Aromatic block copolymer ligand sensitized lanthanide nanostructures as ratiometric fluorescence probe for determination of residual K₂CO₃ in super engineering thermoplastics

The residual catalyst (K₂CO₃) presented in the super engineering polyarylene ethers exerts side effects onto their processability and electrical properties. However, the sensitive and reliable analytical tools, that are able to detect residual K₂CO₃ content in these high performance thermoplastics, are rarely reported. Herein, we firstly synthesized an aromatic amphiphilic block copolymer bearing pendent carboxyl and sulfonate groups (named as D5S5). Next, a lanthanide ions mediated solvent-exchange self-assembly was explored to fabricate fluorescent metallopolymeric nanospheres composed of D5S5 and Tb³⁺ with strong green emission (named as Tb-D5S5). Then, the rhodamine B (RB) dyes were combined with the Tb-D5S5 to obtain the fluorescent probe of Tb-D5S5/RB, which exhibited a ratiometric fluorescence response to K₂CO₃. Specifically, the I₅₄₅/I₅₈₅ (intensity ratio of two emission bands at 545 nm and 585 nm) of probe linearly increased with the increasing K⁺ concentration of K₂CO₃ in the range from 0.05 to 7.41 mM. Furthermore, the sensing mechanism of this probe towards K₂CO₃ was revealed. Finally, the Tb-D5S5/RB probe was employed to determine the residual K₂CO₃ in a super engineering polyarylene ether produced by an industrial plant, which showed 85.98 %–89.31 % recoveries of the benchmark results obtained from the inductively coupled plasma optical emission spectrometer (ICP-OES).