Influences of Polymer-Surfactant Interaction on the Drop Formation Process: An Experimental Study

The interaction between polymer and surfactant molecules affects the physical properties of liquids, which could be of great importance in an abundance of processes related to drop formation. Polymer and surfactant concentration is a factor that dramatically impacts the shape of molecular networks formed in the fluid bulk and the characteristics of a forming drop. In this study, the deformation and detachment of aqueous carboxymethyl cellulose (CMC) solutions' drops containing different concentrations of sodium dodecyl sulfate (SDS) are studied experimentally. Our purpose is to determine the effects of CMC and SDS concentrations on the parameters related to the formation process, including drop length, minimum neck thickness, and formation time. Our results clearly show that the increment of the SDS amount at a constant low CMC concentration increases the drop detachment length and results in a slower thinning process. However, at higher CMC concentrations, the drop limiting length reaches a maximum, indicating the effects of disintegration of molecular structures as the SDS amount exceeds the critical concentration. Moreover, the drop formation time is found to decrease with the increment of the SDS concentration, which could be attributed to the reduction of dynamic interfacial tension.