Structural evolution of aging agar-gelatin co-hydrogels

Agar-gelatin co-hydrogel was investigated over a period of ≈30-days by dynamic light and small angle neutron scattering, and rheology to quantify changes occurring inside the hydrogel. Degree of non-ergodicity was extracted as a heterodyne contribution from the measured dynamic structure factor data. From the analysis of the data, we observed two relaxation modes namely fast and slow modes with relaxation times τf and τs whose dependence with aging time, ta fall on a scaling behavior given by power-laws, τf ∼ (ta)−1/5 and τs ∼ (ta)3/5 respectively. Further the analysis showed the heterogeneity size (ξSANS) obtained from SANS also follows power-law behavior, ξSANS ∼ (ta)−1/5. The data taken together revealed the “speeding up” of fast and “slowing down” of slow mode relaxation processes.