New uperwetting Surfactants

摘要

Surface active agents, or surfactants, are materials that can adsorb onto surfaces or at interfaces and lower the surface or interfacial-free energies of aqueous-formulated systems. Traditionally, surfactants have a characteristic molecular structure that includes a water-loving (hydrophilic) head and an oil-loving (lipophilic) tail. Because of their amphiphilic nature, surfactants will migrate to and accumulate at interfaces and reduce surface and interfacial tensions, even when used at very low concentrations. Conventional surfactants have a polar or ionic hydrophilic head group connected to a hydrophobic, hydrocarbon tail group. In contrast, a particular type of specialty surfactant structure, termed Gemini, has two hydrophobic tails connected to two hydrophilic head groups on the same molecule. As.shown in Figure 1, each half of the "twin" surfactant is joined together by a spacer group, forming the Gemini structure. Because of their unique molecular architectures, these Gemini surfactants are much more surface active than their "monomeric" components. Gemini surfactants are often used in waterborne coating, ink, and adhesive formulations for both dynamic surface tension reduction and foam control.