. The flexural strength increased with a filler content up to 5% and slightly decreased for higher content. SEM analysis confirmed the presence of uniformly distributed HAP. The incorporation of mHAP reduced the bacterial and fungal growth in dose‐dependent manner in comparison with the neat samples. Finally, a prototype of dental bite was built by SLA.

In order to guarantee a very high preservation of stone artworks from water actions, an experimental superhydrophobic photopolymerizable organic–inorganic (O-I) nanostructured hybrid product, namely HEP, has been developed and tested on a calcarenitic stone characteristic of Apulia Region (Italy), i.e., Pietra Leccese (PL). HEP is a “green” product, not containing harmful solvents, and is able to quickly set and harden at room temperature. The first part of the work was devoted to the analysis of the dimension of the silica nanodomains and the suitability of the liquid system produced to be applied on stone surfaces. To this aim, dynamic light scattering and rheological analyses were performed after different times from the preparation of the O-I system. The hybrid mixture was subsequently applied on a glass substrate and photopolymerized by UV lamp. Several physical properties (glass transition temperature, transparency, scratch, and surface hardness) were, then, measured on the hybrid coating: a substantial improvement of all the surface properties measured was observed. HEP was, finally, applied on PL elements and different analytical techniques (contact angle, colorimetric and water absorption measurements, liquid water, and vapor water transmission) were used to fully characterize the product in terms of hydrophobicity, protective efficacy, water penetration resistance, and transpiring capability. The protective properties of the novel hybrid coating were also compared with those of two commercial water-repellent products, applied on the same stone substrate, evidencing that the experimental coating is able to equal the performance of high-quality commercial products. POLYM. COMPOS., 36:1039–1047, 2015. © 2015 Society of Plastics Engineers

The current “gold standard” to treat bone lesions is allografts and autografts, both presenting important disadvantages such as risk of infection and morbidity. Synthetic grafts and scaffolds for bone regeneration represent a promising solution. Fused deposition modeling is a valid tool for developing synthetic bone grafts of complex shapes, which is a key issue. The possibility of building polylactic acid–nanohydroxyapatite (PLA/nanoHA) composites by 3D printing was systematically evaluated. PLA/nanoHA filaments for low-cost 3D printers were produced by a multistep solvent-free procedure and characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry, and rheometry. TGA analysis confirmed the presence of the nanoHA amounts used in the composites, equal to 5 and 15 wt %. The glass-transition temperature and degree of crystallinity of PLA are not influenced by presence of nanoHA, which remains substantially amorphous. The morphological analysis and compression testing on printed samples showed that nanoHA was uniformly dispersed within the PLA matrix and improved the PLA mechanical properties without changing the rheological performance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 134, 44656.

Novel UV-photopolymerizable siloxane-modified methacrylate/Boehmite nanocomposites were experimented as possible protective coatings for different substrates. To this aim, unfilled and Boehmite-filled suspensions were applied and photocured on a glass substrate. A subsequent detailed experimental characterization was performed in order to evaluate the effect of the presence of Boehmite nanoparticles on the surface properties of the coatings and on their durability characteristics. In particular, transparency, glass transition temperature, scratch, and surface hardness, contact angle, and color change were measured on the coatings applied on glass support before and after QUV accelerated weathering cycles. POLYM. COMPOS., 00:000‐000, 2013. a 2013 Society of Plastics Engineers

A deep study on the possibility to increase the quality of the dispersion of organically modified Boehmite nanoparticles into photo-polymerizable methacrylic-siloxane monomers, to be used as coatings, was conducted using unconventional indirect analy- ses. The nanocomposite were produced using two different procedures, starting from the conventional ''solvent dispersion method.'' The two procedures used differ for the technique used to obtain the dispersion of Boehmite, i.e., sonication or magnetic stirring and for the time used in each procedure. The efficiency of each method of preparation of nanostructured systems was analyzed, both in the liquid (uncured) and ultraviolet (UV) cured state. First, dynamic light scattering and rheological measurements were performed on the liquid suspensions, supplying experimental data used in proper theoretical models to estimate the dimensions and distribution of Boehmite particles. The suspensions obtained with the two different methods were, then, UV cured obtaining thin and thick films, on which scanning electron microscopy and transmittance measurements were performed. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 4102-4109, 2013

In this work, nanocomposite adhesives obtained using an organically modified montmorillonite (OMM) in a polyurethane matrix were studied. The basal distance of OMM before and after mixing with the polyol and after curing was characterized by X-Ray diffraction. The viscosity of polyols-OMM systems was studied as function of shear rate in a cone-plate rheometer in order to correlate the viscosity with the aggregation state of OMM. A simple model accounting for an apparent increase of rheological units size associated with the intercalation of macromolecules into OMM galleries is proposed. Curing was performed at room temperature for 1 week. The basal distances of crosslinked PU nanocomposites were obtained by X-ray diffraction. The glass transition temperature, Tg, of PU nanocomposites, as measured using differential scanning calorimetry, increases with increasing volume fraction of OMM. Finally, the permeability to oxygen and water vapor of polyurethane clay-nanocomposites was measured. The gas permeation through the composites was correlated to the volume fraction of the impermeable inorganic part of the OMM. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers