No abstract

Menthol-loaded PLGA micro/nanospheres were synthesized using the multiple emulsion/solvent evaporation technique. Parameters such as stirring rate, external surfactant content, PLGA/menthol weight ratio, solvent evaporation and lyophilization time were evaluated as well as the degradation of micro/nanospheres in an artificial saliva medium. The menthol/PLGA micro/nanospheres thus obtained had a size distribution of between 217 nm and 13 µm and particles with spherical and dense morphology were evidenced by SEM micrographs. FTIR and TGA data showed an increase up to 60% of menthol incorporated in the micro/nanoparticles. The degradation of menthol-loaded PLGA micro/nanoparticles in artificial saliva significantly affected the particles morphology and appears to be an effective medium for releasing menthol.

Elastomeric hybrid films were produced from the epoxidized nitrile rubber with the 3glycidyloxypropyl-trimethoxysilane (GPTMS) inorganic precursor by the sol-gel process. There were no significant changes in the thermal properties of hybrids in relation to pure epoxidized rubber. The degree of swelling decreased while the mechanical resistance increased with increasing GPTMS content. The sol-gel process was performed on metal plates, which were then subjected to a corrosion process by immersion in NaCl solution and evaluated by Electrochemical Impedance Spectroscopy. The resistance and the capacitance values of the nitrile rubber coating are 8.8 × 10 3 Ω cm 2 and 1.9 × 10 −4 F cm −2 , whereas for the hybrid with 38 phr of GPTMS the values are 2.3 × 10 6 Ω cm 2 and 15.8 × 10 −10 F cm −2 , respectively, indicating higher cross-link density, less electrolyte absorption, less degradation, greater adherence to the metal surface via silane groups and, consequently, better corrosion protection achieved by the hybrid films.