Preparation, rheology, and film properties of polyacrylate latex using amphiphilic macroreversible addition‐fragmentation chain transfer agents as surfactants

Abstract

ABSTRACTReversible addition‐fragmentation chain transfer (RAFT) radical emulsion polymerization of n‐butyl acrylate (nBA) and methyl methacrylate (MMA) was successfully performed in the presence of the amphiphilic macro‐RAFT agents poly(acrylic acid‐b‐styrene) (PAA‐PSt) trithiocarbonate. First, the amphiphilic macro‐RAFT agents PAA‐PSt were prepared and their surface activities in aqueous solutions were studied. Subsequently, the effects of pH values of the latexes and degree of polymerization (DP) of the PAA hydrophilic segments in the amphiphilic macro‐RAFT agents on the latex particle size and molecular weight of the polyacrylate products, as well as the rheological properties of the latexes, surface morphology, and water resistance of the latex films were investigated in detail. It was found that the rheological behaviors of the as‐prepared latexes can be tuned by adjusting solid content, temperature, pH value, and DP of the hydrophilic segments, respectively, due to their effects on particle packing, hydrophobic association, hydration layer, and hydrodynamics volume. In addition, atomic force microscopy (AFM) was applied to investigate the surface morphology, and the results demonstrated that the surface phase separation and roughness of the latex films changed with the latex pH values and DP of the hydrophilic segments. Finally, the films with good water resistance were obtained by directly casting the as‐prepared polyacrylate latexes at room temperature. Our study indicated that employing amphiphilic macro‐RAFT agents to prepare polyacrylate latexes with well‐defined chemical compositions and structures is a facile and environmentally friendly strategy, which would have wide potential application in coatings, inks, adhesives and thickening agents, and so on. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47463.