High-water-solubility rhodamine-based polyion liquid and preparation method and application thereof

The invention belongs to the field of detection of heavy metal ions and particularly relates to high-water-solubility rhodamine-based polyion liquid and a preparation method thereof. The high-water-solubility rhodamine-based polyion liquid is applied to quick visual colorimetric detection of pure-water-phase copper ions. The rhodamine-based polyion liquid is formed by copolymerization of ion liquid monomers and salicylide-like rhodamine B hydrazide monomers, and has the advantages that the raw materials are low in cost and easy to obtain, preparation is easy and convenient, the rhodamine content is high, water solubility is excellent, and no nonspecific binding site exists; and efficient colorimetric detection of trace copper can be achieved in the environment of pure water, the detection limit of naked eyes and the detection limit of an ultraviolet-visible light spectrophotometric method are 0.5 micron and 0.15 micron correspondingly and are both far lower than 31 microns specified by the World Health Organi