INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Ultrasound-Assisted Chemisorption of a Silane on Hydroxyapatite for Obtaining Composite Films via Sol-Gel Processing
Autor/es:
HERNÁN E. ROMEO; MARÍA A. FANOVICH
Lugar:
Porto de Galinhas, Pernambuco, Brasil
Reunión:
Simposio; XV Conferencia Internacional Sol-Gel 2009; 2009
Resumen:
  In recent years, considerable attention has been focused on the development of novel composite systems in the biomaterials area  for specific applications [1]. Among the several known calcium phosphates, hydroxyapatite (HA, Ca10(PO4)6(OH)2) is one of the most investigated, due to its excellent biocompatibility and bioactivity. The chemisorption of organic compounds on HA surface allows modifying its surface features, which is very useful to chemically bond this inorganic material to other matrices of different nature [2]. In this work, we have functionalized HA microcrystals with an organically modified silane (3-gycidoxypropyl(trimethoxysilane), GPMS) by employing a novel functionalization method based on the application of ultrasonic irradiation (UI). This allowed the chemisorption of GPMS on HA surface after 1 h of applying UI, which led to the formation of a stable suspension of HA microcrystals in liquid GPMS. Ultracentrifugation of the coarse fraction of suspended HA was employed to narrow down the size distribution of the suspended HA. In this way, employing this functionalization method, it would be possible to suspend and select any desired fractions of solid to be finally incorporated in the resulting hybrid matrix after the hydrolytic condensation of the silane during the sol-gel processing. In order to demonstrate this, the suspension was ultracentrifugated (10000 rpm, 5 min) three times, and the resulting suspension (containing 5-10 mm HA crystals) was used as a precursor system to be hydrolized. The hydrolytic condensation was accomplished by blending the suspension with a THF/n-hexane mixture (1:2 volumetric ratio) and adding (dropwise) formic acid as catalyst and water, with continuous application of UI. The process was ended (after 10 min of irradiation) when a white suspension appeared in the reaction medium. Finally, the obtained product was poured in a Petri dish, and solvents and volatile products were evaporated at 80° C. A trasparent, glassy and very homogeneous film of an organic-inorganic hybrid material containing well-dispersed HA microcrystals was obtained as the end product. FTIR, SEM, 29Si NMR and X-ray fluorescence analyses were employed as characterization methods.