Effect of double thermal and electrochemical oxidation on titanium alloys for medical applications

The research focuses on the development and characterization of innovative thin hybrid oxide coatings obtained in subsequent processes of thermal (TO) and electrochemical (EO) oxidation. Four different surface modifications were investigated and the microstructure was determined, the mechanical, chemical and biological properties of the Ti-13Nb-13Zr alloy were assessed using scanning electron microscopy, X-ray dispersion analysis, glow discharge emission spectroscopy, Raman spectroscopy, nanoindentation and corrosion resistance measurements. The composite layers were evaluated for antimicrobial activity, cytotoxicity bioassays and wettability tests were performed. The conducted studies of two-stage oxidation (TO + EO) have shown that it is possible to obtain layers with a different structure - crystalline and nanotubular. The formation of a nanotube layer on the surface of the crystalline layer is dependent on the thickness of the crystalline layer. The produced double titanium oxide coatings show high surface roughness, high corrosion resistance, are hydrophilic, slightly antibacterial, and not cytotoxic, which has a huge impact on the process of connecting the tissue with the implant

Structural effects of highly pi-conjugated mesogenic Schiff -base moiety on the cationic polymerization of benzoxazine and formation of ordered morphologies

A Schiff -base moiety was introduced into the chemical structure of benzoxazine through the Mannich reaction. With alternative imine groups (C=N) and benzene rings in the chain segment, these highly pi-conjugated systems favored the formation of strong intermolecular hydrogen bonds to the hydroxyl groups generated during polymerization, leading to a thermally initiated cationic polymerization mechanism. Compared with the bisphenol-A-based benzoxazine, the benzoxazine with the Schiff -base moiety needs higher energy to facilitate the realization of polymerization and to increase polymerization degree. In addition to the influences on the polymerization, the highly a -conjugated Schiff -base acting as a mesogenic moiety is found to form liquid crystal (LC) phases, like the nematic phase and smectic phase. Interestingly, some LC-rich domains can be stabilized by the polybenzoxazine network, which will contribute to form nitrogen-rich ordered porous carbon at the carbonization stage. For N-2 and CO2 adsorption-desorption process, the carbon exhibits an enhanced CO2 adsorption performance, suggesting their capture and separation capacity for CO2