Insights into critical rheological and interfacial properties of hydrophobically-modified cellulose sulphate derivatives using molecular modeling

Abstract

Hydrophobically modified cellulose-based polymers are becoming increasingly popular in product development in several industries, including oilfield chemicals. However, there are few studies on understanding the properties of surface-active cellulose sulphates at the molecular level. In this study, two novel hydrophobically modified cellulosic materials, DPEA-Cell-OSO3− I and DPEA-Cell-OSO3− II, were investigated using the MARTINI forcefield. The chain dynamics and fluid-particle interactions in a saline environment, in the presence of oil molecules, at ambient and increased temperatures, were evaluated. Concentration profiles revealed that the new materials adsorbed well at the oil interface, as supported by low interfacial tension measurements in the range of 10−1 to 10−3 mN/m. This can be related to the strong interactions with the oil molecules as dictated by hydrophobic attractive forces. The rheological analysis illustrated that DPEA-Cell-OSO3− II is a thermo-thickening polymer as the viscosity rose from 2.95 cP at 298 K to 7.38 cP at 333 K. Also, the chain dynamics pattern showed the relevancy to a rheopectic material. DPEA-Cell-OSO3− I, on the other hand, is shear thinning with temperature, and a thixotropic material. Overall, the systemic molecular modeling revealed their lucrative potential applications in oilfield operations, especially for improved oil recovery.