Novel Hydrophobic Associating Polymer with Good Salt Tolerance

Jincheng Mao; Hongzhong Tan; Bo Yang; Wenlong Zhang; Xiaojiang Yang; Yang Zhang; Heng Zhang

doi:10.3390/polym10080849

Novel Hydrophobic Associating Polymer with Good Salt Tolerance

Polymers (Basel). 2018 Aug 1;10(8):849. doi: 10.3390/polym10080849.

Authors

Jincheng Mao¹, Hongzhong Tan², Bo Yang³, Wenlong Zhang⁴, Xiaojiang Yang⁵, Yang Zhang⁶, Heng Zhang⁷

Affiliations

¹ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China. jcmao@swpu.edu.cn.
² State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China. 201621000738@stu.swpu.edu.cn.
³ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China. 201611000098@stu.swpu.edu.cn.
⁴ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China. 201711000107@stu.swpu.edu.cn.
⁵ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China. 201511000098@stu.swpu.edu.cn.
⁶ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China. 201521000098@stu.swpu.edu.cn.
⁷ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China. 201621000198@stu.swpu.edu.cn.

Abstract

A hydrophobic associating polymer named DiPHAM (acrylamide/sodium acrylamide-2-methylpropanesulfonic/sodium acrylate/N,N-di-n-dodecylacrylamide) with good salt tolerance was synthesized via photo-initiation polymerization. The critical association concentration (CAC) of DiPHAM was determined by viscosity changes to be 490 mg/L with different DiPHAM concentrations and particle sizes varied under such dynamic conditions. The influences of aqueous metal ions with different charges on its aqueous solution were investigated by measuring apparent viscosity, viscoelasticity, thixotropy, rheology, and particle size, and by SEM observation. The apparent viscosity of the DiPHAM solution was affected by metal ions to some extent, but the viscosity of the polymer can be still maintained at 55 mPa·s under 20 × 10⁴ mg/L NaCl. Divalent metal ions show greater impact on DiPHAM aqueous solutions, but the polymer solutions showed resistance to the changes caused in viscosity, structure, and viscoelasticity by Ca²⁺ and Mg²⁺ ions. The salt tolerance of DiPHAM is due to the combination of hydrophobic association, the electrostatic shield, and double layer compression of the hydration shell. Increasing the ion concentration enhances the dehydration and further compresses the hydration shell, making the non-structural viscosity decrease, even "salting out". Measurements of rheological properties showed that DiPHAM solutions could maintain a relatively high viscosity (0.6%-71 mPa·s/0.3%-50 mPa·s) after 120 min of continuous shearing (170 s^-1) at 140 °C. Under high-salinity (5000 mg/L Ca²⁺/3000 mg/L Mg²⁺) conditions, the solution with 0.6 wt% DiPHAM still maintained a high viscosity (50 mPa·s/70 mPa·s) after continuously shearing for 120 min at 120 °C and 170 s^-1. The good salt tolerance of DiPHAM can lead to a variety of applications, including in fracturing fluids for enhanced oil recovery (EOR) and in sewage treatment.

Keywords: hydrophobic associating polymer; mechanism; salt tolerance.