Study on the enhanced viscosity mechanism of the cyclodextrin polymer and betaine-type amphiphilic polymer inclusion complex

Abstract The betaine-type amphiphilic polymer exhibits excellent salt-thickening properties due to the presence of betaine groups, but it also has some defects, such as poor water solubility at high betaine groups content, the viscosity-thickening ability is poor under the low betaine groups content. In order to solve the problem of poor viscosity-increasing ability of betaine-type amphiphilic polymers at low betaine group content, a cyclodextrin polymer was synthesized through free radical copolymerization. Characterization of the synthesized product was conducted by means of FT-IR and 1H_NMR. The two polymers were subjected to host-guest inclusion. Changes of viscosity, viscoelasticity, shear resistance and micro-morphology of the host-guest inclusion complex were measured by viscometer, rheometer, scanning electron microscope, and atomic force microscopy. The results showed that the optimal inclusion ratio for the complex was cyclodextrin polymer to betaine-type amphiphilic polymer ratio of 1:1. When the concentration of the host-guest inclusion complex reached 3000 mg/L, its viscosity increased twice compared to the betaine-type amphiphilic polymer with the same concentration. The host-guest inclusion complex was also more shear-resistant, which poses great potential application in chemical enhanced oil recovery.