Synthesis and application of fucoidan biological superabsorbent polymer

Objective Using natural fucoidan rich in hydrophilic structures such as L-fucose and sulfated groups as raw material, a superabsorbent polymer (SAP) was synthesized to improve its degradability and renewable capacity.

Method A fucoidan biological SAP was synthesized via aqueous solution polymerization by grafting natural fucoidan onto acrylic acid (AA) monomers using ammonium persulfate (APS) as the initiator and N, N'-methylenebis acrylamide (MBA) as the crosslinker. The preparation process was optimized through single-factor experiments. The product was characterized using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). A pot experiment was conducted to evaluate the effect of the SAP on cabbage growth.

Result The optimal mass ratio of fucoidan to AA was 1.0∶7.5, with a neutralization degree of 70%, and the dosages of APS and MBA were 3.0% and 0.2% of the mass of AA, respectively. The SEM analysis revealed a porous and loose network structure, while FT-IR confirmed the formation of a graft copolymer of fucoidan and AA. The water absorption ratios of the SAP in deionized water and 9 g∙L⁻¹ NaCl solution were 420.9 and 63.8 g∙g⁻¹, respectively. After six cycles of absorption and drying, the water absorption ratio remained 70.8% of its initial value. Additionally, Chinese cabbage grew best when adding 6 g SAP per kilogram of soil, with the total plant biomass significantly increased by 105.5% and soil water content improved by 8.98%.

Conclusion The fucoidan biological SAP exhibits excellent water absorption and reusability, significantly promoting plant growth when applied to soil. This study provides foundational data for the development and agricultural application of algal-derived SAP.