Rheological and mechanical properties of hydrophilic dispersions using a new hydrophobically modified polymer and Igepal® CO520

Abstract Hydroxypropyl cellulose-methyl methacrylate and non-ionic surfactant Igepal ® CO520 (20–25% (w/w)) have been characterized in aqueous-based dispersions for topical application systems. The systems have similar viscosity curves independent of the surfactant's concentration, showing shear-thinning fluids. Also, the elastic and viscous moduli are constant and independent of critical stress values applied; however, the storage modulus was always higher than the loss modulus. Both parameters showed a slightly dependence on the applied frequency, indicating a gel-like behavior. The complex dynamic viscosity increases until 23% (w/w) of surfactant, keeps then constant. The hardness, compressibility and adhesiveness parameters increase when increase the Igepal ® CO520 concentration. The adhesiveness properties are 18–47% higher than the compressibility ones, with low values for hardness (∼0.4 N). While fracture and Hencky's strain values increase when increase the surfactant concentration, fracture work decreased, and no relation is found to deformability modulus. Also, the dispersed system with 20% (w/w) of Igepal ® CO520 has less stiffness than with 25% (w/w).