Techno-functional characterization of chitosan nanoparticles prepared through planetary ball milling.

Planetary ball milling of chitosan microparticles (CMP) for 8 h produced chitosan nanoparticles (CNP) having hydrodynamic diameter of 615.18 nm. The ζ-potential decreased from 56.48 mV (CMP) to 31.52 mV (CNP). High resolution transmission electron microscopy (HRTEM) revealed nanosize, irregular shape and surface roughening of CNP. CNP was whiter than CMP having higher water absorption capacity and decreased flow ability. Both CMP and CNP showed negligible swelling and no water solubility. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) revealed no chemical changes and X-ray diffraction (XRD) showed decreased crystallinity in CNP. In CNP, thermogravimetric analysis (TGA) revealed increased thermal degradation; differential thermogravimetric (DTG) revealed increased rate of thermal degradation; and high temperature differential scanning calorimetry (HDSC) revealed broadening of endothermic and exothermic phases and reduction in glass transition temperature as compared to CMP. In conclusion, planetary ball milling for 8 h produces bright, amorphous and rough CNP with improved functional and comparable thermal properties.