Abstract: Methods for irradiation induced graft polymerization of a monomers, such as styrenes, onto fluoropolymers are provided. The methods, which involve either the use of acids, preferably mineral acids, or creating a rough surface on the fluoropolymer, provide higher levels of grafting of the copolymer than grafting in the absence of the acid or of the rough surface on the fluoropolymer. Also provided are grafted copolymers produced by the methods. Methods for increasing the performance of solid phase assays, such as scintillation proximity assays, are also provided.