## 1 Introduction
Thus, adjustment of the LCST can be achieved, among other ways, by preparing a polymer with well-defined molecular weight followed by copolymerization with a second monomer differing in polarity. For this purpose, ATRP, as one of the most versatile QLRP techniques, can be successfully used. In such a case, choosing the initiator for the ATRP is one the most crucial issues for achieving successful process control. Since contrary to the classical free-radical polymerization, in the ATRP, the initiator takes part in an initiation process and its molecules are not only a source of initiating radicals but also a source of terminal atoms (bromine or chlorine radicals), which reversibly combine with a growing polymer chain. The terminal groups migrate between the active and dormant form of polymer chain, determining in this way the rate of polymerization [7]. In the case of N-isopropylacrylamide amid (NIPAM), which is a very active monomer, the employment of chlorine derivatives, as initiators usually provides good control under the conditions of ATRP. However, for many hydrophobic and less active monomers like a styrene, by applying bromine derivatives, as the initiators, significantly better results might be obtained in comparison with chlorine derivatives. This is because, the bond between the polymer chain terminated by styrene and chlorine is too strong; thus the migration of terminal group between the metal complex and active polymer chain is very slow, if at all possible. So far, copolymers with the sequence PNIPAM-\(b\)-PS have been synthesized by using RAFT polymerization and the self-assembling of such copolymers into micelles has been studied [17; 18]. This type of quasiliving polymerization has been used for preparation of the same blocks in reverse sequence, namely PS-\(b\)-PNIPAM [19; 20]. In the case of RAFT polymerization, the prepared (co)polymers are terminated by dithiocarboxyl groups (S=C(Z)S-) which are able to interact with bioactive compounds, like proteins, therefore their biocompatibility can be limited. ATRP has been employed for the preparation of PNIPAM-\(b\)-PS brushes onto the surface of silicon [21]. To this end, the silicon surface was functionalized with ethyl 2-bromoisobutyrate. Subsequently the ATRP of NIPAM and next styrene were carried out. Bromine derivatives were used as initiators in both polymerization steps. As discussed earlier, in the case of NIPAM polymerization by using chlorine derivatives, better results might be attained. Unfortunately, the copolymers attached to the surface were not analyzed in regard of their polydispersities. Importantly, as it turned out, the silicon wafers covered by PNIPAM-\(b\)-PS, which were obtained via the ATRP technique, are biocompatible. At the same time, such surfaces are thermosensitive which makes them very promising for biomedical applications. In this paper, we report a new synthetic approach for the block copolymers of PNIPAM-\(b\)-PS via the ATRP technique. The proposed method relies on application of 2-chloro-N-(2-hydroxyethyl)propanamide (NCPAE) acting as bifunctional initiator. Functional groups in NCPAE opens up the opportunity to perform ATRP of two monomers differing in activity in a sequential manner. Based on this protocol, copolymers with molecules containing two well-defined polymer chains linked by the proposed initiator were synthesized. To the best of our knowledge, NCPAE has not been used as an initiator in ATRP; and the synthesis of block copolymers via the ATRP technique with a sequence wherein PNIPAM is the first block and PS is the second one has not been reported yet. Importantly, the developed synthetic route allows to build macromolecules with tailor-made length of hydrophobic block. Due to the sequence of the blocks, the synthesized molecules have an active end group on the hydrophobic side. Thanks this, a hydrophobic block can be easily extended, modified and attached to the surface.