## 3 Results and Discussion
Polymerization conditions: [NIPAM]:[NCPAE]:[CuCl]:[Me\({}_{6}\)TREN] = 50:1:1.1, room temperature, isopropanol as a solvent (1:2 NIPAM:solvent, _uvw_). The black and red arrows indicate a proper axis for the relationship shown in the same color. molecular weight determined from SEC is highest among those studied. However, the differences between other samples are insignificant and the peak temperature occurs around 43 \({}^{\circ}\)C. The lack of differences between the CST for the other samples might be a result of relatively small differences between their molecular masses (2-5 kDa). On the other hand, the number-averaged molecular mass of P6 is not significantly higher but its polydispersity is significantly higher (PDI=1.31) and the presence of the fraction with higher molecular mass might be responsible for the decreased CST. The CSTs determined by DSC are very close to the values reported by [PERSON] et al. (2018) for the PNIPAMs with similar molecular weights and MWDs. The phase transition enthalpies, estimated as areas of the corresponding endothermic peaks, are also presented in Table 2. The estimated enthalpies are within the range 3-14 J per 1g of solution with a concentration 1.5% (_w/w_) which corresponds to a concentration of \(1.3\times 10^{-4}\) in repeating units (NIPAM mers) of mol per 1g of solution. These values are several times higher than those determined by [PERSON] and [PERSON] ([PERSON] and [PERSON] (2018) for solutions with similar concentration of PNIPAM. The differences in the determined values may result from the differences in size of polymer molecules and polymer dispersity. [PERSON] and [PERSON] performed DSC measurements for PNIPAM with molecular mass \(5.5\times 10^{2}\) kDa prepared by classical radical polymerization, so with a wide MWD. Probably, in the case of polymers built of molecules with lower molecular weights, like those studied here, a transition from the coiled state to the globular conformation requires more energy. Most likely, more hydrogen bonds between short polymer chains and water molecules must be broken to change the conformational state. The higher transition temperatures for our samples, in comparison to those determined by [PERSON] et al. (2018) also indicate that, in the case of PNIPAMs with smaller molecular mass and lower polydispersity, the phase separation requires more energy and therefore occurs at higher temperature. Nevertheless, we didn't find any correlation between molecular mass and endothermic enthalpy (\(\Delta H\)) of the thermal phase transition. The differences in molecular masses of the prepared polymers are probably too small to see any relationship between them; or such a relationship doesn't exist. On the other hand, as it was recently reported, not only molecular weight has an influence but also the experimental conditions, such as concentration, the heating rate, wavelength of light in optical measurements, have also significant effect on the observed CST ([PERSON] and [PERSON], 2018; [PERSON] and [PERSON], 2018). The dynamic light scattering (DLS) technique was also used to examine the thermosensitivities of the prepared polymers. Importantly, all polymer samples were dissolved in ultra-pure water at least 1 h before the measurements to give sufficient time for hydration sphere formation around the polymer molecules. Figure 5: The heating DSC thermogram for an aqueous solution of P1 (1.5% _w/w_) and photos of the solution below and above the phase transition corresponding to the endothermic effect visible on the curve. The heating rate of 1 K/min. The hydrodynamic diameters of particles were determined in the solutions at 25, 35 and 45 \({}^{\circ}\)C. Figure 6 shows the number-averaged hydrodynamic diameter distributions in aqueous solutions of P1 and P6 with the same concentration (1.5% _w/w_). As can be seen in Figure 6, an aggregation process occurs when the temperature increases to 45 \({}^{\circ}\)C in the solution of P1 and at 35 \({}^{\circ}\)C in solution of P6.