A novel photoluminescent nanohybrid of poly(ε-caprolactone) grafted Mg/Al layered double hydroxides and Tb3+ ions: Synthesis and characterization

Abstract

This paper demonstrates a systematic study of the synthesis and characterization of the hybrid of Mg–Al layer double hydroxides (LDHs), poly(ε-caprolactone) (PCL), and terbium ions (Tb3+). The hybrid LDH-g-PCL-Tb3+-1,10-phenanthroline (Phen) was prepared by the combination of ring opening polymerization (ROP), click chemistry, and coordination chemistry. First, LDHs with a molar ratio of Mg/Al = 2 were prepared by the co-precipitation method, which was subsequently functionalized with (3-chloropropyl) trimethoxysilane in order to introduce azide groups through the reaction of chlorine with sodium azide. Meanwhile, the acetylene functionalized PCL was prepared by ROP of ε-CL, followed by esterification of the hydroxyl groups using succinic anhydride. The click reaction of alkyne-PCL and N3-LDHs successfully afforded LDH-g-PCL, which was coordinated with Tb3+ ions in the presence of Phen. The structure and properties of the nanohybrids were investigated by FT-IR, XPS, EDS, SEM, and TGA analyses. The data indicate the coordination of Tb3+ ions with LDH-g-PCL nanohybrids. The content of Tb3+ ions in the LDH-g-PCL-Tb3+-Phen complex was calculated to be 8.7% (w/w). The LDH-g-PCL-Tb3+-Phen complexes showed four emission bands with high fluorescence intensity centered at 489 nm (5D4 → 7F6), 546 nm (5D4 → 7F5), 586 nm (5D4 → 7F4) and 623 nm (5D4 → 7F3) with excitation at 328 nm (3F6 → 5G6). The stability of LDH-g-PCL-Tb3+-Phen complexes under UV irradiation was high, and no leaching effect was observed.