Trimethylsilylated silicate nanoparticle (termed MQ resin, combining M Me3SiO1/2 and Q SiO4/2 units)/poly(styrene-block-polydimethylsiloxane) (PS-PDMS, 31K-15K, polydispersity PD = 1.15, weight-average molecular weight M-w = 45.5K) blends behave similarly to block copolymers with different PS/PDMS ratios. MQ is localized in the PDMS phase virtually extending the volume fraction in the block copolymer. This allows for microdomain morphology control beyond what can be achieved with the starting block copolymer. Synthesizing siloxane-containing block copolymers targeted at certain equilibrium morphologies can be time-consuming and in some cases technically challenging. This work shows that MQ is a robust morphology modifier, not limited by the occurrence of surface segregation and the high diffusion rates typically associated with homopolymer modification, as confirmed by looking at the PDMS/PS PDMS reference. The convenient and robust structure control MQ nanoparticle modification of PS-PDMS provides could overcome one of the hurdles to adoption of block copolymer lithography.