Alginate hydrogels are attractive for biomedical applications and drug delivery due to their biocompatibility and biodegradability. However, calcium-crosslinked alginates often exhibit only moderate absorption properties compared with synthetic hydrogels. This study examined how the form of calcium ion delivery affects the mechanical, swelling, and morphological characteristics of calcium-crosslinked alginate hydrogels. We prepared four alginate hydrogel samples in which Ca²⁺ was introduced on different polyacrylate polymer carriers, and a reference hydrogel crosslinked with calcium citrate. All samples were characterized by equilibrium swelling, gel fraction determination, and rheological frequency-sweep measurements. Also, the average mesh size was estimated using two independent theoretical approaches. Hydrogels prepared with calcium salt of polyacrylic acid (PAA) exhibited higher mechanical strength and higher water swelling than the citrate-crosslinked reference. Calculated mean mesh sizes for the citrate system ranged from 58 to 221 nm, whereas high-molecular-weight crosslinked systems showed a broader distribution (68–708 nm). These results demonstrate that the form of Ca²⁺ introduction significantly influences network architecture and functional properties and indicates that tuning the carrier form of calcium provides a practical route to design swelling, mesh size, and mechanical behavior of alginate-based hydrogels for specific biomedical or delivery applications.

Alginate films are an attractive material for biomedical applications, so surface morphology is critical at the micro-level of compatibility with living tissues. The effect of calcium ions on the nanoscale topography of films has been studied to a limited extent. Atomic force microscopy of films prepared by the Langmuir-Blodgett method was used in the study, followed by quantitative image analysis and statistical analysis. The introduction of calcium into the sodium alginate system, both before laying on the film (from the solution) and after (by injection), changes the parameters of the asymmetry coefficient, root mean square slope, and spectral exponent. The conversion of sodium alginate into a calcium salt in films significantly affects indicators of the system's adhesive, roughness, and wetting properties.

Developing a new generation of transparent hydrogel firefighting mineral-polymeric materials is an urgent task. These composites are used to produce refractory glass structures, particularly double-glazed windows. These double-glazed windows are multilayer structures made of silicate glass sheets, with gaps filled by a transparent material that turns opaque under flame exposure, reducing heat load and maintaining structural integrity for a specified duration. This article presents research on the synthesis and properties of transparent polysilicon hydrogels, used as a component in hybrid mineral-organic composites for manufacturing fire-resistant transparent glass structures. A method for producing polysilicate acid hydrogels in the presence of polyvalent metal ions has been developed. Full-factor experiment results established the sol-gel process time frame, influenced by many factors. The research demonstrates the feasibility of creating a transparent hybrid polymer-mineral hydrogel material containing polyvalent refractory salts and polysilicate acid, which can transform into a highly porous refractory material under high temperatures.