Copolymerizations of St and NIPAM have been carried out through interfacial-initiated microemulsion polymerization in a frozen state. FT-IR and NMR spectroscopies confirm the occurrence of copolymerization between the two monomers. DSC analysis shows the existence of two glass transition temperatures of the resultant copolymers. The micellization of the copolymers is investigated by DLS and the temperature-responsive behavior of the resultant micelles is observed DSc and DLS results reveal the block feature of the obtained copolymers. Thus amphiphilic poly(styrene-block-N-isopropylacrylamide) is prepared by a one-step interfacial initiated microemulsion polymerization.