The hydroxyl end group of poly(vinyl pyrrolidone) (PVP) has been utilized for the first time to reduce AgNO3 in water, generating the Ag triangular nanoplates shown in the figure via kinetic control. PVP is widely used in the chemical synthesis of many types of colloidal nanocrystals, where it is mainly considered as a steric stabilizer or capping agent that protects the product from agglomeration. It is believed that this new strategy can be extended to other noble metals and polymers.