Synthesis of radiation crosslinked poly(acrylic acid) in the presence of phenyltriethoxysilane

• Phenyltriethoxysilane (PTES) has been used to crosslink poly(acrylic acid).
• Radiation crosslinking of poly(acrylic acid) in the presence of PTES has been studied.
• The synthesized hydrogel showed switchable swelling response against pH changes.
• Highest swelling of 247 g/g is achieved at neutral pH.

Acrylic acid based superabsorbent hydrogel was prepared using phenyltriethoxysilane (PTES) as polyfunctional monomer. Different amounts of PTES were incorporated in acrylic acid and irradiated at different doses upto maximum of 30 kGy. The crosslinked acrylic acid showed hydrogel properties and its swelling kinetics, gel fraction and equilibrium degree of swelling (EDS) were studied. It was found that the increased PTES concentration decreased the EDS of the hydrogels. Infrared spectroscopy confirmed the crosslinking reaction between the feed components and the existence of siloxane bond. Thermogravimetric analysis showed an increase in the stability of the hydrogels having high PTES content. The swelling of the hydrogel was affected by pH, ionic strength and temperature. These hydrogels showed low swelling in acidic and basic pH range and high swelling around neutral pH. This switchable pH response of these hydrogels can be exploited in environmental and biomedical applications.