Small-Angle Neutron Scattering Studies of Chemically Cross-Linked Gelatin Solutions and Gels

Small-angle neutron scattering measurements are reported for experiments performed on mixtures of gelatin and glutaraldehyde (GA) in the aqueous phase, where the gelatin concentration was fixed at 5% (w/v) and the GA concentration was varied from 1.25 × 10 -4 to 3 × 10 -3 % (w/v). Two length scales associated with this system were identified in both sol (60° C) and gel state (28° C). One of these, the correlation length (ξ) or mesh size of the cross-linked network showed negligible dependence on temperature, but a scaling ξ ∼ [GA] ν, where [GA] is the concentration of cross-linker GA, was observed with ν = 0.33 ± 0.04 in the gel state. Other length scale associated was the size of inhomogeneities ζ which showed no [GA] dependence but showed appreciable increase in size as the system transformed from a sol to gel state for all [GA]. Observations are discussed in the context of the results obtained from dynamic light scattering experiments performed earlier.