Compositions for directed self-assembly (DSA) patterning techniques are provided. Methods for directed self-assembly are also provided in which a DSA composition comprising a block copolymer is applied to a substrate and then self-assembled to form the desired pattern. The block copolymer includes at least two blocks of differing etch rates, so that one block (e.g., polymethylmethacrylate) is selectively removed during etching. Because the slower etching block (e.g., polystyrene) is modified with an additive to further slow the etch rate of that block, more of the slow etching block remains behind to fully transfer the pattern to underlying layers.