Research progress on the preparation, characterization, and applications of hydrogels

Abstract

Hydrogels are functional polymeric materials with a three-dimensional network hydrophilic structure. Benefiting from excellent biocompatibility, high water retention, and tunable physicochemical properties, they have become a research hotspot in food, biomedicine, and other fields. This paper systematically reviews the preparation techniques, characterization systems, and diverse applications of natural polymer-based hydrogels. It combs through the principles, advantages, and application limitations of five mainstream preparation methods—thermal induction, physical crosslinking, chemical crosslinking, ionic crosslinking, and enzymatic crosslinking—and clarifies the regulatory mechanisms by which different crosslinking modes affect the microstructure and macroscopic properties of hydrogels. Meanwhile, from the three dimensions of structure, properties, and function, this paper comprehensively presents core characterization techniques such as SEM, FT-IR, XRD, and rheological testing, and elucidates the intrinsic correlations among the microstructure, physicochemical properties, and practical functions of hydrogels. On this basis, it summarizes the core application scenarios and technical advantages of hydrogels in food texture modification, bioactive substance delivery, smart packaging, food 3D printing, and biomedicine.