Synthesis and characterization of hydrogels formed from a glycidyl methacrylate derivative of galactomannan

Abstract

The present investigation describes a procedure for the synthesis of a glycidyl methacrylated derivative from galactomannan, GA-MA, and the respective hydrogel formation. The galactomannan (GA), raw material, was purified and dissolved in DMSO. After dissolution, 4-dimethyl-amino-pyridine (DMAP) and glycidyl methacrylate (GMA) were added. The modified polymer, quoted as GA-MA, was purified by precipitation in ethanol. Hydrogels were obtained from GA-MA in aqueous solution by polymerization of GA-MA using sodium persulfate (SP), as initiator, and N, N, N′, N′-tetramethylethylenediamine (TEMED), as catalyst. For this, the cross-linking process was trigged by the addition of TEMED and sodium persulfate aqueous solutions. Two different concentrations of TEMED and SP were used. GA, GMA and GA-MA were characterized by FT-IR and NMR ( 13 C and 1 H ) spectroscopy. The addition of GMA on GA molecules was confirmed through FT-IR results by appearing of a band at ν=1717 cm −1 and also by the cleavage of CC groups of GA-MA (band at ν=1636 cm −1) during the cross-linking process. The signals attributed to vinyl carbon of methacrylate ( δ 138.52, 130.06 ppm), to carbonyl ( δ 171.87 ppm) and to methyl group ( δ 20.19 ppm) were observed in the 13 C NMR spectra of GA-MA. The addition of methacrylate on GA was also confirmed through the signals present in 1 H NMR spectra of GA-MA. The formation of hydrogel was observed by complete gelation. The hydrogels were characterized by FT-IR and by measuring the equilibrium water content (EWC) in pH=7.0 and 1.0. The hydrogels contain 83 wt.% of water at 25 °C and 85 wt.% at 37 °C. Good resistance to degradation in acidic conditions, pH=1.0, was observed at 37 °C up to 48 h. These properties suggest that the GA-MA hydrogels may be a new material for pharmaceutical use, mainly for drug delivery system.