The Tcp were determined from the transmittance curves as the midpoints between the onset and offset temperatures. The phase diagram shows Tcp decrease with increasing concentration and degree of thionation (Figure ). While at lower concentrations, the decrease of Tcp drops rather steeply with increasing concentration, the change in Tcp seems to level off at above 2 g/L (Figure ). The turbidity curves in all cases sows broader transitions at lower concentrations, especially below 1 g/L. Above the Tcp, transmittance drops to only 50% in very dilute conditions (Figure -S17). In contrast, the correlation between degree of thionation and Tcp seems to be rather linear (Figure ). In addition to the turbidometry, the phase separation of S12 was investigated with variable temperature 1 H NMR spectra and dynamic light scattering (Figure ). For thermoresponsive polymers the phase separation leads to sharp decrease in the intensity of the proton signals because of strongly reduced mobility of the polymer chains. In the case of S12, proton peaks from the side chains decreases but still can be observed above the cloud point, which indicates a remaining presence of mobile and hydrated polymer side chains. Compared to the side chains, the intensity of the backbone signal decreased more noticeably, and signals became broader above the Tcp. These observations are similar to the PEtOx-b-PMeOx block copolymers studied in D2O. DLS data collected for the S12 shows a bimodal size distributions below Tcp, possibly attributable to very minor fraction (as it is not found in the volume % but only in the intensity %) of the polymer with higher thionation degree and lower molar mass, considering the large dispersity of the starting polymer (Figure ). In contrast, above the Tcp, the size distribution shifted essentially quantitatively to micron size aggregates.