A method of forming a pattern comprises diffusing an acid formed by irradiating a portion of a photosensitive layer, into an underlayer comprising an acid sensitive copolymer having acid decomposable groups and attachment groups covalently bonded to the surface of the substrate and/or forming an interpolymer crosslink. Diffusing comprises heating the underlayer and photosensitive layer. The acid sensitive group reacts with the diffused acid to form a polar region on the underlayer, with the shape of the pattern. The photosensitive layer is removed, forming a self-assembling layer comprising a block copolymer having a first block with an affinity for the polar region, and a second block having less affinity for the polar region. The first block forms a domain aligned to the polar region, and the second block forms another domain aligned to the first. Removing either domain exposes a portion of the underlayer.