Effect of Embedded Polyelectrolyte Chains on Microstructure of Polyacrylamide Hydrogels

Abstract

In the present work we have studied the dynamics of chemically cross – linked polyacrylamide (PAAm) hydrogels with and without incorporating polyelectrolyte (pel) chains using dynamic light scattering (DLS) technique. A non – ergodic approach to analyze the intermacromolecular systems suggests stiffening of cross – linked junctions as the concentration of foreign species is increased. Thus the dynamics of parent gels is distinctly different from those in presence of pel chains. To further confirm our observation we have fit the intermediate scattering function to a straight line equation and used it to calculate the diffusion coefficient of the network. It was found that the diffusion coefficient decreased as we increased the added pel chain concentration. The decreased diffusion coefficient indicates an enhanced frozen – in structures in gel matrix.