## 3 Results and Discussion
Among the polymers studied, the P1 sample is the polymer with the lowest molecular weight, and for this sample at 35 \({}^{\circ}\)C only a marginal increase of particle hydrodynamic diameter can be observed. However, an aggregation process is evident at 45 \({}^{\circ}\)C. For the polymer P6, with six times bigger molecular weight, an aggregation occurs at lower temperature and only particles with diameter above 2,000 nm are visible in the solution at 35 \({}^{\circ}\)C. The results from DLS are consistent with the results from DSC measurements, namely for the polymers with lower molecular mass and lower polydispersity the phase transition occurs at higher temperature, which means that the LCST is for them higher. The results from DLS measurement are similar for other polymers (P2-P5) and the determined sizes of particles at temperatures below and above LCST are in the range between these obtained from measurements for P1 and P6 (see Figure S1 in the Supplementary Material). The polymers prepared using NCPAE as an initiator and CuCl/Me\({}_{6}\)TREN as a catalyst are terminated by chlorine (see Figure 1, Stage I). Thus, theoretically it should be possible to use them as macroinitiators in ATRP of styrene. However, our studies proved that the chain extension with styrene of PNIPAMs terminated with chlorine (PNIPAM-Cl) occurs with a very poor initiation efficiency and only 2-8 mers could be attached (see Table S1 in Supplementary Material). Therefore, we decided to develop a procedure which replaces a terminal chlorine atom with a terminal bromine atom; although this replacement doesn't necessarily occur can at the same position in the polymer molecule. To avoid a partial extension of the polymer chains via transfer of chlorine atoms, first the removal of chlorine atoms from the polymer chains was performed through a dehalogenation process. The dehalogenation was carried out using tributyltin hydride according to the procedure described by [PERSON] and [PERSON] [23]. After the dehalogenation process, only minimal changes in molecular weight and molecular weight distribution were observed (see Table S2 in the Supplementary Material). Figure 6: The number-averaged hydrodynamic diameter distributions in aqueous solutions of P1 and P6 at 25, 35 and 45 \({}^{\circ}\)C from Dynamic Light Scattering (DLS) measurements. Due to the presence of hydroxyl groups in the synthesized PNIPAMs they can be facilely modified. In the developed procedure we used \(\alpha\)-bromoisobutyryl bromide as an acylation reagent and in this way, we introduced a bromine atom, which may be transferred using a catalytic system in ATRP (see Figure 1, Stage III). After the esterification the molecular masses and polydispersity indices of the obtained modified polymers were determined using SEC (see Table S2 in the Supplementary Material). Using elemental analysis and the number-averaged molecular mass of the polymers from SEC, the degree of functionalization of the hydroxyl groups in the polymer chain by bromine atom was determined and it was within the range 75-85%. The synthesized polymers functionalized with bromine (PNIPAM-Br) were then used as macroinitiators in Activators Regenerated by Electron Transfer ARGET ATRP with styrene. We chose this type of ATRP for several reasons. First of all, the ARGET modification enables ATRP with a very low concentration (\(<50\) ppm) of the catalytic system. Thus, the synthesized copolymers practically can be used without a laborious procedure of purification from a catalyst. The purity of the polymers is crucial, in particular for their medical applications. The amount of catalyst may be significantly reduced in this technique due to the employment of a reducing agent such as tin(II) 2-ethylhexanoate (Sn(EH)\({}_{2}\)) or ascorbic acid. The reducing agent constantly regenerates an activator, namely Cu(I) species from the Cu(II) compounds. Therefore the polymerization can be initiated using oxidatively stable Cu(II) species instead of Cu(I) compounds [32; 33].