The mean diameter of poly[2-(dimethylamino)ethyl methacrylate]-block-poly[2 -(diisopropylamino)ethyl methacrylatel (PDMA-PDPA) diblock copolymer micelles can be easily adjusted from 27-155 nm (as measured by DLS) by either selective quaternisation of the PDMA block or by adding PDPA homopolymer prior to micellisation; these self-assembled nanostructures can be shell crosslinked with 1,2-bis-(2-iodoethoxy) ethane and subsequently used as templates for the preparation of silica-coated nanoparticles and, ultimately, hollow silica nanoparticles.