Relaxations in gelatin hydrogels probed by dynamic light scattering
1School of Physics, Shri Mata Vaishno Devi University, Katra 182320 (J&K), India
2Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
Adv. Mater. Lett., 2016, 7 (2), pp 136-143
Publication Date (Web): Jan 04, 2016
Copyright © IAAM-VBRI Press
The relaxation behavior of gelatin aqueous solutions has been investigated by time resolved dynamic light scattering (TRDLS) measurements at different temperatures spanning the entire sol to gel phase transition behavior of the system (i.e. from 5 min to 1440 min after a sudden quench from high temperature sol to low temperature gel state), when the chosen gelatin concentration in water was maintained at 5 % (w/v), well over the overlap threshold. The quantity of interest, structure factor S (q,τ), has been obtained from the experimentally measured autocorrelation function, g2(τ), allowing appropriate heterodyne contribution. The nonlinear regression analysis of the obtained scattering profiles (variation of structure factor vs. delay time) exhibited good fits to the function S(q,τ) ~A exp(-Dq2τ) + B exp(-(τ/τc)β), up tosystem evolution time of 360 min, whereas the data obtained after 360 min showed appropriate fits to S(q,τ) ~A exp(-Dq2τ)+ Cτ-α + B exp(-(τ/τc)β). The temporal behavior of different fit parameters defining the transient structural network formed in the system has been quantified and analyzed under the purview of well-defined theories. Furthermore, the evolution of particle dynamics from fast to slow and then to almost frozen behavior has been explored through the continuous evaluation of ‘Gelation factor (κ)’ at different stages of system evolution times during the measurements.
Time resolved dynamic light scattering, gelatin, sol-to-gel transitions, glass transitions,intensity correlation function.