Near-infrared spectroscopy and multivariate curve resolution-alternating least squares for the study of time-dependent structural changes of laponite aqueous colloidal gels
Résumé
Laponite aqueous colloidal suspensions undergo structural evolution with time. The time-dependent changes in chemical or physical structure are usually termed as ageing process. In this work, we study the ageing behavior of Laponite aqueous colloidal gels having 2 and 3 % (w/w) of Laponite using near infrared spectroscopy (NIRS). The aim of this study is to investigate the ability of near-infrared spectroscopy combined with Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) analysis to monitor and detect changes in structural properties of Laponite aqueous colloidal suspensions during the ageing process. To enable resolution and provide meaningful results, difference spectra were used. This strategy enhances the fine spectroscopic changes undergone during the process and allows characterizing the effects of the perturbations on the NIR spectra in terms of changes in hydrogen bonding and scattering phenomena.