Synthesis and rheological investigations of gum-ghatti-cl-poly(NIPA-co-AA)-graphene oxide based hydrogels

Abstract

The purpose of the present work is to study the rheological properties of gum ghatti-cl-poly(NIPA-co-AA)/GO (GNAGO) hydrogels reinforced with graphene oxide (GO) to modify their mechanical and thermal properties. The GNAGO hydrogel was characterized by SEM and the thermal stability of the hydrogel was examined by TGA measurements. The study of the storage (G′) and loss (G′′) modulus shows that the gum ghatti-cl-poly(NIPA-co-AA)/GO (GNAGO) acts elastically in nature. The results showed that gum ghatti-cl-poly(NIPA-co-AA)/GO hydrogels showed greater viscoelastic properties than the gum ghatti-cl-poly(NIPA-co-AA) hydrogel. A decrease in viscosity with the increase in shear rate confirms the non-Newtonian behavior of the hydrogels. The determined covalence crosslinking is confirming the solid-like behavior and elastic nature (G′ > G′′). The flow properties of the hydrogel were studied using rheological models (Herschel–Bulkley and Power law) and based on the R² value, both of the models were found to be best fitted. Furthermore, the damping factor (tan δ) was found to be close to 0.35, indicating that the damping of the materials has been improved due to the interlocking and penetration of GO particles within the hydrogel. The results of this work provided great insight into understanding the relationship between microstructure and mechanical performance of hydrogels and these materials can be applied for adsorption, and controlled drug loading and release due to the presence of GO as a drug-binding effector in the GNAGO hydrogels.