No abstract

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.

Polyurethane (PU) sponge with high elasticity and reproducibility shows promising application in flexible electronic devices. However, the poor conductivity and high flammability limit its application field, which also pose a potential threat to human health. Here, a flexible sponge sensor based on PU and polypyrrole-wrapped halloysite nanotubes (PPy@HNTs) was successfully fabricated by the dip coating technology. The PPy-modified HNTs showed strong binding ability on the PU sponge by employing N,N-dimethylformamide (DMF) as an interfacial solvent. PPy@HNTs can well adhere on the surface of the PU sponge, which endow excellent structural stability to the flexible sponge sensor after 5000 cycles. The response and recovery times during the sensitivity experiment of the flexible sponge sensor are 265.63 and 265.62 ms, respectively. The flexible sponge sensor can effectively detect various physical activities, such as walking, facial expression, and gesture. It can be used as an analytical balance for quality monitoring. Moreover, the flexible sponge sensor exhibits excellent photothermal performance, which is reflected in the good relationship between resistance change and laser irradiation time as well as power intensity. The coating of PPy@HNTs also significantly improved the flame retardancy of the PU sponge. This work developed a mild, high-efficiency, and simple preparation method of flexible sponge sensors, and the prepared sensor displayed multifunctional applications such as biological detection and electronic balances.