Temperature resistance of AM/AMPS/NVP copolymer microspheres

Functional monomers, such as 2-acrylamide-2-methylpropionic sulfonic acid (AMPS), N -vinylpyrrolidone (NVP), and acrylamide (AM), were copolymerized into terpolymer microspheres by inverse suspension polymerization. The structure, morphology, swelling, and temperature resistance of the microspheres were comprehensively characterized through several means, including a 13 C nuclear magnetic resonance spectroscope, scanning electron microscope, optical microscope, and laser particle size analyzer (LPSA). The results showed that the AM, AMPS, and NVP monomers were initially polymerized to form smooth and uniformly dispersed terpolymer microspheres. The particle size distribution of the microspheres ranged from 60 to 90 μm at a stirring speed of 300 rpm. The microspheres fully absorbed water and swelled to 21.9 times at 120 °C compared with dry powder microspheres. The ternary copolymer microsphere/water dispersion system can only withstand a 120 °C temperature for 19 days. However, this temperature resistance of the microspheres can be effectively improved by adding the appropriate stabilizer solution. The microspheres can be stabilized for at least 42 days and 120 days in 0.1% thiourea--cobalt chloride composite stabilizer solution and 0.025% LY stabilizer solution, respectively, at 120 °C. It can be seen that the microspheres, water, and stabilizer systems have excellent long-term thermal stability. The AM/AMPS/NVP microspheres with temperature resistance will have broad application prospects in high-temperature reservoirs.