Colloidal stability of dextran and dextran/poly ethylene glycol coated TiO2 nanoparticles by hydrothermal assisted sol-gel method

Colloidal stability of dextran (Dex) and Dex/poly ethylene glycol (PEG) coated TiO2 nanoparticles (NPs) were investigated. The particles were successfully synthesized by a hydrothermal assisted sol-gel technique. The results of Ultraviolet-visible (UV-vis) spectrophotometry showed that Dex and PEG additions during hydrothermal process (HTP) led to the formation of long-term (more than 60 days) stable colloids, while the addition of dispersants after HTP did not have a significant impact on the colloidal stability of NPs. X-ray diffraction (XRD) and selected area electron diffraction (SAED) analyses proved that PEG and/or Dex coated NPs had less crystallinity than the plain TiO2. Fourier transform infrared (FTIR) spectroscopy demonstrated the formation of primary bonds between NPs and polymeric dispersants. High-resolution transmission electron microscopy (HRTEM) displayed stable particles with a core-shell structure resulting from coating of NPs by polymeric materials. Thermo gravimetric analysis (TGA) was also utilized to calculate the proportion of NPs to polymeric dispersant. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.