The aqueous processing of hydrophobic conjugated polymers to produce nanoparticles is an emerging technology with wide application in photonic, optoelectronic, biological and medical areas. The insertion of 4VP-based tailored segment in the polymeric backbone prevents the surfactant addition during the aqueous nanoparticle fabrication. Four amphiphilic low band gap rod-coil block copolymers, constituted by a semiconducting rigid block and differing in the coil molecular structure and length, were processed in aqueous medium using the miniemulsion approach without surfactant use. Stable water-processable nanoparticles (WPNPs) suspended in aqueous medium were obtained, and WPNP-based films were deposited. The STEM-EDX analysis revealed the WPNP internal composition. The S-concentration, connected with the rod block location, is higher in the WPNP core, and the C-concentration higher on the WPNP edge when pure 4VP-based coils are present, confirming their surfactant-like role.