To improve oil recovery (IOR) performance of polyacrylamide polymer media, the paper presented the nanocomposites (PA-B-S) of acrylamide–styrene–AMPS copolymers (PA-S) with monodisperse SiO₂ particles. The monodisperse particles from 17 to 100 nm with low size deviation were adopted as an inorganic phase, and their nanocomposite properties and morphology were investigated with viscosity measurements, thermal degradation (TGA), flooding test and transmission electron microscopy (TEM) techniques. For 66.7 nm SiO₂ particles at 0.5 wt% load, the nanocomposites produced viscosity enhancement at critical concentration, high salt-tolerance behavior, and the high degradation temperature at 411 °C, which were obviously higher than those of pure PA-S copolymers. These inorganic–organic synergistic or nano size effects were shown in a series of prepared nanocomposite samples. TEM morphology proved that PA-B-S solution at LCST formed uniform dispersion of the SiO₂ particles encapsulated with this associating copolymer and formed stable drop-like emulsion patterns.

In flooding experiments, the PA-B-S solutions at critical viscosity gave the resistance factor of 9.38 and residual resistance factor of 3.39, compared with those of 5.20, 1.51 for pure PA-S, respectively. Such improved properties of PA-B-S were suitable for producing high shearing behavior and sweep volume in IOR or EOR. As the controllable characters of monodisperse SiO₂ particles, the results from their nanocomposites were the good references to the multi-disperse particles acted as IOR media.