We investigate synthetic strategies of cationic slit-face-charged nanoparticles using cyclopropenium-based (CP) monomers and block copolyelectrolytes (BCPEs) via surfactant-free emulsion polymerization. The monomers and BCPEs themselves were found to stabilize oil-in-water emulsions. With these systems, the hydrodynamic diameters of the resultant particles can be reliably tuned from 30 to 100 nm, simply by varying the amount of CP monomer added. As CP is a remarkably stable carbocation, the nanoparticles retain their charge over a Wide pH range. Furthermore, we found that the nanoparticle interior can be covalently functionalized with fluorescent dyes. The ability to easily synthesize sub-100 nm surface-charged particles with narrow polydispersity in one-pot can lead to applications as additives, gene-delivery vectors, and chromatographic separation, among others. Here, we demonstrate the versatility of,CP-based monomers and BCPEs for the synthesis of surface- charged nanoparticles and the modulation of synthetic parameters to tune nanoparticle size and surface functionality.