Cross-Linking Of Gamma-Cyclodextrin Using Non-Toxic Polyethylene Glycol Spacer Units

The crystalline cyclic oligosaccharide gamma-cyclodextrin (gamma CD) is a natural, non-toxic and biodegradable precursor that can be used to prepare innovative polymers. We cross-linked gamma CD with variable quantities of non-toxic polyethylene glycol diglycidyl ether (PEGDGE) in aqueous NaOH to form 3D structures with tunable physicochemical properties. Mixtures with a 5 : 1 PEGDGE:gamma CD molar ratio produced a cross-linked material that was soluble in water and organic solvents, underwent glass transition at -23 degrees C. The properties of this material were further modified by additional curing with PEGDGE or nitration reaction. Curing produced an insoluble polymeric material with excellent swelling abilities (200 % in water) and decreased glass transition temperature to -37 degrees C. The nitrated cross-linked gamma CD was soluble in common organic solvents and underwent glass transition at +19 degrees C, achieving thermal stability below 190 degrees C. These novel gamma CD polymers are promising materials for applications in the pharmaceutical and food industries and environmental remediation.