Effect of the surfactant blend composition on the properties of polymerizing acrylamide-based inverse-emulsions: characterization by small-angle neutron scattering and quasi-elastic light scattering

摘要

In this study of the inverse-emulsion homopolymerization of acrylamide, surfactant blends of traditional fatty acid esters, ethoxylated fatty acid esters and ABA-type block copolymeric stabilizers were employed. Stable and transparent inverse latices with shelf lives of over one year were generated. Particle sizes were determined using quasi-elastic light scattering and small-angle neutron scattering and were found to be close to the threshold traditionally associated with microemulsions (100 nm). The turbidity of the polymer latices and the changes in viscosity during the polymerization are also similar to that observed in inverse-microemulsions. The radii of gyration calculated from SANS data were observed to be consistent with the hydrodynamic radius determined by QELS for the final polymerized products. SANS measurements of the inverse-emulsions at different reaction coordinates revealed a decrease in droplet diameters with conversion, with particles best described using a polydisperse spherical core + shell model. The decrease in droplet diameter with conversion has been attributed to a surfactant rearrangement in the interfacial sheath due to the consumption of surface active acrylamide.