Aqueous solutions of poly(vinyl methyl ether) are experimentally studied at temperatures
below the equilibrium freezing temperature of water. Earlier investigations of the peculiar phase behavior
of PVME/water gave evidence of the existence of a molecular solvent/polymer complex in which (at most)
two water molecules per repeating unit are hydrogen bonded to the polymer chain. In favor of the complex
formation hypothesis is the abrupt arresting of the crystallization and melting of water in mixture with
w
PVME > 0.61. To relate this peculiar crystallization behavior and complex formation to the thermal and
kinetic stability of the complex, the crystallization of water is explored in detail using thermal, volumetric,
spectroscopic, X-ray scattering techniques, and morphological investigations. Our results clearly indicate
the significant influence of the experimental conditions on the crystallization and subsequent melting of
water. In agreement with previous results and for certain experimental conditions used in this study,
the existence of a molecular complex is confirmed. However, additional experiments demonstrate that
the complex is thermodynamically unstable and is only observed under certain kinetic conditions. For
polymer concentrations w
PVME < 0.61 (almost) full crystallization of water can be realized by isothermal
annealing in the temperature region −20 to −30 °C or slow cooling to low temperature. Furthermore,
also in the concentration range w
PVME > 0.61 the crystallization of water can be realized provided the
nucleation of water is facilitated. It is anticipated that the crystallization under previously employed
crystallization conditions does not occur because the activation energy for nucleation is too large under
the experimental conditions, and it is the nucleation that is arrested.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.