Preparation of New pH-Sensitive Nanocomposites through in situ Copolymerization of Methacrylic Acid with Ionic Liquid-Modified Laponite Clay

New pH-sensitive polymer–clay nanocomposites were prepared through in situ copolymerization of methacrylic acid with modified laponite. First, an ionic liquid monomer, 1-(4-vinylbenzyl)-3-methylimidazoliumchloride, was synthesized through the quaternization of N-methylimidazole with 4-vinylbenzylchloride. Then, the ionic liquid monomer was intercalated between the laponite layers by the ion-exchange reaction and subsequently copolymerized with methacrylic acid. The composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy to study their structure and the role, laponite plays. Naproxen, was entrapped into these pH-sensitive nanocarriers and the in vitro release profiles were established separately in both enzyme-free simulated gastric and colonic fluids.