Polymer/C.I. Pigment Red 170 hybrid latexes prepared by RAFT-mediated surfactant-free emulsion polymerization

Abstract

By using organic pigment-based ink-jet inks, the digital ink-jet printing of textiles is one kind of environmentally friendly technology for cleaner dyeing. Due to the shortcomings of easy agglomeration and poor water dispersion stability of organic nanoparticles, however, the encapsulation and dispersion of organic pigment nanoparticles are also hot and difficult research problems. In this work, we report the reversible addition-fragmentation chain transfer (RAFT) polymerization technology was used to synthesize random copolymer of 2-(dimethylamino) ethyl methacrylate (DMAEMA), poly(ethylene glycol) methyl ether methacrylate (PEGA), and methyl methacrylate (MMA) or butyl acrylate (BA) with a trithiocarbonate reactive end-group. These cationic macromolecular RAFT agents (macro-RAFT) with a pH of 5 were subsequently adsorbed at the surface of size-monodisperse colloidal Pigment Red 170 particles. The absorbed macro-RAFT agents were considered to be the living points to mediate the RAFT polymerization of monomers (MMA and BA) by starved feed emulsion polymerization. TEM results shown that the resulting hybrid latexes synthesized in presence of the tri-copolymer macro-RAFT agents resulted in the formation of individually encapsulated pigment particles. In addition, the dynamic light scattering (DLS), zeta potential and stability tests found that the macro-RAFT agent participated in the growing latex stabilization which is the key to obtaining the stable and uniform core-shell hybrid latex. More importantly, the preparation of film-forming copolymer/pigment hybrid latex in this study shown that the high potential of the P(DMAEMA- co -PEGA- co -MMA or BA) macro-RAFT agent for the development of polymer-pigment hybrid latexes which has good application properties. • Cationic and brush-type macro-RAFT agents were synthesized through RAFT polymerization. • Amphiphilic macro-RAFT agent has good adsorption and dispersion properties for the C.I. Pigment Red 170. • The film-forming polymers with lower T g are successfully encapsulated on the surface of pigment. • The encapsulated polymer/pigment hybrid latexes exhibit excellent dispersion stability with freeze-thaw, storage and pH.