Colloidal properties of montmorillonite suspensions modified with polyetheramine

In this work, a systematical evaluation of a polyetheramine (Jeffamine M1000) and polyethylene oxide (PEO), which have a similar number of ethylene oxide units and molecular weight, on modulating colloidal stability of montmorillonite suspensions after the high temperature treatment (120 °C, 16 h) or in the presence of salt was performed at 25 °C. A varied of methods including measurement of adsorption, X-ray diffraction (XRD), zeta potential, transmission electron microscopy (TEM), settlement experiments and rheology measurements were used to illustrate the difference. Results indicate that M1000 molecules adsorb onto the particles mainly through an ion exchange mechanism and adopt a densely packed mushroom configuration on the clay surface. Because of the adsorption properties of M1000, the salt tolerance is improved slightly (from 10 mmol/L to 50 mmol/L NaCl) and the colloidal stability of the high temperature treated suspensions is maintained. Meanwhile, PEO molecules adsorb onto clay via hydrogen bonding and take a compact conformation on the clay surface, which could not improve the salt tolerance effectively and leads to a weak bridge flocculation at high temperature. Thus, this finding not only provides some new guidance on modulating the colloidal stability of dispersions but also would be very useful in specific applications, such as drilling fluids and water treatment.