## 3 Results and Discussion
Nevertheless, these insights are at odds with the claims that the ARGET ATRP enables synthesis of pure block copolymers uncontaminated by homopolymer fractions [33]. On the one hand, the thermal autopolymerization of styrene can be responsible for the presence of homopolymers in our system. However, the formation of polystyrene was observed even for relatively short periods of polymerization time (4 h) and at relatively low temperatures (90 \({}^{\circ}\)C), which suggests the presence of an initiator for styrene polymerization in the system. We speculate that the paramagnetic Cu(II) organic complexes formed as transition states during the polymerization could play the role of such an initiator under the conditions of ARGET ATRP. We did not observe formation of polystyrene in the case when ATRP (instead of ARGET ATRP) was used for the similar system (for the conditions under which chain extension with styrene via ATRP was performed and characteristic of the synthesized polymers see Table S3 and Figure S5 in the Supplementary Material). Figure 8 shows the molecular mass distribution curves determined from the SEC analyses for the synthesized copolymers and for the macroinitiator PNIPAM-Br (denoted in red) used for the preparation PNPS2 and PNPS3 copolymers. Figure 7: The 300 MHz \({}^{1}\)H NMR spectrum of diblock copolymer PNIPAM-\(b\)-PS (recorded for the sample denoted as PNPS2 in Table 3) in CDCl\({}_{3}\). As can be seen in Figure 8, chain extension during the polymerization process is evident. For all the studied copolymers, we observe a monomodal distribution of molecular mass, whereas for PNPS4 and PNPS5 the distribution curves are broad with an accompanying shoulder on the lower masse side. The shoulders visible in the distribution curves are due to the contributions of terminated polymer chain fractions in the polymer sample. On the other hand, the mass distribution curves for PNPS2, PNPS3 are symmetric without the shoulders and the distribution of the molecular mass is relatively narrow for both of them. For the sample denoted as PNPS1, the distribution is narrow, albeit with a small tailing of the peak occurring. It is a likely result of the presence a small fraction composed of fast growing and terminated polymer chains. In general, the SEC analyses proved that the narrowest MWD (among those systems studied) could be achieved using CuCl\({}_{2}\)/PMDETA as a catalytic system via ARGET ATRP procedure. Additionally, decreasing the temperature from 110 \({}^{\circ}\)C to 90 \({}^{\circ}\)C causes a further decrease in PDI value of the synthesized polymers. Taking into account a degree of functionalization of PNIPAMs with bromine (75-85%), we can expect about 15-25% inactive homopolymer molecules in the chain extension with styrene. Thus, most likely, the copolymer samples contain an admixture of PNIPAM. This could explain the presence of the low molecular weight fractions, which are visible in the SEC curves in Figure 8. In our opinion preparative size-exclusion chromatography could be used for the purification of copolymers from residual amount of PNIPAMs. The synthesized block copolymers were analyzed to check their thermosensitivities using DSC and DLS. The aqueous solutions of the prepared copolymers were studied by DSC within the range of temperatures 30-45 \({}^{\circ}\)C. Figure 9 shows an example of a heating DSC thermogram for one sample among the synthesized copolymers (PNPS2) with a heat capacity change observed between 30.1 \({}^{\circ}\)C and 37.5 \({}^{\circ}\)C.  
Figure 8: The molecular mass distribution obtained from the SEC analyses for the synthesized PNIPAM-\(b\)-PS copolymers (see a description of the samples in Table 3) and PNIPAM-Br (denoted in red) used as a macroinitiator for the preparation of PNPS2 and PNPS3. There is no a typical endothermic DSC peak in the thermogram, only a jump of the line within the expected range of temperatures.