Water-soluble grafted sodium polyacrylate with low concentration: Synthesis and thermal properties.

• The thermal-thickening polymer is synthesis by "graft onto" method. • The thickening properties can be designed on demand. • The mechanism of thickening properties is illustrated. The "graft onto" method is used to obtain the "stimuli-responsive water-soluble polymer" with low concentration, where 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and n-hydroxysulfosuccinimide sodium salt as catalyst and sodium polyacrylate as backbone chain. The molecular structure of the polymer is characterized by Nuclear Magnetic Resonance (1H NMR). The influence of temperature on polymer rheological properties and aggregation is studied by rheometer and fluorescence probe respectively. The results show that when the polymer concentration is higher than 1500 mg/L, the thickening properties can be controlled by diacetoneacrylamide, thermal-responsive monomer, NaCl and polymer concentration, where the apparent viscosity max / viscosity min (η max /η min) changes from 18.3 to 39.4, from 2.6 to 45.5, from 9.3 to 36, from 7.8 to 36.9 respectively and the lower critical solution temperature (LCST) changes from 60 °C to 40 °C. The reason for the polymer with controllable thickening properties is that the thermal-responsive monomers change from hydrophilicity to hydrophobicity, thus forming aggregations. At this time, the polymer chains form network structures. Because of controllable thickening properties at low concentration, it has potential application prospects. [ABSTRACT FROM AUTHOR]