Cyclic deformation behavior of agarose hydrogels prepared at different gelation concentrations

Effects of the gelation concentration (c₀) on cyclic deformation behavior of agarose hydrogels have been examined. Agarose hydrogels prepared at c₀ = 10 g L^-1 (A10) show smaller Young's modulus than those prepared at c₀ = 30 g L^-1 (A30) even when the mechanical properties have been measured at the same agarose concentration 50 g L^-1. Moreover, A10 has stronger tendency to exhibit the residual strain in the cyclic deformation curves compared to A30. These results can be explained based on the gelation mechanism specific to agarose, where helices of agarose aggregate via hydrogen bonding to be the crosslinks. It has been proposed from the optical rotation that the helix content just after gelation increases with c₀, while the helix content for A10 was higher than that for A30 at 50 g L^-1. Since the lower helix content at c₀ for A10 results in less stable aggregates of agarose helices, it can be said that the cyclic deformation behavior as well as Young's modulus of agarose hydrogels primarily reflects the network structure determined by c₀.