RESUMO
Preparation of planar alginate hydrogels by external gelling requires slow rate of exposure of alginate solution to gelling ions to control gelling process and hydrogel properties. We tackled this issue by exposing solution of sodium alginate to solution of CaCl2 applied as aerosol at exposure rate of 7.5 mg cm(-2) s(-1). Gelling conditions varied with respect to concentrations of sodium alginate (1-3 wt.%) and CaCl2 (0.5-4 wt.%), exposure time (2.5-40 min), the 2nd gelling step in the presence of barium ions, and the storage step. Dimensional stability and Young's modulus values were the principal determined quantities to examine the correlation between hydrogel properties and gelling protocol. The content of calcium ions in hydrogel after gelling by CaCl2 aerosol reveals that the maximum binding capacity of calcium ions by alginate chains was reached. Obtained data suggest that an unusual gelling mechanism related to exposure of sodium alginate to aerosol of gelling solution does not need to be considered since the properties of planar alginate hydrogels follow the trends relevant to general knowledge about alginate hydrogels.