Hydrophobic Halloysite Nanotubes via Ball Milling for Stable Pickering Emulsions: Implications for Food Preservation

Modification and functionalization of nanomaterials by a facile way are critical for their practical application in many areas. In this work, hydrophobic modified halloysite nanotubes (mHNTs) were efficiently prepared by a ball milling method; then, the mHNTs were used to stabilize oil/water emulsions. Polytetrafluoroethylene in the wall of milling jars adhered to the surfaces of HNTs during the milling process, which changed the hydrophilicity and electrical properties of HNTs. The milling process reduced the length of the tubes and promoted the transformation of the 1D tubes into 2D sheets morphology. mHNTs were then employed as solid particles on the oil–water interface for preparing Pickering emulsions. The morphology and rheological behavior indicated that the oil/water emulsion stability improved with the increasing mHNT concentration and milling time. SEM images showed that the emulsion network became denser with the increasing milling time of mHNTs, which led to the increased stability of the emulsions. In addition, the antibacterial properties of HNT–cassia oil emulsions were investigated. Owing to the uniform distribution and slow release of cassia oil, mHNT-stabilized emulsions exhibited improved antibacterial performance. This work demonstrated that hydrophobic HNTs prepared by ball-milling method show proper wettability, controlled delivery behavior, and scaling-up ability, which have promising applications in Pickering emulsions and food preservation.