Sulfur-free and Surfactant-free RAFT-Mediated Hybrid Emulsion Polymerization: A Model System for Understanding the Controlled Synthesis of Hybrid Latex-Encapsulating Pigment

Reversible addition–fragmentation chain-transfer (RAFT)-mediated hybrid emulsion polymerization is an in situ growth method of increasing interest for preparation of colloidal polymers/inorganic hybrid latex with precise structures and properties. However, the challenges of the conventional organic sulfur-based RAFT agents causing color and undesired odor problems still attract attention. In response to this problem, herein, a cationic amphipathic statistic sulfur-free (SF) macro-RAFT agent with a vinyl end group is proposed to disperse organic pigment particles (C.I. Pigment Red 170), where the vinyl group is the living point to regulate the sulfur-free and surfactant-free RAFT hybrid emulsion polymerization of methyl methacrylate (MMA) or MMA with butyl acrylate (BA). Benefitting from this SF macro-RAFT agent acting as both coupling agent and stabilizer, the “living” chain growth of the polymers onto the C.I. Pigment Red 170 surface causes the formation of encapsulating pigment hybrid particles as proven by size-exclusion chromatography and transmission electron microscopy analyses. As a proof-of-concept experiment, the film-forming P(MMA-co-BA)/pigment hybrid latex particles are applied to textile colorants to pad dyeing cotton fabric. Owing to the unique structure of hybrid particles with high pigment content (81.3%), the dyed cotton fibers exhibit high color strength, dry- and wet-rubbing fastness, good air permeability, and softness in comparison with the traditional mixture system. This study will not only broaden the area of RAFT-mediated hybrid emulsion polymerization for preparing hybrid particles but also provide a facile application for clear production.