Swelling and Diffusion Characteristics of Stimuli-Responsive N-Isopropylacrylamide and κ-Carrageenan Semi-IPN Hydrogels

Abstract

Semi-IPN formation has been achieved in a system comprising N-isopropylacrylamide and κ-carrageenan by an electron beam irradiation technique. The conditions for obtaining mechanically stable gels have been optimized. The gels were characterized by DSC, SEM, and FTIR techniques. Dynamic swelling measurements were carried out under different pH and temperature conditions. The results revealed the structure, pH, and temperature-dependent swelling behavior of the gels. The % swelling (S) of the hydrogels at various pH followed the order 9.0 < 1.2 <4.0 < 7.0. Also, the gels exhibited temperature dependence, with swelling being highest around 30°C. The “n” values for these hydrogels were in the range 0.31–0.79, indicating that the mechanism of water transport changes from Fickian to anomalous diffusion, with change in the network structure of the gel matrix.

Keywords:

• diffusion
• electron beam irradiation
• interpenetrating networks
• stimuli sensitive hydrogels
• swelling

Acknowledgments

The authors acknowledge financial support (Sanction No: 2004/34/28/BRNS) provided by the Board of Research in Nuclear Sciences (BRNS) and Department of Atomic Energy (DAE), Government of India, for carrying out the present work.