Inkjet printable aqueous composite dye–polymer nanoparticles

Here we report the synthesis of polymer stabilised anthraquinone dye-based aqueous nanoparticles using evaporative precipitation from dichloromethane into water and their use as novel aqueous inkjet colorants. Polymer stabilised dye nanoparticles in the 100 nm size range are demonstrated and the mechanism of formation of stable nanoparticles and the role of polymer stabiliser design is discussed. Formation of stable small particle size nanoparticles requires a fast dye crystal nucleation rate followed by a subsequent slow growth rate so as to avoid Ostwald ripening. Rapid nucleation can be achieved by metering small amounts of water-miscible organic solution of the dye to the non-solvent water under rapid mixing, referred to as quasi-emulsion solvent diffusion (QESD). These conditions result in high-supersaturation which causes spontaneous nucleation, followed by a rapid decrease in local supersaturation and hence slow crystal growth rate.

► Synthesis of stable 100 nm aqueous dye–polymer composite particles.
► New process methodology.
► Role of polymer–dye interaction in controlling particle morphology.
► Preliminary data on suitability as water-fast inkjet inks.