چكيده به لاتين
Abstract:
The biological and mechanical properties of substances are relevant to their application as dental materials and tissue engineering scaffolds. To achieve a low rate of shrinkage during polymerization, good mechanical properties, and excellent biocompatibility, benzoxazine monomer was synthesized using a solventless method. FTIR and DSC analysis were carried out to determine the appropriate polymerization temperature of the benzoxazine monomer. The low viscosity of the benzoxazine monomer at 70°C required in situ polymerization after high speed ball milling of the benzoxazine and it mixture with different weight fractions of zirconia particles. SEM images showed good dispersion and adhesion between the ceramic and polymer components. To evaluate the biological properties and toxicity of the polybenzoxazine-based composites reinforced with zirconia particles, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay was carried out. The results of the assay showed excellent in vitro biocompatibility of the composites. The micromechanical properties of each composite were evaluated by more than 20 nanoindentation tests and 3 nanoscratching tests. Surface topography of scratched regions was investigated using Atomic Force Microscopy. Nano indentation force-displacement curves showed matrix, reinforcement and interphase regions in specimens and excellent homogeneity in mechanical properties. The nanoindentation results showed that the addition of zirconia particles to the polybenzoxazine matrix increased the modulus and hardness of the neat polybenzoxazine; however, after reaching an optimum level, the mechanical properties of the composites decreased because of agglomeration of the reinforcement particles and the weak interface between ceramic and polymer particles. Results of nano-scratching tests showed effects of zirconia particles as reinforcement on the coeffiecient of friction of the synthesized composites. Shrinkage was simulated by Materials Studio software and showed a low rate of shrinkage for polybenzoxazine in comparison with other low shrinkage biomaterials, such as Bis-GMA.
Keywords: Polybenzoxazine; Biocomposites; Zirconia; Nanoindentation; Biocompatibility
