In-situ Raman spectroscopy: An effective technique for the quantification of LCST transition of methylcellulose hydrogels

In-situ Raman spectroscopy was employed to investigate the thermo-responsive sol-gel transition of methylcellulose (MC) based hydrogels at their lower critical solution temperature (LCST). By comparing the Raman signature of dry and wet MC samples, C-Hx bands in the 2700–3100 cm−1 range (associated with vibrations of CH3 bonds) were found to respond to the hydration level of MC. In particular, the intensity of the C-Hx peaks of wet samples was demonstrated to depend on temperature variations (25–50 °C). Data fitting allowed to identify the LCST (~39 °C), thereby disclosing the potential of Raman spectroscopy for the precise quantification of the thermo-responsive behavior of MC hydrogels.