Title
Swelling behavior of cross-linked terephthaloylthioureacarboxymethyl chitosan hydrogels
Authors
NADIA A. MOHAMED and NAHED A. ABD EL-GHANY

Published Volume 50 Issue 3-4 March-April
Keywords carboxymethyl chitosan hydrogels, cross-linking, swellability, pH-dependent, temperature-dependent, electrical conductivity

Abstract
Four cross-linked terephthaloylthioureacarboxymethyl chitosan (TTUCM-chitosan) hydrogels were prepared via cross-linking carboxymethyl chitosan (CM-chitosan) with different concentrations of terephthaloyldiisothiocyanate. The swelling behaviors of the hydrogels at different pH values (4, 7 and 9) and temperatures (25, 35 and 45 ºC), as well as their electrical conductivity, have been investigated. The results reveal that the highest swellability was attained at 35ºC in acidic medium (pH 4), which indicated the dependence of the swellability of the hydrogels on pH and temperature. The results also indicated that the swellability percent of the prepared hydrogels increased with increasing of their cross-linking density, reaching their maximum values at 35ºC. On the other hand, the electrical conductivity of the hydrogels decreased with increasing cross-linking density and increased when rising the temperature up to 45ºC. It is expected that these smart hydrogels may be useful to develop drug delivery systems with improved drug loading capacity and controlled release behavior.