Dynamic scaling for gelation of a thermosensitive chitosan-β-glycerophosphate hydrogel

This paper investigates the thermal gelation of a chitosan-β-glycerophosphate system using rheometry. The gelation, performed for two polymer concentrations, was achieved in isothermal conditions to examine the effect of various temperatures (between 35 and 65 °C) on the sol-gel transition. The oscillatory shear data was used to verify the scaling behavior (G′ ~ G″ ~ ω ⁿ ) at the gel point, and the power-law index n was found to be dependent to some extent on chitosan concentration and temperature. The solutions zero shear viscosity (η ₀) and the gels low frequency modulus (G _e) were analyzed in terms of the relative distance to gelation time (ɛ). The two properties showed power–law relationships with ɛ, i.e., η ₀ ~ ɛ ^−s and G _e ~ ɛ ^z, and the indexes slightly increased with temperature. The dynamic scaling theory predicts a relationship between the indexes, i.e., n  =  z/(z  +  s), and this was in reasonably good agreement with the experimental findings.