We report herein the modular synthesis and nanolithographic potential of poly(dimethylsiloxane-block-methyl methacrylate) (PDMS-b-PMMA) with self-assembled domains approaching sub-10 nm periods. A straightforward and modular coupling strategy, optimized for low molecular weight diblocks and using copper-catalyzed azidealkyne click cycloaddition, was employed to obtain a library of PDMS-b-PMMA and poly(dimethylsiloxane-block-styrene) (PDMS-b-PS) diblock copolymers. FloryHuggins interaction parameters, determined from small-angle X-ray scattering experiments, were high for PDMS-b-PMMA (chi similar to 0.2 at 150 degrees C), suggesting this diblock copolymer system has promise for sub-10 nm lithographic applications when compared to the corresponding PDMS-b-PS diblock copolymers (chi similar to 0.1 at 150 degrees C). Performance evaluation in thin film self-assembly experiments allowed domain periods as small as 12.1 nm to be obtained, which is among the smallest highly ordered nanoscale patterns reported hitherto for thermally annealed materials.