Strong yet mechanically flexible thick necked aerogels fabricated via in situ-catalyzed epoxy-thiol polymerization with necking enhancement: A finite element simulation and wastewater treatment applications

Ultralight organic-inorganic-crosslinked aerogels that are strong yet mechanically flexible and multifunctional are attractive for use in versatile applications. However, conventional resorcinol-formaldehyde (RF)-based aerogels are either strong or flexible while Si-based aerogels are brittle, and both have limited long-term practicability. Therefore, the fabrication of mechanically strong yet flexible RFSi-crosslinked aerogels containing S-functional groups (Si) obtained via a new synthetic route involving epoxy-thiol polymerization and necking enhancement is presented herein. Three hybrid RF-Si aerogels that are soft, mechanically strong, and mechanically strong yet flexible are possible according to the synthesis conditions and the amount of neck region enhancement. An epoxy-thiol-polymerized RF-Si aerogel using an ethanol supercritical drying (SCD) process (S-RFSi_SCD) possesses ultralow density (~0.050 g·cm −3 ), excellent mechanical properties with 50 % reversible compression strain, excellent fatigue resistance, high compressive modulus (5.65 MPa), excellent room temperature thermal insulating property (0.026 W·m −1 K −1 ), and multifunctionality due to the presence of S-functional groups. Finite element simulations were employed to investigate the deformation behavior with neck enhancement. When used as an adsorbent, S-RFSi_SCD aerogel shows excellent Hg 2+ adsorption (~699.3 mg/g) and acceptable methylene blue dye adsorption (~105.48 mg/g). This successfully applied novel synthetic approach efficiently provides mechanically strong yet flexible and multifunctional S-functionalized Polymer-Si-crosslinked aerogels addressing limitations of mechanical properties of RF (strong or flexible), and Si aerogel (brittleness). This advancement enhances the sustained viability and adaptability of aerogels for high-performance applications in various industries, including thermal insulation, flexible electronics, pollutant filtration, and medical devices.