Optically active polyimides with different thermal histories of their preparation

• Published in: Chirality (New York, N.Y.) N.Y.), 2022-08, Vol.34 (8), p.1151-1161
• Main Authors: Sysel, Petr, Hovorka, Štěpán, Kohout, Michal, Holakovský, Roman, Žádný, Jaroslav, Čížek, Jan, Izák, Pavel
• Format: Article
• Language: English
• Subjects: Anhydrides; chiral selector; Circular dichroism; Dichroism; Enantiomers; Infrared spectroscopy; Optical activity; Phenylalanine; polarimetry; polyimide; Polyimide resins; Selectors
• ISSN: 0899-0042; 1520-636X
• DOI: 10.1002/chir.23476

Optically active linear polyimides and hyperbranched poly (amic acid–imide) were prepared by using procedures varying in particular in the maximum temperature employed in their synthesis. The two types of linear polyimides were based on 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride and 1,2‐diaminocylohexane enantiomers or 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride and 2,2′‐diamino‐1,1′‐binaphthalene enantiomers. The amine‐terminated hyperbranched poly (amic acid–imide) was prepared from 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride and 4,4′,4″‐triaminotriphenylmethane, and its end groups were modified with the chiral selectors N‐acetyl‐D‐phenylalanine or N‐acetyl‐L‐phenylalanine. The final structure of the products was analyzed by IR spectroscopy, and their optical activity was evaluated and confirmed by polarimetry or circular dichroism. (Modified) polyimides based on enantiomeric low‐molecular‐weight compunds were prepared. The optical activity was transferred from these building blocks into the final polymer structures. The reaction temperatures up to 230°C do not contribute to racemization markedly. These polyimides are potentially suited for the use as enantioselective membranes.