Preparation and Water Absorption Performance of Absorbent Polymer Based on Flexible Polymer Network's Structure

Flexible polymer networks significantly influence the water absorption performance of water-absorbent polymers. Here, we prepared a water-absorbent polymer with a highly flexible network structure by incorporating thermoplastic elastomer styrene-butadiene-styrene (SBS) into the solution polymerization of acrylic acid (AA) and methyl methacrylate (MMA). The butadiene segments within the SBS molecular chain contribute to a highly flexible network structure. Moreover, in comparison with other water-absorbing materials (e.g., polyacrylamide), the SBS system exhibits advantages including lower cost, simpler processing technology, and superior structural compatibility. L 16 (4 4 ) orthogonal experiments were designed and implemented to investigate the main factors that affected water absorption performance of the water-absorbent polymer. Based on the orthogonal experiments, one-way variable experiments were conducted to investigate the influence of SBS content, initiator content, polymerization temperature, and reaction time on water absorption performance, grafting ratio, and grafting efficiency. Experimental results showed the water absorption of SBS-g-AA/MMA reached 31.50 g/g in deionized water, while it still reached 5.25 g/g in physiological saline solution. The water absorption retention after multiple absorption-drying cycles still reached 28 g/g, while the maximum value of weight loss was only 17.96%. This work enhances water absorption performance while reducing weight loss and improving recyclability, broadening water‑absorbent polymer applications in hygiene, agriculture, and beyond.