Non-conjugated AIE Polymers Prepared by Hydrothermal Reaction and Its Application in Fe³⁺ Detection

In recent years, non-conjugated aggregation-induced emission (AIE) polymers without traditional paromatic chromophores have attracted much attention. Although there have been many relevant studies focused on oxygen-, nitrogen-, and heteroatom-containing systems, there is still a lack of researches on those polymers with only oxygen groups. In this study, three novel non-conjugated AIE polymers were prepared with hydrothermal method, in which the poly(maleic anhydride-alt-vinyl acetate) (PMV) prepared by "self-stable precipitation polymerization" is regarded as the raw material. The fluorescence and structural properties of these three polymers and their applications in Fe3+ detection were investigated by using fluorescence spectroscopy, UV-Vis spectroscopy, FTIR, XPS and other characterization methods. It is found that all PMV derivatives have typical AIE characteristcs, and their luminious color is shifted from blue to yellow with the increase of hydrothermal time, in which the maximum emission peaks of these three polymers were 488, 527 and 608 nm, respectively. The highest absolute quantum yield of 17.05% is obtained under the condition that the hydrothermal time is 1 h. Structural characterizations exhibit that none of the three polymers had conjugated groups, and the fluorescent mechanism may be ascribed to the intra- and inter-molecular interaction of oxygen-containing groups caused by hydrothermal reaction. Furthermore, the obtained non-conjugated AIE polymers can be effectively used for Fe3+ detection. Particularly, when the Fe3+ concentration is 5-200 mu mol/L, there is a linear relationship between the quenching efficiency and the Fe3+ concentration, which could be conformed to Stern-Volmer equation. In this case, the adjustment coefficient of determination is 0.9922, and the limit of detect can be as low as 1.22 mu mol/L. This study provided a new strategy to prepare non-conjugated AIE polymers, and further enriched the AIE family.