Water-soluble high molecular compound is also called as water-soluble resin or water-soluble polymer. Usually, the water-soluble high molecular compound is a kind of strong hydrophilic material, which could be dissolved or swollen in water and could form the solution or a kind of dispersing structure.

In the molecular structure of the water-soluble high molecular compound, there are numerous hydrophilic groups. Normally, the hydrophilic group is divided into three types: the cationic group, such as the tertiary amino groups and the quaternary amine groups etc; the anionic group, such as the carboxylic group, the sulfonic group, the phosphate group and the sulfate group etc; the polar nonionic group, such as the hydroxyl group, the ether group, the amino group and the amide group etc.