In this study, we synthesized a triphenylamine-functionalized polytyrosine (PTyr-TPA) through living ring opening polymerization with 4,4'-diamino-4″-methoxytriphenylamine (TPA-NH₂) as an initiator, and used Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy to confirm the chemical structure. Photoluminescence spectroscopy revealed the photophysical properties of TPA-NH₂ and PTyr-TPA and suggested that TPA-NH₂ exhibited aggregation-caused quenching; in contrast, attaching the initiator to the rigid rod conformation of the PTyr segments caused PTyr-TPA to display aggregation-induced emission behavior. Differential scanning calorimetry revealed single glass transition temperatures for miscible PTyr-TPA/P4VP blends, the result of intermolecular hydrogen bonding between the pyridine units of P4VP and the phenolic OH units of PTyr-TPA, as confirmed through FTIR spectroscopic analyses. Furthermore, the chain behavior of PTyr-TPA transformed from a β-sheet conformation to random coils after blending with P4VP, as determined using wide-angle X-ray diffraction. These findings suggest that the decreased emission intensity of PTyr-TPA resulted from release of the restricted intramolecular rotation of the triphenylamine moiety in the polypeptide center.
Keywords: Supramolecular Interaction; aggregation-induced emission; polymer blend; polypeptides; secondary structure.