Participation of water in conformational change of isotactic poly(2-hydroxyethyl methacrylate) as studied by viscometry in various electrolytic solutions

Conformational properties of isotactic poly(2-hydroxyethyl methacrylate) (PHEMA) have been studied by viscometry in various electrolytic solutions. The intrinsic viscosity of isotactic PHEMA at 0.01M salt solution increases with decreasing the B coefficient in Jones—Dole's equation. In respective to water structures, a polymer chain is more expanded in the salt solution including water structure breaker ions. As the concentration of ions increases, the interactions between polymer segments and ions make a major contribution to conformational changes of isotactic PHEMA. Depending on the kind of ions, a salting-in or out effect is observed at higher concentrations than 0.1M salt solution. We observed that the denaturing effects of various anions in isotactic PHEMA salt solutions are as follows; SO₄^2- < F^? < I^? NO₃^? < SCN^-. This order is similar to the Hofmeister series. To investigate the influences of denaturing agents on solvent structures, we also compared the guanidine hydrochloride effect with the tetrabutylammonium chloride effect in isotactic PHEMA solution.