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Preparation and Characterization of Novel Poly(Vinyl Alcohol) (PVA) and Poly(Acrylic Acid) (PAA) Hydrogels for Sensitive Hydrogels
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1  Athlone Institute of Technology, Dublin Rd, Athlone, Co. Westmeath, Ireland

Abstract: Stimuli Sensitive hydrogels have enormous potential in various applications. Various environmental variables are found in the body, such as low pH and elevated temperatures. For this reason, either pH-sensitive and/or temperature-sensitive hydrogels can be used for site-specific controlled drug delivery. Furthermore, hydrogels that are responsive to specific molecules, such as glucose or antigens, can be used as biosensors as well as drug delivery systems. For many applications hydrogels require a very rapid time-response in terms of their sensitivity to either pH and/or temperature. Rapid time-responsive sensitivity is a research field which is still in development. In this research pH-sensitive hydrogels have been made varying the composition and molecular weight of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). After total dissolution of the PVA/PAA the hydrogel was freeze/thawed. The swelling responses were investigated as well as the drug release profile with varying pH. The drug release was studied with a model drug theophylline. The characteristic properties were examined with ac impedance, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), SEM morphology analysis and Energy-dispersive X-ray spectroscopy (EDS). The results showed that the optimum formulation to be used as a stimulus sensitive hydrogel is found with lower concentration of PVA and a higher concentration of PAA. These PVA/PAA polymer exhibited excellent thermal properties and mechanical properties and have potential in biomedical applications.
Keywords: Poly(vinyl alcohol); Poly(acrylic acid); pH-sensitive; Swelling