Directed self-assembly (DSA) of block copolymers (BCPs) is a promising approach for the fabrication of sub 10 nm features. Although a variety of BCPs allow the feature size down to sub-10 nm, most of them are incompatible with the existing manufacturing process employed by the microelectronic industry. Herein, we report the synthesis and DSA of lamellae-forming styrene-methyl acrylate BCPs: poly(styrene-b-methyl acrylate) (PS-b-PMA) diblock copolymers and poly (methyl acrylate-b-styrene-b-methyl acrylate) (PMA-b-PS-b-PMA) triblock copolymers. PS-b-PMA has a similar chemical structure to the benchmark poly(styrene-b-methyl methacrylate) (PS-b-PMMA) for DSA except that PMA does not have the side methyl group in PMMA. The Flory-Huggins interaction parameter (chi) between PS and PMA is much higher than that between PS and PMMA, while the surface energies (gamma) of PS and PMA are nearly equal, which allows the formation of perpendicularly oriented lamellar domains in films with periods down to 13.9 nm under thermal treatment. DSA of PS-b-PMA and PMA-b-PS-b-PMA with density multiplication is demonstrated on chemical patterns, and sub-8.5 nm features are obtained by subsequent pattern transfer using the sequential infiltration synthesis process. These results demonstrate that PS-b-PMA and PMA-b-PS-b-PMA could be the promising next-generation BCPs for DSA lithography.