Résumé
This research presents an experimental analysis of thermally induced phase separation (TIPS) dynamics in a polymer aqueous solution with very different viscosities (a factor of about a thousand) between separated phases but with no elastic character. The study encompasses the determination of the phase diagram for the polymer‐water system, and the exploration of phase separation (PS) dynamics in critical and off‐critical systems using laser scanning confocal microscopy (LSCM). Thus, domain growth is analyzed through a fast Fourier transform (FFT) from the confocal images, providing insights into the characteristic size and the structure factor scaling. The study focuses on 10 and 12 wt. % polyvinyl alcohol (PVA) solutions, revealing distinct morphologies and growth mechanisms. Despite the huge difference in viscosities between separated phases, PVA 10 exhibits characteristics of spinodal decomposition with interconnected structures and linear growth (L m (t) ∼ t 1 ), indicative of hydrodynamic coarsening. Conversely, PVA 12 shows a trend toward discontinuous structures with growth following L m (t) ∼ t 1/3 , suggesting a diffusion‐driven coalescence mechanism. Notably, both systems demonstrate self‐similar growth patterns despite the significant viscosity contrast, as confirmed by scaled structure factor analysis.