Synthesis, characterization and rheological study of Arabic gum-grafted-poly (methacrylic acid) hydrogels

Abstract

Hydrogel synthesis from synthetic and natural polymers display mutual advantages in terms of mechanical strength, biocompatibility, and degradation. Hydrogels have emerged as one of the most effective carriers for drug and therapeutic agents in control delivery. In this research, Arabic gum, a natural polymer and methacrylic acid (synthetic polymer) was grafted through free radical polymerization method to form a smart hydrogel. The non-toxic and biocompatible hydrogels were characterized via Fourier Transform Infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction analysis. The morphology was analyzed by field emission scanning electron microscopy (FESEM) and the mechanical properties by rheological studies. The reaction variables were studied by changing the concentration of initiator, monomer and cross-linking agent. Swelling study revealed high swelling in hydrogels with higher concentration of initiator and a low swelling in hydrogels with higher concentration of cross-linker and monomers; this confirmed the influence of the reacting variables on the swelling. Swelling kinetics follow second order non-Fickian mechanism which depends on the pH and composition of the hydrogel. The rheology revealed the mechanical properties of the hydrogels by amplitude and frequency sweep tests of the elastic modulus and viscous moduli. The storage modulus is higher for hydrogels with high concentration of monomers but lower in hydrogels with high concentration of initiator and cross-linking agents. The degradation depends on the ratio of monomer and cross-linking agents, least degradation was observed in hydrogels with higher percentage of cross-linking agents. The properties displayed reveals the potentials of the Arabic gum-grafted hydrogels for agricultural, biomedical and pharmaceutical applications.