Several strategies are demonstrated for the use of additive-driven chemistries that take place in only one type of the nanosized domains of all-organic and organic-inorganic hybrid block copolymer thin films. Such an approach is used to examine the convergence of "top-down" and "bottom-up" fabrication via light-driven processes. Characterization is carried out with microscopies and grazing-incidence small-angle X-ray scattering (see Figure and cover).