Properties of polyelectrolyte complexes containing poly(N‐tert‐butylaziridine)

Abstract

AbstractInterpolymer reactions between poly(acrylic acid) (PAA) or poly(methacrylic acid) (PMAA) and poly(N‐tert‐butylaziridine) (PTBA) were studied and compared with the corresponding reactions of these polyacids with linear polyethyleneimine (LPEI). In aqueous alkaline and salt media the presence of the bulky non‐polar N‐substituent in the main chain of PTBA results in a decrease of stability of polyacid‐PTBA polyelectrolyte complexes. LPEI, which forms stronger salt bonds with PAA, substitutes PTBA in the PAA‐PTBA polyelectrolyte complexes. Addition of simple salts to aqueous solutions of non‐stoichiometric polyelectrolyte complexes (N‐PEC) PAA‐PTBA and PMAA‐PTBA at room temperature causes a phase separation due to macromolecular exchange and disproportionation reactions. At elevated temperatures (T = 40 ‐ 60 °C), however, the macromolecular exchange between different N‐PEC particles does not occur and phase separation in aqueous salt solution of the N‐PEC's PAA‐PTBA, PMAA‐PTBA is not observed. This is attributed to hydrophobic interactions in polyacid‐PTBA complexes due to the presence of the tert‐butyl groups in the latter.