Polymerization of e-caprolactone initiated by nano-hydroxyapatite with different thermal treatments

M.A. GIARDINA; M.A. FANOVICH; G.A. ABRAHAM

Los Cocos, Córdoba, Argentina

Simposio; V Simposio Chileno-Argentino de Polímeros, ARCHIPOL; 2009

Polymer matrix composites are being increasingly studied for different biomedical applications. Many composites have been considered as bioresorbable materials for use in bone substitutes and regeneration strategies. Recently, polymer/ceramic nanocomposites have gained much recognition as scaffolds for bone tissue engineering not only due to their composition and structural similarity with natural bone, but also because of their unique functional properties. Ceramic particles increase the mechanical properties of the resulting composites, being suitable for orthopedic applications. Moreover, the bonelike inorganic fillers influences the general properties of many synthetic polymers. Hydroxyapatite (HA) is the most-used ceramic in biomedical composites due to its bioactivity help in promoting bone-bonding properties. Polycaprolactone (PCL) is a nontoxic, biodegradable and biocompatible polyester widely proposed for use in tissue engineering scaffolding. Thus, PCL/HA composites have demonstrated great potential in the biomedical field (Choi et al., 2004). These composites are mainly prepared by incorporating the ceramic particles into a polymeric solution. The resulting suspension may then be dried under vacuum and shaped using different processing techniques. Composites can also be obtained by mixing HA particles with lactones or lactides before polymerization. The production of composites requires a very good dispersion of the reinforcement bioactive particles, ensuring that the particles are perfectly surrounded by the matrix and not as agglomerates. It is well known that the interface between inorganic phase and polymeric matrix plays a key role in the mechanical properties of composites. In order to achieve a good interfacial adhesion HA nanoparticles can be chemically bonded to polymeric chains. Thus, hydroxyl groups of HA can initiate the ring-opening polymerization of lactones or lactides and form HA nanoparticles with grafted PCL chains (Helwig et al., 2001), (Hong et al., 2005). The aim of this study was to develop and characterize PCL/HA nanocomposites, wherein the superficial OH groups of the HA nanoparticles act as initiators of the polymerization reaction. The effect of different thermal treatments of nano-HA powders on polymerization of e-caprolactone was analized.