Related Experiment Video
Updated: May 8, 2026

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Specific anion effect in water-nonaqueous solvent mixtures: interplay of the interactions between anion, solvent, and
Lvdan Liu1, Tao Wang, Chang Liu
1Department of Chemical Physics, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China , Hefei, 230026, P. R. China.
Abstract:
Ethanol (EtOH) and dimethylsulfoxide (DMSO) are polar protic and aprotic organic solvents, respectively. In the present work, we have investigated the anion-specific lower critical solution temperature (LCST) and upper critical solution temperature (UCST) behaviors of poly(N-isopropylacrylamide) (PNIPAM) in the H2O-EtOH and H2O-DMSO mixtures. The turbidity and differential scanning calorimetry studies show that the LCST for the anions follows the Hofmeister series at the molar fraction of EtOH (xE) or DMSO (xD) of 6%. At xE of 26%, the UCST for the anions also follows the Hofmeister series because the dominating interactions for the UCST behavior are similar to that for the LCST behavior in the H2O-EtOH mixtures. In the H2O-DMSO mixture at xD of 70%, an inverted V-shaped anion series is observed for the UCST behavior of PNIPAM. Our studies demonstrate that the specific anion effect on the phase transition behaviors of PNIPAM is influenced not only by the anionic polarization of hydrogen bonding between solvent molecules and PNIPAM but also by the anion adsorption on the PNIPAM chain surface.
More Related Videos
Related Concept Videos
Intermolecular Forces
Solvating Effects
Intermolecular Forces in Solutions
When the strengths of the intermolecular forces of attraction between solute and solvent species in a solution are no different than those present in the separated components, the solution is formed with no accompanying energy change. Such a solution is called an ideal solution. A mixture of ideal gases (or gases such as helium and argon,...
Aqueous Solutions and Heats of Hydration
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
Common Ion Effect
Ion Exchange

