Synthesis and characterization of a new Polylactic acid-Siloxane- Polyethylene oxide organic-inorganic nanocomposite presenting simultaneously high thermal stability, high resistance to degradation and absence of brittleness
This work presents the synthesis, structural investigation and some properties of a new PLA-Siloxane-PEO hybrid presenting covalent bonds between polymers and siloxane nanoparticles.The structural features, thermal properties and chemical stability of this biocompatible system have been studied by Fourier-Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, 29 Si Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (MEV), X-Ray Diffraction (XRD), Small-Angle X-ray Scattering (SAXS), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). SEM and SAXS measurements showed that the siloxane nodes act as crosslinks between the polymer chains promoting miscibility between PLA and PEO. FTIR, Raman XRD, DSC and TGA results evidenced that presence of the siloxane nanoparticles diminishes crystallinity of both polymers and increases their thermal resistance. The same techniques also showed that the high miscibility between polymers in this system enhances PLA thermal stability and prejudices PLA crystallization. Among the absence of brittleness due to the low crystalline character of PLA, this new material exhibits a fantastic resistance to PLA degradation in aqueous medium, attributed both to the presence of the siloxane particles acting as a barrier towards water diffusion and to the hydrophilic PEO segments which may attract water molecules, preventing PLA hydrolysis. All these characteristics open amazing perspective for use of this hybrid material in biological and pharmaceutical applications.