Enhancement swelling properties of PVGA hydrogel by alternative radiation crosslinking route

The development of environmentally friendly materials based on non-toxic absorbent polymers, which can ensure high water absorption for several applications in biomedical or agricultural areas, is one of the most complexes problems. In the literature, the non-toxic biodegradable polymer poly(vinyl alcohol) (PVA) was chemically modified with glyoxylic acid to obtain poly(vinylglyoxylic acid) (PVGA) as a biodegradable superabsorbent hydrogel polymer (SHAP), but in fact, the chemical crosslinking reaction decreases the water absorption capacity. In order to crosslink PVGA without losing its absorbent capacity; an alternative radiation-crosslink route has been studied. Radiation-induced crosslinking in the main C-C chain of PVGA where not all free hydrophilic groups (COOH) are involved in a crosslinking reaction as occurs in a traditional chemical reaction. The aim of this work was not only the chemical modification of 99% hydrolyzed PVA to obtain the linear and non-crosslinked PVGA at certain conditions, but also radiation crosslinking at different doses, at dose rate of 5 kGy h−1 attempting to increase the superabsorbent capacity. The samples were characterized by Scanning Electron Microscopy (SEM), Thermo-gravimetrical Analysis (TGA), Nuclear Magnetic Resonance (1H) (NMR) and Infrared Spectroscopy (FTIR). The swelling behavior was measured gravimetrically in different solvents as pure water, buffer pH 3, 7 and 10. Results showed that radiation-crosslink route improves the swelling behavior of PVGA in approximately 215% when compared with PVGA chemically crosslinked, swelled in pure water.