Synthesis and characterization of poly(AM-SSS-AMPS)/ O-MMT nanocomposite microspheres with tailored nanomechanical properties

In order to overcome the inherent defects of traditional polymer microspheres as plugging agent used in oilfields, including weak mechanical properties , low dispersity in water and poor adaptability to harsh conditions, an organo-modified montmorillonite (O-MMT) was incorporated to form an exfoliated structure in acrylamide/sodium 4-styrenesulfonate/2-acrylamido-2-methyl propane sulfonic acid (AM-SSS-AMPS) terpolymer matrix via in-situ polymerization. Such exfoliated structure not only exhibited a considerable enhancement in the comprehensive properties of nanocomposites , such as viscoelasticity , heat and shear-resistance, but also improved nanomechanical properties of microspheres. The results of nanomechanical properties showed that the energy dissipation and adhesion of nanocomposite with 3.0 wt% O-MMT were decreased to only 1.9% and 4.7% of those of the original terpolymer, respectively, implying the reduction in the agglomeration and energy consumption of microspheres in aqueous suspension. Rheology test demonstrated that the suspension (5.0 wt%) of nanocomposite microsphere with 2.0–3.0 wt% O-MMT behaved as pseudoplastic fluid, Newtonian fluid and dilatant fluid in turn at the shear rate from 10 s −1 to 1000 s −1 , which indicated a better arrangement of microspheres in suspension under shear stress. G′ and G′′ of the suspension of nanocomposite microspheres with 3.0 wt% O-MMT were 696.6 times and 84.4 times higher than those of the terpolymer suspension, respectively, and the corresponding viscosity was 10.4 times higher at 90 ℃. These superior properties of nanocomposite microspheres will meet the tough requirements of oilfield development.