Functional polymers with azetidinium groups in the backbone are synthesized via the reaction of aminotelechelic polymers, containing primary and secondary amino groups, with epichlorohydrin. During the reaction, the secondary amino groups are transformed into azetidinium groups and the primary amino groups are transformed into amino-chlorohydrin, amino-epoxide, and azetidinium groups. The formation of desired functional groups in the polymer is controlled by tuning the reaction conditions. To understand the infl uence of reaction conditions generating the desired functional groups, model reactions of primary and secondary amines with epichlorohydrin are studied in detail, including the infl uence of the mole ratio of the starting materials, effect of solvent, effect of pH, and reaction kinetics. high binding capacity of Hercosett 125 due to its ionic nature and cross linking ability, as the four membered strained rings can react with free secondary amino groups of the polymeric resin. The main disadvantage of Hercosett 125 is its low stability. The polymer can be handled only in solution; once the solvent is removed crosslinking occurs. This problem can be solved by synthesizing polymers containing a lower concentration of azetidinium groups in the chain compared to Hercosett 125 and, in addition, hydrophobic segments. Research was started with a hydrophobic polymer containing two primary and a secondary amino groups (Scheme 2 ).These polymers are expected to absorb strongly on a wide range of substrates due to two type of interactions: i) Ionic interactions. It is believed that the cationic azetidinium moiety, which is expected to be formed in the reaction of the secondary amino groups with epichlorohydrin, interacts with the negatively charged surface of the substrate. ii) Hydrophobic interactions. The hydrophobic polymer backbone is responsible for the interaction with hydrophobic domains of the substrate.The main problem for the synthesis of the above designed polymers is the lack of selectivity for the