Amphiphilic Janus Nanoparticles with Enhanced Sealing Properties as Follower Sealants

Follower sealant can be widely used in many fields because it has a strong sealing effect on liquids. However, most follower sealants often have a short sealing cycle and poor thermal stability. Herein, the hydrophilic and hydrophobic SA-NSiO 2 Janus nanoparticles were synthesized via the emulsion interfacial synthesis method using stearic acid (SA) and silanized SiO 2 (NSiO 2 ) as raw materials. The characteristic peaks of Janus nanoparticles were clearly seen in Fourier-transform infrared, while snowman-like Janus nanoparticles were clearly observed in scanning electron microscopy and transmission electron microscopy, and the successful synthesis of Janus particles (SA-NSiO 2 ) was indicated in both energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The synthesized SA-NSiO 2 (Janus nanoparticles) was added to the follower sealant PDMS/PPG@SA-NSiO 2 (PPSN for short) composed of polydimethylsiloxane (PDMS)/poly(propylene glycol) (PPG), which was found to have excellent thermal stability and sealing performance even under high temperature and negative pressure, and the sealing cycle was increased by 300%, a long time of efficient sealing was also achieved, and the high and low temperature viscosity ratio was reduced from 2 to 1.5, with a 50% increase in centrifugal negative pressure capability. MS simulation results showed that the high sealing performance of PPSN was attributed to the entanglement of the hydrophobic phase of SA-NSiO 2 with the hydrophobic chain of PDMS, and the hydrophilic phase was hydrogen-bonded and cross-linked with the hydrophilic group of PPG in PPSN. This study provides an effective method for realizing nanoparticle-enhanced follower sealants, which are sustainable as well as environmentally friendly, giving them great potential for industrial processing.