Xanthan <i>versus</i> gellan in composite hydrogels with polyacrylamide for the biomimetics of soft tissues

Abstract This study presents the swelling, thermodynamic and viscoelastic properties of double‐network hydrogel composites based on polyacrylamide (PAAm) and natural polysaccharide: gellan or xanthan. Hydrogels were synthesized by radical polymerization of acrylamide in water solutions of polysaccharides of 0.2%, 0.4%, 0.6%, 0.8% and 1.0% concentration by weight. Molecular interactions between polymers and water and between polymers were estimated using a thermodynamic approach based on water vapor sorption and microcalorimetry. It was found that both gellan and xanthan had higher thermodynamic compatibility with water than PAAm. The enthalpy of the PAAm–polysaccharide interaction was found to be negative for all compositions. The minimal value for the PAAm–gellan blend was −10.3 ± 1.1 J g −1 and for PAAm–xanthan blend it was −7.3 ± 0.9 J g −1 . In the mechanical analysis, cylindrical gel samples with a diameter of 10 mm and a height of 10 mm were subjected to sinusoidal compressive mechanical deformations to determine the values of storage modulus, loss modulus and shift angle. Gradual increase in the polysaccharide concentration in the composite was accompanied by a significant increase of the mechanical parameters but to different extents for gellan‐ and xanthan‐based gels. Thus, at 0.01 Hz the storage modulus increased from 10.2 ± 1.9 kPa for single‐network PAAm gel to 15.5 ± 0.4 for double‐network PAAm/gellan composite and to 24.2 ± 2.4 kPa for PAAm/xanthan composite with 0.6% of polysaccharide in both cases. Possible interconnections between the thermodynamic and mechanical data are discussed. It is concluded that double‐network PAAm/gellan composites are a more suitable material for designing soft tissue biomimetics than PAAm/xanthan composites. © 2026 Society of Chemical Industry.