Investigation on the Interaction Between Hydrophobically Modified Polyacrylic Acid and Wormlike Micelles Under Shear

The interactions between hydrophobically modified polyacrylic acid (HMPAA) and wormlike micelles (worms) were investigated by a well-designed rheological measurement procedure. For worms formed by sodium oleate and benzyltrimethylammonium bromide, remarkable rheology enhancement was observed once a small amount of HMPAA was introduced. Moduli enhancement and varied shear thickening or hysteresis behaviors were observed with changing HMPAA content of the mixture. Only at low HMPA content and low shear rate was shear-thickening observed. With the support of DPD simulation, it was found that low-rate shear can induce a coil-to-bridge transition of HMPAA conformation at low concentration. The relationship between the network structure and rheological properties are discussed. The transition of aggregation modes and the enrichment of the network should be responsible for the enhancement of the rheology.