Here we report recent developments in the stabilisation and delivery of hydrophobic crystalline dyes nanoparticles, into novel aqueous inkjet colorants. For the manufacture of stable nanoparticles two aspects are considered and controlled; generation of small particle size colorant by careful control of precipitation conditions in the 20 – 100 nm size range, and subsequent stabilisation of precipitated colorant by surfactant and/or copolymer. Colorant precipitation involves the initial creation of crystal nuclei, and their subsequent growth. Formation of stable nanoparticles with the smallest particle size requires a high nucleation rate but a low growth rate so as to avoid Ostwald ripening. Both process rates are dependent upon temperature and degree of supersaturation. Here we report the synthesis of copolymer stabilised anthraquinone nanoparticles using evaporative precipitation from dichloromethane into water. Copolymer stabilised dye nanoparticles in the 100nm size range are demonstrated and the role of copolymer on nanoparticle stabilisation and morphology discussed.
Jonathan Henry Wilson, Stephen G. Yeates, R. Bradbury, Tom Annable, "Bottom up assembly of copolymer stabilised aqueous anthraquinone nanoparticles" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP24), 2008, pp 359 - 362, https://doi.org/10.2352/ISSN.2169-4451.2008.24.1.art00093_1