Abstract
The direct synthesis of segmented poly(urethane-urea)s (DSPUU) from an isocyanate-terminated prepolymer (ITPP) and reaction products (AE) from acetone and ethylenediamine consisting of N-isopropylideneethylenediamine (1), N,N′-diisopropylideneethylenediamine (2), 2,2-dimethylimidazolidine (3), water and the unreacted diamine was kinetically investigated. The following elementary reactions forming the desired urea structure linkage take place simultaneously in the absence of an acid at 40°C; (i) reaction of NCO groups with amino groups of the unreacted diamine and (1), (ii) direct reaction of NCO groups with (3), (iii) ring opening reaction of (3), and (iv) reaction of NCO groups with the ketimine groups in (1) and (2). The side reactions of NCO groups with water (Urea II formation reaction) catalyzed by both the ketimine groups and the imino groups occurred. Dramatic decrease of the yield of Urea II in the presence of acetic acid is attributed to the acid-catalyzed ring opening of the imino groups of (3) in particular and acid-catalyzed hydrolysis of the ketimine groups.
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Hanahata, H., Yamazaki, E., Hiwatari, Ji. et al. Segmented Poly(urethane-urea)s Synthesized Directly from Isocyanate-Terminated Prepolymers and Masked Diamines III. Kinetic and Mechanistic Study on Polymerization Reactions. Polym J 29, 826–835 (1997). https://doi.org/10.1295/polymj.29.826
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DOI: https://doi.org/10.1295/polymj.29.826