Changes in the polymerization process can achieve a weight-average molecular weight ranging from 4×10⁴ to 16×10⁴ to meet different usage requirements. Through the end-capping control during the polymerization process, an average of 1.0 to 1.9 terminal hydroxyl groups can be achieved per 100 repeating polymerization units, which can provide good adhesiveness. Phenolphthalein groups and bisphenol A structures can be introduced, and copolymer modification can be realized during the PESU polymerization stage. In the post-treatment process, the particle size of the powder can be controlled to make the D90 range of the powder particle size 40 μm to 200 μm, adapting to different application environments.