Preparation and properties of functional ionic liquid cross-linked polyacrylamide-based gel microspheres with compressive strength and stability

Polyacrylamide-based gel microspheres have low compressive strength and relatively poor thermal stability, which makes them susceptible to mechanical stress damage and prone to degradation or dissolution in high-temperature environments, thereby limiting their application under such conditions. In this study, an imidazolium-based characteristic was incorporated into the acrylamide-acrylic acid (AA) system to synthesize a gel with enhanced compressive strength and stability. Firstly, a one-step method was used to synthesize a bipartite vinyl imidazolium bromide ionic liquid, using N -vinyl imidazole and 1,8-dibromooctane. Secondly, polymer gel microspheres (P(AA-AM-ILs)) were designed and synthesized using the microfluidic technique and titration gel method, with acrylamide (AM), AA, and β-hydroxyethyl methacrylate as raw materials, and potassium persulfate as the initiator. The morphology and structure of the polymer gel microspheres were characterized, and the effects of the ionic liquid cross-linker content on the water-absorbing properties and compressive strength of the gel microspheres were investigated. At 800°C, the gel microspheres did not fully decompose, indicating that the material possessed high stability. When the ionic liquid cross-linker content was 15%, the water absorption ratio reached its highest value at various temperatures, consistently exceeding 3.5 mm mm −1 . Additionally, it exhibited excellent aging resistance, maintaining a compressive strength of 110 kPa after being immersed at 70°C for 120 days, suggesting its suitability for long-term use. Highlights Imidazole ionic liquids cross-linking exhibits excellent thermal properties. For P(AA-AM-ILs), excellent stability and compressive strength. The appropriate content of ionic liquid cross-linkers significantly improves the gel performance.