Hydrogel membranes based on gum tragacanth with tunable structure and properties. I. Preparation method using Taguchi experimental design

Gum tragacanth (GT) was exploited to create a series of novel hydrogel membranes with diverse swelling properties. The films of this biopolymer were crosslinked with applying heat only, as well as application of four types of chemical crosslinking reagents, including glycerin, ethylene glycol, triethylene glycol, and glutaraldehyde. The effects of the crosslinking agent concentration, crosslinking reaction temperature (57-97 degrees C) and reaction time (2-24 h) on the equilibrium swelling of each series of the synthesized hydrogels were investigated by the aid of Taguchi method of experimental design. This approach facilitated the study of interaction of a large number of variables spanned by factors and their levels with a small number of experimental runs. In all cases, it was found that by increasing the concentration of each type of the crosslinking reagent and extension of the crosslinking reaction time, the swelling capacity of the prepared hydrogel films decreased. However, by increasing the crosslinking temperature, the equilibrium swelling capacity changed by passing through a minimum. As a whole, the equilibrium swelling values of the hydrogels proved that a broad range of hydrogel membranes having the crosslinking densities of 0.83-23.87 x 10(-6) mol/cm(3) and swelling capacities of 120-1580 g/g was achieved successfully from GT. Thus, GT was assigned as a promising biopolymer for preparing membranes with diverse structural and swelling characteristics. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 99-108, 2012