Application Potential of Temperature-Responsive Polyaspartic Acid-Based Superabsorbent Composites in Abiotic Stress Environments.

Abstract

Superabsorbent composites (SACs) play a crucial role in mitigating issues related to abiotic stresses such as soil drought and salinization. However, high costs and various environmental challenges severely limit their widespread application. Herein, low-cost inorganic clay diatomaceous earth (DT), biodegradable polyaspartic acid (PASP), acrylic acid (AA), and <i>N</i>-isopropylacrylamide (NIPAM) were utilized as raw materials to synthesize PASP-<i>g</i>-P-(AA-<i>co</i>-NIPAM)/DT SACs through aqueous free radical polymerization. The water absorption properties of SACs were optimized by varying the reactant content. The water uptake capacities in distilled water, tap water, and 0.9 wt % NaCl solutions were 672.7, 147.9, and 80.4 g g^-1, respectively. Additionally, the SACs were evaluated for water retention, repeated swelling, and salinity resistance. At 40 °C, the water retention was 62.06% after 12 h, and even after five expansion cycles, SACs retained 65.32% of their initial water retention capacity. Notably, SACs exhibited unique temperature responsiveness, attributed to the presence of hydrophilic -CONH- and hydrophobic -CH-(CH₃)₂ on the PNIPAM molecular chain, which underwent conformational changes with temperature fluctuations. Furthermore, SACs demonstrated excellent salt resistance and pH stability. These results indicate that SACs hold significant potential for applications in abiotic stress environments.