Abstract
The self-emulsifying acrylate-based emulsions with solid content 45 wt.% were prepared in 3.5 h by reverse iodine transfer polymerization (RITP), and the polymer molecular weight (Mn) could be 30,000 g·mol−1. The influences of methacrylic acid (MAA) amount, soft/hard monomer mass ratio, and iodine amount on polymerization and latex were investigated. A moderate amount of ionized MAA was needed to stabilize the emulsion. Glass transition temperature (Tg) was decreased with the increasing mass ratio of soft/hard monomer. A higher iodine amount resulted in lower Mn. The increased Mn after chain extension of the polymer with water-insoluble monomers in iterative one-pot method proved the living of polymer. Compared with conventional emulsion polymerization, molecular weight (Mn) could be controlled, and Mn of polymer synthesized in RITP emulsion polymerization is higher; emulsion of polyacrylate-containing hydroxyl monomer units prepared by RITP emulsifier-free radical polymerization is more stable. Good properties, such as hardness, water resistance, adhesion, and increased value of maximum tensile of films modified by reaction of polyacrylate with melamine–formaldehyde (MF) resin, indicated potential application in baking coating.
Highlights
Acrylate-based emulsions are widely used in industrial and consumer coating for the advantages of photo stability, resistance to hydrolysis, and excellent outdoor durability [1]
Effect of HEMA on Emulsion Prepared by Random Copolymerization of Acrylate
The hydroxyl group from the HEMA unit in polymer chain can react with MF resin to improve the mechanical property of the polymer
Summary
Acrylate-based emulsions are widely used in industrial and consumer coating for the advantages of photo stability, resistance to hydrolysis, and excellent outdoor durability [1]. The conventional radical emulsion polymerization [2,3] is often used to prepared this kind of emulsion, and nonpolymeric emulsifiers, such as sodium dodecyl sulfate (SDS), are usually added into the system [4]. Dispersed system in emulsion is thermodynamically unstable, and the system can be stable when hydrophilic groups from emulsifiers are incorporated into the polymer [5]. With the use of nonpolymeric emulsifier, acrylate-based latex with high solid content (over 40 wt.%) and low viscosity can be prepared. Water-insoluble monomer can take part in the polymerization with the emulsification of emulsifier that stabilizes the latex particle, and the synthesized polymers can be dispersed in water. Polymeric emulsifier, which can be chemically bonded to the polymer chain, is introduced into the emulsion system [12,13,14,15]
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