Color-Tunable and Stimulus-Responsive Luminescent Liquid Crystalline Polymers Fabricated by Hydrogen Bonding

• Published in: ACS applied materials & interfaces 2019-04, Vol.11 (16), p.15051-15059
• Main Authors: Tao, Lei, Li, Ming-Li, Yang, Kai-Peng, Guan, Yan, Wang, Ping, Shen, Zhihao, Xie, He-Lou
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.9b01476

Luminescent liquid crystalline polymers (LLCPs) show extensive application potentials, such as liquid crystal displays and circularly polarized luminescence. In this work, we employ a hydrogen-bonding strategy different from the traditional covalent-bonding method to fabricate LLCPs. First, the acceptor and donor of hydrogen bonding, (4,4′-dibutanoxy tetraphenylethylene)-1-pyridine (PTPEC4) and poly­(2-vinyl terephthalic acid) (PPA), respectively, are successfully synthesized. Then, mixtures with different molar ratios (x’s) of PTPEC4 to PPA are used to prepare a series of LLCPs [denoted as PPA­(PTPEC4) x ]. The resultant LLCPs show a smectic A phase (x ≥ 0.8), a columnar nematic phase (0.6 ≤ x ≤ 0.05), and an amorphous state (x = 0.025), depending on the x value. Meanwhile, all polymers exhibit typical aggregation-induced emission behavior. More interestingly, with the variation of the PTPEC4 content, the series of LLCPs show different colors, that is, the emission peak red shifts from 510 nm (x = 1.0) to 551 nm (x = 0.025). Furthermore, because of the reversible protonation effect of the N atom of pyridine in PTPEC4 by the strong proton acid, PPA­(PTPEC4) x shows reversible color transformation. This work provides a new method to construct LLCPs with different emission colors and reversible color transformation.