Novel thermothickening copolymers composed of acrylamide and a macromer bearing hydrocarbon end-capped oxyethylene units were synthesized. Influences of polymer concentration, salt content, shear rate, and temperature on the solution behavior were investigated. The polymer solution exhibited shear-thickening behavior at low-to-moderate shear rates (<50 s(-1)), and the shear-thickening behavior was dependent on polymer concentration, NaCl content, and temperature. With the increase of salinity, apparent viscosity of polymer solution increased dramatically (especially at low shear rates). At higher NaCl content (>20 wt %), polymer solutions became physical gel, and the apparent viscosity increased by several orders of magnitude. The polymer solutions exhibited excellent thermothickening behavior, even at the low concentration of 0.15 wt %. The results of rheological measurements showed that the storage and loss modulus were successfully fitted to a single Maxwell element at low temperature (<60 degrees C). (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1799-1808, 2010