Stimuli-responsive luminescent supramolecular polymers based on hydrogen bonding: molecular fabrication, phase structure, and controllable-rewritable behavior†
Abstract
Luminescent materials with stimuli-responsive behavior have good prospects for application in displays, sensors, and other fields. In this research, a type of luminescent supramolecular polymer was fabricated, via hydrogen bonding, that shows stimuli-responsive behavior with different types of acid. Firstly, the acceptor material luminogen (4,4′-dibutanoxy tetraphenylethylene)-1-pyridine (PTPEC4) is synthesized. Then, the PTPEC4 is used to prepare luminescent supramolecular polymer PVA(PTPEC4)x by complexing the donor material poly(vinyl alcohol) (PVA) with different amounts of PTPEC4. The PVA(PTPEC4)x exhibits a lamellar structure at x ≥ 0.6, whereas a crystalline structure forms with x ≤ 0.4. Because of the protonation effect of the pyridine group in PTPEC4, PVA(PTPEC4)x not only exhibits solid-state emission behavior but also presents multicolor luminescence switching under different acid vapors. Moreover, because of the existence of the hydrogen bonds, PVA(PTPEC4)1.0 shows a reversible, spontaneous fluorescence switch under acid vapor with a pKa > 5.25. If the sample is fumed with acid vapor with pKa < 5.25, PVA(PTPEC4)1.0 only exhibits a larger luminescence red shift but cannot recover unless the sample is treated with triethylamine vapor. Furthermore, a rewritable paper with tunable multicolor emission and high contrast is prepared based on the fluorescence response and recovery behavior, which may be applied in optical memory systems.