The Interfacial Tension between Acrylic Monomers and Polymers and Non-ionic Surfactants Investigated by the Automatic...

Time dependent interfacial tensions between CCl4, butyl acrylate (BA), and methyl methacrylate (MMA) and water have been measured, using nine different aryl and alkyl poly(oxyethylene) surfactants with between 10 and 40 OE-groups. The effect of adding BA/MMA and BA/MMA/acrylic acid (AA) polymers to the monomer systems has also been evaluated. In all systems the interfacial tension, after a very fast initial drop, decreases slowly due to dissolution of the surfactant inside the oil. The magnitude of this decrease is dependent on the hydrophilicity of the surfactant and the oil. The equilibrium values, when plotted against the HLB of the surfactants show a minimum that shifts toward higher HLB as the oil's polarity increases. BA and CCl4 show similar behavior, but with MMA as a more polar oil. Added polymer generally lowers the time dependent decrease because of decreased surfactant solubility in monomer/polymer mixtures. The BA/MMA copolymer also generally increases the interfacial tension both with and without surfactants, but the increase is less with surfactants around the surface tension minimum. A BA/MMA/AA terpolymer neutralizes or even reverses the increasing effect in the BA/polymer system because of this polymer's more hydrophilic nature. Copyright 1999 Academic Press.