Effects of water-soluble polymers dissolved in an aqueous secondary fluid on the rheological properties of “capillary” suspensions

Ternary colloidal or “capillary” suspensions comprising bulk and secondary fluids (S) and particles have attracted considerable attention in recent years. The addition of a suitable S can readily initiate the transition of a fluid-like pre-mixture into a gel-like capillary suspension. However, the precise control of rheological properties of such suspensions in the gel state is still challenging. In this study, we investigated the effects of the addition of various water-soluble polymers in an aqueous S on the rheological properties of the capillary suspensions. Results suggest that all the investigated systems maintained the gel state. Cellulose-type polymers with high molecular weights increased the sample strength, which was attributed to the gelation and reduced rupture of interparticle capillary bridges. In contrast, the non-cellulose-type polymers decreased the sample strength, which may be attributed to the interparticle repulsion and/or decrease in the capillary force. We believe this study will aid the design of various industrial complex fluids that often contain multiple immiscible fluids and polymeric additives.