Thermodynamics of Swelling of Polyacrylamide and Poly(methacrylic acid) Lyophilized Xerogels in Water

Autor: Alexander P. Safronov, A. V. Klyukina, P. A. Shabadrov, T. V. Terziyan, L. V. Adamova
Rok vydání: 2018
Předmět:
Zdroj: Polymer Science, Series A. 60:190-197
ISSN: 1555-6107
0965-545X
DOI: 10.1134/s0965545x18020013
Popis: The structure and thermodynamic functions of water mixing with polyacrylamide and poly(methacrylic acid) xerogels prepared via drying of chemically crosslinked hydrogels equilibrium swollen in water are studied by methods of scanning electron microscopy, low-temperature nitrogen adsorption, differential scanning calorimetry, isothermal interval sorption of water vapor, and microcalorimetry. The liquid-phase drying in air at 70°C and solid-phase lyophilic drying under vacuum are used. Samples dried by different methods have dissimilar structures, which significantly affects the thermodynamics of the interaction of xerogels with water. The Flory–Huggins parameter of interaction of polyacrylamide and poly(methacrylic acid) with water and also its enthalpy and entropy components are independent of the procedure of xerogel preparation. The influence of the latter component manifests itself only in the thermodynamics of the relaxation of the nonequilibrium glassy structure of polymer.
Databáze: OpenAIRE