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

Abstract 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.