Abstract: Provided is a recycling method of waste polystyrene. In the recycling method, the waste polystyrene is subjected to first swelling and dissolving in water at 140° C. to 300° C. The waste polystyrene may swell and depolymerize in water at 140° C. to 300° C.; meanwhile, the waste polystyrene could self stretch and depolymerize chain segments thereof at 140° C. to 300° C. Under the dual depolymerization mechanism, the polystyrene is remodeled.

Abstract: The present invention relates to a benzylamine derivative, a preparation method therefor and use thereof, and in particular, to a benzylamine derivative as represented by general formula (I), or a pharmaceutically acceptable stereoisomer, salt, solvate or prodrug thereof, which has a strong binding capability with human PD-L1, can obviously inhibit the interaction of PD-1/PD-L1, and has significant anti-tumor efficacy in vivo. Therefore, the present invention also relates to a preparation method for the benzylamine derivative and use thereof in preparing a drug for treating PD-1/PD-L1-related diseases.