Synthesis and characterization of simultaneous IPNs. Evidence of the IPN structure by selective chemical attack on the cross-linker

Abstract

Interpenetrating polymer network hydrogels based on fluoro-, siloxane-acrylates and N-vinylpyrrolidone were synthesized using simultaneous photopolymerization technique in presence of poly(ethylene glycol diacrylate) as cross-linker. These hydrogels were characterized by Fourier-transform infrared spectroscopy and by their swelling properties. Evidence of the semi-IPN structure was shown thanks to the selective chemical attack on the cross-linker. Poly(ethylene glycol diacrylate) crosslinks of prepared hydrogels were attacked by concentrated basic solution leading to the hydrolysis of the poly(ethylene glycol diacrylate) molecules and the degradation of the polymer network. The solid residue and the liquid phase after degradation were analyzed by gas chromatography with mass spectrometry analyzer and by FTIR spectroscopy. These analyses gave evidence of the presence of non-crosslinked poly(N-vinylpyrrolidone) chains in the acrylate network. Henceforth, the synthesized hydrogel should be associated to a semi-IPN structure.