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-NSiO2 Janus nanoparticles were synthesized via the emulsion interfacial synthesis method using stearic acid (SA) and silanized SiO2 (NSiO2) 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-NSiO2) was indicated in both energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The synthesized SA-NSiO2 (Janus nanoparticles) was added to the follower sealant PDMS/PPG@SA-NSiO2 (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-NSiO2 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.