Synthesis of Supramolecules as Adjustable Viscosity Modifiers and Study of Their Interfacial Behavior and Applications
Abstract
Recently, the interest in stimuli-responsive and adaptable materials has continuously grown in various fields and applications. For such responsive systems, different triggers, including pH, light, pressure, temperature, and electric field, have been utilized to control dynamics and assembly. Among these, pH is one of the most convenient, energy-efficient, and economic modalities. Besides, viscosity modifying agents are one of the most critical components of hydraulic fracturing fluids. To improve the productivity index of hydraulic fracturing processes, better viscosifiers with a higher proppant carrying capacity and a lower potential of formation damage are needed. However, plenty of traditional materials have poor thermal and salt stability, limiting their applications.
Herein, we report several findings of supramolecular systems including a new design of a pH-responsive viscoelastic supramolecular complex (VSC) by complexing a new long-chain amino-amide and maleic acid. The system demonstrated a sol-gel-sol transition from pH 2 to 10, with the largest static viscosity occurring at pH 6 (~1000 Pa·s) and the smallest viscosity at pH 4 (~3.3 Pa·s), indicating ~300-fold control over the viscosity; a novel pH- and temperature-responsive binary supramolecular assembly involving a long-chain hydroxyamino amide (HAA) and an inorganic hydrotrope, boric acid, with highly-tunable viscous and viscoelastic properties. The system under investigation demonstrates a high degree of control over its viscosity, with the capacity to achieve over four orders of magnitude of control through the concomitant manipulation of pH and temperature; a novel viscoelastic system relying on the complexation of zwitterionic octadecylamidopropyl betaine (OAPB) and diethylenetriamine (DTA) in water. At a concentration of 2 wt%, the zwitterionic complex fluid had a static viscosity of 9 to 200 poise, which could be reversibly adjusted by changing the suspension pH; and investigate the influence of alkyl chain length on the self-assembly of long-chain amidopropyl betaines (CnDAB) and the effect of complexation with various degree of amines on viscoelastic supramolecular structures.
Aside from applications in hydraulic fracturing and enhanced oil recovery, we anticipate that the intriguing rheological properties of this viscoelastic system can be beneficial for other chemical engineering applications including personal care products, cosmetics, lubricants, and biomedical gels.
Description
Keywords
supramolecular assemblies, viscosity, viscoelastic, pH-stimuli, reversible, hydraulic fracturing