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.