ORGS1-1213
Modulation of Antifouling Properties and pH Responsiveness by Carboxyl Group Position in Ethylenediamine-Derived Polymer Betaines
Topic
GS1. Graduate Student Oral Session I: Colloidal and Interfacial Polymer Science
When and Where
Sep 28, 2026
14:24 - 14:36
Room 101
Session Chairs
Yoon-Ho HWANG
Jang-Hwan KIM
Hyosung AN
Presenter(s)
Hiina Danno (Kyoto Prefectural University of Medicine)
Co-Author(s)
Abstract
In general, betaine structures consist of one cationic and one anionic moiety, allowing electrically neutral over a wide pH range for excellent antifouling properties. In contrast, we have demonstrated that diamine-derived betaine structures can be designed to switch the antifouling property to be tissue-interactive within the intended pH range. For example, ethylenediamine is mono-protonated at pH 7.4, but the di-protonation proceeds at pH < 6.5, enabling neutral net charge at physiological pH but cationic net charge under weakly acidic conditions. In this regard, pH responsiveness of cationic moieties is influenced by the adjacent chemical structures, which has prompted us to investigate the design principles based on the rearrangement in the diamine-based structures for tuning the pH responsiveness. To this end, we synthesized two ethylenediamine-derived poly(carboxybetaine)s [PGlu(DET-Car)], in which the carboxy group was appended to different amino groups of the ethylenediamine structure via an ethylene spacer: PGlu(DET-Car)_1 containing two secondary amines and PGlu(DET-Car)_2 containing one primary and one tertiary amine.
pH titration revealed comparable pKa values between the two poly(carboxybetaine)s, indicating their similar protonation behavior. Nevertheless, they exhibited different trend in interaction with anionic polymers; PGlu(DET-Car)_1 formed complexes with dextran sulfate at pH < 7, whereas complex formation occurred at pH < 6 for PGlu(DET-Car)_2 system. These results suggest that rearrangement in the betaine structures arising from the carboxyl group position is a key factor governing the pH-responsive behavior of diamine-derived betaine structures.
pH titration revealed comparable pKa values between the two poly(carboxybetaine)s, indicating their similar protonation behavior. Nevertheless, they exhibited different trend in interaction with anionic polymers; PGlu(DET-Car)_1 formed complexes with dextran sulfate at pH < 7, whereas complex formation occurred at pH < 6 for PGlu(DET-Car)_2 system. These results suggest that rearrangement in the betaine structures arising from the carboxyl group position is a key factor governing the pH-responsive behavior of diamine-derived betaine structures.
