Effect of Surfactant Type and Concentration on Surfactant Migration,Surface Tension,and Adhesion of Latex Films

The effect of surfactant type and concentration on the migration behavior of surfactant in a latex film was investigated. Two types of surfactant, including an anionic (sodium lauryl sulfate, SLS) and a non-ionic (nonylphenol ethoxylate, average number of ethylene oxide units = 40, NP-40) surfactant, were used in an emulsion polymerization of methyl methacrylate butyl acrylate copolymer (MMA–BA). The total amount of surfactant was varied in three levels, i.e., 1.5, 3, and 4.5 wt%, and the surfactants were used both pure and in a mixture state. The surfactant migration to the film–air (F–A) and film–substrate (F–S) interfaces of the latex films was determined by using an attenuated total reflection-Fourier transform infrared (ATR-FTIR) method. In addition, the adhesion of the latex films to glass substrates was measured by a pull-off test. The results showed that the migration of anionic surfactant to the interfaces was greater than the non-ionic one. It was also found that the use of non-ionic surfactant along with anionic surfactant could decrease the migration of the anionic surfactant to the interfaces.