The formation of highly ordered patterns of block copolymers (BCPs) with high. is important for next-generation lithography applications. We demonstrate here a surface-engineering methodology to enhance the self-assembly of poly (styrene-b-dimethylsiloxane) (PS-b-PDMS) BCPs with high. by employing a hydroxyl-terminated polystyrene (PS-OH) brush. By precisely controlling the molecular weight (MW) and weight percent of PS-OH, well-ordered sub-20-nm BCP patterns were obtained over a large area in a short annealing time (< 10 min) with the use of guiding templates. We systemically analyzed how the PS-OH brush affects the self-assembly kinetics of BCPs with various MWs and volume fractions. Moreover, the transmission electron microscopy (TEM) results strongly support that the PS-modulated surface plays an important role in the ordering of BCP patterns. We also achieved well-aligned 12 nm line and 18 nm dot patterns within 3 min by means of binary solvent vapor annealing at a moderate temperature under the optimum PS-OH brush conditions. These results provide a new platform for effective engineering and manipulation of the self-assembly of other BCPs for advanced BCP nanotechnologies.