Preparation and characterization of BaSO4/poly(ethylene terephthalate) nanocomposites

Viscous Oil De-Wetting Surfaces Based on Robust Superhydrophilic Barium Sulfate Nanocoating

Viscous oil adherence onto solid surfaces is ubiquitous and has caused intractable fouling problems, impairing the function of solid surfaces in various areas such as optics and separation membranes. Materials with superhydrophilicity and underwater superoleophobicity are very effective in elimination of oil fouling. However, most of them cannot dewet viscous oils and may malfunction without prehydration treatment. Herein, we report a facile and environmental strategy to prepare barium sulfate (BaSO₄) nanocoating to dewet viscous oils on dry surfaces. Abundant surface polar groups (surface hydroxyl) on BaSO₄ nanocoating enhance both hydrophilicity after oil fouling (underoil water contact angle <10°) and underwater superoleophobicity (underwater-oil contact angle >155°) and then facilitate oil dewetting ability. Different oils with viscosity up to 900 mPa·s can be easily eliminated after immersion into water. The results and force analysis also demonstrate that small surface roughness and ultrahydrophilicity under oil are beneficial to achieve oil dewetting property on dry surfaces. Furthermore, BaSO₄ nanocoating displays excellent mechanical, thermal and chemical stability and can maintain oil repellency through various harsh conditions. Outstanding antioil fouling ability also enables the fabric coated by BaSO₄ nanocoating to separate crude oil/water with flux higher than 28 000 Lm^2-h^-1 and separation efficiency larger than 99.9% and maintain effective separation performance even after 100 times of separation. Thus, the robust superhydrophilic BaSO₄ nanocoating is potential in oil dewetting and waste oil remediation.

Development of barium-based low viscosity contrast agents for micro CT vascular casting: Application to 3D visualization of the adult mouse cerebrovasculature

Recent advances in three-dimensional (3D) fluorescence microscopy offer the ability to image the entire vascular network in entire organs, or even whole animals. However, these imaging modalities rely on either endogenous fluorescent reporters or involved immunohistochemistry protocols, as well as optical clearing of the tissue and refractive index matching. Conversely, X-ray-based 3D imaging modalities, such as micro CT, can image non-transparent samples, at high resolution, without requiring complicated or expensive immunolabeling and clearing protocols, or fluorescent reporters. Here, we compared two "homemade" barium-based contrast agents to the field standard, lead-containing Microfil, for micro-computed tomography (micro CT) imaging of the adult mouse cerebrovasculature. The perfusion pressure required for uniform vessel filling was significantly lower with the barium-based contrast agents compared to the polymer-based Microfil. Accordingly, the barium agents showed no evidence of vascular distension or rupture, common problems associated with Microfil. Compellingly, perfusion of an aqueous BaCl₂ /gelatin mixture yielded equal or superior visualization of the cerebrovasculature by micro CT compared to Microfil. However, phosphate-containing buffers and fixatives were incompatible with BaCl₂ due to the formation of unwanted precipitates. X-ray attenuation of the vessels also decreased overtime, as the BaCl₂ appeared to gradually diffuse into surrounding tissues. A second, unique formulation composed of BaSO₄ microparticles, generated in-house by mixing BaCl₂ and MgSO₄ , suffered none of these drawbacks. These microparticles, however, were unable to pass small diameter capillary vessels, conveniently labeling only the arterial cerebrovasculature. In summary, we present an affordable, robust, low pressure, non-toxic, and straightforward methodology for 3D visualization of the cerebrovasculature.

Radiopaque Fully Degradable Nanocomposites for Coronary Stents

Bioresorbable scaffolds (BRS) were introduced to overcome limitations of current metallic drug-eluting stents and poly-L-lactide (PLLA) has been used in the fabrication of BRS due to its biodegradability and biocompatibility. However, such polymers have weaker mechanical properties as compared to metals, limiting their use in BRS. We hypothesized that nanofillers can be used to enhance the mechanical properties considerably in PLLA. To this end, polymer-matrix composites consisting of PLLA reinforced with 5-20 wt% barium sulfate (BaSO4) nanofillers as a potential BRS material was evaluated. Stearic-acid (SA) modified BaSO4 nanofillers were used to examine the effect of functionalization. Rigid nanofillers improved the tensile modulus and strength of PLLA (60% and 110% respectively), while the use of SA-BaSO4 caused a significant increase (~110%) in the elongation at break. Enhancement in mechanical properties is attributed to functionalization which decreased the agglomeration of the nanofillers and improved dispersion. The nanocomposites were also radiopaque. Finite element analysis (FEA) showed that scaffold fabricated from the novel nanocomposite material has improved scaffolding ability, specifically that the strut thickness could be decreased compared to the conventional PLLA scaffold. In conclusion, BaSO4/PLLA-based nanocomposites could potentially be used as materials for BRS with improved mechanical and radiopaque properties.

Spectroscopic studies and antibacterial activities of pure and various levels of Cu-doped BaSO₄ nanoparticles

The present study was made to design the pure and various levels of Cu doped (0.025 M, 0.05 M and 0.075 M) BaSO4 NPs synthesized by chemical precipitation method. The synthesized products have been characterised by X-ray Diffractometer (XRD), Fourier transform infrared (FT-IR) spectrometer, thermogravimetric and differential thermal analysis (TG-DTA), UV-Vis-diffused reflectance spectroscopy (UV-Vis-DRS), field emission-scanning electron microscopy with energy dispersive spectroscopy (FE-SEM with EDS), transmission electron microscopy (TEM) and application oriented study like antibacterial activity also reported. The result determined from XRD was affirmed by the results obtained from electron microscopic measurements. XRD study revealed that the synthesized products were composed of orthorhombic structure and highly crystalline in nature. Furthermore, flaky like morphology of pure and Cu-BaSO4 nanoparticles have been observed from the images obtained from these studies. The existence of Cu(2+) was confirmed by EDS analysis. The functional groups of the synthesized samples were analysed by FT-IR study. The band gap energies of pure and doped samples were accomplished using UV-Vis-DRS analysis. Also, the kinetic parameters were evaluated and reported from the thermal stability of nanoparticles. Eventually, gram-negative bacteria shows the less antibacterial activities compared to gram-positive bacteria due to adsorption of BaSO4 nanoparticles on the surface of the used bacteria.

Studies on synthesis and characterization of surface-modified mullite fibre-reinforced epoxy nanocomposites

The present work describes the development of epoxy composites using varying weight percentages (0.5, 1.0 and 1.5 wt%) of glycidyl-functionalized mullite (GM) fibre and diglycidyl ethers of bisphenol-A epoxy resin cured with diamino diphenyl methane. The mullite fibre was synthesized via the sol–gel method and its surface was modified with 3-glycidoxypropyltrimethoxysilane. The glycidyl functionality in the mullite fibre has been confirmed by Fourier transform infrared and thermogravimetric analyses. The data obtained from the thermal, mechanical, dielectric water absorption studies and contact angle showed that the GM fibre had a significant impact in the resultant epoxy nanocomposites compared to neat epoxy matrix. The molecular level dispersion of mullite fibres into the epoxy matrix was confirmed by the scanning electron microscopy and x-ray diffraction analyses.