Preparation of redispersible polymer latexes using cationic stabilizers based on 2-dimethylaminoethyl methacrylate hydrochloride and 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride

Abstract

Redispersible polystyrene (PS) latexes were prepared through surfactant-free emulsion polymerization (SFEP), employing only 0.54 mol% (with respect to styrene) of the monomer 2-dimethylaminoethyl methacrylate hydrochloride (DMAEMAH+Cl−) and 0.25 mol% of the initiator 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride (VA-044) as positively charged stabilizing moieties. The polymer particles can be dried into powder by air-drying and be readily redispersed by adding water with ∼90 s of sonication to yield latexes with similar particle size and zeta potential as the original latexes. The resulting polymer particles, ranging in diameter from ∼180 to 400 nm, are spherical with narrow size polydispersity (PDI ≤ 0.05) as confirmed by TEM, SEM and DLS. This is the simplest method reported to date to prepare PS latexes which can be dried and then be redispersed, using only low amounts of stabilizer and requiring low energy input for redispersion. This facile redispersion process could enable energy reduction and cost savings in the transportation of polymeric dispersions.