*Article* **Physicomechanical and Morphological Characterization of Multi-Structured Potassium-Acrylate-Based Hydrogels**

**José Luis Gradilla-Orozco <sup>1</sup> , José Ángel Hernández-Jiménez <sup>2</sup> , Oscar Robles-Vásquez <sup>3</sup> , Jorge Alberto Cortes-Ortega <sup>4</sup> , Maite Renteria-Urquiza <sup>4</sup> , María Guadalupe Lomelí-Ramírez <sup>2</sup> , José Guillermo Torres Rendón 2 , Rosa María Jiménez-Amezcua 3,\* and Salvador García-Enriquez 2,\***


salvador.genriquez@academicos.udg.mx (S.G.-E.)

**Abstract:** In this work, a photo-polymerization route was used to obtain potassium acrylate-coacrylamide hydrogels with enhanced mechanical properties, well-defined microstructures in the dry state, and unique meso- and macrostructures in the hydrated state. The properties of the hydrogels depended on the concentration of the crosslinking agent. Mechanical properties, swelling capacity, and morphology were analyzed, showing a well-defined transition at a critical concentration of the crosslinker. In terms of morphology, shape-evolving surface patterns appeared at different scales during swelling. These surface structures had a noticeable influence on the mechanical properties. Hydrogels with structures exhibited better mechanical properties compared to unstructured hydrogels. The critical crosslinking concentration reported in this work (using glycerol diacrylate) is a reference point for the future preparation of multistructured acrylic hydrogel with enhanced properties.

**Keywords:** hydrogels; photo-polymerization; potassium acrylate-co-acrylamide; swelling capacity; multistructured
