Bio-based polyureas (PUs) are prepared by the polyaddition of a multifunctional bio-photodimer 4,4'-diamino-α-truxillic acid having two amines and two carboxyls with an aromatic isocyanate comonomer. The films of PUs show high transparency and swell in the alkaline solution when the PU carboxyls are anionized. If metal nitrate salts are added to the films, mechanical properties are increased by the double interaction of the metal cation with carboxylate and nitrate with urea, which causes the films to change the color.
- Xin Jin
- Seiji Tateyama
- Tatsuo Kaneko