Wetting agents for water-based coatings are classified into anionic and non-ionic.
Wetting agents and dispersants can be used in combination to achieve ideal results. The amount of humectant is generally several thousandths. Its negative effect is foaming and reducing the water resistance of the coating film.
One of the development trends of humectants is to gradually replace polyoxyethylene alkyl (phenyl) phenol ether (APEO or APE) humectants, because it leads to reduced male hormones in rats and interferes with endocrine. In emulsion polymerization, polyoxyethylene alkyl (phenyl) phenol ethers are widely used as emulsifiers.
Gemini surfactants are also new developments. It is two amphiphilic molecules connected by a spacer. The most significant feature of twin cell surfactants is that their critical micelle concentration (CMC) is an order of magnitude lower than their "monocell" surfactants, followed by high efficiency. Such as TEGO Twin 4000, it is a disiloxane surfactant, and has unstable foaming and defoaming properties.
Air Products has developed Gemini surfactants. Traditional surfactants have a tail of a hydrophobic group and a head of a hydrophilic group, but this new surfactant has two hydrophilic groups and two or three hydrophobic groups. It is a multifunctional surfactant , Called acetylene glycols.