Characterization of new thermo-responsive hydrogels for optical sensing applications

Abstract

We report the use of new hydrogels based on poly-N-isopropylacrilamide and MeOXA in order to measure temperature using optical transmittance. We have obtained thermo-responsive hydrogels based on the radical copolymerization of N-isopropylacrylamide (NIPAAm) and bis-macromonomers of 2-methyl-2-oxazoline (MeOXA). The hydrogels show conformational transitions at defined temperatures, which are a function of the molar ratio NIPAAm / MeOXA inside of the hydrogel. The temperatures of transition have been determined by means of 1H NMR spectroscopy and by turbidity measurements using an optical setup with optical fibers and a diode laser. We show the first experimental results and we discuss some future applications such as an optical switch or a device for optical sensing.