Thermothickening Behavior of Self-Stabilized Colloids Formed from Associating Polymers

Abstract

The complexation of partially ethyl-quaternized poly(4-vinyl pyridine) (QVP) and poly(methacrylic acid) (PMAA) induces a dramatic change in solution viscoelasticity. In this work, we investigated a model system consisting of QVP (with 2% charge), PMAA, and dimethyl sulfoxide (DMSO)−water mixed solvent (85 wt % DMSO− 15 wt % water), which exhibits a remarkable thermothickening behavior, characterized by an increase of viscosity by 3 orders of magnitude when the temperature is increased by 20 °C. At low temperatures, this system behaves as a lowviscosity milky colloidal suspension that remains stable for periods of at least 1 year. At higher temperatures, the colloids swell, increasing their effective volume fraction and giving rise to the observed viscosity increase. The thermothickening/ thermothinning transition temperature could be tuned by varying the stoichiometry of the mixed polymers. We utilized rheometry, UV−vis spectroscopy, and dynamic light scattering to shed light on the mechanism of this phenomenon. This simple approach for achieving tunable thermothickening capability provides a new platform for designing thermoresponsive solutions from simple polymer mixtures.

Dynamics and Rheological Behavior of Chitosan-Grafted-Polyacrylamide in Aqueous Solution upon Heating

“…Thermo-responsive polymers have been extensively studied over the past few decades owing to their industrial and biomedical applications [1][2][3][4][5][6][7]. Among them, thermo-thickening has received much attention from academic and industrial fields because of its huge application potential in many fields [3,[7][8][9][10][11][12], especially in oil recovery [9,11]. It is always a great challenge in oil recovery to keep high viscosity of polymer displacement agent at a high temperature because the viscosity of most current oil displacement agents will decrease upon heating or in a high-temperature environment [9,11].…”