Synthesis and evaluation of novel water-soluble copolymers based on acrylamide and modular β-cyclodextrin

Mono-6-(allyl amino)-β-cyclodextrin (N-β-CD) and mono-2-O-(allyl oxygen radicals-2-hydroxyl propyl)-β-cyclodextrin (O-β-CD) were copolymerized with acrylamide (AM), acrylic acid (AA), and 1-llyl-3-oil acyloxyimidazole-1-ammonion bramide (AOAB) initiated by redox initiation system in an aqueous medium. The AM/AA/AOAB/N-β-CD and AM/AA/AOAB/O-β-CD were prepared by adjusting the reactive conditions, such as initiator concentration, pH, temperature, and monomer ratios. The obtained copolymers were characterized by means of infrared (IR) spectroscopy, 1H NMR spectroscopy, scanning electron microscope (SEM), rotational rheometer, intrinsic viscosity, salt resistance, core flood test, etc. The temperature-tolerance, shear-tolerance, salt-resistance and thickening function of these copolymers are improved remarkably compared with partially hydrolyzed polyacrylamide (HPAM). About 18.3% and 12.5% oil recovery could be enhanced by 2000 mg/L AM/AA/AOAB/N-β-CD and AM/AA/AOAB/O-β-CD comparing with water-flooding. In addition, the result of X-ray diffractometry (XRD) test showed that the solutions of obtained copolymers could remarkably reduce the crystalline interspace of sodium montmorillonite (from 18.9 Å to 15.3 Å).