## 3 Results and Discussion
Furthermore, we changed the method of preparation of the polymerization mixture before addition of the initiator. According to our procedure NIPAM, CuCl and half of the total volume of isopropanol used in the polymerization were placed directly in a reaction vessel. Next, the mixture was degassed; and then Me\({}_{6}\)TREN was introduced into the vessel. In this way, we could omit a step aimed at transferring the mixture with suspended CuCl (not dissolved in this mixture) to the reaction vessel, as required by the procedure of [PERSON] et al. [22] We observed that this step in the procedure can lead to loss of some CuCl and may therefore be responsible for poorer polymerization control. The polymerization was carried out with molar ratios of initiator to monomer 1:50 and 1:200 and for periods of time from 2 h to 23 h (see Table 1). The obtained polymers were purified and analyzed by SEC. Table 1 presents the comparison of theoretical molecular weights for the obtained polymers (calculated using a molar ratio of initiator (I) to monomer (M) and obtained conversion (conv)) with the molecular weights determined for them from the SEC analyses as well as polydispersity indices. Most of the SEC analyses were carried out using 1% solution (_w/v_) LiBr/DMF as the mobile phase. This is because our earlier studies proved that, in the case of separation of hydrophilic polymer materials on a column packed with cross-linked polystyrene (PS)-divinylbenzene (DVB) copolymer particles, using THF as an eluent is difficult. Application of DMF with the addition of LiBr as an eluent allows lower retention of such by the PS-DVB stationary phase [24; 25]. Application of NCPAE as an initiator and modification of the procedure reported by [PERSON] and co-workers [22] allowed very good control of NIPAM polymerization, and high functionality could be achieved. The molecular weights expected on the basis of the applied molar ratios M:I and the obtained conversions are very close to those obtained from the SEC analyses. For the same molar ratio of NIPAM to methyl 2-chloropropionate, as an initiator, [PERSON] et al. [22] reported higher conversions at for the same polymerization time and molecular weights from SEC almost twice as high as predicted theoretically. A similar situation was observed by these authors for higher [M]:[I] ratios, namely 100:1, 200:1 and 400:1. In our system, we observed the opposite situation for the higher ratio 200:1--the molecular weight determined from SEC analysis is smaller than the theoretical weight (sample P6). It is likely that both the application of the initiator proposed in this work and modification of the procedure caused the polymerization to run slower. The polydispersity indices PDI (defined as the ratio of weight-average molecular mass and number average molecular mass \(M_{\text{w}}\)/\(M_{\text{n}}\)) determined from SEC analyses are relatively low, close to 1 (\(<\)1.2) for the polymers that were obtained using a molar ratio M:I = 50:1. In the case of the molar ratio 200:1, the polydispersity is insignificantly higher (1.31). Importantly, the application of NCPAE as an initiator in molar ratio [M]: [I] 50:1, together with modification of the procedure proposed by [PERSON] and co-workers, gave excellent agreement between theoretical and experimental \(M_{\text{n}}\) molecular weights (see Table 1). However, when the molar ratio [M]: [I] = 200:1 was used, the experimental molecular weight from SEC (11,700 Da) was significantly lower than theoretical one (14,400 Da) and PDI index was higher (1.31). Figure 2 depicts the molecular weight distribution from SEC analyses for all the prepared PNIPAMs. For P1-P5 the curves are very narrow whereas for P6 they are relatively narrow with tailing on higher molecular weight side.